Radiographic Laxity of the Trapeziometacarpal Joint Is Correlated With Generalized Joint Hypermobility

Abstract

Increased joint laxity has been associated with the risk of ligament injury and development of osteoarthritis in large joints such as the knee, but this has not been investigated in depth in the hand. We hypothesized that generalized joint laxity would correlate with radiographic measures of trapeziometacarpal (TM) joint subluxation, as measured in carpometacarpal stress view radiographs. We recruited volunteer subjects of all ages and examined them for generalized laxity using the Beighton-Horan index. A total of 163 subjects, 81 men and 82 women, with an average age of 48 years (range, 20-83 y), were examined. Each subject underwent a stress view radiograph of both TM joints using a previously described technique. Different examiners independently measured radial subluxation of the thumb metacarpal over the trapezium and the articular width of the thumb metacarpal and averaged them. The ratio of the radial subluxation to the articular width was calculated as a measure of radiographic TM laxity. The average Beighton score was 2 (range, 0-9). A total of 40 subjects had Beighton scores greater than 4. The mean stress view ratio was 0.31 (range, 0.06-0.58). When we calculated the Pearson correlation coefficient to assess the relationship between the stress view ratio and the Beighton score, a statistically significant correlation was demonstrated. In normal volunteers generalized joint laxity is positively correlated with increased mobility of the TM joint, as demonstrated on carpometacarpal stress view radiographs. Diagnostic I.