Partial Trapeziotrapezoid Resection and Thumb Range of Movement After Trapeziometacarpal Joint Fusion-A Biomechanical Study

Biomechanical Comparison of 5 Different Fixation Constructs in a Trapeziometacarpal Joint Arthrodesis Model

PURPOSE

Trapeziometacarpal joint (TMC) arthrodesis has a high rate of nonunion. This biomechanical analysis sought to determine the stiffness of 5 fixation methods in a TMC joint arthrodesis model.

METHODS

Five fixation constructs were tested in a validated porcine model: crossed 1.1-mm K-wires, crossed 1.6-mm K-wires, crossed headless compression screws (HCSs), compression plating (CP), and locked compression plating (LCP). The cantilever bending stiffness was measured in abduction, adduction, flexion, and extension. Samples were loaded to failure in extension, and the mode of failure was examined.

RESULTS

The crossed HCSs performed consistently well in all tests. Loading to failure resulted in screw pullout. In abduction and adduction, HCS and 1.6-mm K-wires were significantly stiffer than the other constructs. The mean load to failure in extension was similar in the HCS, CP, and LCP groups (304 N/mm, 311 N/mm, and 293 N/mm, respectively). There were no differences between CP and LCP in any biomechanical tests, and the mode of failure was through plate bending. The crossed 1.1-mm K-wires performed poorly in all tests.

CONCLUSIONS

Crossed HCS displayed the greatest overall stability. Standard plating in compression mode and LCP had a similar biomechanical performance.

CLINICAL RELEVANCE

The ideal construct stiffness required for the successful union after TMC joint arthrodesis is unknown, but HCS has the best overall biomechanical performance and, therefore, might be considered the best choice for this clinical setting.

Carpometacarpal Arthrodesis: Indications and Techniques

Trapeziometacarpal arthrodesis is a beneficial surgery for young and higher-demand patients who have trapeziometacarpal arthritis. Surgical techniques can vary, but certain aspects of the surgery are critical, including bony preparation and positioning of the thumb in space. Reported outcomes are generally favorable, although the quality of evidence is poor. There are no comparison studies assessing different arthrodesis techniques, and only a few comparing arthrodesis to the trapeziometacarpal arthroplasty procedures. Most published results are case series with retrospectively collected data.