Objective: To study the corrections of the neck-shaft angle (NSA) and the related clinical symptoms after proximal femoral varus osteotomy (PFVO) for the treatment of Legg-Calve-Perthes syndrome (LCPS).
Material and Method: Retrospective cohort study. Consecutive cases of LCPS treated at Lerdsin General Hospital during 1999 to 2010 were reviewed. The patients were excluded if they had less than 3 years of follow-up, there was incomplete data, and bilateral involvement. Demographic data and clinical symptoms were collected. The NSA were measured before and after PFVO.
Results: Twenty-two patients were treated by PFVO. The mean pre-operative NSA was 140 degrees. The mean varus angle created by PFVO was 20 degrees. The mean post-operative NSA at 6 weeks, 6 months, 1 year, 2 years and 3 years were 119, 119, 118, 120 and 120 degrees respectively. No statistical difference between the mean NSA at 6 weeks and 3 years (p = 0.65). There were 9 patients whose NSA increased more than 5 degrees at 3 years after operation. This group of patients had a more varus angulation at the early post-operative period. No physeal arrest was detected in any cases at 3 years after PFVO. No correlation between the NSA and pain or limitation of the hip abduction were observed. There were 3 patients, who had NSA less than 110 degrees after PFVO, had limping gait.
Conclusion: It is difficult to predict the degree of remodeling of an individual hip after proximal femoral varus osteotomy. Special attention should be paid to avoid excessive varus of the proximal femur less than 110 degrees whenever PFVO is performed.

Keywords: Legg-Calve-Perthes syndrome, Perthes, Neck-shaft angle, Proximal femoral varus osteotomy, Remodeling, Treatment