Parents seeking information and advice on the treatment of Perthes’ disease of the hip unknowingly confront
longstanding medical controversies that surround the management of this condition. After the initial
diagnosis of the condition it is not unusual that parents will receive as many different recommendations as
the number of opinions obtained. So the parents, who are already upset with the unexpected news that
their child has a disease, are placed into the unusual position that they must pick among widely different
medical opinions and procedures. This adds confusion to an already troubled situation for parent and child.
With the intent to help parents, I am writing this information so they can better understand the issues and
hopefully make more informed decisions for their child’s treatment.
What is Perthes?
Legg-Calve-Perthes disease is an uncommon condition (1/5000) that affects one, or sometimes both, hips
of a child between the ages of 3-15. Despite the coincidence, the condition isn’t named Legg nor Calve
because these areas are affected. Rather these names apply because doctors Arthur Legg, Jacques Calve,
and Georg Perthes independently identified the disease in the early part of the 20th century shortly after x-
ray diagnosis tools became available. The disease is commonly known as Perthes or simply the abbreviation
LCPD.
In adults, there is a condition similar to Perthes called avascular necrosis (AVN) or osteonecrosis of the hip.
With both of these conditions, and for unknown reasons, the femoral head loses part (or all) of its blood
supply and part (or all) of the bone of the femoral head dies. (Dead bone in the body is called “necrotic”
bone.) The actual loss of blood circulation is an acute event and is the root cause of Perthes. The “loss of
blood supply” event happens without the awareness of the patient and is usually not associated with
obvious symptoms. In fact, the first symptoms of Perthes may not develop for several months after the
initial “loss of blood supply” episode. Once the femoral head dies it takes roughly 1-2 years for the body to
absorb the dead bone and then 1-3 additional years as the body attempts to re-grow and re-form the
femoral head. This lengthy timeline and the body’s responses during the timeline is part of what is called
the “natural history” of Perthes.
longstanding medical controversies that surround the management of this condition. After the initial
diagnosis of the condition it is not unusual that parents will receive as many different recommendations as
the number of opinions obtained. So the parents, who are already upset with the unexpected news that
their child has a disease, are placed into the unusual position that they must pick among widely different
medical opinions and procedures. This adds confusion to an already troubled situation for parent and child.
With the intent to help parents, I am writing this information so they can better understand the issues and
hopefully make more informed decisions for their child’s treatment.
What is Perthes?
Legg-Calve-Perthes disease is an uncommon condition (1/5000) that affects one, or sometimes both, hips
of a child between the ages of 3-15. Despite the coincidence, the condition isn’t named Legg nor Calve
because these areas are affected. Rather these names apply because doctors Arthur Legg, Jacques Calve,
and Georg Perthes independently identified the disease in the early part of the 20th century shortly after x-
ray diagnosis tools became available. The disease is commonly known as Perthes or simply the abbreviation
LCPD.
In adults, there is a condition similar to Perthes called avascular necrosis (AVN) or osteonecrosis of the hip.
With both of these conditions, and for unknown reasons, the femoral head loses part (or all) of its blood
supply and part (or all) of the bone of the femoral head dies. (Dead bone in the body is called “necrotic”
bone.) The actual loss of blood circulation is an acute event and is the root cause of Perthes. The “loss of
blood supply” event happens without the awareness of the patient and is usually not associated with
obvious symptoms. In fact, the first symptoms of Perthes may not develop for several months after the
initial “loss of blood supply” episode. Once the femoral head dies it takes roughly 1-2 years for the body to
absorb the dead bone and then 1-3 additional years as the body attempts to re-grow and re-form the
femoral head. This lengthy timeline and the body’s responses during the timeline is part of what is called
the “natural history” of Perthes.
| Perthes’ for Parents by Dror Paley, MD, FRCSC |
During the 8 to aproximately18 months after the initial “loss of blood supply” episode, the disease progresses due to the body’
s normal repair mechanisms to remove and replace the dead bone of the femoral head. During this repair process the femoral
head may be sufficiently weakened such that it collapses leading to deformation of the joint surface. This deformation creates a
non-spherical femoral head inside of a spherical socket and ultimately leads to joint stiffness, arthritis and pain.
How does a normal repair process designed to rid the body of dead bone go so awry. To understand this it is important to
know something about the normal repair process. The femoral head is made up of a core of bone surrounded by cartilage.
The cartilage of the femoral head gets its oxygen and nutrition from the fluid in the hip joint. The bone in the femoral head
gets its oxygen and nutrition from blood vessels that enter the femoral neck from outside the bone. The femoral neck is
separated from the rest of the femur bone by the growth plate (growing zone) of the upper femur. When there is blockage or
damage to these blood vessels the bone in the femoral head dies due to loss of oxygen and nutrition. The cartilage on the
outside of the femoral head which surrounds the underlying dead bone does not die since it gets its oxygen and nutrition by
diffusion from the fluid inside the hip joint. The dead bone is removed by special bone eating cells (osteoclasts). New living
bone is produced by special bone making cells (osteoblasts). As the dead bone is removed from the femoral head, the support
of the cartilage of the joint is weakened. If the surrounding cartilage structure is thick and strong enough, there will be enough
time for new bone to be deposited to replace the removed bone and there will be no change in shape of the femoral head. If
too much support is removed and the surrounding cartilage cannot withstand the load, then the weight bearing surface of the
femoral head will slowly collapse under the body’s weight and the normally spherical femoral head becomes flattened to a more
egg shaped configuration.
To help explain the collapsing process, I like to use the analogy that compares the femoral head (that has been damaged by a
previous loss of blood supply episode), to the renovation of a building. Imagine an old building that, although still intact, has
severely weakened internal support structures that must be replaced with new internal supports in order to prevent the roof
from collapsing. If the “demolition team” removes some old support beams and the rest of the building structure can
withstand this weakening, then the roof will not cave in and there will allow enough time for the “construction team” to replace
the old support beams with new beams. If, however, too many of the old support beams are removed before the construction
team can replace the supports then the roof will cave in. A caved in roof is hard to rebuild and unfortunately can lead to a
deformed new roof- especially if the crashed roof has lots of weight on it like a snow covered roof.
Bringing this analogy back to the femoral head, the roof of the building is the hard, dense outer surface of the femoral head
that is called “subcondral bone” that supports the overlying cartilage of the femoral head. The supporting beams within the
building are a low-density, honeycomb like bone called “trabecular bone” that forms the core of the femoral head. The old
supports are dead trabecular bone that died from lack of blood supply and are eaten away by osteoclast cells. The new
supports are the reforming trabecular bone installed by the osteoblast cells. The tons of wet snow on the rooftop, represents
the body’s weight and muscle forces that continuously apply load through the hip joint tending to crush and permanently
deform the weakened, fragile femoral head that while it is trying to renovate its structure.
The best results in Perthes occur when the roof of the femoral head does not collapse or when it only minimally deforms, and
when there is plenty of time to repair the damage such as in a younger child. The worst results in Perthes occur when the roof
caves in badly and the older child doesn’t have adequate growing time to repair the damage.
Unfortunately, if the roof deforms, the resulting egg shaped, femoral head is no longer shaped as sphere and therefore cannot
move in all directions like a ball in a socket. This reduces the normal range of motion (ROM). Furthermore if the shape of the
ball (femoral head) is mismatched with that of the socket (acetabulum) there will be abnormal wear and tear in the joint
leading first to stiffness, then to pain and eventually to loss of the joint cartilage (arthritis). This early osteoarthritis often
leads to total hip replacement (THR) as an adult as early as the 30’s, but more likely the 40’s, 50’s or beyond depending on the
degree of deformation and joint shape mismatch left behind by the Perthes disease process.
Why does Perthes’ occur?
