Biomechanical comparison of the holding strength of a peek-optima circular plate versus a stainless steel oblique T-plate for radioscapholunate arthrodesis.

PURPOSE

Radioscapholunate arthrodesis is an accepted treatment for posttraumatic radiocarpal arthritis that preserves some wrist motion. Good results are dependent on secure fixation while avoiding hardware-related side effects. A small radiolucent countersunk circular plate placed over the radiocarpal joint may offer a low-profile technique for achieving secure fixation of the radioscapholunate joint. The purpose of this study was to compare the biomechanical performance of this circular plate, when applied in this manner, to that of a more conventional fixation technique such as a 3.5-mm T-plate.

METHODS

Ten pairs of fresh-frozen cadaveric wrists were amputated 7 cm proximal to the radiocarpal joint. One wrist from each pair was fixed with a T-plate (DePuy, Inc., Warsaw, IN), and the contralateral wrist was fixed with a circular plate (Xpode plate; TriMed, Inc., Valencia, CA). The radius and scaphoid-lunate complex were each rigidly held and mounted into a materials testing machine. Translational forces to mimic extension and flexion movements were applied cyclically for 40 cycles, followed by failure testing in extension.

RESULTS

Cyclic tests revealed no statistically significant differences between the 2 fixation plates although resistance to flexion motion was higher than resistance to extension motion. The average load at failure was no different between the T-plate and circular plate. However, a ratio of the failure loads (T-plate to circular plate) demonstrated a 58% higher load for the circular plate.

CONCLUSIONS

A countersunk circular plate provides similar biomechanical performance to the T-plate for radioscapholunate arthrodesis.