Dror Paley, MD, FRCSC
|ORTHOPEDIC EDUCATIONAL SITE BY THE MOST
EXPERIENCED LIMB LENGTHENING SURGEON IN THE
In August 2011, a new implantable lengthening device, the PRECICE, was approved by the FDA. It was developed by Ellipse Technologies, out
of California in conjunction with a team of orthopedic surgeon consultants, myself included. The Precice has an internal lengthening mechanism
that consists of a magnet connected to three sets of planetary gears (1/64 reduction), connected to a threaded rod. The threaded rod drives a
telescopic tube which can expand. Using an external rotating magnet (ERC device) applied close to the skin at the level of the magnet inside the
rod the internal magnet can be rotated. Rotating one way causes lengthening which rotating the magnet the opposite way causes shortening. It
takes hundreds of revolutions of the external magnet to effect a 1 mm change in length of the nail. It takes 7 minutes to achieve 1mm.Unlike
previous devices the Precice has excellent rate control in both directions. The nail is designed to be able to lengthen against a force of 80kg
(176 lbs). The forces that need to be resisted inside the limb have been reported to be up to 50 kg (110 lbs). Therefore this nail is more than
strong enough to lengthen even the largest bone (femur).
The FDA clearance of the Precice 2 in Nov. 2013, heralds in a new era for limb lengthening but especially for cosmetic limb
lengthening. We now finally have a device that can be implanted with minimal incision surgery and which can perform lengthening
by a remotely controlled mechanism without rate control problems. The safety factor with this device is excellent since it can be
lengthened at any rate and can even be reversed to shorten the limb.
Despite the ease of insertion and use, the limb lengthening process remains the same and the risks associated with limb
lengthening remain unchanged. For these reasons it is still essential that a surgeon experienced in limb lengthening and in the
treatment of lengthening complications be he one performing the procedure and following the patient. (see complications section
Recovery from Implantable Limb Lengthening (also see FAQ's)
The typical recovery from bilateral femoral or tibial lengthening is as follows:
1) surgery and hospitalization: 3-4 days
2) distraction phase (weight bearing (WB) for transfers only; daily PT). Femur:one day for each mm of lengthening (65 mm
= 65 days); Tibia ¾ mm per day (65mm=87 days)
3) consolidation phase until full WB permitted = 4-6 weeks in most but can be longer. The end of this phase is when the
bone on the x-ray appears to bridge the lengthening gap at least on one side. WB is progressed from transfers only to full WB.
4) Rehabilitation phase: full WB without crutches. Regaining of muscle strength and joint range of motion to normal.
Usually 1-3 months.
5) Return to sports usually by 4-6 months after surgery.
Removal of Implant
The implantable lengthening device should be removed. Although it is made of inert metal (titanium), there are also other
materials including rare earth magnets, etc. The moving parts also can lead to wear and even corrosion. For these reasons it is
preferable to remove the device. The device can usually be removed as early as one year after surgery. There is no urgency in
the timing of removal but it should be done. The removal is an outpatient procedure but does add some cost to the total costs
of this surgery. It can be deferred for more than one year.
Historical perspective on implantable limb lengthening devices:
I have been performing Limb Lengthening Surgery since 1986. The two main indications for such surgery are limb length equalization for limb
length discrepancy (LLD) and stature lengthening for short stature. Since 1986 I have performed over 17,000 limb lengthening surgeries. This is
more than any other surgeon in the US or the world. The majority of these surgeries were for LLD. Over 1500 were for short stature related to
dwarfism and cosmetic reasons.
Dr. Paley’s history with cosmetic lengthening for stature is as follows:
Dr. Paley started with the Ilizarov method for lengthening of both tibias in 1987 and soon after switched to the lengthening over
nail method he had developed in 1990. Although his results were excellent, the scars, the pain, the suffering, the pin site
infections were not conducive to a cosmetic procedure.
