The comparison of biomechanical strengths offixation techniques with screw and endobutton inlatarjet procedure: A cadaver study

The Comparison of Biomechanical Strength of Various Fixation Techniques in Latarjet Procedure – A Cadaver Study, Hacettepe University Faculty of Medicine, Orthopaedics and Traumatology Department, Thesis, Ankara, 2019. Shoulder dislocations are one of the most frequently encountered problems in orthopaedics and traumatology practice. Latarjet procedure is widely used if capsulolabral repair fails and a major glenoid defect exists. Coracoid fixation with screws was discussed in detail in the current literature, but there is not enough data about biomechanical features of endobutton fixation technique, which was recently defined. In our study, biomechanical strengths of two 3.5 mm partial threaded cannulated screws technique and endobutton fixation technique were compared in 10 cadaver shoulders. Cadavers were randomized into two groups. The muscles and soft tissues around the scapula were dissected carefully, preserving the conjoint tendon (short head of biceps and coracobrachialis muscle tendons). Anteroposterior radius of glenoid was measured and a 25% bony defect was created in anteroinferior rim of the glenoid. Coracoid process was transferred from its original location into the bony defect area of the glenoid. In the first study group, the coracoid process was fixed with 2 3.5 mm cannulated partial threaded screws. An endobutton was used to fix the coracoid process in the second study group. All samples was subjected to a mechanical tensile test in anteroinferior direction. Fixation failure criteria was determined as rupture of tendon-bone interface, >5 mm disintegration of the fixed coracoid process, failure of endobutton, breakage of cannulated screws and fracture of coracoid process. Rupture of tendon-bone interface, breakage of screws and failure of endobutton was not observed in any sample but >5 mm disintegration and fracture of coracoid process was observed as fixation failure criteria in the study. The results were compared using a force-strength graph. Maximum and minimum forces that the screw construct can resist were 533.93 N and 102.85 N, respectively. The mean force was measured as 295.21 N and the median value was 257.59 N. In the endobutton group, maximum and minimum forces were 270.17 N and 74.10 N, respectively. Mean value was 133.23 N and the median 87.06 N. As a result, screw fixation is biomechanically superior to endobutton fixation technique.