Femoral lengthening with lengthening over a nail has fewer complications than intramedullary skeletal kinetic distraction

Abstract

Background: Lengthening over a nail and internal lengthening nails have been developed to minimize or eliminate patients' time wearing a frame during femur lengthening. However it is unclear whether either of these two approaches results in faster times to union or fewer complications over the other.

Questions/purposes: We asked which technique better achieved: (1) the lengthening goals, (2) the distraction rate control, (3) quality of the regenerate bone, (4) fewer complications, and (5) if SF-36 scores and American Academy of Orthopaedic Surgeons Lower Limb Module (AAOS LLM) scores differ in each treatment modality?

Methods: We retrospectively reviewed the records and radiographs of 11 patients who had 12 Intramedullary Skeletal Kinetic Distractor (ISKD) procedures between 2002 and 2005, and 21 patients with 22 femoral lengthenings performed as lengthening over nail procedures between 2005 and 2009. Details such as leg length discrepancies, operative time, time of removal of the external fixator or ISKD, and any complications encountered were recorded. SF-36 and AAOS LLM scores also were compiled. The minimum followups for the ISKD and the lengthening over nail cohorts were 62 months (average, 76 months; range, 62-93 months) and 13 months (average, 27 months; range, 13-38 months), respectively.

Results: We observed no difference in achieving the lengthening goals between the two procedures. Distraction was not well controlled in the ISKD group; the distraction rates were 1.7 mm per day for the fast group (distraction rate greater than 1 mm/day) and 0.84 mm per day for the slow group (less than 1 mm/day). The lengthening over nail group had an average distraction rate of 0.88 mm per day. One of 20 of the patients who had lengthening over a nail had complications requiring additional unanticipated surgeries whereas six of 12 patients who had femoral lengthening in the ISKD group had such complications.

Conclusions: Based on our observations, we believe the lengthening over nail technique for femoral lengthening is associated with fewer complications than the ISKD.

Level of evidence: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Fig. 1A–D

(A) A preoperative radiograph obtained before LON shows the lower extremities of a 17-year-old male patient with a history of proximal focal femoral deficiency and a 3-cm leg length discrepancy on the left side. (B) A postoperative radiograph taken 4 weeks after surgery shows the distraction performed by the external rail. (C) At 8 weeks, the rail has been removed and the intramedullary nail has been locked distally to protect the well-formed regenerate bone. (D) At 5 months, the regenerate bone has fully consolidated. LON = lengthening over nail.

Fig. 2A–D

(A) A clinical photograph of the lower extremities of a 30-year-old man with a history of a femur fracture and a 4-cm leg length discrepancy is shown. (B) The fracture is evident on this preoperative radiograph of his left lower extremity. The patient was treated nonoperatively with the ISKD. (C) Five weeks after surgery, his postoperative radiograph shows full distraction and evidence of bone regenerate forming. (D) At 5 months, the regenerate is well healed in all cortices. ISKD = Intramedullary Skeletal Kinetic Distractor.