Single harvesting in the all-inside graft-link technique: is the graft length crucial for success? A biomechanical study.

BACKGROUND: The all-inside graft-link technique for anterior cruciate ligament reconstruction is performed with two cortical suspension devices with adjustable loops on both femur and tibia. This technique requires meticulous graft preparation. The aim of this study was to biomechanically test three different graft configurations resulting from differences in initial graft length.

MATERIALS AND METHODS: Thirty bovine digital extensor tendons were arranged in three different ways: "half-quadrupled", "tripled" and "quadrupled". The final graft length was 65-75 mm. The specimens were fixed vertical to the loading axis of a tensile testing machine. After a static pre-conditioning of 50 N for 5 min, a load to failure test was performed and data regarding the ultimate failure load (UFL), the stiffness and mode of failure were recorded.

RESULTS: The evaluation of UFL showed a significant differences between group means as determined by one-way analysis of variance (F = 21.92, p = 0.002). Post hoc comparisons showed a significantly better UFL of "tripled" (p = 0.007) and "quadrupled" preparations (p = 0.014) compared to the "half-quadrupled" configuration, with no significant differences between "tripled" and "quadrupled" grafts (p = 0.061). No significant differences were found when evaluating the stiffness between the groups. Failure occurred by tendon slippage across the suture in all specimens.

CONCLUSION: The "quadrupled" tendon achieved the best UFL, with even the "tripled" configuration having sufficient biomechanical characteristics to withstand the loads experienced during early rehabilitation. For this reason, with a total semitendinosus length of less than 260 mm it could be better to "triple" instead of "half-quadruple" it to achieve better performance of the graft.