Short-Term Complications of Relative Femoral Neck Lengthening Combined with Extra-Articular Osteotomies of the Proximal Femur.

PURPOSE: Relative femoral neck lengthening (RNL) is a newer technique to correct coxa breva and coxa vara to relieve a femoro-acetabular impingement and improve hip abductor function without changing the position of the head on the shaft. Proximal femoral osteotomy (PFO) changes the position of the femoral head relative to the shaft. We studied the short-term complications of procedures that combined RNL with PFO.

METHODS: All hips that underwent RNL and PFO using a surgical dislocation and extended retinacular flap development were included. Hips that were treated only with intra-articular femoral osteotomies (IAFO) were excluded. Hips that underwent RNL and PFO, with IAFO and/or acetabular procedures were included. Intra-operative evaluation of the femoral head blood flow was performed with the drill hole technique. Clinical evaluation and hip radiographs were obtained at 1 week, 6 weeks, 3 months, 6 months, 12 months and 24 months.

RESULTS: Seventy two patients (31 males, 41 females, 6-52 years of age) underwent 79 combined RNL and PFO. 22 hips underwent additional procedures like head reduction osteotomy, femoral neck osteotomy, and acetabular osteotomies. There were 6 major and 5 minor complications noted. Two hips developed non-unions, both with basicervical varus-producing osteotomies. Four hips developed femoral head ischemia. Two of these hips avoided collapse with early intervention. One hip had persistent abductor weakness requiring hardware removal and three hips, all in boys developed symptomatic widening of the hip on the operated side from varus-producing osteotomy. One hip had asymptomatic trochanteric non-union.

CONCLUSION: RNL is routinely performed by releasing the short external rotator muscle tendon insertion from the proximal femur to raise the posterior retinacular flap. Though this technique protects the blood supply from direct injury, it seems to stretch the vessels with major corrections in the proximal femur. We recommend evaluating the blood flow intraoperatively and postoperatively and taking necessary steps early to decrease the stretch on the flap. It may be safer to avoid raising the flap for major extra-articular proximal femur corrections.

SIGNIFICANCE: The results of this study suggest ways to improve the safety of procedures that combine RNL and PFO.