Gap formation after single lateral row versus dual-row suture bridge cuff repair: An ovine biomechanical model.

BACKGROUND: The aim of this study is to compare two types of suture bridging constructs; a laterally based bridging single row (SR) construct and a classic dual row (DR) suture bridge construct. The hypothesis is that the DR construct will demonstrate superior biomechanical properties. METHODS: Six matched pairs of sheep infraspinatus tendon tears repaired with these two different types of suture bridging techniques were tested for gap formation, ultimate failure load and mode of failure. The specimens were pre-cycled for 10 cycles before they were subjected to a constant pre-load of 10N. The specimens were then subjected to cyclic loading at a speed of 8.33 mm/s. The test was stopped after every 500 cycles for a total of 3000 cycles. RESULTS: Mean gap formation after 3000 cycles was lower in the DR group (0.81 ± 0.2 mm versus 2.44 ± 0.27 mm; p = 0.002). Mean change in gap (with every 500 cycles) was also lesser for the DR group after 1500 cycles. DR repairs failed at a higher load (523.4 ± 80.4 N) compared to the SR repairs (452.3 ± 66.3 N) but this did not reach significance. All repairs failed with sutures pulling through the tendon during load to failure testing. CONCLUSIONS: Gap formation is significantly lower with a dual row suture bridge construct than a laterally based bridging single row construct. LEVEL OF EVIDENCE: Biomechanical study.

A Biomechanical Study Comparing Cerclage Wiring Performed with a Power Tool versus the Manual Method.

INTRODUCTION: We conducted a biomechanical study comparing cerclage wiring using a power tool with the traditional manual method. MATERIALS AND METHODS: Our study consisted of 4 experimental arms based on the method of fixation and diameter of wires. The 4 arms were: 1) power tool method using 0.8 mm cerclage wires, 2) power tool method using 1.0 mm cerclage wires, 3) conventional manual method using 0.8 mm cerclage wires, and 4) conventional manual method using 1.0 mm cerclage wires. Synthetic femur bones were employed in our study. Six specimens were prepared for each arm. Each specimen was cut lengthwise and pressure sensors were placed in between. For the power tool method, while maintaining tension, wires were coiled using the Colibri power tool until just before secondary coiling occurred. For the conventional manual method, each specimen was compressed by plier twisting for 10 rounds, while maintaining tension. Cerclaging and data recording was done thrice for each specimen, giving a total of 18 readings per arm. Peak and steady-state forces were recorded. RESULTS: There was no significant difference between the peak forces recorded between the power drill and manual methods. The steady-state forces achieved using the power tool method were significantly higher than that achieved in the manual fixation method (0.8 mm wires: 54.89N vs 27.26N, P = 0.037; 1.0 mm wires: 71.59N vs 39.66N, P = 0.025). CONCLUSION: The power tool method achieved a superior steady-state force of compression across the fracture site for both 0.8 mm and 1 mm wires.