For information on a specific type of limb problem go to Orthopedic Conditions

The history of external fixation
How the Ilizarov method was introduced and developed in the west

Limb Lengthening Concept, Methods and Complications
Limb Lengthening Methods video presentation

Limb Lengthening: How Does It Work?
The limb lengthening process works by gradually growing new bone and soft tissues
(skin, muscle, nerves, blood vessels, etc). This new growth is called tissue regeneration.
Bone and soft tissue regenerate when they are distracted (pulled apart) at a very slow
rate of approximately 1 mm per day. If the rate of distraction is faster than this, bone
may fail to form between the two ends of the bone that are being pulled apart and soft
tissues, such as muscle, may experience contracture (get too tight) or nerves may
become paralyzed. If the rate of distraction is too slow, premature consolidation may
occur (the bone may consolidate too soon), preventing the lengthening device from
further pulling it apart. There are many different lengthening devices used. The most
common are external fixators, which are devices that attach to the bone by means of thin
wires or thicker pins that have a screw threading at their attachment to the bone. There
are also lengthening devices that are fully implanted inside the bone. These devices do
not require external pins. The different devices are described separately.

There are two phases of lengthening until the bone is fully healed: the distraction phase
and the consolidation phase. The distraction phase is the lengthening phase. After the
desired length is obtained, the newly regenerated bone is still very weak because of lack
of calcium within it. The hardening and calcification of this new bone is called the
consolidation phase.
Methods of Lengthening
I  use a variety of orthopedic devices to distract the bone and soft tissues. The decision regarding which device to use is
individualized for each case, so that the best method to achieve the desired correction can be chosen. There are two general
types of devices: external fixators and internal fixators. The external devices attach to the bone from outside the body by
means of wires and threaded pins. The internal devices are implanted inside the body and lie on the bone or inside the marrow
cavity of the bone. The best known and most versatile techniques are with monolateral (one-sided, or straight bar) external
fixators (e.g., Orthofix, EBI) and circular external fixators (e.g., Ilizarov, TSF). External fixators are applicable to almost all
cases. To shorten the time in the external fixator, I often combine the external fixator method with an internal nail to perform
the lengthening over nail (LON) technique. This method is not applicable to all cases. I also use a fully implantable self-
lengthening nail (ISKD) that has an internal mechanism that performs the lengthening and thereby eliminates the need for an
external fixator. This method is available for certain cases.

External Fixation Alone
When only an external fixator is used, the fixator needs to remain in place for both the distraction and consolidation phases. If
the fixator were removed at the end of the distraction phase, the new bone would collapse and reshorten. Therefore, the
external fixator needs to remain in place until the regenerated bone appears solid enough on the radiographs (x-rays). At that
point, the device can be removed. Often, a cast is applied to temporarily protect the bone from breakage for an additional short
time. The total time in the external fixator can be estimated to be approximately 1 month for each centimeter lengthened in
children and 1.5 to 2 months or longer per centimeter in adults.

Lengthening over Nail
To decrease the external fixator treatment time, eliminate the need for post-removal casting, and decrease the risk of breakage
of the new bone, I developed a method called LON. With LON, I insert a metal rod into the bone together with the external
fixator. The rod fits in the marrow cavity of the center of the bone, and the external fixator is applied around the peripheral part
of the bone so that the external fixator pins do not come in contact with the metal rod. The bone is lengthened as described
above. After lengthening is completed, the patient goes back to the operating room for the insertion of special screws that lock
the rod to the bone. With screws at both ends of the rod on opposite sides of the lengthening zone, the external fixator is no
longer needed. The external fixator is removed during the same operation. Therefore, the total external fixation treatment time
is much shorter and is equal to the distraction phase instead of the distraction plus consolidation phase. This usually reduces
external fixator time to less than half.

Fully Implantable Lengthening Nails and Prostheses
The most recent development is that of fully implantable devices that can lengthen the limb from within without the need for an
external fixator. This has many advantages, including no risk of pin infection, no muscle tethering by the pins, less pain, and
better comfort. Unfortunately, this method is mostly limited to older children and adults. Therefore, many patients cannot be
treated by this method.