Unlike other joints in the body, the femoral head within the hip joint has a very unique, but precarious blood supply where
almost all the blood going to the femoral head is delivered by one main blood vessel system that must enter the femoral head
by traveling across the femoral neck into the hip joint and finally into the head at its junction with the femoral neck. Since the
hip joint is designed to permit motion in all planes, these blood vessels must move with the femoral head throughout its
complete range of motion. In certain positions, these vessels may get kinked as the femoral neck presses against the edge of
the acetabulum. Moreover, certain mechanical positions of the leg may promote this kinking for prolonged periods of time. For
example, prone sleeping on the belly with hips extended and toes pointed outward may restrict blood flow to the femoral head.
There is a lot of interest to as to why some children have loss of blood supply episodes and others do not. Research has
identified some factors that may predispose children to Perthes disease. Hypercoagulability (faster clotting of blood) is
considered a risk factor. Hypercoagulability means that the blood clots abnormally quickly. It is theorized that the combination
of hypercoagulability (which may be genetic) and mechanical episodes of kinking of the blood vessels of the femoral neck can
lead to clotting off of these arteries and loss of the normal blood flow to the femoral head. Studies on hypercoagulability are
still inconclusive. While some studies have shown that patients with Perthes’ have abnormal clotting factors compared with
other children, other studies have refuted this claim. External environmental factors such as exposure to second hand smoke
has also been implicated as a causative factor. Repetitive mechanical trauma (e.g. gymnasts) to the hip joint may also
predispose children to loss of blood supply to the hip joint. Researchers have also observed that many Perthes children have
delayed skeletal maturity at onset. The bone age (measured from a hand x-ray) is often 2 years or more behind the
chronologic age. Finally, there are some underlying disease conditions that increase the risk of Perthes or Perthes-like disorder,
such as: sickle cell anemia; hypothyroidism; epiphyseal dysplasia; Gaucher’s disease; graft versus host reaction after bone
marrow transplant; leukemia. Such underlying disease conditions also predispose the child to the much less common bilateral
Perthes’ where both the left and right femoral heads are affected. About 15% of children afflicted with Perthes in one hip will
get it in the other hip.
What is the long-term prognosis for Perthes’?
Ultimately, the long-term prognosis depends on the mechanical shape of the femoral head as it interfaces to the acetabulum
within the hip joint. However, the final mechanical interface won’t be known until the disease runs through the lengthy repair
process that can last up to 5 years after the loss of blood supply episode. So the short-term problem confronting orthopedic
specialists is that they need to examine the hip very early in the process and they need to estimate the final mechanical
configuration and then make informed judgment about the necessity and type of treatment.
The best method to estimate the prognosis for child can be used very early in the disease process (only a few months after the
no blood episode). This prediction technique is based on two pieces of information: 1) the age of the child at onset and, 2)
the degree of necrotic bone involvement within the femoral head. The older the child when diagnosed, the worse is the
prognosis. Children under age six have the best prognosis even without treatment. For children over age of six, the best
prognosis is between 6-8 years of age. The prognosis worsens between ages 8-10 years and is often quite poor after age 10.
The relationship between age at onset and prognosis is widely agreed upon by pediatric orthopedic surgeons.
The other major prognostic factor evident early, is the extent of femoral “head involvement”. The smaller the amount of
femoral head involved (with loss of blood supply) the lower the risk of long-term femoral head deformation. The simplest
classification of Perthes’ (Salter-Thompson classification) divides cases into “partial” vs. “whole head” involvement which
corresponds to <50% and >50% of the head affected respectively. Obviously the prognosis is better with partial head
involvement than with whole head involvement. Most agree that partial head involvement cases require no treatment.
What are the treatment alternatives for Perthes’?
If your child is older and has greater than 50% head involvement then treatment may be indicated. Treatment for Perthes’ can
be generally divided into four categories:
1) Range of motion (ROM) only treatment
2) Trans-Neck-Head Tunneling (TNHT)
3) Containment Treatment. (There are 5 different types of containment treatment)
4) Distraction Treatment
1. ROM Treatment: Everyone agrees that maintaining hip ROM is a good for patients with Perthes because it helps prevent
stiffness of the femoral head. It is thought to help the injured femoral head maintain and regain its spherical shape. ROM
exercises are a component of all treatment regimens. Nevertheless in children, over age six, with whole head involvement, it
has been shown that any treatment is better than ROM alone. Although ROM has also been combined with prolonged bed rest
or non-weight bearing by crutches or wheelchair, this only provides symptomatic relief initially when the child is first having pain
and limp, and has no proven long-term benefit.
2. Trans-Neck-Head Tunneling (TNHT): The TNHT method was developed in Portugal by Dr. Nuno Lopes. He has used it for
over 20 years and has drilled over 200 hips. This technique involves making a 5 mm hole with a drill, or a device called a
trephine, from the lateral side of the femur up the femoral neck, across the growth plate, and into the center of the dead bone
within the femoral head. The function of growth plate (physis) of the upper femur is to cause the femoral neck to grow in
length adding to the growth in length of the femur. The growth plate acts as a barrier to blood vessel communication between
the bone of the upper femur and the femoral head and neck. In adults when the growth plate closes and disappears there is a
communication between the circulation of the two parts of the bone. When there is loss of blood flow from the arteries
entering the femoral neck from the outside the circulation of the rest of the femur cannot provide blood flow to the femoral
head because the growth plate acts as a barrier. By drilling a hole through the growth plate a portal of communication is
opened between the rest of the femur and the avascular femoral head. The blood vessels from the upper femur grow through
the hole in the growth plate to resupply circulation to the avascular femoral head.
Dr. Lopes has observed that drilling leads to more rapid reconstruction of the femoral head in early Perthes. Using MRI and
ultrasound to screen patients at risk he has identified a pre-Perthes stage of disease. He claims that TNHT at this very early
stage can lead to complete resolution of the problem and avert the resorption and reossification phases of Perthes. His
indications for this procedure are children with whole head involvement who are identified at the pre-Perthes’ (MRI changes
only) or very early Perthes’ stage (e.g. subchondral fracture). According to Lopes this method is almost universally successful
at the pre Perthes’ stage and about 50% successful at the early Perthes’ stage so that no further surgical treatment is
required. I have been using this method since 2001. My results in early Perthes are similar to Lopes. External bracing is
indicated after TNHT to protect the fragile head. Interestingly, TNHT may have a special role to prevent the progression on the
opposite hip. The second hip is identified on the MRI in the prePerthes stage which is when it is completely curable by TNHT.
For further information on this please refer to Dr. Lopes web site (http://clientes.netvisao.pt/nfrancac/). The attractive aspect
of this method is that it is minimally invasive and technically simple for any orthopedic surgeon to perform. TNHT is similar to a
procedure called “core decompression” has been used in AVN cases in adults for over thirty years. In adults, like children,
drilling only works well in very early stages of disease.
The main risks of TNHT are fracture and growth arrest of the femoral neck. However, since the hole diameter is small compared
to the overall cross-section of the neck, the risk of fracture is minimal. Neither Dr. Lopes nor I have experienced any fractures
after TNHT. Growth arrest of the proximal femoral growth plate can occur if a bony bridge develops across the drill channel
joining the femoral head and neck with upper femur bone thus tethering further growth by the growth plate. If a bridge
develops it can stop the growth of the upper femur or if it is too near the edge of the growth plate this can also lead to a
deformity since one side of the growth plate will continue to grow while the other side might be arrested. Dr. Lopes research
has shown that as long as the drill hole is less than 10% of the area of the growth plate, then the growth plate will not stop
growing since the growing forces within the growth plate will be strong enough to prevent growth arrest. Our results are too
early to comment on this, but certainly we are wary of this potential complication of an otherwise minimally invasive surgical
method. It is important to note that closure of the growth plate of the femoral neck is a well recognized and common
complication of Perthes’ even when no treatment is performed. Therefore it may be difficult to separate growth arrest due to
drilling versus those due to Perthes’. I think this method is promising and may have an expanded role on its own or in
conjunction with other treatments.
