Biomechanical analysis of distal biceps tendon repair methods

Background: The 1-incision and 2-incision techniques are commonly used methods to repair a distal biceps rupture, and they differ in the location of reinsertion of tendon into bone. Hypothesis: The native distal biceps brachii tendon inserts on the posterior-ulnar aspect of the bicipital tuberosity, which functions as a cam, increasing the tendon's moment arm during its principal action of forearm supination. Repair of the distal biceps tendon to the anterior aspect of the tuberosity compromises forearm supination due to absence of the bicipital tuberosity's cam effect. Study Design: Controlled laboratory study. Methods: Eleven matched pairs of fresh-frozen cadaveric upper extremities were prepared for repair of the distal biceps tendon using either anterior or posterior reattachment with transosseous suture fixation. Specimens were tested on a materials testing machine with intact distal biceps insertion and after repair. A load cell at the distal radial-ulnar joint measured resultant elbow flexion and forearm supination torque produced by 100-N force applied to the proximal aspect of the tendon. Results: Although there was a trend (P =.104) toward loss of supination torque with the anterior reconstruction method, no significant differences in torque (0.80 vs 0.89 N center dot m) or flexion force (11.87 vs 12.07 N) were found between the anterior and posterior reconstruction techniques. Conclusion: There is no statistically significant difference in flexion force or supination torque between the anterior and posterior reconstruction techniques. Clinical Relevance: This study supports existing limited clinical data suggesting no functional differences exist between 2 common repair methods. Further biomechanical and clinical investigations directly comparing the results of distal biceps tendon repairs made to the anterior aspect versus the posterior aspect of the tuberosity are necessary to definitely determine if differences exist in resultant elbow flexion and forearm supination functions.