Relationship of radiographic and clinical variables to pinch and grip strength among individuals with osteoarthritis

Objective. Little is known about how specific radiographic features are related to hand strength in osteoarthritis (OA). This study examined associations of radiographic variables with pinch and grip strength among individuals with radiographic hand OA. Methods. Participants (n = 700, 80% female, mean age 69 years) were part of a study on the genetics of generalized OA. All had bilateral radiographic hand OA. Linear models were used to examine associations of grip and pinch strength with 1) OA in joint groups (proximal interphalangeal, metacarpophalangeal [MCP], carpometacarpal [CMC]), 2) OA in rays (first through fifth), and 3) summed Kellgren/Lawrence (K/L) grades for severity of OA in all joints. Adjusted models controlled for age, sex, hand pain, chondrocalcinosis, and hand hypermobility. Mixed models accounted for clustering within families. Results. In bivariate analyses, all joint groups, all rays, and total summed K/L grades were significantly negatively associated with grip and pinch strength (P < 0.05). In adjusted models, the only joint group significantly associated with grip strength was the CMCs, and only OA in the MCP joint was significantly associated with pinch strength (P < 0.05). The only ray significantly associated with grip strength (P < 0.05) was ray 1, and no individual rays were significantly associated with pinch strength. A higher summed K/L grade was significantly associated with both lower grip strength and lower pinch strength. Conclusion. Among individuals with radiographic hand OA, increasing radiographic severity is associated with reduced grip and pinch strength, even when controlling for self-reported pain. Individuals with radiographic OA in specific locations (CMC joints, MCP joints, and ray 1) may be at particular risk for reduced hand strength.