Abstract
Purpose
Transposition osteotomy of the acetabulum (TOA), a type of periacetabular osteotomy, has demonstrated long-term efficacy in pain relief and joint preservation in symptomatic developmental dysplasia of the hip (DDH). However, its impact on the natural history of DDH and borderline DDH (BDDH) remains uncertain. This study aimed to determine the efficacy of TOA in altering the natural history of DDH and BDDH by comparing postoperative joint survival to that of untreated contralateral hips.
Methods
A retrospective cohort study was conducted on 683 hips treated with TOA for DDH or BDDH with Tönnis grade 0 or 1 between 1998 and 2021, and 353 untreated contralateral (native) hips. Median follow-up was 10 years (range, 2-30). Hips were categorized by lateral center-edge angle (LCEA) as normal (25° ≤ LCEA < 40°), BDDH (20° ≤ LCEA < 25°), and DDH (LCEA < 20°). Cumulative joint survival was estimated using Kaplan-Meier method, with Tönnis grade 3 or total hip arthroplasty as the endpoint. The log-rank test with Bonferroni correction was used for subgroup comparison. Multivariate Cox models were used to identify independent risk factors for osteoarthritis progression.
Results
In native hips, 20-year joint survival was significantly lower in DDH (65%) compared to normal (100%) and BDDH (95%) (p < 0.05), with no difference between normal and BDDH (p = 0.806). BMI (p = 0.002) and LCEA (p < 0.001) were independent predictors of osteoarthritis progression. In DDH, the 20-year survival after TOA was significantly higher than in native hips (88% vs. 65%, p < 0.001). Independent predictors of progression included native hip status (p < 0.001), age (p = 0.002), and BMI (p = 0.004). In BDDH, TOA-treated hips had comparable 20-year survival to native hips (100% vs. 95%, p = 0.422), with BMI as the only significant risk factor.
Conclusion
Untreated DDH showed significantly lower long-term joint survival compared to normal and BDDH hips. TOA significantly improved joint survival in DDH, supporting its role in modifying the natural history of DDH. Conversely, similar survival rates in TOA-treated and untreated BDDH suggest the need for careful consideration of surgical indications for BDDH.