The Modified Tonnis Triple Pelvic Osteotomy in the Young Adult - Early Results

Acetabular dysplasia may present as previously undiagnosed or as a sequel to treated DDH in a young adult, with a natural history of subsequent development of early osteoarthritis. Patients with acetabular dysplasia, a normal neck shaft angle, no significant leg length inequality and who demonstrate congruency at arthrogram are considered suitable for realignment pelvic osteotomy. We report the results of 15 young adults who underwent a modified Tonnis triple osteotomy with a mean 22-month follow-up. The modification was that the ischial osteotomy was performed through a groin incision. The only common complication was the requirement of catheterisation post-operatively (60%). There were no infections. There was one delayed union but no non-unions. One patient developed a deep vein thrombosis. All patients reported an improvement in their symptoms and level of activity, with a mean post-operative Harris hip score of 92. All showed an improved centre-edge angle of 28° (mean increase of 18°) and acetabular angle of 37° (mean decrease of 13°). The early results of this procedure show it to be a safe and useful option to delay the natural history of early osteoarthritis in the young adult.