Rate of Osteonecrosis After Femoral Lengthening with Intramedullary Lengthening Nails.

Background: There has been historical concern that the use of intramedullary nails could present undue risk of osteonecrosis of the femoral head due to compromise of the femoral blood supply. Intramedullary lengthening nails are rapidly becoming commonplace in lengthening procedures. As such, the primary objective of this study was to analyze the rates of osteonecrosis following femoral lengthening. The secondary objective was to characterize general trends in femoral lengthening.

Methods: This retrospective cohort study evaluated patients who had undergone femoral lengthening at a single institution from 2012 to 2021. Retrospective chart review and radiographic evaluation of osteonecrosis were conducted. The primary end point was radiographic evidence of osteonecrosis. The secondary variables were the starting point of the femoral nail, the total amount of lengthening, and the time to consolidation.

Results: Two hundred and forty-seven patients were included in the analysis, including 111 males and 136 females, with a mean age of 17 years. No patient had radiographic evidence of osteonecrosis (0%) or coxa valga (0%). The average amount of lengthening was 4.88 cm (range, 1.5 to 8.5 cm). No patient had any extensive complications, such as alterations in the proximal femoral anatomy.

Conclusions: This largest study to date investigating complications following femoral lengthening using intramedullary lengthening nails revealed that femoral lengthening is a well-tolerated procedure, and osteonecrosis is an infrequent complication.

Level of evidence: Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.