Abstract
Early mobilisation following Anterior Cruciate Ligament(ACL) reconstruction surgery is indicated for optimum results for accelerated rehabilitation. However, the graft used in reconstruction is at it’s weakest during the early post-operative period and can be prone to slipping.
Aim: This study compared two types of graft, bone-patellar tendon-bone (BPTB) and soft tissue tendon, with the hypothesis that BPTB grafts would lead to less slippage under cyclical loading conditi ons.
Materials & Method: A comparative biomechanical study was carried out using sixteen proximal tibiae of calves, aged 20–26 weeks and carrying out ACL reconstruction, 8 constructs with human Cadaveric BPTB and another 8 with calves’ extensor tendons. An interference screw measured 9 x 25mm was used to fix graft tissue in the transosseous tunnel. The specimens were tested in material-testing machine using Merlin software.
The constructs were subjected to cyclical loading. A load cycle of 0-150-0N was applied at a crosshead speed of 100mm/min, approximately 80 load cycles per minute simulating the forces applied in post-operative mobilisation. The crosshead position was noted at peak load at 1, 100, 300, and 1000 cycles.
Results: The value of the graft slippage found in the soft tissue tendon model was 1.83 ± 0.54 and that of bone tissue (BPTB) model was 0.76 ±0.29. Creep value showed no statistical significance. There was significantly less slippage when using BPTB-to-bone fixation than with soft tissue tendon-to bone fixation (p< 0.005).
Clinical relevance: BPTB grafts are more likely to resist the return of anterior-posterior laxity in the immediate post-operative period, prior to graft fixation by tissue healing. BPTB grafts should be used when accelerated rehabilitation is required.
Honorary Secretary Mr Bimal Singh. Correspondence should be addressed to BOSA (British Orthopaedic Specialists Association), c/o Royal College of Surgeons, 35 – 43 Lincoln’s Inn Fields, London WC2A 3PE.
Acknowledgement to Prof A A Amis.
