Effect of Interference Screw Depth on Fixation Strength in Biceps Tenodesis
The function of the long head of the biceps tendon (LHBT) remains under intense debate. It has been postulated as both a stabilizer within the glenohumeral joint and a vestigial structure assisting with proprioception. Although the exact function of the LHBT remains unclear, it has long been recognized as a source of pain. Pathology of the LHBT has been associated with various shoulder pathologic conditions, including arthritis, impingement syndrome, labral lesions, and rotator cuff tears. Examination of the proximal biceps during both open and arthroscopic surgery has provided significant information in the understanding of biceps pathology, which ranges from tendinitis to more complex pathologies such as instability and partial- or full-thickness tendon tears.
Biceps tenodesis has become a well recognized and effective treatment for pathology of the LHBT. Tenodesis screws have been introduced for secure fixation of the biceps tendon to the diaphyseal or metaphyseal area of the humerus. However, because this procedure is often accomplished through a small incision without direct visualization of the screw-bone interface, precise screw depth placement can be problematic, often leaving the screw proud or even recessed beyond the near cortex of the humerus. To date, no study has determined the security of screw fixation in relation to overall screw depth relative to the humeral cortex.
The purpose of this study was to evaluate the biomechanical performance of LHBT tenodesis with interference screw fixation with respect to interference screw depth. Our hypothesis was that there is no difference in biomechanical strength and stiffness of a biceps tenodesis construct fixed with an interference screw regardless of the depth at which the screw is placed in relation to the anterior humeral cortex.