Limb Lengthening Process

1: Surgery
For lengthening and deformity correction, the bone is usually cut through a very small incision to minimize injury to tissue. After
surgery, most patients remain in the hospital for 1 to 3 days. A more complex procedure may require a longer inpatient hospital
stay. Rehabilitation starts the day after surgery. Occupational therapists prepare special splints to support the hand or foot
during treatment. Before discharge, all patients are taught to transfer from bed to chair to toilet and to walk using crutches or a
walker, if allowed. Before discharge patients are taught how to adjust their lengthening device to accomplish the necessary
corrections of deformity or length. Patients are also taught how to care for pin sites in cases of external fixation.

2: Distraction Phase
Lengthening usually begins a few days or a week after surgery (latency period). With external fixation, this is done manually.
The manual turns are performed by the patient or their family. With implantable lengthening devices, the lengthening is
performed either by small twists or pressure on the leg. Because bone is a living substance, when the bone ends are gradually
distracted (pulled apart), new bone grows between the bone ends. The lengthening rate is usually 1 mm per day but may be
slower or faster depending on the tolerance of the bone and soft tissues to the distraction process. Most patients experience
little pain during the day. Aching or difficulty sleeping at night is not unusual but is well controlled with medications as needed.
This varies from patient to patient according to individual pain tolerance and the type of treatment being performed. Physical
therapy is required on an outpatient basis in all cases during the distraction phase. These sessions are designed to stretch
muscles to help them to grow and to maintain joint flexibility. In most cases, we allow partial or complete weight bearing as
tolerated. Weight bearing actually stimulates the bone to grow, much in the same way stretching stimulates muscles and other
soft tissues to grow. Most patients are allowed to shower and even to swim during the lengthening process, even with an
external fixator in place. During the distraction phase, patients need to be examined and x-rays obtained every 2 to 3 weeks to
evaluate bone growth, nerve and muscle function, and pin sites and to monitor for and prevent complications from occurring.
The lengthening rate may be adjusted at these visits.

3: Consolidation Phase
After the desired lengthening or deformity correction has been achieved, all adjustments to the lengthening device cease. Newly
regenerated bone is weak at that point in time and would be unable to resist shortening or breakage without the continued
support of the external or internal fixation device. When lengthening is performed with external fixation alone, the external
device remains in place until the end of the consolidation phase. The average total external fixation treatment time for children is
1 month per centimeter and for adults can be as long as 2 months per centimeter. The longer treatment time for adults is the
reason we prefer to use the lengthening over nails (LON) or fully implantable method in adults whenever possible. In the case of
LON, the external fixator is removed at the end of the distraction phase by performing minor outpatient surgery in which the
internal rod is connected to the bone at its sliding end. The external fixator can be removed because the bone is supported
from the inside by the rod. Therefore, the external fixator is in place only for the distraction phase. The consolidation occurs
with the rod alone. In the case of internal lengthening, the device stops automatically at the desired length and the rod supports
the bone until it is fully hardened. Bone healing is judged based on the x-rays. X-rays show us how much calcium is in the bone.
(Calcium appears white on radiographs; the whiter the bone is, the more calcium is present.) When there is sufficient calcium
throughout the region where the bone was separated (distraction gap), the bone is judged to be healed. The x-rays must be
obtained approximately once per month to evaluate bone healing. Once the bone looks sufficiently healed that it will not collapse
the external fxiator rods are temporarily removed to reduce the tension on the bone. This is called dynamization and is the last
step before fixator removal. Usually the external fixator is removed one month after dynamization. The apparatus can usually be
removed one month later.

Phase 6: Removal of the External Fixator
For patients who undergo treatment with external fixation alone, the apparatus can be removed with the patient awake or under
anesthesia. Most patients prefer a general anesthetic. Removal of an external fixator is an outpatient procedure. After removal,
many patients require a cast for a month of additional protection. Patients with internal fixation in place usually do not require a
cast because the internal hardware protects the bone until it is fully hardened.
Complications of Lengthening Surgery

There are many potential complications with lengthening surgery. Meticulous surgical technique, vigilant followup and aggressive
rehabilitation are the most important factors to prevent and even treat complications. Because lengthening occurs gradually the
complications also occur in slow motion. It is important to prevent complications and to recognize if they are occurring. Most
complications are completely reversible by nonoperative or operative means. It is critical to treat complications very aggressively
to end up with normal function and no negative sequellae from surgery. This is why the results of lengthening are very
dependant on the experience of the surgeon. A more experienced surgeon not only knows how to perform the surgery better
but knows how to prevent and treat complications so that there is no residual problem at the end of treatment.

