Implant survival after primary total hip arthroplasty due to childhood hip disorders: results from the Danish Hip Arthroplasty Registry.

BACKGROUND: Childhood hip disorders including acetabular dysplasia, congenital hip dislocation, epiphysiolysis, and morbus Calve-Legg-Perthes are well-established risk factors for the development of early osteoarthritis of the hip. These patients have an increased risk of undergoing a total hip arthroplasty (THA) operation early in their life. However, there are very few data on implant survival in such patients.

METHODS: We used data from the Danish Hip Arthroplasty Registry to identify patients who had been treated with a primary THA in Denmark between 1995 and 2005. Implant survival during early and late postoperative follow-up (< 6 months and>6 months, respectively) was assessed for patients treated with a primary THA due to childhood hip disorders, and compared with implant survival for THA patients with primary osteoarthritis.

RESULTS: 56,087 THA procedures included 53,694 (96%) hips with primary osteoarthritis, 890 (1.6%) with acetabular dysplasia, 565 (1.0%) with congenital hip dislocation, 267 (0.5%) with epiphysiolysis, and 404 (0.7%) hips with morbus Calve-Legg-Perthes Patients with acetabular dysplasia had an increased risk of revision during the 0-6-month postoperative period compared to patients with primary osteoarthritis (adjusted relative risk (RR)=1.9 (95% CI: 1.2-3.1)). These revisions were mainly performed due to dislocation of the THA, providing an adjusted RR of revision due to dislocation of 2.8 (95% CI: 1.6-4.9) compared to patients operated due to primary osteoarthritis. We found no statistically significant differences in risk of revision for the other childhood hip disorder groups during the early postoperative phase. In addition, we found no substantial differences in revision risk during later follow-up (0.5-12 years) for any of the childhood hip disorders compared to patients with primary osteoarthritis.

INTERPRETATION: We found an encouraging rate of long-term implant survival for patients with childhood hip disorders. The major concern is the increased risk of revision because of dislocation in the first 6 postoperative months for patients with acetabular dysplasia. However, the advent of alternative bearings and the use of large-diameter femoral heads may improve the outcome after primary THA in these patients.