The Future of Intramedullary Limb Lengthening

and Mark T. Dahl2



(1)
Department of Orthopedic Surgery, University of California – Irvine, Orange, CA, USA

(2)
Limb Length and Deformity Correction Clinics, Gillette Children’s Specialty Healthcare and University of Minnesota, St. Paul / Minneapolis, MN, USA

 



Keywords
Opening wedgeHigh tibial osteotomyCompression osteosynthesisAcute fracturesBone transportCosmetic stature surgery


Once a reliable mechanism for intramedullary lengthening nails was developed, surgeons immediately began to conceive of other ways to eliminate external fixation—with its pain, inconvenience, and pin site infections—with the same ingenious technology. The pattern of innovation resembles the evolution of total knee, shoulder, elbow, and ankle arthroplasties after Sir John Charnley’s monumental development of total hip replacement.


Device Modifications



Lengthening Plates


One limitation of intramedullary lengthening nails, when used for pediatric patients, concerns potential damage to the growth plate by a device that crossed such a sensitive structure. This has led surgeons to hope that someday lengthening plates will be forthcoming. Development in this area is likely to be slow because of two issues: concern about cantilever bending by an off-axis implant and the thickness of such a device in a child’s juxtacortical soft tissues.

The junior author, Mark Dahl, has used the PRECICE® nail in a far off-label application as an internal lengthening implant (Fig. 10.1).

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Fig. 10.1
Intramedullary lengthening nail as extra-osseous lengthener in pediatric patient. (a) Standing AP x-ray image of patient after valgizing osteotomy of hip in proximal femoral focal deficiency. (b) Clinical photograph. (c) Off-label use of lengthening nail as internal distractor. Red arrows point to cortical screws that surround nail to secure it in place. The proximal and distal locking screws have been tapped into the implant for added stability


Trauma Nail


An individual submitting to elective limb lengthening understands in advance the requirements for limited weight bearing while the distraction regenerate matures. Traumatically injured patients, perfectly healthy and functional before their accident, are typically far less cooperative in this regard. Nevertheless, they too will someday soon benefit from motorized intramedullary nails, used as either a distraction device (for post-trauma shortening and bone loss) or in a compression mode (for interfragmentary compression of fresh fractures and non-unions).

The illustrated example consists of a comminuted humeral shaft fracture treated by Dr. J. Tracy Watson of St. Louis. After inserting a pre-lengthened PRECICE® intramedullary nail, he used the External Remote Controller to compress the fracture site until the fracture gap is eliminated. Thereafter, Dr. Watson reassesses the x-ray image and adds additional compression to close residual fracture gap, if present. Once callus begins to appear, Dr. Watson compresses the implant 0.3 mm every 3 weeks to maintain preload and tension in the construct (similar to re-tensioning wires in an Ilizarov circular external fixator) (Figs. 10.2 and 10.3).

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Fig. 10.2
Comminuted humerus fracture treated with PRECICE® intramedullary nail. (a) Initial condition. (b) After nail insertion and interfragmentary compression via External Remote Controller. (c) Union at 4 months


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Fig. 10.3
Technique details of Fig. 10.2: (a) entry point. (b) Guide wire in distal fragment. (c) Nail insertion at fracture site. (d) Insertion completed. Small diameter nail fits well in distal fragment. (e) Proximal locking with guide. (f) Distal locking with alignment circle. (g) Nail fully locked, but gap persists at fracture site (blue bracket). (h) Gap compressed with External Remote Controller


High Tibial Osteotomy


Osteoarthrosis of the knee is an increasingly common problem in every society where aging athletes—professional and amateur—continue to participate in sports long past their prime. Likewise, obesity, previous arthroscopic knee surgery, occupational and avocational injuries, and natural propensities all contribute to the epidemic of gonarthrosis. Total knee replacement (or hemiarthroplasty), while remarkably effective in dealing with the problem, is better suited for older individuals.

For this reason, the high tibial osteotomy has gained popularity as a temporizing procedure, gaining up to 10 years of additional knee function before knee replacement surgery is required. In the past, opening and closing wedge osteotomies have each had their proponents. Likewise, distraction osteogenesis has been employed in conjunction with external fixation to gradually effect opening wedge correction while creating new regenerate bone in the widening distraction zone.

With the advent of intramedullary lengthening, the prospect for a fully implantable alignment device especially designed by the junior author for high tibial osteotomy is on the near horizon, although, as of this writing, not yet approved for marketing by the FDA (Fig. 10.4).

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Fig. 10.4
High tibial osteotomy with specialized intramedullary lengthening nail. (a) Initial condition, comparing actual weight-bearing line (red) to ideal weight-bearing line (blue). (b) Image during nail insertion. Note oval proximal hole that allows proximal tibial to angulate around the implant (red arrow). (c) After distraction, slight overcorrection (red line). (d) Nail compressed slightly to eliminate overcorrection . (e) Result (Courtesy Matt Dawson, FRSC (Tr & O), ESSKA Osteotomy Committee)


Residual Limb Elongation


A short residual limb proves a serious challenge for any amputee. Prosthetic fitting, especially around the hip, may be impossible with a very short remaining femur. Such amputees are often restricted to ischial weight-bearing prostheses—with the associated limp—rather than a suction quadrilateral socket that is suspended from a longer stump.

Ilizarov developed a method of elongating residual limbs, but the process is painful because the external fixation frame must be suspended from the remaining bone, while a fragment of the bone’s tip is pulled through the floppy soft tissues at the end of the stump.

Mark Dahl of Minneapolis employed (on a compassionate use basis) a very short Fitbone® intramedullary nail for residual limb lengthening (Fig. 10.5). The product, however, is not yet FDA cleared for marketing in the United States. Dahl therefore proposed a double telescoping nail for lengthening very short residual femurs, based on the PRECICE® nail technology. Called the Freedom® nail, the device has been cleared for marketing by the FDA and is now available for elongating short femoral residual limbs (Fig. 10.6).

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Fig. 10.5
Residual limb elongation with intramedullary lengthening nail. (a) Initial situation. (be) Progressive elongation with Fitbone® nail. (f) Insertion of longer Fitbone® nail. New osteotomy (cyan line). (g) At completion of second lengthening. (h) Trauma nail exchange to begin weight bearing with prosthesis


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Fig. 10.6
The Freedom® nail , a double telescopic nail for elongating short residual femora. ©2016 NuVasive

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Nov 5, 2018 | Posted by in RHEUMATOLOGY | Comments Off on The Future of Intramedullary Limb Lengthening
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