2017 ISAKOS Biennial Congress ePoster #1610
Posterior Tibial Subchondral Bone and Meniscal Slope Correlate with in Vivo Internal Tibial Rotation
Elmar Herbst, MD, PhD, Muenster GERMANY
Tom Gale, MS, Pittsburgh, PA UNITED STATES
Kanto Nagai, MD, PhD, Kobe, Hyogo JAPAN
Yasutaka Tashiro, MD, PhD, Kitakyushu JAPAN
James J. Irrgang, PT, PhD, FAPTA, Pittsburgh, PA UNITED STATES
William Anderst, PhD, Pittsburgh, PA UNITED STATES
Scott Tashman, PhD, Vail, CO UNITED STATES
Freddie H. Fu, MD, Pittsburgh, PA UNITED STATES
Biodynamics Laboratory, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, UNITED STATES
FDA Status Not Applicable
Lateral posterior subchondral tibial bone and meniscal slope correlate positively with internal tibial rotation during level walking and downhill running and should therefore be taken into account when evaluating rotatory knee laxity.
Increased posterior tibial slope (PTS) results in an anteriorly directed force on the knee and is associated with a high-grade pivot shift. However, all published articles on this topic draw conclusions based on static measurements, while no study investigated the role of the PTS and posterior meniscal slope (PMS) on in vivo knee kinematics. Therefore, the purpose of this study was to correlate the lateral and medial PTS and PMS with in-vivo anterior tibial translation (ATT) and internal tibial rotation during level walking and downhill running on both the ACL reconstructed and healthy knee six months after index surgery. It was hypothesized that an increased lateral PTS and lateral PMS is associated with increased ATT and internal tibial rotation.
Forty-two individuals (twenty-six males; mean age 21.2 ± 6.9 years) who underwent unilateral ACL reconstruction were included in this study. Morphologic parameters were measured on three tesla magnetic resonance images (MRI) using the 3D DESS sequence (0.45 x 0.45 x 0.70) on the ACL reconstructed and healthy contralateral knee. Lateral and medial PTS and PMS were measured according to the method described by Hudek et al.
Three-dimensional in vivo kinematics data were acquired using dynamic stereo x-ray during level walking (1.3 m/s) at 100 Hz and downhill running (3.0 m/s, 10° slope) at 150 Hz, respectively, six months after unilateral ACL reconstruction. Correlations between bone morphology and dynamic kinematics were evaluated using Spearman´s Rho. The significance level was set at p < .05.
In ACL intact knees, ATT did not correlate significantly with PTS and PMS (all p > .264). Internal tibial rotation was associated with higher posterior slopes in the lateral knee compartment as well as a larger difference between lateral and medial PTS and PMS (all p < .010), while medial PTS and PMS did not significantly correlate with in vivo tibial rotation (all p > .457).
In ACL reconstructed knees ATT was positively correlated with an increased lateral PMS during level walking (p < .035). ACL reconstructed knees were found to have higher internal tibial rotation with higher lateral compartment slopes, and larger differences between the lateral and medial PTS and PMS during level walking (all p < .035).
The most important finding of the present study is that both lateral PTS and PMS are related to dynamic, functional in vivo kinematics, especially internal tibial rotation. ATT was only associated with lateral PMS in ACL reconstructed knees. Taking into account the results of the present study, the lateral PTS and PMS and the slope differences between the lateral and medial joint compartment may contribute to internal rotation when an ACL injury occurs. However, the analyzed movement was a straight-ahead walk and run without any cutting or pivoting maneuvers commonly related to ACL tears. In such motion patterns, the correlations may be even stronger compared to the results of the present study. However, this novel study is the first to assess the relationship between articulating surface morphology of the knee and in vivo functional movement.