3. Containment Treatment: In a normal hip joint, the acetabulum only covers two thirds of the spherical surface of the femoral
head. In a healthy hip joint, this partial coverage is not an issue, however, if the femoral head has been severely weakened by
the death of the underlying honeycomb bone then there is a serious mechanical problem that contributes to the collapse of the
weakened bone. To understand the mechanical problem, you must understand the acetabulum is oriented at 45° to the pelvis
facing forward and outward, the front (anterior) and side (lateral). Thus, the lateral rim of the acetabulum is the point where
the femoral head enters and exits the socket during normal use. At the point of mechanical transition from the perfectly
molded acetabulum where the load of weight bearing and muscle compressive forces are distributed over the large surface area
of the femoral head and acetabulum, and the outside uncovered and unloaded femoral head, there is a high stress point called
a “stress riser”. This “stress riser” and is essentially a high pressure point on the femoral head which contributes to the
collapse of the weakened femoral head.
Returning to the analogy of the building under reconstruction... think of the “stress riser” as a spot near the center of the roof
where the wet snow is much thicker and heavier causing high crushing pressure on the roof in that spot. The biggest concern
about the “stress riser” is that the most common part of the femoral head to be affected by the avascular necrosis is the
“antero-lateral quadrant” which is in exactly the spot where the stress riser is greatest! This is bad news and is often where
the collapse of the weakened head begins.
Containment treatment refers to moving more of the uncovered femoral head (especially the affected part) inside the
acetabulum where there is no “stress riser” pressure point. Mechanically this is accomplished by moving the femoral head into
“abduction” and “flexion”. “Abduction” is the movement of the limb to the side (outward like the leg in Jumping Jack position)
so that the femoral head tilts into the socket where it is safe from excessive pressure. “Flexion” is the movement of the thigh
towards the chest. In the abducted and flexed position, the antero-lateral (front and outside) quadrant of the femoral head is
covered and protected by the acetabulum. One of the prerequisites for containment treatment is that the hip must be easily
moved into an abducted and flexed position. If the hip cannot go into that position easily, then containment treatment is not
an option. Containment can be achieved by external bracing or by several types of surgeries as outlined:
A) Abduction Bracing by external bracing systems worn by the child
B) Femoral Varus Osteotomy surgery
C) Pelvic Osteotomy surgery
D) Shelf Augmentation surgery
E) Combination Pelvic and Femoral surgery
A) Abduction Bracing: This is a non-operative method of containment. It is most useful in children between ages 6-8 years.
While there are numerous types of braces, the best known is the Scottish Rite abduction brace which has two thigh cuffs and a
bar in between them. Another version of this type of brace that I prefer is two thigh cuffs connected by a pelvic band with no
bar between the knees. While it is more flexible, I feel this is an advantage in that it moves the hip through a greater range of
motion as the thighs come together and apart during walking. For the brace to be effective, it must to be worn 20 hours a day
until reossification of the lateral pillar (outer rim) of the femoral head. In a child aged 6-8 years old this can mean at least a year
and half. Furthermore, the brace is only effective if ROM is maintained during treatment. To assist in ROM, it is sometime
necessary to perform an adductor tenotomy where some hip tendons are cut and actually lengthened. In general, bracing has
gotten a bad reputation because it is often used in the face of a stiff hip and as mentioned, stiffness is a contraindication to
bracing. Also, in older children, bracing may not be practical since it must continue for two years or more to be effective and
older children often refuse to wear the brace for cosmetic reasons leading to battles between the patient and parents.
B) Femoral Varus Osteotomy: The word “varus” means “inward”. The word “osteotomy” means to cut bone. It might be
easiest to understand that a varus osteotomy of the upper femur is an operation where the bone of the upper femur is cut and
a wedge shaped piece of is removed so that the neck of the femur tilts inwards moving the normally uncovered portion of the
head inside the acetabulum. In affect, the varus osteotomy achieves good coverage, like that obtained with bracing, but
without the need for the brace.
While this method is very good at getting good coverage and containment, it unfortunately does two bad things to the hip
joint. First it alters the hip mechanics by changing the tension of the hip abductor muscles as they attach to the “other” top of
the femur known as the greater trochanter. These muscles, as they attach to the greater trochanter, are responsible for
maintaining the pelvis level when standing on one leg (which occurs with every step). Therefore the varus osteotomy has the
unfortunate side affect of causing a limp, called a Trendelenburg limp, even after femoral head has healed from Perthes. As a
result, the varus osteotomy may need to be “undone” surgically at a later date to correct the Trendelenburg limp. Secondly,
the varus shortens the femur producing or contributing to a common complication of Perthes called “leg length discrepancy”
(LLD). Children with Perthes often develop a LLD due to premature closure of the upper femoral growth plate and loss of
height in the femoral head due to flattening. The surgically induced varus adds to LLD. Because of Trendelenberg limp and
LLD complications, varus osteotomy is my least preferred surgery for Perthes’.
C) Pelvic Osteotomy: Pelvic osteotomy is an operation where the pelvic bone is cut in a manner that permits reorientation of
the acetabulum over top the affected anterior and lateral parts of the femoral head thus improving containment. The most
common pelvic osteotomy is also known as the “innominate” osteotomy (the innominate bone is one of the three bones of the
pelvis). This surgery is also known as the Salter osteotomy because it was pioneered by Dr Robert Salter of Toronto, Canada.
This is a more complex operation than the femoral varus osteotomy with more potential for blood loss, however, when properly
done by an experienced surgeon, excellent coverage can be achieved. Some surgeons find it difficult to achieve extensive
coverage with this operation, but because I have been trained by Dr. Salter, I have a personal preference and a great deal of
experience with this procedure. Its advantages are that the distortion of anatomy produced by this operation are not clinically
significant or problematic as they are with femoral varus osteotomy. In fact, this operation tends to add length to the femur
that helps compensate for the LLD produced by Perthes’. Critics of this procedure claim that the surgery increases the
pressure on the soft and reforming femoral head. However, if the psoas and adductor tendons are lengthened, as
recommended by Dr Salter, this effect is not significant. There is another type of pelvic osteotomy called the “triple
osteotomy” where the pelvis is cut in three places and the acetabulum reattached in a manner to improve coverage over the
femoral head.
D) Shelf procedure: A shelf is a ledge of bone that is added to the existing acetabulum; overtop the anterior and lateral
aspects of the femoral head. This helps cover and contain the femoral head to more evenly distribute the body’s weight. After
the shelf has healed, it is believed that it helps prevent superior (upward) and lateral (outward) subluxation (partial dislocation)
of the femoral head from the acetabulum. Some consider it the best surgery to prevent subluxation. The shelf can be done
through a fairly small incision and requires a bone graft. It does not distort the orientation of the upper femur or the
acetabulum. Its only down side is that eventually the capsule of the hip that lies between the femoral head and the shelf is
transformed to fibrocartilage. Fibrocartilage may not last and I have seen cases in which arthritis develops prematurely under
the shelf.. One of the most common techniques for a shelf is called the Staheli shelf procedure.
E) Combined Femoral and Pelvic osteotomies: To achieve more extensive coverage some surgeons recommend combined
femoral and pelvic osteotomies. This is a very big operation with large potential blood loss and morbidity. Combination
osteotomies are not common.
For all containment surgeries, hip stiffness must be treated prior to surgery because the hip must be mobile before one of the
osteotomy treatments. Some surgeons achieve this by performing an adductor tenotomy (lengthening of the adductor longus
tendon) followed by application of Petrie casts (casts which are long leg casts with a bar between them to keep the legs in wide
abduction and are applied to both legs). After the hip loosens up then the osteotomy surgeries can be performed.
4. Distraction Treatment: This method was initially developed in Italy for a variety of stiff hip problems, using an external
mechanical apparatus which is attached to the patients femur and pelvic bones. Distraction treatment is also called
arthrodiatasis. Starting in 1989, I applied distraction treatment for Perthes disease. The word distraction simply means pulling
apart. I apply distraction using a mechanical device we call an external fixator (EF). The EF is attached to the body by
connecting to 6mm diameter pins that are drilled through the skin into the femur and pelvis through the skin. Once installed,
the EF device carries the weight of the body thereby relieving the bones of their normal task of carrying weight. In this way,
the EF takes the crushing pressures off the injured femoral head and allows it a chance to re-grow more rapidly and
presumably more spherically. The EF removes the weight off the roof.
