Tendon fixation in arthroscopic latissimus dorsi transfer for irreparable posterosuperior cuff tears: an in vitro biomechanical comparison of interference screw and suture anchors.

BACKGROUND The fixation of the tendon to the bone remains a challenging problem in the latissimus dorsi tendon transfer for irreparable cuff tears and can lead to unsatisfactory results. A new arthroscopic method of tendon to bone fixation using an interference screw has been developed and the purpose of this study was to compare its biomechanical properties to the ones of a standard fixation technique with anchors. METHODS Six paired fresh frozen cadaveric human humeri were used. The freed latissimus dorsi tendon was randomly fixed to the humeral head with anchors or with interference screw after a tubularization procedure. Testing consisted to apply 200 cycles of tensile load on the latissimus dorsi tendon with maximal loads of 30 N and 60 N, followed by a load to failure test. The stiffness, displacements after cyclic loadings, ultimate load to failure, and site of failure were analysed. FINDINGS The stiffness was statistically higher for the tendons fixed with interference screws than for the ones fixed with anchors for both 30 N and 60 N loadings. Likewise, the relative bone/tendon displacements after cyclic loadings were lower with interference screws compared to anchors. Load to failure revealed no statistical difference between the two techniques. INTERPRETATION Compared to the standard anchor fixation, the interference screw fixation technique presents higher or similar biomechanical performance. These results should be completed by further biomechanical and clinical trials to confirm the interest of this new technique as an alternative in clinical use.