Tension band wire fixation for anterior cruciate ligament avulsion fracture: biomechanical comparison of four fixation techniques.

PURPOSE: The purpose of this study is to design a new fixation method to treat tibial eminence fractures and assess its stability compared with conventional fixation methods.
METHODS: Eighty fresh porcine knees were stripped of all soft tissue, leaving intact only the femur-anterior cruciate ligament (ACL)-tibia complex. A standardized type III fracture was simulated at the anterior cruciate ligament attachment region using an osteotome. Then, the 80 specimens were randomly divided into 4 groups consisting of 20 knees each. The bony fragments were, respectively, fixed with sutures, steel wire, screws, and the newly designed tension band wire. All specimens were subsequently tested on a Material Testing Machine at a load rate of 60 mm/min. The statistically significant difference between the methods in terms of ultimate failure load, yield load, and displacement of the fragment under single-cycle loading and cyclic loading were analysed.
RESULTS: Steel wire encircling K-wire fixation showed significantly higher maximum loads, yield loads, and less displacement than all the other fixation methods tested. Specimens fixed with steel wire had the second highest maximal load followed by fixation with the cannulated screw. The lowest maximal load was observed in the group using PDS II suture.
CONCLUSIONS: The ultimate strength of tension band wire fixation of tibial eminence fractures in these specimens was significantly greater than those of the other three fixation methods. Tension band wire fixation of eminence fractures appears to provide biomechanical advantages over the other three fixation methods; hence, it is a practical alternative to conventional fixation techniques.