The EF spans the hip joint allowing flexion and extension motion and at the same time holds the femur in 15° of abduction to
provide containment. However the EF does restrict rotation, abduction, and adduction motions of the hip. The EF has special
adjustment mechanism that permits gradual distraction of the hip joint by turning a screw daily during the distraction phase.
The gradual distraction gently pulls the femur away from the socket to reduce pressure on the head, yet allows surrounding
soft tissues time to stretch. Distraction is the only method of treatment that truly unloads the hip joint and allows the injured
femoral head a chance to re-grow without significant pressure bearing down. Non-weight bearing methods (e.g. crutches or
wheelchair) do not take the load off the hip because of the large muscles and ligaments around the hip keep strong pressures
on the femoral head. For example, when standing on one leg, we say that the hip joint is sustaining “4X body weight”. Such
high pressures can be observed by simply turning over in bed. As another example, when a patient uses a bed pan, pressures
equal to “1-2X body weight” can be induced. Given these examples, we know that crutches and wheelchair do not remove high
pressures off the hip joint.
One of the repair responses of the femoral head is for the cartilage surrounding the head to be stimulated to grow especially
laterally in the region where it is uncovered and under no pressure. This contributes the femoral head getting larger (coxa
magna) and the femoral head getting more elliptical or flatter (coxa plana). My hypothesis is that if the pressure can be
removed from the rest of the depressed and deformed femoral head it might be stimulated to grow and resume its spherical
shape especially if the spherical acetabulum is there to mold its growth. This is one of the effects we hope to achieve by
distraction. The second effect is to reduce the subluxation of the femoral head. The subluxation is proximal (upward) and
lateral (sideward) and anterior (forward). The distraction we do is downward which most readily reduces the upward
subluxation. Also, the lateral subluxation is often reduced by the abducted position of the hip during distraction. It is difficult
to assess and treat the anterior subluxation.
To reduce the pressure on the hip and the EF, we perform an adductor and psoas tenotomy (tendon lengthening) when the EF
is surgically applied. The distraction proceeds at 1/2mm per day until the upward subluxation is reduced about 1 cm past a
preset line which is observed in hip x-rays and is called Shentons line. During the distraction process, sometimes the hip goes
into flexion and refuses to distract so an additional external rod is connected to the EF which helps corrects the legs tendency
to go into flexion.
Typically, it takes between 6 and 8 weeks for the proper amount of distraction to be achieved. After the distraction process
has been completed, the fixator is left in place so that the patient has the EF for a total of 4 to 5 months. Daily physical
therapy (PT) is important to maintain hip flexion and extension mobility while wearing the EF. After 4 months for children under
13 and 5 months for children over 13, the EF is removed under general anesthesia. After EF removal, an abduction brace is
worn for six weeks day and night and PT and ROM exercises are resumed. Six weeks after removal the brace is worn at night
only. It takes several additional months to get all the hip motion and muscular strength back.
What is the best age, stage and indications for distraction treatment? We have applied distraction treatment successfully for
all ages between 6 and 15 yrs. While it works just as well for younger or older children, its biggest advantage compared to
other methods is for the older child age 9 and older when the other methods have high failure rates. Distraction does not work
if applied too early during the subchondral fracture phase, therefore, we recommend that the femoral head at least be in the
early fragmentation-collapse phase. Distraction also works well even at the late resorption and re-ossification phases. The best
indication for distraction treatment is the child with evidence of collapse, flattening and subluxation.
What are the advantages of distraction treatment: There are several advantages of distraction over the surgical containment
methods: 1) distraction does not alter the anatomy of the femur or pelvis and is a smaller surgical procedure than containment
surgery; 2) distraction directly reduces subluxation of the hip; 3) distraction stretches out the contracted capsule (soft tissues)
of the hip joint; 4) distraction improves the sphericity of the collapsed femoral head; 5) distraction improves the mobility of a
stiff hip; 6) distraction does not require invasive surgery of the hip joint itself.
What are the disadvantages of distraction treatment: 1) The biggest disadvantage of distraction treatment is the need to wear
an external fixator with pins going through the skin for four months. The pin sites can become painful and infected. Pin site
infection is easy to treat with oral antibiotic and good hygiene and rarely leads to deep infection. Most patients tolerate the EF
very well during which time patients must maintain only partial weight bearing for four to five months using crutches or a walker
in order to minimize undue mechanical stress on the pins.
What are the results of distraction treatment: I have achieved 95% good or excellent results with distraction treatment for
Perthes, independent of age. This is the only method where the results do not correlate with age. For this reason, it is the
treatment of choice in patients over the age of 10 and at least as good as other methods prior to age 10. Distraction
significantly improves hip range of motion and especially functional sphericity (hip motion like a sphere). It also significantly
reduces the subluxation of the hip joint and the spherical shape of the femoral head. These are considered positive prognostic
factors for longevity of the hip joint. The final shape of the femoral head is the single most prognostic factor for developing
early arthritis of the hip. The more spherical femoral head joint will allow good ROM that leads to good longevity for the hip
joint.
Have any other centers performed distraction treatment or corroborated my results? There have been several centers around
the world that have achieved similar results to mine. These include centers in Brazil, Turkey, Israel, India and Portugal. The
group in Sao Paolo, Brazil compared distraction treatment to containment treatments and concluded that it produced the same
or better results. The group in Turkey initially published poor results with distraction treatment attempted with the Ilizarov
device with a different treatment protocol than mine. Since their publication they have changed to our protocol and are now
enjoying a similar success rate to mine. Similar results have been achieved for the groups in Israel and in Portugal. Dr. Lopes
in Portugal has applied distraction treatment to cases that are not good candidates for TNHT or who have failed TNHT. In the
US, a few centers have tried distraction in a handful of cases usually with good success. In Israel two separate centers have
reported excellent results.
I hope this method will eventually be as available as other surgical methods for the treatment of Perthes’. The fact that
distraction it is not being used by many in the US is mostly caused by a lack of training and exposure to this method.
What are the long term results from distraction treatment. Now that I have followed some of my patients up to 20 years after
distraction I realize that in many cases the femoral head is what we call a Stulberg 3. In the past we considered a Stulberg 3
femoral head shape an excellent results since arthritis would not develop usually until after age 50. Nevertheless in recent years
I have observed that some patients develop some pain related to impingement and some wear of the hip due to the aspherical
nature of the femoral head. Until 3 years ago we did not have any treatment for this. We now do in the form of femoral head
reshaping osteotomy.
Femoral Head Reshaping Osteotomy
This is the newest surgical treatment and one of the most exciting for Perthes. The femoral head after healing often is ellipsoid
rather than spherical shaped. The acetabulum however often remains spherical. This causes a larger than normal femoral head
to deform the labrum cartilage and the joint cartilage. Tears in the cartilage lead to pain and wear and arthritis. Even worse
than the ellipsoid femoral head is the saddle shaped femoral head. In both the femoral head is longer in the frontal plane while it
is usually still cylindrical in the sagital plane. I use an osteotomy developed by Dr. Reinhold Ganz in Switzerland. To my
knowledge I became the first surgeon outside of Switzerland to do this procedure and have performed over 15 of these during
the past 3 years. As yet no other center in the US has performed this procedure. The central third of the femoral head is
removed to change the shape of an ellipse to a circle. This reduces the size of the femoral head in the frontal plane and
restores the sphericity and containment of the femoral head. I have used this procedure to salvage the hip in cases who
became symptomatic after previous distraction.
How to decide what to do for your child:
If you obtain multiple opinions regarding your child’s Perthes’ you may get as many different opinions as the number of people
you consult. This is not unusual with Perthes. It also does not imply that one opinion is more right than the others. To help
you make your decision for your child let’s review what most orthopedic surgeons agree about and where the areas of
controversy are.
What everyone agrees upon:
1) Range of motion is good for the hip
2) The long-term prognosis is worse with increasing age
3) Children under age 6 rarely require treatment
4) Partial head involvement does not require treatment
5) Whole head involvement in children over age six, have a better prognosis with any type of treatment than with no
treatment
6) There is no evidence that one method of containment is better than any other method.
