Does valgus femoral osteotomy improve femoral head roundness in severe Legg-Calvé-Perthes disease?

BACKGROUND: Many surgeons perform a varus femoral or Salter pelvic osteotomy in patients with Legg-Calvé-Perthes (LCP) disease. However, more severely deformed femoral heads show greater congruency in adduction rather than in abduction. Therefore, a valgus-(flexion) femoral osteotomy (VFO) seems preferable rather than a varus femoral or Salter pelvic osteotomy. QUESTIONS/PURPOSES: We evaluated whether the VFO improves (1) femoral head roundness, (2) radiographic parameters reflecting hip subluxation, and (3) function.
METHODS: We treated 25 patients (25 hips; 18 lateral pillar C and seven B) in the late fragmentation stage by VFO. Seven patients had additional pelvic procedures. VFO was performed at a mean age of 9.8 years. Three hips were Stulberg Class II, 20 were Class III, and two were Class IV. The following components of femoral head roundness were calculated from preoperative MRI and final radiographs: lateral and medial head roundness (LHR and MHR); anterior and posterior head roundness (AHR and PHR); central head height; and the ratios MHR/LHR and PHR/AHR. Continuity of Shenton's line, medial gap ratio were evaluated. Function was determined with the Iowa hip score. Minimum followup was 3.1 years (mean, 6.3 years; range, 3.1-11.2 years).
RESULTS: All femoral head roundness measurements improved, with greatest improvement in the lateral and anterior head. Pillar C hips showed greater relative improvement than pillar B hips. The continuity of Shenton's line improved and the mean medial gap ratio decreased. Mean Iowa hip score improved from 71 before surgery to 90 at the last followup.
CONCLUSIONS: VFO appears to help the deformed femoral head in the fragmentation stage to remodel to fit the acetabulum. LEVEL OF EVIDENCE: Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.