Tendon involvement and its association with pain and hand function in patients with osteoarthritis of the hand.

Objective: To characterize the frequency and influence of tenosynovitis and tendon damage on pain and hand function using clinical examination and US in hand OA.

Methods: We included 86 patients with hand OA and 23 age- and sex-matched control subjects. Extensor and flexor tendons of both hands were assessed by clinical examination and US for tenosynovitis and tendon damage. Conventional radiographs were acquired. Hand function was evaluated by the function subtest of the M-SACRAH (modified Score for the Assessment and Quantification of Chronic Rheumatoid Affections of the Hands) questionnaire and the Moberg pick-up test. K-means cluster analyses was calculated to assess clusters based on radiographic features and sonographic tendon scores.

Results: US identified the involvement of one or more tendon in 60/86 (69.8%) hand OA patients compared with 2/23 (8.7%) subjects (P < 0.01) in the control group. In the hand OA group, US detected tendon damage more often in flexor tendons compared with extensor tendons (2.1% vs 0.9%, P = 0.03), while tenosynovitis was observed more often in extensor tendons compared with flexor tendons (8% vs 0.6%, P < 0001). The sensitivity and specificity of clinical examination to detect tendon involvement was 81.4% and 34.6%, respectively, on the patient level and 14.5% and 83.8% on the tendon level. The cluster analyses revealed one cluster with more radiographic features of hand OA and more tendon damage while more tenosynovitis was found in cluster 2. M-SACRAH function did not correlate with tendon involvement on US.

Conclusion: This study revealed a high frequency of tendon involvement in hand OA. Tendon involvement on US did not impact hand function or self-reported pain.