Bone Complications

Delayed Union or Nonunion
Bone regeneration is usually reliable especially in children. It is important to monitor the bone healing by x-ray every two weeks
to make sure it is keeping up with the increasing distraction gap. If the bone healing lags behind the rate of lengthening should
be decreased. Delay in bone healing can be due to damage to the periosteal and endosteal tissues of the bone at the time of the
osteotomy. For this reason using a small incision and performing the osteotomy in a low energy minimal invasive fashion is
important. Instability of the external fixation is another cause of delayed healing. It is important to recognize this and to
stabilize the external fixator. Delay in bone healing leads to delay in removal of the external fixator. If the bone fails to heal
completely then a bone defect or nonunion may result. It is important to recognize this and then to perform surgery to excise
the cyst or fibrous tissue in the gap and to bone graft the defect. This usually results in healing of the bone within three months
of the surgery. ‘

Premature Consolidation
If the bone healing is abundant or fast the bone may heal prematurely. This can be recognized on the x-rays and the rate of
lengthening should be increased to 5 quarter turns a day or to 3 half turns a day. This should only be done for a week at a time
to make sure that the bone formation does not suddenly get delayed. If there is a failure to increase the distraction gap then
the bone is prematurely consolidated. In these cases the bone should be reosteotomized in the operating room.

Axial Deviation
During lengthening the muscle, fascia and bone regenerate tissue create forces to resist the lengthening. These forces are often
unbalanced and tend to bend the bone during the lengthening. The resultant deformity needs to be recognized and corrected at
the end of the distraction phase. If the deformity is not recognized or corrected then the bone will heal with deformity.

Soft Tissue Complications

Muscle Contractures
Contractures occur when the soft tissues cannot accommodate changes in bone length. To treat contractures effectively, one
needs to identify the potential problem muscles. In tibial lengthening, for example, the problem muscles are the gastrocnemius
and toe flexors. As a result, patients can develop knee flexion, ankle plantar flexion, and toe flexion contractures. In the femur,
both rectus femoris and hamstring muscles resist lengthening. This can result in a fixed flexion deformity of the knee and a
flexion range of motion deficit. Lengthening of the humerus involves the fewest problems. If problems do arise, they are the
result of biceps and brachioradialis tightness. In the forearm, finger flexors tighten more quickly, causing proximal and distal
interphalangeal flexion and hyperextension of the metacarpophalangeal joints. Despite these problems, contractures can be
treated with the following modalities.

Passive stretching and soft tissue mobilization: Patients should take pain medications 30 minutes before receiving therapy.
A muscle is prepared for stretching by applying moist heat for 15 minutes before activity. The antagonist muscle should always
be activated before stretching the agonist muscle. The muscle can thereby be relaxed by means of reflexive inhibition. Another
effective method of reducing pain during range of motion exercises is to immobilize the skin over the pin site with tight gauze
wraps. This reduces skin motion around the pins.

In general, biarticular muscles (muscles that work on two joints) should be stretched 20 to 30 times per session and uniarticular
muscles (muscles that work on one joint) should be stretched 10 to 15 times per session. When stretching a biarticular muscle,
obtain maximum stretch in the direction opposite that of the muscle action at both proximal and distal joints and hold each
stretch for 20 to 30 seconds. Some examples of biarticular muscle stretch include rectus femoris stretch with the hip in full
extension and knee flexion and ankle dorsiflexion with knee extension to stretch the gastrocnemius muscle.

Positioning: Optimal maximal positions vary based on the body parts that are affected. For example, patients who are
undergoing tibial lengthening should be positioned with the knee extended straight and the ankle flexed up. Knee extension
along with hip abduction is a desirable position for patients who are undergoing femoral lengthening. Patients undergoing
humeral lengthening need elbow extension. Patients undergoing forearm lengthening require elbow extension (elbow straight),
wrist in slight dorsiflexion (bent upward and backward), and finger extension (straight).

