Coracoclavicular ligament reconstruction: biomechanical comparison of tendon graft repairs to a synthetic double bundle augmentation

For currently presented anatomical coracoclavicular ligament repairs issues such as autologous tendon graft versus synthetic suture augmentation and the optimum fixation strategies for both types of reconstruction are not solved. The purpose of the study was to compare the biomechanical properties of different tendon graft repairs to the characteristics of a synthetic polyester augmentation. Four anatomical coracoclavicular ligament repairs were biomechanically tested: 5 mm coracoclavicular tendon loop with suture fixation, tendon loop with flip button fixation, tendon loop with interference screw fixation versus a double 1.0-mm polyester repair with flip button fixation. The biomechanical testing included cyclic superio-inferior loading and a subsequent load to failure protocol. The ultimate failure loads were significantly higher for the double polyester/flip button repair (927 N) compared to all tendon repair techniques (maximum 640 N). In contrast the stiffness level was higher for the tendon repairs compared to the polyester/flip button repair (68.7 N/mm) but strongly dependent on the fixation technique (interference screw 97.2 N/mm, flip button 84.9 N/mm, side to side suture 60.9 N/mm). A synthetic coracoclavicular augmentation using a polyester suture provides adequate structural properties compared to a tendon repair. Therefore the decision for a tendon graft should be made by the necessity of a biologic substrate rather than by the assumption of a biomechanical advantage.