A BIOMECHANICAL ASSESSMENT OF LIGAMENTS PREVENTING DORSORADIAL SUBLUXATION OF THE TRAPEZIOMETACARPAL JOINT

Degenerative arthritis of the trapeziometacarpal joint is commonly ass ociated with ligament laxity and joint subluxation. Specifically, key pinch in an affected joint often results in dorsoradial joint subluxat ion. This study examined the role the 4 ligaments of the trapeziometac arpal joint play in preventing dorsoradial subluxation. Six fresh-froz en cadaver hands were dissected of all soft tissue to expose the joint capsule and ligaments of the trapeziometacarpal joint. Serial random sectioning of the intermetacarpal ligament, anterior oblique ligament, palmar oblique ligament, and dorsoradial collateral ligament (RCL) wa s performed. Dorsoradial displacement of the metacarpal shaft in relat ion to the trapezium was measured using a linear variable dimension tr ansformer. In all 6 specimens, sectioning of the RCL resulted in the g reatest dorsoradial subluxation of the metacarpal. The mean displaceme nt due to sectioning of the RCL was 1.4 mm, compared with 0.08 mm for the intermetacarpal ligament, 0.06 mm for the anterior oblique ligamen t, and 0.2 mm for the palmar oblique ligament. The importance of the R CL in preventing dorsoradial subluxation may have clinical significanc e. This study suggests that repairing or reconstructing the RCL during ligament reconstruction of the trapeziometacarpal joint should be con sidered. (J Hand Surg 1998;23A: 607-611. Copyright (C) 1998 by the Ame rican Society for Surgery of the Hand.)