Knee Kinematics During Noncontact Anterior Cruciate Ligament Injury as Determined From Bone Bruise Location

Abstract

Background The motions causing non-contact ACL injury remain unclear. Tibiofemoral bone bruises are believed to be the result of joint impact near the time of ACL rupture. The locations and frequencies of these bone bruises have been reported, but there is limited data quantifying knee position and orientation near the time of injury based on these contusions. Hypothesis Knee position and orientation near the time of non-contact ACL injury include extension and anterior tibial translation. Study Design Descriptive Laboratory Study Methods Magnetic resonance (MR) images of eight subjects with non-contact ACL injuries were acquired within one month of injury and subsequently analyzed. All subjects exhibited bruises on both the femur and tibia in both medial and lateral compartments. The outer margins of bone and the bone bruise surfaces were outlined on each image to create a 3D model of each subject’s knee in its position during MR imaging (MRI position). Numerical optimization was used to maximize overlap of the bone bruises on the femur and tibia and predict the position of injury. Flexion angle, valgus orientation, internal tibial rotation, and anterior tibial translation were measured in both the MRI position and the predicted position of injury. Differences in kinematics between the MRI position, which served as an unloaded reference, and the predicted position of injury were compared using paired t-tests. Results Flexion angle was near full extension in both the MRI position and the predicted position of injury (8° versus 12°, p=0.2). Statistically significant increases in valgus orientation (5°, p=0.003), internal tibial rotation (15°, p=0.003), and anterior tibial translation (22mm, p<0.001) were observed in the predicted position of injury relative to the MRI position. Conclusions These results suggest that for the bone bruise pattern studied, landing on an extended knee is high risk for ACL injury. Extension was accompanied by increased anterior tibial translation (22mm), internal tibial rotation (15°), and valgus rotation (5°) in the predicted position of injury relative to the MRI position. Clinical Relevance This study provides novel data characterizing the motions associated with ACL injury, information critical to improving strategies aimed at injury prevention.

Bone Bruise Distribution Patterns After Acute Anterior Cruciate Ligament Ruptures: Implications for the Injury Mechanism

“…15,22 Moreover, 2 recent studies demonstrated that a large anterior tibial translation was measured in patients at the predicted position of injury. 16,24 Given that the ACL is a primary restraint to anterior shear loading, a large anterior tibial translation could produce large anterior tibial shear forces and cause an ACL injury. 38 Therefore, these results combined together suggest that anterior tibial shear force in the sagittal plane could also be a key risk factor for ACL injuries.…”

Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs

“…Using the same technique, Brown et al 39 found that landing with an increased initial knee flexion angle decreased peak ACL length during both prelanding and landing phases of a drop vertical jump task. Kim et al 40 recently estimated knee kinematics at the time of ACL injury for eight patients following ACL injuries through reconstruction of the relative positions of the femur and tibia at the time of ACL injury by maximizing the contact of bone bruise areas between the femur and tibia in MRI. Their results showed a mean tibial anterior translation of 22 mm, a mean knee flexion angle of 12 , and a mean knee valgus angle of 5 at the time of ACL injury.…”

ACL biomechanical risk factors on single-leg drop-jump: a cohort study comparing football players with and without history of lower limb injury

“…They concluded that knee valgus motion along with an almost extended knee are risk factors that cause ACL strain. In a similar study, Kim et al (29) found that the mean angle of knee valgus was 5° at the time of ACL tear in eight patients. The present study evidenced statistically significant differences between the two groups in the case of KFA observed during both the jump with the least ground contact time and the three trials' mean KFA, with the mean KVAs ranging from 4.10° to 5.50°.…”