He sought a fully implantable lengthening solution. When the Alibizzia nail, developed by Guichet became available he worked
with the French company that made the nail to develop a tibial lengthening Albizzia for stature lengthening. He started using this
in 1996. The severe pain experienced by patients from the 15 rotation of the thigh through the break in the bone, as well as
several implant failures lead him to stop using this non-FDA approved device. In 2001, when the ISKD, developed by Dr. Cole
was approved by the FDA and marketed by Orthofix became available, Dr. Paley was the first surgeon after Dr. Cole to implant
this device. This device turned out not to be a great device for stature lengthening. Although he performed over 350 ISKD
implantable limb lengthenings, more than anyone in the world, the lack of rate control with this device caused many
complications. The other problem with the ISKD was frequent malfunction of the mechanism, which for unexplained reasons
would fail to lengthen in the middle of the distraction phase. This lead to increased numbers of procedures to treat
complications. For stature patients this also meant increased costs. Despite this his final results were excellent in almost every
patient with the ISKD. The ISKD, the Albizzia and the Fitbone are all contemporary devices. They can all be considered first
generation lengthening nails. They all suffer from significant mechanical and other problems.
The first second generation device on the market is the Precice. On December 1, 2011, Dr. Paley implanted the first 3 Precice
nails in the United states. By November 2013, he performed over 155 Precice cases (more than any other surgeon worldwide).
These cases include femoral, tibial and humeral lengthening with the Precice. The results with this device were excellent. The
most serious shortcomings of the device were breakages of the nail that occurred in three cases and breakages of the
mechanism that occurred in 5 cases. All the breakages of the device occurred at the welds connecting the mechanism to the rest
of the nail. The mechanism breakages occurred between the magnetic driveshaft to gear coupling of the nail mechanism when
too much resistance from dense bone formation occurred. Dr. Paley was the first to identify these problems and together with
Ellipse Technologies they set out to redesign the nail without welds and with a stronger coupling. The improved device is called
the Precice2 and has increased the strength of the nail shell by up to 4X and of the mechanism by up to 3X. This is expected to
eliminate the uncommon problem of breakage and mechanism failure and allow for increase weightbearing. Dr. Paley was the
first surgeon to implant the Precice 2 for stature lengthening in Nov. 2013. He has now successfully used this device in over 20
Here are the links to first PRECICE lengthenings we performed in the news:
History of Implantable Limb Lengthening
Surgical limb lengthening dates back to the turn of the 20th century with the publication of Codivilla. Over the first half of the
20th century, the lengthening devices ranged from the traction Thomas splint device of Codivilla, to various bed mounted and
semi-portable external fixation devices. The early limb lengtheners employed distraction osteogenesis to fill the distraction gap
produced by their fixators. It was not however until the 1950’s and 60’s that the biology of distraction osteogenesis became
understood. This was largely due to Ilizarov and his group in Kurgan, USSR. Despite their ability to predictably achieve desired
length, external fixators are plagued by high complication rates secondary to pin tract infections, associated risk of deep
infection, neurovascular injuries, prolonged treatment time until removal, muscular and soft tissue transfixation that lead to
contractures and stiffness, pain and discomfort, refracture after removal of the fixators, as well as, psychosocial burden,
requirement to perform daily pin cleaning and physical awkwardness.
Due to all of the above reasons many postulated and conceived of internal implants to achieve limb lengthening. Implantable
Limb Lengthening using distraction osteogenesis also takes it origins in the Soviet Union. Alexander Bliskunov from Sinferopel,
Ukraine first published his method in 1983. This was before most of the Western world had heard of Ilizarov. Bliskunov
developed a telescopic lengthening nail that used a crankshaft connected to the pelvis to drive his mechanism and lengthen the
femur. Rotational motion of the femur produced lengthening of the nail. The rotation was through the hip joint and not through
the osteotomy. His technology was not available outside of the Soviet Union. Even today it is only used by a few in Ukraine.
