Objectives To explore the association between radiographic and clinical involvement of the thumb base joint with patient and disease characteristics and with pain and limitations in activities in hand osteoarthritis (OA).
Methods Baseline data of 151 patients with hand OA participating in a randomized clinical trial on the effectiveness of a multidisciplinary treatment program was used. Clinical involvement of the thumb base joint was defined as tenderness at palpation in at least one thumb base joint whereas radiological involvement was defined as Kellgren and Lawrence score ≥ 2 in at least one thumb base joint. Multivariable linear and logistic regression analyses were used, where appropriate, to estimate the independent association of clinical and radiological thumb base joint involvement as independent variables with patient and disease characteristics, hand functions and activities, psychosocial variables and health-related quality of life as dependent variables.
Results: In 38% (n=58) of the patients (mean age 59.2 years, 83% female) ≥ 1 thumb base joint was tender on palpation whereas in 69% (93 out of 135 patients) ≥ 1 thumb base joints had K&L score ≥2. 36% patients showed neither clinical nor radiological involvement, whereas 42% showed both clinical and radiological involvement of the thumb base joint. On joint level, the presence of radiological involvement of the thumb base joint showed a clear association with joint tenderness (odds ratio 5.4, 95% CI: 1.5 – 8.7).
Clinical involvement of the thumb base joint was, adjusted for radiological involvement, associated with the number of tender hand joints (B (CI): 6.3 (4.2;8.4)), number of co morbidities (B(CI): 0.5 (0.0;1.0)), limitations in hand activities (Australian Canadian Osteoarthritis Hand Index) (B(CI): 4.0 (1.7;6.3)), passive coping strategies and pain (subscale “bodily pain” of the short form health survey (SF-36)) (B(CI): -6.8 (-12.8; -0.8)). Radiological involvement of the thumb base joint was, adjusted for clinical involvement, associated with age (B (CI): 4.8 (1.9; 7.7)), number of hand joints with K&L score ≥2 (B (CI): 5.2 (2.8;7.8)) and presence of erosions (yes/no) (odds ratio (CI): 4.1(1.9;9.2)).
Conclusions In patients with established hand OA clinical involvement of the thumb base is associated with a higher clinical burden whereas radiological involvement of the thumb base joints is associated with older age and more structural abnormalities. Our results imply that clinical involvement of the thumb base joint rather than radiological involvement should be a starting point for symptomatic treatment. An aberrant pain behavior style might underlie the expression of OA-related symptoms.
Disclosure of Interest None Declared