Prophylactic Intramedullary Rodding Following Femoral Lengthening in Congenital Deficiency of the Femur.

Femoral fracture after lengthening of congenital femoral deficiency (CFD) is a common complication with a high incidence, up to 50%. The purpose of this study is to determine whether prophylactic intramedullary Rush rodding after lengthening for CFD is an effective method to prevent femoral fracture and to assess any complications that may result. Forty-five femoral lengthenings (43 CFD patients) were performed using external fixation. At the time of frame removal (except for 3 cases, 8 d later), prophylactic intramedullary Rush rods were inserted. Special reaming techniques were developed to pass a Rush rod through the solid regenerate bone and past sclerotic pin sites. Mean age at time of rodding was 6.9 years (range, 2.9 to 14.2 y). Mean duration of treatment with external fixation was 184 days (range, 146 to 461 d). Mean follow-up was 4.2 years (range, 1.3 to 8.2 y). This group of cases was compared with a historical cohort of 95 femoral lengthening procedures for CFD without prophylactic intramedullary rodding after frame removal previously performed at the same institute by the same surgeons. Eight cases (18%) developed fracture despite intramedullary rodding (1 case with relatively high-energy trauma, 3 cases during physical therapy, and 4 cases spontaneously). Only 4 of these fractures required intervention. Fractures were more common when a 3.18 mm Rush rod was used (28%) compared with 4.76 mm (8.3%). Patients with prophylactic rodding had a significantly lower incidence of femur fracture rodding than those who did not (18% vs. 34%, respectively; P=0.04). Three out of 45 Rush rods (7%) developed infection that were treated by debridement and removal of the rod, and all healed uneventfully without residual or recurrent infection. There were no cases of avascular necrosis. Prophylactic intramedullary rodding is a safe and effective method to prevent femoral fractures after CFD lengthening. Use of 4.76 mm rod is preferred. The risk of infection is acceptable, when compared with the risk of fracture, loss of length, and angulation. Level III-a retrospective comparative study.