Over the last three decades, other fully implantable lengthening nails have been developed. Baumgart and Betz from Germany
developed a motorized nail in 1991 (now called Fitbone). The Fitbone (Wittenstein, Igersheim, Germany) is a fully implantable
lengthening nail whose mechanism is driven by an internal motor that requires an external transmitter. An antenna comes out of
one end of the nail and is implanted subcutaneously. It is powered and controlled by radiofrequency and the lengthening is
performed at night when the patient is in bed to mimic natural growth. Data is limited, as there are only three studies in the
English literature that have reviewed a total of 37 implants , although they report good overall results. The series by Singh et
al. reported that 3/24 nails in 2 patients required later bone grafting. They also had 2 implants that needed to be removed and
exchanged for large diameter implants because the gears in the original nails were not strong enough to achieve distraction.
Baumgart et al. reported that 2/12 nails had faulty motors that required re-operation and only one patient required a later bone
graft procedure. The Fitbone is the only motorized nail available. It is on limited release. To obtain permission to use it one has
to either receive agreement from Dr. Baumgart or the Wittenstein company.
Guichet and Grammont from France, developed a telescopic nail in 1994 using a ratchet mechanism which rotated the two
segments of the nail through the osteotomy and callus of the distraction gap. The Gradual Lengthening Nail also known as
Albizzia (Depuy, Villerbuane, France) was later modified and released as the Betzbone and the Guichet nail for use by its two
namesakes respectively. It takes 20 degrees of rotation to move the ratchet one notch. Each notch is 1/15 of a millimeter. Many
reports exist of patients suffering from severe pain and discomfort, which limit their ability to independently perform the
lengthenings. In some cases, these patients required readmission to the hospital with general anesthesia and closed
manipulation. In other reports, 12% of the lengthenings remained incomplete because the patients were simply unable to
tolerate the pain of the manipulation.
Using the same concept of lengthening by rotation through the callus, Cole developed a double clutch mechanism to cause
distraction. Only 3-9 degrees of rotation was required to cause the nail to lengthen. The intramedullary Skeletal Kinetic
Distractor [ISKD] (Orthofix, Inc., McKinney, Texas) was FDA approved in 2001. It was recently removed from the market and is
no longer available. Since the lengthening was so easy to activate, and since there was no ‘governor’ to the lengthening
mechanism, the nail is free to lengthen at any rate. Too rapid distraction was a frequent complication. This was referred to as a
‘runaway nail’ or ‘runaway lengthening’. Due to the uncontrolled lengthening rate and rhythm the ISKD had a very high
complication rate. The nail would often lengthen at a rate that exceeded the ability for distraction osteogenesis of bone and
histogenesis of soft tissues leading to many complications. Restriction of activities and bracing were required to try and prevent
and control too rapid lengthening. Failure of bone formation required separate bone grafting procedure for deficient regenerate
Arnaud Soubieran from France developed the Phenix nail. The Phenix has a mechanism activated by a large external, hand held
magnet. By rotating the magnet around the leg an internal crankshaft mechanism in the nail was rotated. This lead to traction
on a wire pulley, which caused distraction of the nail. The mechanism for the Phenix was first used in a spinal distractor, and, in
a lengthening prosthesis manufactured by the same company. Rotating the magnet one direction leads to lengthening while
rotating it the other way leads to shortening. This device was self marketed by Soubieran until 2012 at the time of his accidental
death. The Phenix produced excellent results in the small number of cases in which it was used. There were anecdotal reports
that the nail was not able to lengthen against too much force. A version of his mechanism is contracted to Smith and Nephew
and awaits FDA clearance and release.
Ellipse Technologies(Ellipse Technologies, Irvine, California) developed the Precice nail with a team of surgeons (Dr. Paley
included) headed by Dr. Stuart Green. Ellipse used the same mechanism that they had developed for their spinal growing rod
called “the MAGEC System” . There is a magnetic metal spindle that is connected to a series of gears. The gears are connected
to a coupling, which is connected to a threaded drive shaft. The mechanism is activated by an external remote control (ERC)
device. The ERC employs two motor driven rotating magnets to magnetically couple to and rotate the magnetic metal spindle.
