Biomechanical In Vitro Validation of Intramedullary Cortical Button Fixation for Distal Biceps Tendon Repair

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Distal biceps tendon rupture typically occurs in middle-aged male patients who suffered an acute trauma with massive eccentric loading of the biceps brachii. In the past few decades, the incidence of this injury has increased from 3% to 10%. For pathogenesis, focal degenerative processes caused by hypovascularity within the tendon and mechanical impingement on the biceps tendon during forearm rotation continue to be cited in the literature as the reason for rupture at the tendinous insertion at the radial tuberosity. Furthermore, the abuse of steroids and nicotine has been discussed to cause the tendon tear. Operative repair of these injuries has shown improved functional elbow outcome compared with nonoperative treatment.

Currently, anatomic reinsertion of the biceps tendon to the radial tuberosity has been recognized as the treatment of choice to restore normal flexion and supination strength. Because of the increased risk of heterotopic ossification or radioulnar synostosis using the ‘‘classic’’ or ‘‘modified’’ 2-incision technique, the 1-incision technique for distal biceps tendon repair has become more popular in recent times. Via a single anterior approach, a variety of surgical repair techniques using suture anchors, interference screws, and cortical fixation buttons have shown both good clinical results and near preinjury strength of forearm supination and elbow flexion. For fixation to the bone, the construct with the strongest biomechanical data is a titanium extra-medullary cortical fixation button (‘‘EndoButton technique’’), which is anchored to the tendon by sutures and deployed on the posterior cortex of the proximal radius. The strength of this construct may allow earlier, more aggressive protocols for postoperative rehabilitation. Possible gap formations using a double- or single- fixation method for distal biceps repair are controversially discussed in the current literature. The ‘‘EndoButton technique’’ may provide minor displacement of the repair and is able to maintain bone-tendon continuity because of its intramedullary placement of the restored tendon.40 How- ever, this cortical button–based technique cannot restore the anatomic footprint of the distal biceps tendon and furthermore runs the risk of posterior interosseous nerve (PIN) injury as well as loss of motion attributable to heterotopic ossification.

The purpose of the present study is to demonstrate the new technique of intramedullary cortical button fixation (Biceps- button, Arthrex, Naples, Florida) for distal biceps tendon repair and to evaluate this procedure with respect to fixation strength to the bone versus the standard extramedullary cortical button–based technique. Our hypothesis is that double intramedullary cortical button fixation will provide superior loads to failure when compared with the traditional single extramedullary cortical button–based technique.

Full Article: Biomechanical In Vitro Validation of Intramedullary Cortical Button Fixation for Distal Biceps Tendon Repair

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