Primary Total Hip Arthroplasty in Patients Less Than 30 Years of Age: Durable, But Not Free of Complications.

Background: Primary total hip arthroplasty(THA) in young patients presents surgical challenges due to preoperative conditions and the likelihood of an active postoperative lifestyle. This study assesses mid-term (mean 7.5 years) survivorship and risk factors for revisions and reoperations in patients aged 30 years or younger undergoing primary THA.

Methods: There were 353 patients (428 hips) aged ≤ 30 years who underwent primary THA between 2000- 2020 reviewed. The average follow-up was 7.5 years(range, two to 22),mean age at surgery was 23 years(range, 11 to 30),with 51% being women. The mean BMI was 27(range, 15 to 51). Common diagnoses included osteonecrosis(30%), hip dysplasia(25%), and osteoarthritis(14%). All acetabular components were cementless, with bearing surfaces comprising ceramic-on-highly-cross-linked polyethylene(C-XP) in 192 hips(45%), ceramic-on-ceramic(CoC) in 156 hips(37%), and metal-on-highly-cross-linked polyethylene(M-XP) in 78 hips(18%). Of the stems, 92% were cementless. Data on revision, reoperation, and the latest follow-up were utilized as endpoints in survivorship analyses, employing a Cox regression model to identify predictive variables.

Results: Survivorship-free of revision was 97,94,and 88% at five,10, and15 years,respectively, while survivorship-free of any reoperation was 96,93,and 87% at the same time intervals. Complications occurred in 67 cases, with the most common being instability(28%), intraoperative fractures(18%), and periprosthetic joint infection(15%). Index THA secondary to infection increased the risk of reoperation(HR [hazard ratio]=11.48,P =0.0081). 28 mm femoral head sizes and M-XP bearings of increased risk for complications(HR = 1.88,P < 0.043 and HR=1.89,P < 0.031). Cemented femoral components, common in diverse unusual diagnoses, were associated with complications(HR=2.53,P<0.0036), revision(HR=7.79,P<0.0001),and reoperations(HR=8.02,P<0.0001). Atypical approaches, such as extended femoral osteotomy and lateral approaches,were associated with higher complication rates(HR=7.49,P<0.0008 and HR=9.70,P<0.0001,respectively).

Conclusion: At 15 years, patients under 30 undergoing modern THA showed high survivorship. Factors associated with increased complexity, such as the use of cemented stems, preoperative infection, and extended approaches, were associated with higher failure rates.