Anatomic limitations of biceps tenodesis using an interference screw for Asian people: a cadaveric study

BACKGROUND: Biceps tenodesis using an interference screw has been commonly performed in clinical practice because of pathologic changes. Especially, the tenodesis distal to the bicipital groove, such as suprapectoral tenodesis (SPT) and subpectoral tenodesis (SBT), has been performed to avoid residual anterior shoulder pain. However, the techniques were developed based on research tested on Western population, and it is unknown whether they are applicable to Asian individuals, who have a smaller humerus than Western. The purpose of this study was to investigate the anatomic limitations of the biceps tenodesis using an interference screw for Asians. METHODS: We analyzed 22 fixed Japanese cadavers. We measured the length of the suprapectoral tenodesis zone (STZ), which is the area from the distal end of the lesser tuberosity to the proximal border of the insertion of the pectoralis major muscle tendon (PMMT) along the course of the biceps tendon, for the SPT. We also measured the bone tunnel depths (BTDs) for the SPT just distal to the lesser tuberosity along the course of the biceps tendon and, similarly, for the SBT just distal to the PMMT insertion. Finally, we analyzed the sexual differences and correlations of the measured values with the entire humeral length. RESULTS: In 9 shoulders (40.9%), the proximal border of the PMMT insertion was attached more proximally than the distal end of the lesser tuberosity, and the length of the STZ was negative. The mean BTDs in the SPT and SBT zones were 19.6 and 14.9 mm, respectively. In 11 shoulders (50%), the BTD in the SBT zone was shorter than 15 mm. The lengths of the STZ or BTDs in the SPT and SBT zones did not show statistical differences between sexes and were not correlated with the entire humeral length. CONCLUSION: Asian patients would have anatomic limitations as follows for the biceps tenodesis regardless of their sex or body size. In anomalous PMMT cases, when the SPT was performed just proximal to the PMMT insertion, the bone tunnel entered into the bicipital groove. On the other hand, when the SPT was performed distal to the lesser tuberosity, a part of the PMMT insertion would be injured. Regarding the SBT, an interference screw with a length of ≥12 mm, which is commonly used in Western countries, is too long for Asians.