High prevalence of hip involvement and decrease in inflammatory ultrasound lesions during tumour necrosis factor-α blocking therapy in ankylosing spondylitis

To assess the prevalence of clinical, US and radiographic hip involvement in AS patients with active disease and to explore the associations between these assessments. Furthermore, to evaluate the effect of 6 months of TNF-α blocking therapy on tender and inflammatory power Doppler US lesions of hip joints. Consecutive AS patients starting TNF-α blocking therapy were evaluated for hip joint involvement. At baseline, patient-reported history of hip involvement was assessed and radiographic evaluation (BASRI-hip) was performed. Clinical examination (tender hip joints) and US examination took place before and after 6 months of treatment. Of the 111 included patients, 20% reported a history of hip involvement. At baseline, tender hip joints were present in 23% of patients. US examination showed inflammatory lesions in 17% of patients, of which 74% had positive power Doppler. Structural lesions were present in 20% of patients, of which 55% had osteophytes. Structural radiographic damage was seen in 10% of patients. Highest concordance was found between history of hip involvement and radiographic hip involvement (phi coefficient 0.333). After 6 months of TNF-α blocking therapy, significant decrease was found in tender hip joints (from 29 to 11), total number of inflammatory US lesions (from 29 to 9) and positive power Doppler (from 22 to 6). The prevalence rate of hip involvement in AS patients varies from 10 to 23%, depending on the type of hip assessment. TNF-α blocking therapy significantly improved tender hip joints, and inflammatory US lesions including positive power Doppler.