Due to the complex shape of the carpometacarpal (CMC) joint, a fixed joint collapse deformity of the thumb CMC (CMC1) and metacarpophalangeal (MCP1) joint can present in advanced stages of CMC1 osteoarthritis (OA), resulting in adduction of the first metacarpal (MC1) and hyperextension of the MCP1.
To determine whether joint collapse deformity is associated with worse pain and/or functional impairment.
Cross-sectional.
This study used the baseline data from 140 patients enrolled in a longitudinal study of treatment for CMC1 OA. (efficacy of combined conservative therapies on clinical outcomes in patients with CMC1 OA). Joint collapse was determined at baseline using a pinch gauge. Pain was assessed on a visual analog scale (0-100) and function was assessed using the Functional Index for Hand Osteoarthritis questionnaire (0-30). Pain and function and the presence of joint collapse were entered in a univariate logistic regression. The final adjusted model for pain and joint collapse included age and sex. The final adjusted model for function and joint collapse included Kellgren Lawrence grade and grip strength.
About 20% of participants demonstrated joint collapse on the tip-pinch test. The presence of joint collapse was associated with increased pain in the unadjusted [P = .047, OR = 2.45, 95% CI (1.01, 5.910)] and adjusted model [P = .049, OR = 2.45, 95% CI (1.00, 5.98)].
CMC1 patients with joint collapse reported increased pain compared with those without joint collapse. Future studies should determine the relationship between thumb hypermobility and joint collapse and how to manage these conditions effectively.