Objective: Osteoarthritis (OA) of the thumb carpo-metacarpal joint is a common condition that can lead to substantial pain, instability, deformity, and loss of motion. It has been hypothesized that instability of the trapeziometacarpal joint combined with strenuous use can potentially lead to OA. However, as yet there have been no longitudinal evaluations to determine if this hypothesis is true. We examined the relation of radial subluxation to the risk of radiographic OA at trapeziometacarpal joint.
Methods: We conducted a nested case-control study. We restricted our evaluation of cases to subjects with no radiographic trapeziometacarpal OA at baseline (1967). We defined incident trapeziometacarpal OA as the development of a modified Kellgren and Lawrence grade>or=2 in that joint at a later examination (1992-1993). Radial subluxation of the base of the first metacarpal off the trapezium and the amount of the base of the first metacarpal covering the articulating surface of the trapezium were measured using a digital calculation caliper. We examined the relation of gender-specific quartile groups of radial subluxation to the risk of trapeziometacarpal OA using a conditional logistic regression model.
Results: We assessed 203 men and 431 women. After adjusting for age, handedness, number of other joints with OA, and grip strength, the odds ratios for the risk of trapeziometacarpal OA in men were 1.0, 1.8, 2.7, and 3.1 from the lowest quartile of radial subluxation to the highest quartile, respectively (P for trend=0.015). There was no significant relationship between radial subluxation quartiles and incident trapeziometacarpal OA in women.
Conclusion: This study provides evidence that radial subluxation predisposes to subsequent OA of the trapeziometacarpal joint in men.