Controversies:
1) Best method of containment treatment: femoral vs pelvic osteotomy vs brace vs shelf
2) TNHT- Unproven—should it be used in early cases or is the risk of premature growth arrest too high
3) Distraction treatment: better than containment? Best treatment in older child?
4) Children should not be treated after age 10 since results of containment are poor?
How to reconcile the controversies for your own child
1) Best method of containment?; if you can maintain ROM and tolerate the external brace for 1-2 years (less in younger
children) then go with brace; If you cannot tolerate the brace, then look at the pros and cons listed above and see what you
feel most comfortable with. Discuss with your surgeon. Discuss with your child.
2) TNHT?: go to Dr. Lopes web site. At this point, it is a low risk procedure and if it works you win. If it does not work
there is minimal risk.
3) Distraction Treatment?: all investigators results seem to indicate that distraction is at least as good as containment
methods. If planning a containment surgery then consider this as an alternative. For children over age 9, distraction may
become the method of choice. For failure with containment method, distraction can still salvage the hip. This method may not
be available in your area, therefore you need to decide if you are prepared to travel to obtain this treatment.
4) > 10 years don’t treat?: probably true for containment methods. Not true for distraction. Nothing to lose with
distraction by doing treatment. Failed distraction treatment no worse than failed no treatment.
I hope this helps clarify some of the issues surrounding this controversial disease. Certainly, I recommend that you continue to
learn all that you can about this condition and then consider the various factors as you face the important decisions you must
make for your child. Obtain different opinions; speak with other Perthes parents about their experiences. This can help guide
your process.
Dror Paley, MD
dpaley@lengthening.us
s normal repair mechanisms to remove and replace the dead bone of the femoral head. During this repair process the femoral
head may be sufficiently weakened such that it collapses leading to deformation of the joint surface. This deformation creates a
non-spherical femoral head inside of a spherical socket and ultimately leads to joint stiffness, arthritis and pain.
How does a normal repair process designed to rid the body of dead bone go so awry. To understand this it is important to
know something about the normal repair process. The femoral head is made up of a core of bone surrounded by cartilage.
The cartilage of the femoral head gets its oxygen and nutrition from the fluid in the hip joint. The bone in the femoral head
gets its oxygen and nutrition from blood vessels that enter the femoral neck from outside the bone. The femoral neck is
separated from the rest of the femur bone by the growth plate (growing zone) of the upper femur. When there is blockage or
damage to these blood vessels the bone in the femoral head dies due to loss of oxygen and nutrition. The cartilage on the
outside of the femoral head which surrounds the underlying dead bone does not die since it gets its oxygen and nutrition by
diffusion from the fluid inside the hip joint. The dead bone is removed by special bone eating cells (osteoclasts). New living
bone is produced by special bone making cells (osteoblasts). As the dead bone is removed from the femoral head, the support
of the cartilage of the joint is weakened. If the surrounding cartilage structure is thick and strong enough, there will be enough
time for new bone to be deposited to replace the removed bone and there will be no change in shape of the femoral head. If
too much support is removed and the surrounding cartilage cannot withstand the load, then the weight bearing surface of the
femoral head will slowly collapse under the body’s weight and the normally spherical femoral head becomes flattened to a more
egg shaped configuration.
To help explain the collapsing process, I like to use the analogy that compares the femoral head (that has been damaged by a
previous loss of blood supply episode), to the renovation of a building. Imagine an old building that, although still intact, has
severely weakened internal support structures that must be replaced with new internal supports in order to prevent the roof
from collapsing. If the “demolition team” removes some old support beams and the rest of the building structure can
withstand this weakening, then the roof will not cave in and there will allow enough time for the “construction team” to replace
the old support beams with new beams. If, however, too many of the old support beams are removed before the construction
team can replace the supports then the roof will cave in. A caved in roof is hard to rebuild and unfortunately can lead to a
deformed new roof- especially if the crashed roof has lots of weight on it like a snow covered roof.
Bringing this analogy back to the femoral head, the roof of the building is the hard, dense outer surface of the femoral head
that is called “subcondral bone” that supports the overlying cartilage of the femoral head. The supporting beams within the
building are a low-density, honeycomb like bone called “trabecular bone” that forms the core of the femoral head. The old
supports are dead trabecular bone that died from lack of blood supply and are eaten away by osteoclast cells. The new
supports are the reforming trabecular bone installed by the osteoblast cells. The tons of wet snow on the rooftop, represents
the body’s weight and muscle forces that continuously apply load through the hip joint tending to crush and permanently
deform the weakened, fragile femoral head that while it is trying to renovate its structure.
The best results in Perthes occur when the roof of the femoral head does not collapse or when it only minimally deforms, and
when there is plenty of time to repair the damage such as in a younger child. The worst results in Perthes occur when the roof
caves in badly and the older child doesn’t have adequate growing time to repair the damage.
Unfortunately, if the roof deforms, the resulting egg shaped, femoral head is no longer shaped as sphere and therefore cannot
move in all directions like a ball in a socket. This reduces the normal range of motion (ROM). Furthermore if the shape of the
ball (femoral head) is mismatched with that of the socket (acetabulum) there will be abnormal wear and tear in the joint
leading first to stiffness, then to pain and eventually to loss of the joint cartilage (arthritis). This early osteoarthritis often
leads to total hip replacement (THR) as an adult as early as the 30’s, but more likely the 40’s, 50’s or beyond depending on the
degree of deformation and joint shape mismatch left behind by the Perthes disease process.
Why does Perthes’ occur?
Unlike other joints in the body, the femoral head within the hip joint has a very unique, but precarious blood supply where
almost all the blood going to the femoral head is delivered by one main blood vessel system that must enter the femoral head
by traveling across the femoral neck into the hip joint and finally into the head at its junction with the femoral neck. Since the
hip joint is designed to permit motion in all planes, these blood vessels must move with the femoral head throughout its
complete range of motion. In certain positions, these vessels may get kinked as the femoral neck presses against the edge of
the acetabulum. Moreover, certain mechanical positions of the leg may promote this kinking for prolonged periods of time. For
example, prone sleeping on the belly with hips extended and toes pointed outward may restrict blood flow to the femoral head.
There is a lot of interest to as to why some children have loss of blood supply episodes and others do not. Research has
identified some factors that may predispose children to Perthes disease. Hypercoagulability (faster clotting of blood) is
considered a risk factor. Hypercoagulability means that the blood clots abnormally quickly. It is theorized that the combination
of hypercoagulability (which may be genetic) and mechanical episodes of kinking of the blood vessels of the femoral neck can
lead to clotting off of these arteries and loss of the normal blood flow to the femoral head. Studies on hypercoagulability are
still inconclusive. While some studies have shown that patients with Perthes’ have abnormal clotting factors compared with
other children, other studies have refuted this claim. External environmental factors such as exposure to second hand smoke
has also been implicated as a causative factor. Repetitive mechanical trauma (e.g. gymnasts) to the hip joint may also
predispose children to loss of blood supply to the hip joint. Researchers have also observed that many Perthes children have
delayed skeletal maturity at onset. The bone age (measured from a hand x-ray) is often 2 years or more behind the
chronologic age. Finally, there are some underlying disease conditions that increase the risk of Perthes or Perthes-like disorder,
such as: sickle cell anemia; hypothyroidism; epiphyseal dysplasia; Gaucher’s disease; graft versus host reaction after bone
marrow transplant; leukemia. Such underlying disease conditions also predispose the child to the much less common bilateral
Perthes’ where both the left and right femoral heads are affected. About 15% of children afflicted with Perthes in one hip will
get it in the other hip.
What is the long-term prognosis for Perthes’?
Ultimately, the long-term prognosis depends on the mechanical shape of the femoral head as it interfaces to the acetabulum
within the hip joint. However, the final mechanical interface won’t be known until the disease runs through the lengthy repair
process that can last up to 5 years after the loss of blood supply episode. So the short-term problem confronting orthopedic
specialists is that they need to examine the hip very early in the process and they need to estimate the final mechanical
configuration and then make informed judgment about the necessity and type of treatment.
