Muscle strength improves after abductor-sparing periacetabular osteotomy.

UNLABELLED: We measured muscle strength after curved periacetabular osteotomy, one form of abductor-sparing periacetabular osteotomy, and then investigated the factors influencing postoperative muscle strength recovery. Curved periacetabular osteotomy was performed for acetabular dysplasia on 24 hips in 22 patients. All patients were females, with a mean age of 34.4 years. We based the severity of hip disease on the Tönnis classification. Isokinetic muscle strengths of the hips were measured preoperatively and 6 months and 12 months postoperatively. At 12 months postoperatively, the mean muscle strength (percentage difference to preoperative value) of the abductor was 42.2 Nm (129.6%), adductor 39.4 Nm (131.4%), flexor 48.4 Nm (121%), and extensor 45.8 Nm (130.5%), all of which exceeded the preoperative values. The 12-month postoperative muscle strength of patients with Grade 0 disease based on the Tönnis classification was greater in all directions than that of patients with Grades 1 and 2 disease. The preoperative stage was thought to be an essential factor in postoperative muscle strength recovery. LEVEL OF EVIDENCE: Prognostic study, Level II (lesser quality prospective study--eg, patients enrolled at different points in their disease or < 80% followup). See the Guidelines for Authors a complete description of levels of evidence.