Introduction

Current anatomical descriptions of the medial knee ligaments differ in the number and the location of their attachments and provide therefore only inaccurate information for medial collateral ligament (MCL) refixation or reconstruction techniques. The purpose of this study was to quantitatively and qualitatively define the anatomy of the superficial MCL (sMCL), the deep MCL (dMCL) and the posterior oblique ligament (POL).

Material And Methods

Ten unpaired cadaveric knees were dissected and the femoral and tibial attachments from the sMCL, the dMCL, and the POL were outlined by radiopaque staples. The respective attachment sites were obtained via true lateral radiographs and by a 3-dimensional Polaris optical tracking system. The location, the surface area, and the morphology of each ligament and its relation to osseous structures were analyzed and compared across the two modalities. The location of each femoral insertion was normalized to the AP medial femoral condyle (MFC) diameter (=100%) and referenced to the medial epicondyle (ME), whereas the tibial insertions were normalized to the AP dimension of the tibial plateau (TPD, =100%), respectively. The measurements of each method were given in mean ± standard deviation and intra-class correlation coefficient was calculated to find intraobserver reliability between two independent observers.

Results

The femoral sMCL attachment enveloped the ME, centred 1 mm proximal to it, at 37±2 mm (normalised at 53±2%) posterior to the most-anterior ME border. The tibial sMCL attachment spread from 42 to 71 mm (81–137% of A-P plateau width) below the tibial plateau. The femoral dMCL attachment was 6 mm (8%) distal and 5 mm (7%) posterior to the ME. It then fanned out anterodistally to a wide tibial attachment 8 mm below the plateau with the oblique anterior fibres attaching far more anterior than the sMCL at 17 mm (33%) A-P. The femoral POL attachment was 4 mm (5%) proximal and 11 mm (15%) posterior to the ME. It attached 5 mm below the plateau at the posterior plateau rim and posteriorly to the dMCL. The 95% CI intra-observer was ±0.6 mm, inter-observer ±1.3 mm for digitisation. The inter-observer ICC for radiographs was 0.922.

Conclusion

The precise locations and surface area of the femoral and tibial attachment sites of each soft-tissue structure of the medial knee complex have been described in relation to AP knee dimension and to osseous landmarks. The anatomical insertions were visualized in true-lateral radiographs to transfer the findings into an intraoperative setting. These data facilitate repairs and reconstructions that can restore physiological laxity and stability patterns across the arc of knee flexion.