The best method to estimate the prognosis for child can be used very early in the disease process (only a few months after the
no blood episode). This prediction technique is based on two pieces of information: 1) the age of the child at onset and, 2)
the degree of necrotic bone involvement within the femoral head. The older the child when diagnosed, the worse is the
prognosis. Children under age six have the best prognosis even without treatment. For children over age of six, the best
prognosis is between 6-8 years of age. The prognosis worsens between ages 8-10 years and is often quite poor after age 10.
The relationship between age at onset and prognosis is widely agreed upon by pediatric orthopedic surgeons.
The other major prognostic factor evident early, is the extent of femoral “head involvement”. The smaller the amount of
femoral head involved (with loss of blood supply) the lower the risk of long-term femoral head deformation. The simplest
classification of Perthes’ (Salter-Thompson classification) divides cases into “partial” vs. “whole head” involvement which
corresponds to <50% and >50% of the head affected respectively. Obviously the prognosis is better with partial head
involvement than with whole head involvement. Most agree that partial head involvement cases require no treatment.
What are the treatment alternatives for Perthes’?
If your child is older and has greater than 50% head involvement then treatment may be indicated. Treatment for Perthes’ can
be generally divided into four categories:
1) Range of motion (ROM) only treatment
2) Trans-Neck-Head Tunneling (TNHT)
3) Containment Treatment. (There are 5 different types of containment treatment)
4) Distraction Treatment
1. ROM Treatment: Everyone agrees that maintaining hip ROM is a good for patients with Perthes because it helps prevent
stiffness of the femoral head. It is thought to help the injured femoral head maintain and regain its spherical shape. ROM
exercises are a component of all treatment regimens. Nevertheless in children, over age six, with whole head involvement, it
has been shown that any treatment is better than ROM alone. Although ROM has also been combined with prolonged bed rest
or non-weight bearing by crutches or wheelchair, this only provides symptomatic relief initially when the child is first having pain
and limp, and has no proven long-term benefit.
2. Trans-Neck-Head Tunneling (TNHT): The TNHT method was developed in Portugal by Dr. Nuno Lopes. He has used it for
over 20 years and has drilled over 200 hips. This technique involves making a 5 mm hole with a drill, or a device called a
trephine, from the lateral side of the femur up the femoral neck, across the growth plate, and into the center of the dead bone
within the femoral head. The function of growth plate (physis) of the upper femur is to cause the femoral neck to grow in
length adding to the growth in length of the femur. The growth plate acts as a barrier to blood vessel communication between
the bone of the upper femur and the femoral head and neck. In adults when the growth plate closes and disappears there is a
communication between the circulation of the two parts of the bone. When there is loss of blood flow from the arteries
entering the femoral neck from the outside the circulation of the rest of the femur cannot provide blood flow to the femoral
head because the growth plate acts as a barrier. By drilling a hole through the growth plate a portal of communication is
opened between the rest of the femur and the avascular femoral head. The blood vessels from the upper femur grow through
the hole in the growth plate to resupply circulation to the avascular femoral head.
Dr. Lopes has observed that drilling leads to more rapid reconstruction of the femoral head in early Perthes. Using MRI and
ultrasound to screen patients at risk he has identified a pre-Perthes stage of disease. He claims that TNHT at this very early
stage can lead to complete resolution of the problem and avert the resorption and reossification phases of Perthes. His
indications for this procedure are children with whole head involvement who are identified at the pre-Perthes’ (MRI changes
only) or very early Perthes’ stage (e.g. subchondral fracture). According to Lopes this method is almost universally successful
at the pre Perthes’ stage and about 50% successful at the early Perthes’ stage so that no further surgical treatment is
required. I have been using this method since 2001. My results in early Perthes are similar to Lopes. External bracing is
indicated after TNHT to protect the fragile head. Interestingly, TNHT may have a special role to prevent the progression on the
opposite hip. The second hip is identified on the MRI in the prePerthes stage which is when it is completely curable by TNHT.
For further information on this please refer to Dr. Lopes web site (http://clientes.netvisao.pt/nfrancac/). The attractive aspect
of this method is that it is minimally invasive and technically simple for any orthopedic surgeon to perform. TNHT is similar to a
procedure called “core decompression” has been used in AVN cases in adults for over thirty years. In adults, like children,
drilling only works well in very early stages of disease.
The main risks of TNHT are fracture and growth arrest of the femoral neck. However, since the hole diameter is small compared
to the overall cross-section of the neck, the risk of fracture is minimal. Neither Dr. Lopes nor I have experienced any fractures
after TNHT. Growth arrest of the proximal femoral growth plate can occur if a bony bridge develops across the drill channel
joining the femoral head and neck with upper femur bone thus tethering further growth by the growth plate. If a bridge
develops it can stop the growth of the upper femur or if it is too near the edge of the growth plate this can also lead to a
deformity since one side of the growth plate will continue to grow while the other side might be arrested. Dr. Lopes research
has shown that as long as the drill hole is less than 10% of the area of the growth plate, then the growth plate will not stop
growing since the growing forces within the growth plate will be strong enough to prevent growth arrest. Our results are too
early to comment on this, but certainly we are wary of this potential complication of an otherwise minimally invasive surgical
method. It is important to note that closure of the growth plate of the femoral neck is a well recognized and common
complication of Perthes’ even when no treatment is performed. Therefore it may be difficult to separate growth arrest due to
drilling versus those due to Perthes’. I think this method is promising and may have an expanded role on its own or in
conjunction with other treatments.
3. Containment Treatment: In a normal hip joint, the acetabulum only covers two thirds of the spherical surface of the femoral
head. In a healthy hip joint, this partial coverage is not an issue, however, if the femoral head has been severely weakened by
the death of the underlying honeycomb bone then there is a serious mechanical problem that contributes to the collapse of the
weakened bone. To understand the mechanical problem, you must understand the acetabulum is oriented at 45° to the pelvis
facing forward and outward, the front (anterior) and side (lateral). Thus, the lateral rim of the acetabulum is the point where
the femoral head enters and exits the socket during normal use. At the point of mechanical transition from the perfectly
molded acetabulum where the load of weight bearing and muscle compressive forces are distributed over the large surface area
of the femoral head and acetabulum, and the outside uncovered and unloaded femoral head, there is a high stress point called
a “stress riser”. This “stress riser” and is essentially a high pressure point on the femoral head which contributes to the
collapse of the weakened femoral head.
Returning to the analogy of the building under reconstruction... think of the “stress riser” as a spot near the center of the roof
where the wet snow is much thicker and heavier causing high crushing pressure on the roof in that spot. The biggest concern
about the “stress riser” is that the most common part of the femoral head to be affected by the avascular necrosis is the
“antero-lateral quadrant” which is in exactly the spot where the stress riser is greatest! This is bad news and is often where
the collapse of the weakened head begins.
Containment treatment refers to moving more of the uncovered femoral head (especially the affected part) inside the
acetabulum where there is no “stress riser” pressure point. Mechanically this is accomplished by moving the femoral head into
“abduction” and “flexion”. “Abduction” is the movement of the limb to the side (outward like the leg in Jumping Jack position)
so that the femoral head tilts into the socket where it is safe from excessive pressure. “Flexion” is the movement of the thigh
towards the chest. In the abducted and flexed position, the antero-lateral (front and outside) quadrant of the femoral head is
covered and protected by the acetabulum. One of the prerequisites for containment treatment is that the hip must be easily
moved into an abducted and flexed position. If the hip cannot go into that position easily, then containment treatment is not
an option. Containment can be achieved by external bracing or by several types of surgeries as outlined:
A) Abduction Bracing by external bracing systems worn by the child
B) Femoral Varus Osteotomy surgery
C) Pelvic Osteotomy surgery
D) Shelf Augmentation surgery
E) Combination Pelvic and Femoral surgery
A) Abduction Bracing: This is a non-operative method of containment. It is most useful in children between ages 6-8 years.
