Abstract:

Objective　To develop and validate a navigational template for Salter osteotomy by digital technology.　Methods　Between April 2012 and June 2015, 21 children with unilateral developmental dislocation of the hip underwent Salter osteotomy. Preoperative CT scan pelvic images were obtained. Applying digital technology, Salter osteotomy were simulated and navigational templates for assisting in accurately cutting out a triangular bone graft from  ilium were  designed and manufactured. Then the navigational templates were use in the operations. The acetabular indexes(AI) of both hips were measured before and after surgery and at the latest follow-up. The efficacy wasevaluated according to Mckay clinical effects grading standard and Severin X rays grading standard.　Results　The AIs of both hips measured before and after surgery and at the last follow-up were analyzed with repeated measures analysis of variance. There is significant main effect in time(F=357.72, P=0.00) and in part (F=221.05, P=0.00). There is significant interaction effect between time and part（F=1984.82, P=0.00）. There is significant difference between all the time levels（P=0.00）.The Pearson correlation analysis indicates that the reduction of  AIs of the disordered hip joints is positively related to the angels of the navigational templates（r=0.91，P=0.00） or to the apex angles of the triangular bone grafts from  iliums（r=0.96，P=0.00）. According to Severin X rays grading standard, 14 cases were excellent, 5 cases were good, and 2 cases were poor. The excellent and good rate was 90.48%. According to Mckay clinical effects grading standard, 13 cases were excellent, 7 cases were good, and 1 case was poor. The excellent and goodrate was  95.24%.　Conclusion　The computer-assisted navigational templates can assist in cutting out triangular bone grafts from  ilium more rapidly and more accurately in Salter osteotomy. It can improve the success rate and accuracy of the operations, and shorten the operation time.

Key words:  Hip dislocation;　Osteotomy, 　Computer-aided design