Anatomical features of tibia and femur: Influence on laxity in the anterior cruciate ligament deficient knee

Background: Until now, there has been a lack of in vivo analysis of the correlation between bony morphological features and laxity values after an anterior cruciate ligament (ACL) injury.Methods: Forty-two patients who underwent ACL-reconstruction were enrolled. Static laxity was evaluated as: antero-posterior displacement and internal-external rotation at 30 degrees and 90 degrees of flexion (AP30, AP90, 1E30, 1E90) and varus-valgus rotation at 0 degrees and 30 degrees of flexion (WO, W30). The pivot-shift (PS) test defined the dynamic laxity. Using magnetic resonance imaging, we evaluated the transepicondylar distance (TE), the width of the lateral and medial femoral condyles (LFCw and MFCw) and tibial plateau (LTPw and MTPw), the notch width index (NWI) and the ratio of width and height of the femoral notch (N-ratio), the ratio between the height and depth of the lateral and medial femoral condyle (LFC-ratio and MFCratio), the lateral and medial posterior tibial slopes (LTPs and MTP5) and the anterior subluxation of the lateral and medial tibial plateau with respect to the femoral condyle (LTPsublx and MTPsublx).Results: Concerning the AP30, LTPs (P = 0.047) and MTPsublx (P = 0.039) were shown to be independent predictors while for the AP90 only LTPs (P = 0.049) was an independent predictor. The LTPs (P = 0.039) was shown to be an independent predictor for 1E90 laxity, while for the WO test it was identified as the LFCw (P = 0.007).Conclusions: A higher antero-posterior laxity at 30 degrees and 90 degrees of flexion was found in those with a lateral tibial slope <5.5 degrees. (C) 2018 Elsevier B.V. All rights reserved.