The ERC performs 30 revolutions per minute. It takes 7 minutes and 210 revolutions to achieve one mm of lengthening. Facing
the ERC one direction causes the nail to lengthen, while facing it the other direction would go in the reverse (shortening)
direction. The Precice is the second FDA cleared implantable lengthening nail device (July 2011) and the first one to have
bidirectional control (lengthening and shortening). I had the privilege of implanting the first Precice nail in the US on Dec. 1,
2011. The initial experience with this device in the US and several countries around the world has been excellent. Nevertheless,
there have been many lessons from the learning curve of this device.
Device evolution is part of progress. Dr. Paley had the privilege of being involved in the development of four of the implantable
lengthening nails that are used today. He was a consultant to the Medinov of the Landinger group (Nancy, France) regarding the
Albizzia nail and designed and first implanted their tibial nail (femoral nail developed by Guichet and Grammont). This non-FDA
approved device was used as a compassionate use device in the US in the mid 1990’s by Dr. Paley. This experience uncovered
an essential design problem that led to frequent failure due to wear ratchet gear. Hardening the metal used for this part solved
this problem. The current Albizzia has also been strengthened to use cobalt chrome instead of stainless steel to permit greater
weight bearing in bilateral lengthening cases. It is currently marketed as either the Guichet nail or Betz bone device by these two
surgeons respectively. Despite the increased strength of cobalt chrome there continue to be fatigue failures of the stainless
steel screws due to excessive loading, as a reminder that unprotected weightbearing until distraction gap consolidation is not a
good idea. Dr. Paley was also the first user of the ISKD device after its inventor Dean Cole, MD. As a consultant to Orthofix at
that time, the company was advised in the first year of ISKD device use (2001-2002), that the lack of rate control was a major
problem. Certainly many of the problems of not being able to get the nail going which plagued the Albizzia, were solved by the
smaller degree of rotation required to actuate the lengthening. These were replaced by the ‘runaway’ phenomenon of too rapid
distraction. While surgeons worked around this problem by decreasing patient activity, using bulky braces such as hip-knee-
ankle-foot orthotics, no fix to the problem was offered by the company. The device was finally withdrawn from the market in
2011. It is unknown whether an ISKD2 with better rate control will be available in the future. Dr. Paley also worked with Arnaud
Soubieran while he was developing the Phenix nail. There were many trials and tribulation with the initial mechanism. After
Soubieran solved most of these, the Dr. Paley introduced this nail to Smith and Nephew and worked briefly as a consultant for
them on this device. In 2010, Dr.Paley elected to leave the Smith and Nephew team and to become part of the Precice nail
development team headed by Stuart Green, MD. In that capacity he worked with former company engineer Scott Pool to
redesign the Precice, leading to the release and FDA clearance of the Precice 2 in Nov. 2013.
The future for non-invasively adjusted limb lengthening devices is very exciting. Future innovation will likely produce a bone
transport nail to treat bone defects, limb lengthening plate for children with open growth plates, and gradual deformity
correction plates. Miniaturization and new mechanisms will allow greater application of such technology. Adjustable nails could
eventually replace simple locking nails for trauma, allowing adjustability of length postoperatively. The same technology as
applied to prostheses will also find its way from growing prostheses for bone tumors in children to adjustable length joint
replacement for the treatment of arthritis.
