Elbow strength and endurance in patients with a ruptured distal biceps tendon

Background: Patients with complete distal biceps tendon ruptures complain of fatigability with repeated elbow flexion and forearm supination. Some studies have documented changes in strength, but limited information is available about the effects of biceps tendon rupture on endurance. Hypothesis: A ruptured distal biceps tendon results in decreased strength and enducance. Materials and methods: Isokinetic strength and endurance in elbow flexion and forearm supination were measured in both arms of 9 patients with an untreated unilateral complete distal biceps tendon rupture. One additional patient underwent isokinetic testing only. Tests were conducted using a dynamometer at 60° per second for isokinetic strength and 240° per second for endurance. Paired t tests were used for statistical analysis. Results: The peak torque was significantly lower in involved limbs for both flexion (involved, 26.5 ± 11.1 Nm; uninvolved, 41.0 ± 12.6 Nm, P < .001) and supination (involved, 4.5 ± 2.4 Nm; uninvolved, 8.3 ± 2.9 Nm; P < .001). No significant differences were found in the fatigue index between involved and uninvolved limbs for flexion (involved, 43.2 ± 14.1; uninvolved, 45.9 ± 13.5; P = .659) or supination (involved, 58 ± 17.0; uninvolved, 54.3 ± 14.8; P = .592). Discussion: Complete rupture of the distal biceps tendon results in substantial reductions in elbow flexion and forearm supination strength. Endurance of the remaining intact musculotendinous units does not seem to increase or decrease over time. Nonoperative treatment is rarely recommended, but when selected, rehabilitation should concentrate on improving strength, not endurance. Conclusion: A ruptured distal biceps tendon results in a substantial decrease in flexion and supination strength.