Commentary & Perspective Considerations of Distal Biceps Tendon Reinsertion Commentary on an article by Christopher C. Schmidt, MD, et al.: “Factors That Determine Supination Strength Following Distal Biceps Repair” Ralph Hertel, MD In consideration of the relatively benign natural history of distal biceps tendon avulsions, indications for operative treatment require a balanced appraisal. To meet our value proposition, the aim of surgical reinsertion must be the restoration of nearly full function. In simple words, the result of surgical treatment must be clearly better than the result of conservative treatment. Historically, surgeons have focused on the restoration of biceps tendon continuity with the primary aim of regaining elbow flexion force. This led to the development of techniques using transosseous suture passages introduced from an anterior approach and tied posteriorly over the cortex of the radius using a second posterior approach. It was soon realized that the relative contribution of the biceps muscle to elbow flexion force was small (on the order of 10% to 15%) and that weak and sometimes incomplete active forearm supination persisted. Thus, restoration of supination force and motion was recognized as the main potential benefit of surgical reinsertion of a torn distal biceps tendon. The evolution of the technique was then complicated by the advent of suture anchors. It was now possible to directly reattach a torn tendon to the radius, without the need for transosseous suture passage. Suddenly, reattachment was feasible through a single anterior approach and surgeons praised the benefits of a single anterior approach, namely the preservation of supinator muscle integrity and the ability to better expose and protect the posterior interosseous nerve from inadvertent iatrogenic damage. Un- fortunately, at that time, the required supination force vector was not yet considered. In their article, Schmidt et al. clarify the fact that a single anterior approach may not be sufficient for anatomic reinsertion of the biceps tendon because anterior anchors, even when inserted with the arm in full supination, cannot be placed at the required anatomic position. The perfect position to obtain the desired wraparound supination effect is the posteromedial ridge of the insertion facet. In recent years, the restoration of supination force has been recognized as the key element related to the surgical value proposition. The recognition that the tendon does not insert directly onto the radius, but rather it wraps around the radial tuberosity to insert on the posteromedial slope (versant) of the tuberosity, led to the development of techniques that foster anatomic footprint reinsertion. It was largely considered that the insertion facet could be exposed and prepared better from a posterolateral approach, and the tendon could be best prepared and instrumented with sutures from an anterior approach. This led to the development of the new version of the combined approach for which the transosseous sutures are now passed from a posterior to an anterior direction (and not from an anterior to a posterior direction). The sutures are then either tied anteriorly or fixed with an anterior suture button. Alternatively, the tendon can be simply fixed with suture anchors inserted from the posterior approach. In general, to adequately position and pass the sutures or to introduce the anchors, it is essential to adjust the forearm rotation to the specific needs of the surgeon. Although the force vector has been optimized, anchor and button techniques still fail to provide full footprint contact. Generally, they provide only a series of point contacts and nothing that would be comparable with a double-row or transosseous repair of the rotator cuff. This is somewhat disturbing, considering our ambition to anatomically restore the tendon enthesis. The posterior approach requires at least partial transection of the supinator muscle. This leads to permanent, although partial, fatty infiltration of the supinator muscle, as has been precisely shown by Schmidt et al. Supinator muscle fat content was indeed a significant predictor of supination strength in 60° of supination. But why not in pronation or in neutral rotation? Are our instruments to measure reduced supinator muscle function too coarse? In this regard, I have found that a forearm supination lag was very useful to assess supination insufficiency. The surgeon holds the arm in 90° of elbow flexion and in full forearm supination; the patient is asked to actively hold this position, and then the surgeon releases the forearm grip. The sign is positive if an automatic, involuntary pronation occurs. The amount of pronation (in degrees) determines the severity of the functional deficit. Usually, a distal biceps rupture leads to about 10° of lag, sometimes less when the supinator muscle is functionally predominant. The same sign can be used to assess the outcome of the surgical procedure. It would be less influenced by variations of force (and strength) measurements and would add an edge to our ability to provide a strong value proposition. e61(1) COPYRIGHT Ó 2016 BY THE J OURNAL OF BONE AND J OINT SURGERY,I NCORPORATED J Bone Joint Surg Am. 2016;98:e61(1-2) d http://dx.doi.org/10.2106/JBJS.16.00513