Preoperative planning is important before surgery to determine the ideal nail length, insertion point (e.g. trochanteric vs
piriformis), osteotomy level and direction of the nail (antegrade vs retrograde). The nail length and osteotomy level are very
inter-related. To avoid too much friction the osteotomy level is planned to leave one to three centimeters of the wider tube of
the nail engaged in the opposite segment of the bone (this is explained in detail below). When there is a larger femoral bow we
prefer to make the osteotomy at the level of the apex of the bow. Working backwards this can help calculate the ideal length of
the nail to use. In most cases a relatively short nail is used compared to nailing for fixation of fractures. The femur can be
reamed with flexible or straight rigid reamers. The latter are less available and less forgiving. However they conform to the shape
of the nail better and are preferred if available. Piriformis start is preferred in most adult femurs unless there is a coxa breva or
valga. In children with open proximal femoral physes, a trochanteric start point is preferred to minimize the risk of avascular
necrosis. Retrograde nailing is used in the femur in conjunction with angular deformity correction of the distal femur or if there
is a quadriceps lag that needs to be tightened (one case in the series below had retrograde nailing for the quadriceps lag).
Retrograde tibial nailing is used in patients with pantalar arthrodesis.
Dr. Paley’s Surgical Technique Femur:
Step 1: The patient is positioned supine on a radiolucent operating table. A radiolucent bump (usually a folded towel or sheet)
is placed underneath the ischium on the operative side. This allows good visualization of the hip on both AP and cross table
Step 2: Using the image intensifier (fluoroscopy) the tip of the level of the greater trochanter is marked on the skin. Knowing
the length of the nail to be used for the surgery, a ruler is used to mark the distal end of the nail.
Step 3: The level of the osteotomy is determined by knowing the amount of distraction planned. One must plan to end up with
the larger diameter of the nail always engaged on both sides of the distraction gap at the end of lengthening. Assuming one
wants to have 2cms of the larger diameter of the nail engaged, then add 2cms plus the 3cms of smaller diameter nail, which is
exposed plus the distraction amount. This total measured from the distal end of the nail represents the level of the desired
osteotomy that will leave at least two cms of the larger diameter of nail always engaged.
Step 4: Make a 1cm incision laterally at the level of the osteotomy. Drill holes using a 4.8mm drill bit. I prefer one entrance and
three exit holes; anteromedial, anterolateral, and medial. Then make two more holes anterolateral and posterolateral at the level
of the other holes. These holes will serve to vent the canal from fat emboli and to allow the reamings that spill out to help
fertilize the bone formation at the distraction gap.
Step 5: Get your starting point using a Steinmann pin in the piriformis fossa for adults or children with closed growth plates.
Enlarge this opening using an ACL reamer. For open growth plates insert the Steinmann pin into the tip of the greater
Step 6: Open the fossa or trochanter with an ACL reamer.
Step 7: Insert a beaded guide rod down the femur.
Step 8: Ream in one mm increments until there is chatter and then in ½ mm increments. Ream to 12.5 mm for the 10.7mm nail
and to 14.5 for the 12.5mm nail.
Step 9: Prepare the nail for insertion. Precice 2, the nail is not modular and one must choose the length of the entire nail in
Step 10: Apply the proximal targeting device and test its alignment to the screw holes by insertion the drill guides and bits.
Step 11: Place the nail under the beam of the image intensifier to see if the mechanism is not pre-distracted. Save this image for
Step 12: Remove the initial beaded guide wire used for reaming, as the nail is not cannulated. Insert the nail into the canal up to
the level of the planned osteotomy (drill holes).
Step 13: Have one assistant lift the foot off the table. Have the other assistant lift the proximal end of the nail using the
insertion guide. The two assistants are applying an extension moment to the femur to prevent displacement of the femur during
Step 14: Use a sharp osteotome to osteotomize the femur through the one cm lateral incision. The femur will easily break
through the six drill holes. Listen for the break and once it occurs withdraw the osteotome. Test that the femur is fractured
while maintaining the extension moment. Move the femur gently into varus and valgus and watch it move on the image
Step 15: Once the break is confirmed to be complete, advance the nail by gently hammering on the impactor until the upper end
is at the level of the base of the piriformis fossa or just inside the greater trochanter for piriformis and trochanteric nails
Step 16: Lock the nail proximally with two screws. For distal locking screws, my personal preference is to insert a long 1.8mm
wire into the locking hole, followed by a 3.8mm cannulated drill for the distal 10.7 nails and a 4.8mm cannulated drill for the
distal 12.5mm drills. In the 10.7 over drill with a solid 4.0 mm drill after removing the cannulated one.
