Abstract
Purpose
The purpose of this study was to determine whether intra-operative identification of osseous ridge anatomy (lateral intercondylar “residents” ridge and lateral bifurcate ridge) could be used to reliably define and reconstruct individuals' native femoral ACL attachments in both single-bundle (SB) and double-bundle (DB) cases.
Methods
Pre-and Post-operative 3D, surface rendered, CT reconstructions of the lateral intercondylar notch were obtained for 15 patients undergoing ACL reconstruction (11 Single bundle, 4 Double-bundle or Isolated bundle augmentations). Morphology of native ACL femoral attachment was defined from ridge anatomy on the pre-operative scans. Centre's of the ACL attachment, AM and PL bundles were recorded using the Bernard grid and Amis' circle methods. During reconstruction soft tissue was carefully removed from the lateral notch wall with RF coblation to preserve and visualise osseous ridge anatomy. For SB reconstructions the femoral tunnel was sited centrally on the lateral bifurcate ridge, equidistant between the lateral intercondylar ridge and posterior cartilage margin. For DB reconstructions tunnels were located either side of the bifurcate ridge, leaving a 2mm bony bridge. Post-operative 3D CTs were obtained within 6 weeks post-op to correlate tunnel positions with pre-op native morphology.
Results
Pre-op native ACL attachment site morphology was very similar to previous in-vitro studies: the mean centre was found at 27% along Blumensaat's line (range 19-33%) and 38% the width of the lateral femoral condyle (range 31-43%). Despite the variability between individuals there was close correlation between pre-operative localization of the femoral attachment centre and position of single bundle ACL reconstructions tunnels on the post-op CT (R=0.92). Similar results were observed for double-bundle and isolated bundle augment reconstructions.
Conclusion
ACL attachment site morphology varies between individuals. Intra-operative localization of the osseous landmarks (lateral intercondylar and bifurcate ridges) appears to lead to accurate, individualised anatomical tunnel placement whether using single or double-bundle reconstruction techniques.
