Inflammatory changes of hip synovial structures in polymyalgia rheumatica.

OBJECTIVE To investigate the hip inflammatory lesions and to evaluate the accuracy of clinical examination compared to magnetic resonance imaging (MRI) in patients with polymyalgia rheumatica (PMR) with pelvic girdle symptoms. Secondary end-point was to evaluate the sensitivity and specificity of ultrasonography (US) compared to MRI in the assessment of hip lesions. METHODS Case-control study of 20 consecutive PMR patients and 40 controls with different rheumatic conditions. Both groups were clinically assessed for the presence of hip synovitis, trochanteric, iliopsoas and ischiogluteal bursitis. Hip MRI was performed in all case-patients and in 10 controls. Both groups were examined by US. An additional group of 10 healthy controls was examined by hip US. RESULTS Both MRI and US detected trochanteric bursitis in 100% of PMR patients, bilateral in 18/20 (90%), and in 12/40 (30%) controls (p < 0.001). Hip synovitis was detected in 17/20 (85%) by MRI and in 9/20 (45%) by US (p < 0.02) in case-patients and in 18/40 (45%) controls. In PMR, MRI and US showed iliopsoas bursitis in 10/20 (50%) and 6/20 (30%) and ischiogluteal bursitis in 5/20 (25%) and 4/20 (20%) with no differences compared to controls. Clinical examination showed a good accuracy for hip synovitis, trochanteric and ischiogluteal bursitis, while it overestimated the presence of iliopsoas bursitis. US was less sensitive than MRI for the detection of hip synovitis and iliopsoas bursitis (53% and 60%). CONCLUSION Trochanteric bursitis represents the most frequent hip lesion in PMR. A careful physical examination allows to detect all inflammatory lesions excluding iliopsoas bursitis. US is less sensitive than MRI in the assessment of hip synovitis and iliopsoas bursitis.