Step 17: Lock the nail distally with two screws. Avoid inserting the antero-posterior middle screw because it can act as a stress
riser for fracture of the femur.
Step 18: Insert the end cap into the proximal part of the nail.
Step 20: Close all the incisions
Step 21: Insert the ERC device into a sterile sleeve. Mark out the level of the magnet on the skin using fluoroscopy. Apply, the
ERC directly over the magnetic spindle, using the image intensifier to mark out the magnet. It takes 7 minutes to lengthen the
femur 1mm. Remember to program the ERC for antegrade or retrograde use.
Step22: Check if the distraction gap is seen radiographically and compare it to the pre-distraction space. If an objective increase
in space is seen the procedure is completed. If not do a second millimeter of distraction to confirm. In the rare case where the
bone does not separate, the nail must be extracted and tested on the bench and if it does not distract then replaced with
another nail. An incomplete osteotomy can cause a failure of distraction and can even lead to failure of the mechanism due to
the high force of resistance.
Dr. Paley’s Surgical Technique Tibia:
Step 1: Mark the proximal and distal end of the nail as before.
Step 2: Mark the level of the osteotomy as before.
Step 3: Make a single drill hole anteriorly at the level of the tibial osteotomy. Avoid getting into the anterior compartment.
Additional holes can be made medially and postero-medially under the subcutaneous border.
Step 4: Insert temporary arthrodesis screws just proximal to the distal tibio-fibular joint. Start with a wire from the fibular side
and make sure it passes relatively posteriorly into the tibia. This wire should be oriented distal on the fibula and proximal on the
tibia. A second wire of equal length can be used to measure the appropriate length of the screw. Bring the wire out the tibial
side and then antegrade drill it with a 3.2mm cannulated drill bit. Measure and insert a solid (non-cannulated) 4.5mm screw of
the correct length antegrade.
Step 5: Make a 3cms incision posterolateral in the midlevel of the leg. Dissect between the peroneals and gastro-soleus muscles
anterior to the intermuscular septum. Dissect down to the fibula. Incise and elevate the periosteum off of the lateral aspect of
the fibula and insert a Hohmann elevator anterior and posterior to the fibula. Make multiple drill holes in the fibula with a 1.8mm
wire. Use a narrow osteotome to break the fibula. Confirm that the osteotomy is complete by displacing the osteotomy.
Step 6: Insert a Steinmann pin into the proximal tibia at the level of the joint in line with the medial tibial spine, medial to the
patellar tendon. Start as high and posterior as possible. Use an ACL reamer to open the starting point.
Step 7: Ream the tibia in one mm increments until there is chatter and then in half mm increments until 12.5 mms for the 10.7
mms nail and 14.5mms for the 12.5mms nail.
Step 8: Osteotomize the tibia with a sharp osteotome.
Step 9: Insert the Precice tibial nail down the tibia.
Step 10: Orient the upper end of the nail so that the upper medial locking screw is oriented towards the tibio-fibular joint. Drill
this screw into the head of the fibula. Insert this screw to fix the tibia and fibula. Lock the second proximal locking screw from
the lateral side. If the first drill hole and screw misses the fibula, then lock the fibula separately with another 4.5mm screw in a
retrograde fashion using a wire and cannulated drill first.
Step 11: Free hand lock two of the three distal screws leaving either the middle or distal one empty.
Step 12: Perform a distraction test of one mm using the ERC.
Click here to read Cosmetic Stature Lengthening Frequently Asked Questions (FAQ’s)
Paley Institute Surgical Limb Reconstruction Fellowship Program
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developing an expertise in pediatric and adult limb reconstruction/deformity
surgery of the lower and upper extremities. For more information Click Here