Altered knee kinematics in ACL‐deficient non‐copers: A comparison using dynamic MRI

Abstract

Kinematics measured during a short arc quadriceps knee extension exercise were compared in the knees of functionally unstable ACL-deficient patients, these patients' uninjured knees, and uninjured control subjects' knees. Cine phase contrast dynamic magnetic resonance imaging, in combination with a model-based tracking algorithm developed by the authors, was used to measure tibiofemoral kinematics as the subjects performed the active, supine posture knee extension exercise in the terminal 30 degrees of motion. Two determinants of tibiofemoral motion were measured: anterior/posterior location of the tibia relative to the femur, and axial rotation of the tibia relative to the femur. We hypothesized that more anterior tibial positioning, as well as differences in axial tibial rotation patterns, would be observed in ACL-deficient (ACL-D) knees when compared to uninjured knees. Multifactor ANOVA analyses were used to determine the dependence of the kinematic variables on (i) side (injured vs. uninjured, matched by subject in the control group), (ii) flexion angle measured at five-degree increments, and (iii) subject group (ACL-injured vs. control). Statistically significant anterior translation and external tibial rotation (screw home motion) accompanying knee extension were found. The ACL-D knees of the injured group exhibited significantly more anterior tibial positioning than the uninjured knees of these subjects (average difference over extension range ¼ 3.4 AE 2.8 mm, p < 0.01 at all angles compared), as well as the matched knees of the control subjects. There was a significant effect of interaction between side and subject group on A/P tibial position. We did not find significant differences in external tibial rotation associated with ACL deficiency. The changes to active joint kinematics documented in this entirely noninvasive study may contribute to cartilage degradation in ACL-D knees, and encourage more extensive investigations using similar methodology in the future. ß

Can Joint Contact Dynamics Be Restored by Anterior Cruciate Ligament Reconstruction?

“…However, their work was unable to establish specific relationships between altered kinematics and the location of cartilage damage. Previous studies have suggested alteration of the joint contact point and pressure could contribute to cartilage degeneration after ACL injury and reconstruction [6,27,28,37]. These studies, however, have generally investigated only the path of tibial contact and have ignored the complex rolling and sliding components of the articular surface interaction.…”

“…Most previous studies exploring joint contact mechanics after ACL injury and reconstruction have focused on the tibial surface [6,27,28,37], though joint contact mechanics is defined between two articulating surfaces. Joint sliding distance, which compares femoral and tibial joint contact paths, was introduced as a kinematic surrogate for joint shear stress [21].…”

Laboratory Evaluation of the Pivot-Shift Phenomenon with Use of Kinetic Analysis

“…However, this technique has a number of disadvantages: (1) the impossibility of measuring the internal knee torques, limiting the understanding of the internal stress on the knee during a task that involves rotation 14,15 ; and (2) the movement of skin, fat, or muscle around the bone affects the marker position and can cause error in the analysis 16 . Other in vivo techniques, such as dynamic magnetic resonance imaging, computer-assisted navigation, and threedimensional radiostereometric analysis, are limited to environments too restrictive to perform high-demand activities [17][18][19] . According to Strobel and Stedtfeld 20 , functional tests are designed to reproduce the symptomatic subluxating process or to provoke an ''avoidance behavior'' to guard against subluxation, which likewise is interpreted as a positive sign.…”

The Biomechanics of the Anterior Cruciate Ligament and Its Reconstruction

“…Studies using cadaveric knees (Bach & Hull, 1998;DeMorat et al, 2004;Renström et al, 1986) have shown that simulated quadriceps activity significantly increases ACL strain with the knee in up to 60° of flexion, and that ACL force peaks around 30° flexion (Li et al, 1999;Li et al, 2004). This was corroborated by in vivo studies, showing that actual quadriceps contraction causes ACL strain increases to 30° flexion (Beynnon et al, 1992), and that ACLdeficient knees show increased anterior translation on quadriceps contraction in the same range (Bach & Hull, 1998;Barrance et al, 2006;DeMorat et al, 2004). Studies examining the behaviour of the two bundles of the ACL on quadriceps contraction have shown equal band strain throughout flexion range (Bach & Hull, 1998;Wu et al, 2010).…”