Comparison of In Vitro Motion and Stability Between Techniques for Index Metacarpophalangeal Joint Radial Collateral Ligament Reconstruction

Abstract

To evaluate a technique using interference screws to secure a tendon graft for reconstruction of the radial collateral ligament (RCL) of the index finger metacarpophalangeal (MCP) joint. We hypothesized that this technique would provide equivalent stability and flexion as a 4-tunnel reconstruction. We isolated the RCL in 17 cadaveric index fingers. A cyclic load was applied to the intact RCL across the MCP joint to assess flexion, ulnar deviation at neutral (UD 0), and ulnar deviation at 90° of MCP joint flexion (UD 90). The RCL was excised from its bony origin and insertion. We performed each reconstruction (4-tunnel and interference screw) sequentially on each specimen in a randomized order using a palmaris longus tendon graft. We repeated testing after each reconstruction and compared differences from the intact state between techniques using paired t-tests for all joint positions (flexion/UD 0/UD 90). There was no statistically significant difference in UD 0 or UD 90 between the intact state and after interference screw reconstruction. Compared with the intact state, there was significantly less UD 0 and significantly more UD 90 after 4-tunnel reconstruction. There was no statistically significant difference between techniques when we compared changes in -UD 0 or UD 90. Change in flexion was statistically significantly different, which indicates that the interference screw technique better replicated intact MCP joint flexion compared with the 4-tunnel technique. Interference screw reconstruction of the index RCL provides stability comparable to 4-tunnel reconstruction and is less technically challenging. These results substantiate our clinical experience that the interference screw technique provides an optimal combination of stability and flexion at the index MCP joint. Using an interference screw to reconstruct the index RCL is less challenging than 4-tunnel reconstruction and provides stability and range of motion that closely resemble the native MCP joint.