A comprehensive evaluation of radiographic trochanteric enthesitis in axial spondyloarthritis: Prevalence, disease activity, and functional impairments

Objective: Enthesitis is a hallmark of axial spondyloarthritis (axSpA) with a notable impact on quality of life. However, information on the prevalence, burden of damage, and associated characteristics of trochanteric enthesitis is lacking. This novel study aimed to explore the prevalence of radiographic trochanteric enthesitis in axSpA patients and analyze its association with disease activity and functional impairments in detail. Methods: This retrospective cross-sectional observational study included 165 patients diagnosed with axSpA who underwent pelvic radiography. Clinical and demographic data were collected, including disease activity scores, functional status, and spinal mobility. Statistical analyses examined associations with trochanteric enthesitis; binary logistic regression identified independent predictors. Results: Radiographically, trochanteric enthesitis was observed in 19 patients (11.5%), more commonly bilaterally (89.5%) and more prevalently in radiographic axSpA (17.7% vs. 5.8%, p = 0.032). Patients with trochanteric enthesitis had higher inflammatory markers (erythrocyte sedimentation rate [ESR], C‑reactive protein [CRP]; p = 0.034, p = 0.006), disease activity scores (axial spondyloarthritis disease activity score with CRP [ASDAS-CRP], ASDAS-ESR, Bath Ankylosing Spondylitis Disease Activity Index [BASDAI]; p = 0.004, p = 0.034, p = 0.032), and impaired spinal mobility (Bath Ankylosing Spondylitis Metrology Index [BASMI], p = 0.014). Functional impairments were observed in lumbar lateral flexion, intermalleolar distance, cervical rotation, and chest expansion (p = 0.048, p = 0.009, p = 0.029, p = 0.029). In binary logistic regression, age (p = 0.015) and CRP (p = 0.011) emerged as independent predictors of radiographic trochanteric enthesitis. Conclusion: Trochanteric enthesitis affects a notable subset of axSpA patients, especially those who are older and have elevated CRP. It is associated with higher disease activity, increased systemic inflammation, and functional impairment.