Triceps tendons: a biomechanical comparison of intact and repaired strength

Abstract

Our hypothesis was that the autograft-augmented direct repair of torn triceps tendons would have strength superior than that of direct repair when compared to the strength of intact distal triceps tendons. The strength of the intact distal triceps tendon in 8 unpaired, fresh frozen cadaver specimens was measured to tendon failure by uniaxial tension in the sagittal plane. The torn triceps tendons were then repaired by direct repair (sutures through drill holes) or an autograft-augmented direct repair. Each tendon repair was biomechanically tested to failure, and load to displacement curves and the site of tendon failure were recorded. Tendon strength after each repair was compared with that of the other repair technique and with that of the intact triceps tendon. Significance was set at P < .05. Average failure loads for intact, direct repair, and augmented repair tendons were 1741, 317, and 593 N, respectively; augmented repairs were significantly stronger than direct repairs. In the intact tendon, failure occurred at the insertion site through a tear at the bone tendon interface or through a small cortical avulsion. In the repaired tendons, all but 1 failure occurred through the suture; 1 augmented repair failed first at the tendon and then through the suture. There is a paucity of clinical data regarding the optimal repair for distal triceps avulsion. We found that triceps repair affords less strength than the intact tendon, but augmented repair was nearly twice as strong as that of direct repair. Augmented repair may allow earlier range of motion, weightbearing, and rehabilitation, theoretically decreasing complications associated with the procedure. Augmented triceps repair is superior to direct triceps repair for a distal triceps avulsion produced in a cadaver model.