Strength Changes Associated with Elongation in Distal Biceps Tendon Repair

OBJECTIVES: Operative repair of distal biceps tendon ruptures have shown successful outcomes. However, little is know about the amount of tendon or repair site lengthening after repair and how this may affect strength. The purpose of our study was to evaluate distal biceps tendon repair via radiostereometric analysis and correlate with final strength changes. METHODS: Eleven patients with distal biceps ruptures were recruited. During repair, two 2-mm tantalum beads with laser-etched holes were sutured to the distal biceps tendon. Beads were evaluated via CT scans immediately post-operatively and at 16 weeks. X-rays were obtained at time 0 and then at 4, 8, and 16 weeks. Seven patients were available for final strength testing at minimum of 9 months postoperative. RESULTS: The mean amount of tendon lengthening after surgery was 22.8 mm (range 11.2 - 30.9 mm, p < 0.05). The greatest change in lengthening was noted between time 0 and week 4 (mean: 11.3 mm, p<0.05), with the least amount of lengthening between week 8 and week 16 (mean: 2.6 mm, p<0.05). DASH averaged 8.2. Strength testing performed at final follow-up (n=7) showed 78% supination and 88% flexion strength compared to contralateral side (33% with dominant arm repaired). Supination strength loss showed the greatest decreases with increased lengthening from 0-4 weeks (Correlation coefficient: -0.39). Final ultrasound evaluations found all tendons to be in continuity. CONCLUSION: This study’s findings suggest that all patients undergoing distal biceps tendon repair have significant lengthening after surgery. The greatest amount of lengthening was noted in the early post-operative period, in which the greater the amount of lengthening trended toward a greater loss of supination strength. Further studies will focus on post-operative protocols as they may have an impact on early tendon lengthening and could be adjusted to minimize this consequence on long-term supination strength.