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Summary: Implantable limb lengthening using noninvasively adjusted telescopic nails dates back to 1983. The newest technology is the Precice (Ellipse Technologies). A retrospective study of the first 65 Precice nails was carried out for the treatment of limb length discrepancy (unilateral) and short stature (bilateral). Successful lengthening was achieved in all patients. There were numerous distraction and hardware complications. Despite these, implantable limb lengthening appears to be the direction for the future of limb lengthening.

Key Words: limb lengthening—distraction osteogenesis—lengthening nails—implantable lengthening nail—leg length discrepancy—stature lengthening.
(Tech Orthop 2014;29: 72–85)

Surgical limb lengthening dates back to the turn of the 20th century with the publication of Codivilla.1 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 semiportable external fixation devices. The early limb lengtheners2–6 employed distraction osteogenesis to fill the distraction gap produced by their fixators. It was not, however, until the 1950s and 1960s 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 awkwardness7–13

Because of all of the above reasons many postulated and conceived of internal implants14–19 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 198313,20 (Fig. 1). 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 3 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 are limited, as there are only 3 studies in the English literature that have reviewed a total of 37 implants,21–23 although they report good overall results. The series by Singh and colleagues 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 and colleagues reported that 2/12 nails had faulty motors that required reoperation and only 1 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 2 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 2 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. 24–26 In other reports, 12% of the lengthenings remained incomplete because the patients were simply unable to tolerate the pain of the manipulation.25

Using the same concept of lengthening by rotation through the callus, Cole developed a double-clutch mechanism to cause distraction. Only 3 to 9 degrees of rotation was required to cause the nail to lengthen. The intramedullary Skeletal Kinetic Distractor (ISKD) (Orthofix Inc., McKinney, TX) was Food and Drug Administration (FDA) approved in 2001. It was recently removed from the market and is no longer available. As the lengthening was so easy to activate, and as 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.27–30