Repair strength of tendons of varying gliding curvature: a study in a curvilinear model.

PURPOSE

This study was done to investigate changes in the strength of the repaired tendons by different curvatures of tendon motion arcs.

METHOD

Forty-two fresh-frozen digital flexor tendons were divided into 4 groups and were repaired by the modified Kessler method with a running peripheral suture. The tendons were pulled over pulleys with tension at a fixed angle of 90 degrees, but radii of gliding curvature of the pulleys were set at 2.0, 1.5, and 1.0 cm in 3 groups, respectively. The tendons in the other group were subjected to linear tension. These tendons were tested in an Instron tensile machine to determine the 2-mm gap formation force and ultimate strength of the repairs.

RESULTS

The 2-mm gap formation force of the tendons pulled over the curvature of a 2.0-, 1.0-, and 0.5-cm radius was, respectively, 69%, 61%, and 49% of that pulled linearly. The ultimate strength of the tendons over curvatures of 2.0-, 1.5-, and 1.0-cm radius was, respectively, 77%, 73%, and 63% of that of tendons pulled with linear tension. The gap formation force and ultimate strength were statistically the lowest in the tendons with a gliding radius of curvature of 1.0 cm. Both the gap formation force and the ultimate strength of tendon repairs decreased as the radius decreased.

CONCLUSIONS

The curvature of tendon motion arcs affects the repair strength of the tendons. The findings suggest an increased likelihood of repair ruptures in the tendons that glide along curvatures over the sheaths, pulleys, or joints.