While there are numerous types of braces, the best known is the Scottish Rite abduction brace which has two thigh cuffs and a
bar in between them. Another version of this type of brace that I prefer is two thigh cuffs connected by a pelvic band with no
bar between the knees. While it is more flexible, I feel this is an advantage in that it moves the hip through a greater range of
motion as the thighs come together and apart during walking. For the brace to be effective, it must to be worn 20 hours a day
until reossification of the lateral pillar (outer rim) of the femoral head. In a child aged 6-8 years old this can mean at least a year
and half. Furthermore, the brace is only effective if ROM is maintained during treatment. To assist in ROM, it is sometime
necessary to perform an adductor tenotomy where some hip tendons are cut and actually lengthened. In general, bracing has
gotten a bad reputation because it is often used in the face of a stiff hip and as mentioned, stiffness is a contraindication to
bracing. Also, in older children, bracing may not be practical since it must continue for two years or more to be effective and
older children often refuse to wear the brace for cosmetic reasons leading to battles between the patient and parents.
B) Femoral Varus Osteotomy: The word “varus” means “inward”. The word “osteotomy” means to cut bone. It might be
easiest to understand that a varus osteotomy of the upper femur is an operation where the bone of the upper femur is cut and
a wedge shaped piece of is removed so that the neck of the femur tilts inwards moving the normally uncovered portion of the
head inside the acetabulum. In affect, the varus osteotomy achieves good coverage, like that obtained with bracing, but
without the need for the brace.
While this method is very good at getting good coverage and containment, it unfortunately does two bad things to the hip
joint. First it alters the hip mechanics by changing the tension of the hip abductor muscles as they attach to the “other” top of
the femur known as the greater trochanter. These muscles, as they attach to the greater trochanter, are responsible for
maintaining the pelvis level when standing on one leg (which occurs with every step). Therefore the varus osteotomy has the
unfortunate side affect of causing a limp, called a Trendelenburg limp, even after femoral head has healed from Perthes. As a
result, the varus osteotomy may need to be “undone” surgically at a later date to correct the Trendelenburg limp. Secondly,
the varus shortens the femur producing or contributing to a common complication of Perthes called “leg length discrepancy”
(LLD). Children with Perthes often develop a LLD due to premature closure of the upper femoral growth plate and loss of
height in the femoral head due to flattening. The surgically induced varus adds to LLD. Because of Trendelenberg limp and
LLD complications, varus osteotomy is my least preferred surgery for Perthes’.
C) Pelvic Osteotomy: Pelvic osteotomy is an operation where the pelvic bone is cut in a manner that permits reorientation of
the acetabulum over top the affected anterior and lateral parts of the femoral head thus improving containment. The most
common pelvic osteotomy is also known as the “innominate” osteotomy (the innominate bone is one of the three bones of the
pelvis). This surgery is also known as the Salter osteotomy because it was pioneered by Dr Robert Salter of Toronto, Canada.
This is a more complex operation than the femoral varus osteotomy with more potential for blood loss, however, when properly
done by an experienced surgeon, excellent coverage can be achieved. Some surgeons find it difficult to achieve extensive
coverage with this operation, but because I have been trained by Dr. Salter, I have a personal preference and a great deal of
experience with this procedure. Its advantages are that the distortion of anatomy produced by this operation are not clinically
significant or problematic as they are with femoral varus osteotomy. In fact, this operation tends to add length to the femur
that helps compensate for the LLD produced by Perthes’. Critics of this procedure claim that the surgery increases the
pressure on the soft and reforming femoral head. However, if the psoas and adductor tendons are lengthened, as
recommended by Dr Salter, this effect is not significant. There is another type of pelvic osteotomy called the “triple
osteotomy” where the pelvis is cut in three places and the acetabulum reattached in a manner to improve coverage over the
femoral head.
D) Shelf procedure: A shelf is a ledge of bone that is added to the existing acetabulum; overtop the anterior and lateral
aspects of the femoral head. This helps cover and contain the femoral head to more evenly distribute the body’s weight. After
the shelf has healed, it is believed that it helps prevent superior (upward) and lateral (outward) subluxation (partial dislocation)
of the femoral head from the acetabulum. Some consider it the best surgery to prevent subluxation. The shelf can be done
through a fairly small incision and requires a bone graft. It does not distort the orientation of the upper femur or the
acetabulum. Its only down side is that eventually the capsule of the hip that lies between the femoral head and the shelf is
transformed to fibrocartilage. Fibrocartilage may not last and I have seen cases in which arthritis develops prematurely under
the shelf.. One of the most common techniques for a shelf is called the Staheli shelf procedure.
E) Combined Femoral and Pelvic osteotomies: To achieve more extensive coverage some surgeons recommend combined
femoral and pelvic osteotomies. This is a very big operation with large potential blood loss and morbidity. Combination
osteotomies are not common.
For all containment surgeries, hip stiffness must be treated prior to surgery because the hip must be mobile before one of the
osteotomy treatments. Some surgeons achieve this by performing an adductor tenotomy (lengthening of the adductor longus
tendon) followed by application of Petrie casts (casts which are long leg casts with a bar between them to keep the legs in wide
abduction and are applied to both legs). After the hip loosens up then the osteotomy surgeries can be performed.
4. Distraction Treatment: This method was initially developed in Italy for a variety of stiff hip problems, using an external
mechanical apparatus which is attached to the patients femur and pelvic bones. Distraction treatment is also called
arthrodiatasis. Starting in 1989, I applied distraction treatment for Perthes disease. The word distraction simply means pulling
apart. I apply distraction using a mechanical device we call an external fixator (EF). The EF is attached to the body by
connecting to 6mm diameter pins that are drilled through the skin into the femur and pelvis through the skin. Once installed,
the EF device carries the weight of the body thereby relieving the bones of their normal task of carrying weight. In this way,
the EF takes the crushing pressures off the injured femoral head and allows it a chance to re-grow more rapidly and
presumably more spherically. The EF removes the weight off the roof.
The EF spans the hip joint allowing flexion and extension motion and at the same time holds the femur in 15° of abduction to
provide containment. However the EF does restrict rotation, abduction, and adduction motions of the hip. The EF has special
adjustment mechanism that permits gradual distraction of the hip joint by turning a screw daily during the distraction phase.
The gradual distraction gently pulls the femur away from the socket to reduce pressure on the head, yet allows surrounding
soft tissues time to stretch. Distraction is the only method of treatment that truly unloads the hip joint and allows the injured
femoral head a chance to re-grow without significant pressure bearing down. Non-weight bearing methods (e.g. crutches or
wheelchair) do not take the load off the hip because of the large muscles and ligaments around the hip keep strong pressures
on the femoral head. For example, when standing on one leg, we say that the hip joint is sustaining “4X body weight”. Such
high pressures can be observed by simply turning over in bed. As another example, when a patient uses a bed pan, pressures
equal to “1-2X body weight” can be induced. Given these examples, we know that crutches and wheelchair do not remove high
pressures off the hip joint.
One of the repair responses of the femoral head is for the cartilage surrounding the head to be stimulated to grow especially
laterally in the region where it is uncovered and under no pressure. This contributes the femoral head getting larger (coxa
magna) and the femoral head getting more elliptical or flatter (coxa plana). My hypothesis is that if the pressure can be
removed from the rest of the depressed and deformed femoral head it might be stimulated to grow and resume its spherical
shape especially if the spherical acetabulum is there to mold its growth. This is one of the effects we hope to achieve by
distraction. The second effect is to reduce the subluxation of the femoral head. The subluxation is proximal (upward) and
lateral (sideward) and anterior (forward). The distraction we do is downward which most readily reduces the upward
subluxation. Also, the lateral subluxation is often reduced by the abducted position of the hip during distraction. It is difficult
to assess and treat the anterior subluxation.
