Clinical and radiological outcomes of direct anterior versus posterolateral total hip arthroplasty in ankylosing spondylitis: A propensity-matched study | Online First

Xingshan Wang^1#, Shaoyi Guo^1#, Dazhao Chen¹, Yixin Zhou¹, Tao Bian¹, Siliang Man², Liang Zhang¹

¹Department of Orthopaedic Surgery, Beijing Jishuitan Hospital, Capital Medical University, Beijing, China
²Department of Rheumatology and Immunology, Beijing Jishuitan Hospital, Capital Medical University, Beijing, China

Keywords: Ankylosing, arthroplasty, articular, hip, range of motion, replacement, spondylitis, treatment outcome.

Abstract

Objectives: This study aims to compare the clinical and radiological outcomes of the direct anterior approach (DAA) and the traditional posterior-lateral approach (PLA) for total hip arthroplasty (THA) in patients with ankylosing spondylitis (AS).

Patients and methods: Between July 2001 and May 2024, a total of 137 patients (117 males, 20 females; mean age: 40.21±13.28 years; range, 17 to 73 years) with AS who underwent THA using the DAA or PLA were retrospectively analyzed. Using propensity score-matching, we retrospectively analyzed data on 164 hips with AS for which THA was performed, with 41 and 123 hips in the DAA and PLA groups, respectively. Preoperative baseline characteristics, surgical data, clinical and radiological outcomes at follow-up were collected and compared between the two groups.

Results: The mean follow-up was 68.05±38.09 months. There were no significant intergroup differences in terms of surgical data, postoperative complications, clinical scores, or patient satisfaction (p > 0.05). Compared to the PLA group, the DAA group had a significantly higher rate of achieving hip flexion over 90° (82.93% vs. 60.98%, p = 0.010), with fewer patients in the group reporting difficulty with putting on socks (p = 0.003). The DAA group exhibited a smaller acetabular anteversion (17.10±6.60° vs. 20.68±8.73°, p = 0.031), with a higher proportion of acetabular components positioned within the Lewinnek safe zone (82.93% vs. 60.16%, p = 0.008).

Conclusion: Although both surgical approaches are effective for managing hip involvement in ankylosing spondylitis undergoing THA, the DAA may offer functional benefits and improved prosthetic alignment. These advantages support its consideration as a favorable surgical option in appropriately selected patients,

# Xingshan Wang and Shaoyi Guo contributed equally to this manuscript and should be considered co-first authors

Citation: Wang X, Guo S, Chen D, Zhou Y, Bian T, Man S, et al. Clinical and radiological outcomes of direct anterior versus posterolateral total hip arthroplasty in ankylosing spondylitis: A propensity-matched study. Jt Dis Relat Surg 2026;37(x):i-x. doi: 10.52312/jdrs.2026.2738.