Which Muscles’ Strength in Upper Extremity are Related to Disease Activity, Functionality, and Disability in Patients with Rheumatoid Arthritis?

The aim of this study is to investigate which muscle groups are affected in dominant upper extremity, and relation of these effects with disease activity, functionality, disability in patients with rheumatoid arthritis (RA) which causes muscle strength loss. 30 RA patients, 30 healthy volunteers were included in this study. In patient group, "disease activity score-28 (DAS28)", "upper extremity functional index-15 (UEFI-15)", "health assessment questionnaire (HAQ)" scores were calculated. From dominant upper extremities of volunteers; maximum and average muscle strengths of thumb interphalangeal (IP), metacarpophalangeal (MCP), proximalinterphalangeal (PIP) and MCP joint flexors of other fingers, wrist and elbow flexors/extensors, flexor, extensor, internal rotator (IR), external rotator (ER), abductor/adductor muscles of shoulder were measured. Total PIP/MCP (PIPtotal, MCPtotal) values of patients were obtained. There was no significant difference between patient and control groups in age/height. In muscle strengths; thumb IP, MCP/PIPtotal, MCPtotal, wrist flexion mean and maximum values were significantly lower in RA group than control group; mean shoulder extension, maximum adduction/abduction, mean muscle strengths were low in RA group. DAS28, finger flexors, wrist extensors, shoulder muscles except ER were negatively related; UEFI-15 scores, wrist extensor, shoulder girdle muscles were positively related. HAQ scores were associated with mean wrist flexion, elbow extension, shoulder girdle muscles. Although hand and wrist muscles are the most affected by disease activity, it has been observed that elbow and shoulder girdle muscles affect functionality and disability more. Total strength of upper extremity muscles has been associated with disease activity, functionality and disability