To reduce the pressure on the hip and the EF, we perform an adductor and psoas tenotomy (tendon lengthening) when the EF
is surgically applied. The distraction proceeds at 1/2mm per day until the upward subluxation is reduced about 1 cm past a
preset line which is observed in hip x-rays and is called Shentons line. During the distraction process, sometimes the hip goes
into flexion and refuses to distract so an additional external rod is connected to the EF which helps corrects the legs tendency
to go into flexion.
Typically, it takes between 6 and 8 weeks for the proper amount of distraction to be achieved. After the distraction process
has been completed, the fixator is left in place so that the patient has the EF for a total of 4 to 5 months. Daily physical
therapy (PT) is important to maintain hip flexion and extension mobility while wearing the EF. After 4 months for children under
13 and 5 months for children over 13, the EF is removed under general anesthesia. After EF removal, an abduction brace is
worn for six weeks day and night and PT and ROM exercises are resumed. Six weeks after removal the brace is worn at night
only. It takes several additional months to get all the hip motion and muscular strength back.
What is the best age, stage and indications for distraction treatment? We have applied distraction treatment successfully for
all ages between 6 and 15 yrs. While it works just as well for younger or older children, its biggest advantage compared to
other methods is for the older child age 9 and older when the other methods have high failure rates. Distraction does not work
if applied too early during the subchondral fracture phase, therefore, we recommend that the femoral head at least be in the
early fragmentation-collapse phase. Distraction also works well even at the late resorption and re-ossification phases. The best
indication for distraction treatment is the child with evidence of collapse, flattening and subluxation.
What are the advantages of distraction treatment: There are several advantages of distraction over the surgical containment
methods: 1) distraction does not alter the anatomy of the femur or pelvis and is a smaller surgical procedure than containment
surgery; 2) distraction directly reduces subluxation of the hip; 3) distraction stretches out the contracted capsule (soft tissues)
of the hip joint; 4) distraction improves the sphericity of the collapsed femoral head; 5) distraction improves the mobility of a
stiff hip; 6) distraction does not require invasive surgery of the hip joint itself.
What are the disadvantages of distraction treatment: 1) The biggest disadvantage of distraction treatment is the need to wear
an external fixator with pins going through the skin for four months. The pin sites can become painful and infected. Pin site
infection is easy to treat with oral antibiotic and good hygiene and rarely leads to deep infection. Most patients tolerate the EF
very well during which time patients must maintain only partial weight bearing for four to five months using crutches or a walker
in order to minimize undue mechanical stress on the pins.
What are the results of distraction treatment: I have achieved 95% good or excellent results with distraction treatment for
Perthes, independent of age. This is the only method where the results do not correlate with age. For this reason, it is the
treatment of choice in patients over the age of 10 and at least as good as other methods prior to age 10. Distraction
significantly improves hip range of motion and especially functional sphericity (hip motion like a sphere). It also significantly
reduces the subluxation of the hip joint and the spherical shape of the femoral head. These are considered positive prognostic
factors for longevity of the hip joint. The final shape of the femoral head is the single most prognostic factor for developing
early arthritis of the hip. The more spherical femoral head joint will allow good ROM that leads to good longevity for the hip
joint.
Have any other centers performed distraction treatment or corroborated my results? There have been several centers around
the world that have achieved similar results to mine. These include centers in Brazil, Turkey, Israel, India and Portugal. The
group in Sao Paolo, Brazil compared distraction treatment to containment treatments and concluded that it produced the same
or better results. The group in Turkey initially published poor results with distraction treatment attempted with the Ilizarov
device with a different treatment protocol than mine. Since their publication they have changed to our protocol and are now
enjoying a similar success rate to mine. Similar results have been achieved for the groups in Israel and in Portugal. Dr. Lopes
in Portugal has applied distraction treatment to cases that are not good candidates for TNHT or who have failed TNHT. In the
US, a few centers have tried distraction in a handful of cases usually with good success. In Israel two separate centers have
reported excellent results.
I hope this method will eventually be as available as other surgical methods for the treatment of Perthes’. The fact that
distraction it is not being used by many in the US is mostly caused by a lack of training and exposure to this method.
What are the long term results from distraction treatment. Now that I have followed some of my patients up to 20 years after
distraction I realize that in many cases the femoral head is what we call a Stulberg 3. In the past we considered a Stulberg 3
femoral head shape an excellent results since arthritis would not develop usually until after age 50. Nevertheless in recent years
I have observed that some patients develop some pain related to impingement and some wear of the hip due to the aspherical
nature of the femoral head. Until 3 years ago we did not have any treatment for this. We now do in the form of femoral head
reshaping osteotomy.
Femoral Head Reshaping Osteotomy
This is the newest surgical treatment and one of the most exciting for Perthes. The femoral head after healing often is ellipsoid
rather than spherical shaped. The acetabulum however often remains spherical. This causes a larger than normal femoral head
to deform the labrum cartilage and the joint cartilage. Tears in the cartilage lead to pain and wear and arthritis. Even worse
than the ellipsoid femoral head is the saddle shaped femoral head. In both the femoral head is longer in the frontal plane while it
is usually still cylindrical in the sagital plane. I use an osteotomy developed by Dr. Reinhold Ganz in Switzerland. To my
knowledge I became the first surgeon outside of Switzerland to do this procedure and have performed over 15 of these during
the past 3 years. As yet no other center in the US has performed this procedure. The central third of the femoral head is
removed to change the shape of an ellipse to a circle. This reduces the size of the femoral head in the frontal plane and
restores the sphericity and containment of the femoral head. I have used this procedure to salvage the hip in cases who
became symptomatic after previous distraction.
How to decide what to do for your child:
If you obtain multiple opinions regarding your child’s Perthes’ you may get as many different opinions as the number of people
you consult. This is not unusual with Perthes. It also does not imply that one opinion is more right than the others. To help
you make your decision for your child let’s review what most orthopedic surgeons agree about and where the areas of
controversy are.
What everyone agrees upon:
1) Range of motion is good for the hip
2) The long-term prognosis is worse with increasing age
3) Children under age 6 rarely require treatment
4) Partial head involvement does not require treatment
5) Whole head involvement in children over age six, have a better prognosis with any type of treatment than with no
treatment
6) There is no evidence that one method of containment is better than any other method.
Controversies:
1) Best method of containment treatment: femoral vs pelvic osteotomy vs brace vs shelf
2) TNHT- Unproven—should it be used in early cases or is the risk of premature growth arrest too high
3) Distraction treatment: better than containment? Best treatment in older child?
4) Children should not be treated after age 10 since results of containment are poor?
How to reconcile the controversies for your own child
1) Best method of containment?; if you can maintain ROM and tolerate the external brace for 1-2 years (less in younger
children) then go with brace; If you cannot tolerate the brace, then look at the pros and cons listed above and see what you
feel most comfortable with. Discuss with your surgeon. Discuss with your child.
2) TNHT?: go to Dr. Lopes web site. At this point, it is a low risk procedure and if it works you win. If it does not work
there is minimal risk.
3) Distraction Treatment?: all investigators results seem to indicate that distraction is at least as good as containment
methods. If planning a containment surgery then consider this as an alternative. For children over age 9, distraction may
become the method of choice. For failure with containment method, distraction can still salvage the hip. This method may not
be available in your area, therefore you need to decide if you are prepared to travel to obtain this treatment.
4) > 10 years don’t treat?: probably true for containment methods. Not true for distraction. Nothing to lose with
distraction by doing treatment. Failed distraction treatment no worse than failed no treatment.
I hope this helps clarify some of the issues surrounding this controversial disease. Certainly, I recommend that you continue to
learn all that you can about this condition and then consider the various factors as you face the important decisions you must
make for your child. Obtain different opinions; speak with other Perthes parents about their experiences. This can help guide
your process.
Dror Paley, MD
dpaley@lengthening.us
 |  |  |  |  |  |
| | | | | |
 |  |  |  |  |  |
Limb Lengthening.us
Dror Paley, MD, FRCSC
Dror Paley, MD, FRCSC
| ORTHOPEDIC EDUCATIONAL SITE BY THE MOST EXPERIENCED LIMB LENGTHENING SURGEON IN THE WORLD |
