PubMed · 15592228
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Christopher D Harner, Gary G Poehling. 2004. Double bundle or double trouble?. https://doi.org/10.1016/j.arthro.2004.10.002
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Residual pivot shift after ACL reconstruction is a crucial factor related to poor clinical outcome. However, no method exists that is able to evaluate pivot shift quantitatively and noninvasively. We propose a new measurement system for the pivot shift test using an electromagnetic device and have evaluated its reliability and clinical usefulness. Posterior translation, lateral translation and maximum velocity during the reduction phase of pivot shift were calculated and used as parameters for evaluation. In measurement system analysis, discrepancies of motion between the bones and the sensors were minimal, while reproducibility in repeated measurement was acceptable. Next, clinical usefulness was evaluated by correlating the values obtained by kinematic measurement with the clinical grade. We found differences in each of the measured parameters among clinical grades. These data suggest the system is a valuable measurement tool for clinical evaluation of the pivot shift test.
The anterior cruciate ligament (ACL) consists of two major fiber bundles, namely the anteromedial and posterolateral bundle. When the knee is extended, the posterolateral bundle (PL) is tight and the anteromedial (AM) bundle is moderately lax. As the knee is flexed, the femoral attachment of the ACL becomes a more horizontal orientation; causing the AM bundle to tighten and the PL bundle to relax. There is some degree of variability for the femoral origin of the anterome-dial and posterolateral bundle. The anteromedial bundle is located proximal and anterior in the femoral ACL origin (high and deep in the notch when the knee is flexed at 90 degrees ); the posterolateral bundle starts in the distal and posterior aspect of the femoral ACL origin (shallow and low when the knee is flexed at 90 degrees ). In the frontal plane the anteromedial bundle origin is in the 10:30 clock position and the postero-lateral bundle origin in the 9:30 clock position. At the tibial insertion the ACL fans out to form the foot region. The anteromedial bundle insertion is in the anterior part of the tibial ACL footprint, the posterolateral bundle in the posterior part. While the anteromedial bundle is the primary restraint against anterior tibial translation, the posterolateral bundle tends to stabilize the knee near full extension, particularly against rotatory loads.
The anterior cruciate ligament (ACL) is the most commonly injured intra-articular ligament of the knee. The insufficient vascularization of this tissue prevents it from healing completely after extreme tearing or rupture, creating a need for ACL grafts for reconstruction. The limitations of existing grafts have motivated the investigation of tissue-engineered ACL grafts. A successful tissue-engineered graft must possess mechanical properties similar to the ACL; to date no commercially available synthetic graft has achieved this. To accomplish this goal we have combined the techniques of polymer fiber braiding and twisting to design a novel poly L-lactic acid (PLLA) braid-twist scaffold for ACL tissue engineering. The scaffold is designed to accurately mimic the biomechanical profile and mechanical properties of the ACL. In this study, braid-twist scaffolds were constructed and compared to braided scaffolds and twisted fiber scaffolds. The addition of fiber twisting to the braided scaffold resulted in a significant increase in the ultimate tensile strength, an increase in ultimate strain, and an increase in the length of the toe region in these constructs over scaffolds that were braided. Based on the findings of this study, the braid-twist scaffold studied was found to be a promising construct for tissue engineering of the ACL.