Predictors of Reoperation and Survival Experience (Minimum 1 Year) for Primary Versus Conversion Total Hip Arthroplasty in Young Patients.

Background: Total hip arthroplasty (THA), including primary and conversion procedures, is commonly used for many types of joint disease in patients aged below 65 years, though few studies have evaluated THA outcomes in young patients (≤ 40 years old). This study examined a large cohort of patients who underwent THA at a young (≤ 40 years old) age to identify predictors of reoperation and compare survivorship between primary and conversion THAs.

Methods: A retrospective study was conducted on 497 patients who underwent 612 primary and conversion THAs at 40 years old or younger between 1990 and 2020. Medical records were reviewed to collect patient/surgical data. A multivariable logistic regression model identified independent predictors of reoperation, and Kaplan-Meier analysis with log-rank tests was used to compare survival curves by THA type.

Results: The median age at surgery (interquartile range) was 31 years (25 to 36). The median follow-up time was 6.6 years (range, 3.8 to 10.5). Conversion THAs had an increased rate of both revisions (12.3 versus 5.6%, P = 0.02) and nonrevision reoperations (8.9 versus 3.2%, P = 0.03) compared to primary THAs. A ceramic-on-ceramic articulation (odds ratio: 5.17; P = 0.03) and a higher estimated blood loss (odds ratio: 1.0007; P = 0.03) were independent predictors of reoperation for primary and conversion THA, respectively. Conversion THAs had a lower 15-year survival (77.8 versus 90.8%, P = 0.009) compared to primary THAs.

Conclusions: Patients ≤ 40 years old who underwent primary and conversion THAs demonstrated an impressive 15-year survival comparable to that of older populations (74 to 93%), while conversion procedures had a higher reoperation rate. Although primary THA may be more ideal, there are promising outcomes for patients who need THA at a younger age than typically implemented, especially for those who are very young (≤ 30 years old).