Partial ruptures of the distal triceps tendons show only slightly lower ultimate load to failure: a biomechanical study

Objective: Partial ruptures of the distal triceps tendon are usually treated surgically from a size of > 50% tendon involvement. The aim of this study was to compare the ultimate load to failure of intact triceps tendons with partially ruptured tendons and describe the rupture mechanism. Methods: Eighteen human fresh-frozen cadaveric elbow specimens were randomly assigned to two groups with either an intact distal triceps tendon or with a simulated partial rupture of 50% of the tendon. A continuous traction on the distal triceps tendon was applied to provoke a complete tendon rupture. The maximum required ultimate load to failure of the tendon in N was measured. In addition, video recordings of the ruptures of the intact tendons were performed and analysed by two independent investigators. Results: A median ultimate load to failure of 1,390 N (range Q_0.25—Q_0.75, 954 – 2,360) was measured in intact distal triceps tendons. The median ultimate load to failure of the partially ruptured tendons was 1,330 N (range Q_0.25—Q_0.75, 1,130 – 1.470 N). The differences were not significant. All recorded ruptures began in the superficial tendon portion, and seven out of nine tendons in the lateral tendon portion. Discussion: Partial ruptures of the distal triceps tendon demonstrate a not statistically significant lower ultimate load to failure than intact tendons and typically occur in the superficial, lateral portion of the tendon. This finding can be helpful when deciding between surgical and conservative therapy for partial ruptures of the distal triceps tendon.