Pathologic changes of the long head of the biceps tendon (LHB) frequently cause shoulder pain, because the proximal third of the tendon has a high degree of innervation. Biceps pathologies include tendinitis, fraying, instability, SLAP lesions, and partial or complete tears. Isolated biceps pathologies are rare, because lesions are often associated with other pathologies, such as rotator cuff tears6 or anterosuperior impingement syndromes. Tenodesis of the LHB has been shown to be a reliable and effective therapy option for these pathologies.
Numerous techniques for biceps tenodesis have been described, varying in terms of open versus mini-open or arthroscopic approach, proximal versus distal location of tenodesis, and fixation method. The tenodesis can be performed through a suprapectoral approach, at the entrance of the bicipital groove, or through a sub- pectoral approach, approximately 50 mm farther distal, under the tendon of the pectoralis major. Fixation techniques include bone tunnel or soft-tissue tenodesis, keyhole procedure, and anchor or screw fixation.
Several cadaveric studies have already reported on different techniques for biceps tendon refixation, showing the interference screw to provide the highest biomechanical stability. There has been a trend toward subpectoral interference screw fixation because it is easy to perform, is reliable in relief of pain, and has been shown to improve function. Moreover, any further sawing of the LHB through the rotator cuff tendons can be eliminated by using this technique. The clinical results of subpectoral biceps tenodesis are good to excellent, with reliable pain relief and improvement of function.
Despite these benefits, complications have been reported after subpectoral tenodesis with interference screw fixation, including implant failure, bioabsorbable screw reaction, persistent pain, neurovascular complications, and humeral fractures. Nevertheless, the overall complication rate is reported to be as low as 2%.
In a biomechanical study, Siebenlist tested a novel technique of intramedullary cortical button fixation for distal biceps tendon repair and found that there are no significant differences in the biomechanical properties between single intramedullary and single extramedullary cortical button fixation. However, for clinical use, the intramedullary positioning of the button may minimize the potential risk of nerve and vessel injury at the spiral groove as an iatrogenic complication.
The purpose of this study was to biomechanically evaluate a new technique of intramedullary cortical button fixation for subpectoral biceps tenodesis and to compare it with the interference screw technique. Our hypothesis was that intramedullary cortical button fixation would provide superior fixation strength in static and cyclic loading when compared with the interference screw fixation.