Background Ankylosing spondylitis(AS) is characterized by inflammation of the sacroiliac joints and spine, resulting in narrowing, sclerosis, erosions and ankylosis. Hip joint involvement in ankylosing spodylitis patients is clearly related to restricted body function due to the important and central function of the hip. However, it seems that limited data are available regarding the epidemiology, and the pathophysiological nature of hip joint involvement.
Objectives Therefore, we described the epidemiology of hip joint involvement in patients with AS, association of hip joint involvement, factors associated with severe hip destruction, leading to the replacement surgery.
Methods 1198 patients with AS (1029 men, 169 women, mean age 33.4 years) were recruited for this study. Radiographs of pelvis and hips were scored by using the Bath Ankylosing Spondylitis Radiology Index (BASRI), and the involvement of hip was determined when the score was above 2. Frequency of hip involvement by age, sex, duration of disease, age at onset of AS symptoms, history of uveitis, peripheral arthritis, enthesitis, and HLA-B27 carrier status was analyzed. Statistical analyses were performed using t-tests for continuous measures, and χ2 tests for categorical measures.
Results The mean age (SD) of the AS patients was 33.4 (9.9) years. The mean onset age (SD) was 22.7 (8.9) years. The mean disease duration (SD) was 10.7 (7.7) years. The male was 1029 (85.9%) patients. 474 patients (39.6%) were found to have a history of peripheral arthritis. 367 (30.6%) patients were found to have a history of radiographic hip joint involvement. 257 (21.5%) patients was found to have JoAS. 1150 (96.0%) patients were HLA-B27 carrier. 332 (27.7%) patients were found to have a history of uveitis. 317 (26.5%) patients were found to have an evidence of enthesitis around pelvic bone and trochanteric areas.
The hip involvement was observed more frequently in male patients. The mean age (SD) of hip joint involvement group was 34.7 (9.7) years, and that was significantly higher than that of control group. The patients of hip joint involvement had an earlier disease onset and a longer disease duration. History of uveitis, enthesitis, and HLA-B27 carrier state were more frequent in the hip involvement group. However, there was no significant difference of peripheral arthritis between two groups.
Conclusions In conclusion, the hip involvement is a common disease manifestation of AS. Long-term studies are needed to evaluate the effect of therapeutic strategies that can prevent hip involvement and the need for hip replacement surgery.
Disclosure of Interest None Declared
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