Splints: Custom designed splints help to keep the soft tissues (muscles and tendons) stretched properly. Using a splint to
place a muscle under tension for as many hours as possible helps prevent contractures by obtaining plastic response in the
connective tissue.

Dynamic splinting: In certain situations, we use special dynamic splints. These are different from static splints because they
include a spring-like or elastic mechanism to produce elongation of the tissues through a low load prolonged duration stretch.
Dynamic splints work most effectively in treating knee and elbow flexion contractures. Note that splints work only in optimal
positions and that their tension should always be increased gradually. These types of splints are also often used for the fingers
and toes.

Muscle Weakness
In addition to joint stiffness, patients may experience muscle weakness. This is caused by lack of use (because the patient
cannot walk normally). Pain can also inhibit muscle function, adding to weakness. The following modalities help in the
management of muscle weakness.

Electrical stimulation: Electrical stimulation can be used as an adjunct to a strengthening program and to augment voluntary
muscle contraction. To accomplish this, a muscle stimulator machine is applied to the surface of the limb (thigh, for example)
and a low level electrical signal stimulates the underlying muscle to contract. Some children do not tolerate this well.

Hydrotherapy (water therapy): Hydrotherapy helps patients avoid significant muscle weakness, especially when both legs are
being lengthened. It promotes active range of motion. The natural buoyancy allows simulated weight bearing. The higher the
level of the water (chest deep versus waist deep, for example), the more "weightless" one feels. Hydrotherapy also helps in
keeping pin sites clean.

Progressive weight bearing: Programs of progressive weight bearing are important during all phases of limb lengthening
rehabilitation. During the lengthening phase, patients should be encouraged to perform weight bearing as prescribed. Some
patients may experience pain from increased weight bearing, and the increased weight bearing can cause undue stress on the
pins or wires. Weight bearing is even more critical during the consolidation phase. The patient should progress from two
crutches to one and then to none. He or she should also perform closed chain exercises. (Closed chain exercises are defined as
resistive exercises with which the load is applied through the feet; some examples of closed chain exercises are leg press, stair
climber, and bicycle). Many patients can walk without assistive devices and have no limp during the latter part of the
consolidation phase.

Nerve Injury
Nerve injury is not common and occurs primarily in patients who are undergoing tibial lengthening. It happens when certain
nerves do not stretch enough to accommodate the bone lengthening. Peroneal nerve symptoms during tibial lengthening are
caused by referred pain in the dorsum of the foot. This pain may present initially as hyperesthesia (increased sensitivity) and
then as hypoesthesia (reduced sensitivity). Weakness in the muscles that control toe and foot action are sometimes observed.
Pain medications usually do not help. Referred pain in the top of the foot is increased with knee extension and is relieved by
flexing the knee. When signs of peroneal nerve irritation occur, the use of a dynamic knee extension splint should be
discontinued and knee extension exercises should be reduced. A patient who may be developing this condition should notify the
doctor as soon as possible. In most cases, reducing the rate of lengthening reduces the symptoms of nerve. In cases in which
patients do not respond to rate reduction, peroneal nerve decompression surgery is required. This is a small procedure that
involves a small incision and, at most, an overnight hospital stay. When indicated, nerve decompression prevents permanent
nerve injury and allows the nerve to recover. This, in turn, allows the lengthening to continue.

Physical and occupational therapists play a critical role in limb lengthening and skeletal deformity correction. A successful
functional outcome depends on the quality and amount of therapy a patient receives. Success also depends on the involvement
of the family members and caregivers. Physical therapists should encourage families and care providers to attend the physical
therapy sessions. There, they can learn the optimal positions for stretching and the passive stretching exercises. With team
effort, limb lengthening rehabilitation can be successful.

Other Websites/Links of Interest
Dror Paley, MD, FRCSC
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Paley Institute Surgical Limb Reconstruction Fellowship Program
This UNIQUE fellowship is designed for orthopedic surgeons interested in
developing an expertise in pediatric and adult limb reconstruction/deformity
surgery of the lower and upper extremities
. For more information Click Here