Anterior distal femoral hemiepiphysiodesis can reduce fixed flexion deformity of the knee: a retrospective study of 83 knees

Abstract

Background and purpose - Fixed knee flexion deformity in children is a common problem in various diseases including myelomeningocele and cerebral palsy. Until now, only a few studies focusing on the surgical procedure of anterior distal femoral hemiepiphysiodesis have been published. We analyzed outcome and correction rate in the largest case series to date of patients treated by staples or 8-plates. Patients and methods - We reviewed the medical records of all patients with fixed knee flexion deformity who were treated with anterior distal femoral hemiepiphysiodesis using either staples or 8-plates between the years 2002 and 2017 (73 patients; 130 knees). 49 patients (83 knees) had completed treatment with implant removal at the time of full correction of the deformity or at skeletal maturity and were included. The average age at operation was 12 years (6-20). Patients were assigned to 3 different groups based on their diagnosis: cerebral palsy, myelomeningocele, and the "other" group.d Results - Mean fixed knee flexion deformity improved from 21° (10-60°) to 8° (0-50°) (p < 0.001) with an average correction rate of 0.44° per month (range -2.14° to 1.74°). The correction rate per month was lowest for patients with cerebral palsy (0.20°), followed by the myelomeningocele group (0.50°), and the "other" group (0.58°). Implant loosening occurred in 10% of the treated knees with consecutive re-implantation in 5% of the cases. Interpretation - Anterior distal femoral hemiepiphysiodesis is an effective and safe method for the treatment of fixed knee flexion deformity in children. The optimal timing depends on the remaining individual growth potential, the underlying disease, and the extent of the deformity.

Figure 1.

Patients and follow-up. a 4 patients (7 knees) had no follow-up after removal and 1 patient (2 knees) had a permanent epiphysiodesis at the time of implant removal. Some patients had implant removal on one side only, although both sides had been treated.

Figure 2.

10-year-old boy with myelomeningocele. Before (a, b) and after (c, d) anterior distal femoral hemiepiphysiodesis. Initial radiographs (a, b) show an avulsion fracture of the lower patellar pole in addition. The small patellar fragment was also resected during surgery (c, d). Radiographs taken 3 years after hemiepiphysiodesis and before the implants were removed (e, f). Flexion deformity improved from 10° extension defi ciency to 0°.