Tibiofemoral Kinematics During Compressive Loading of the ACL-Intact and ACL-Sectioned Knee

Abstract

Background: Tibial geometry and knee laxity have been identified as risk factors for both noncontact anterior cruciate ligament (ACL) rupture and instability in the setting of ACL insufficiency via clinical studies; yet, their biomechanical relationships with tibiofemoral kinematics during compressive loading are less well understood. The purpose of this study was to identify the relative contributions of sagittal tibial slope, medial tibial eminence volume, and anterior knee laxity to tibiofemoral kinematics with axial compression in both ACL-intact and ACL-sectioned cadaveric knees. Methods: Computed tomography (CT) data were collected from 13 human cadaveric knees (mean donor age, 45 ± 11 years; 8 male). Validated algorithms were used to calculate the sagittal slope of the medial and of the lateral tibial plateau as well as volume of the medial tibial eminence. Specimens were then mounted to a robotic manipulator. For both intact and ACL-sectioned conditions, the robot compressed the knee from 10 to 300 N at 15° of flexion; the net anterior tibial translation of the medial and lateral compartments and internal tibial rotation were recorded. Simple and multiple linear regressions were performed to identify correlations between kinematic outcomes and (1) osseous geometric parameters and (2) anterior laxity during a simulated Lachman test. Results: In ACL-intact knees, anterior tibial translation of each compartment was positively correlated with the corresponding sagittal slope, and internal tibial rotation was positively correlated with the lateral sagittal slope and the sagittal slope differential (p ≤ 0.044). In ACL-sectioned knees, anterior tibial translation of the medial compartment was positively associated with medial sagittal slope as well as a combination of medial tibial eminence volume and anterior laxity; internal tibial rotation was inversely correlated with anterior knee laxity (p < 0.05). Conclusions: Under compressive loading, sagittal slope of the medial and of the lateral tibial plateau was predictive of kinematics with the ACL intact, while medial tibial eminence volume and anterior laxity were predictive of kinematics with the ACL sectioned. Clinical Relevance: The relationships between tibial osseous morphology, anterior laxity, and knee kinematics under compression may help explain heightened risk of ACL injury and might predict knee instability after ACL rupture.

Posterior tibial slope and meniscal slope correlate with in vivo tibial internal rotation during running and drop jump

“…Understanding of ACL injury risk is improved by this in vivo study that links bone and meniscus morphology to dynamic kinematics during running and drop jump. A study of 13 cadaver knees that found internal tibial rotation was positively correlated to lateral sagittal slope contradicts our results [37]. One explanation for these contrary results is that the knee was loaded with only 300 N of compression at a ixed lexion angle of 15° in that cadaver study.…”

Association Between Meniscal Allograft Tears and Early Surgical Meniscal Allograft Failure

“…One reason might be the increased translation in the lateral versus medial tibiofemoral compartment in combination with the fact that meniscal allograft bodies are fixed using sutures, limiting the mobility of the graft as compared with the native lateral meniscus. 29,41 In addition, a steep posterior tibial slope has been shown to be associated with increased anterior tibial subluxation, 11 which may increase the stress on the anterior parts of meniscal allografts. Preoperative sizing of meniscal allografts is usually based on the length and width of the corresponding tibial plateau.…”

Measurement of Medial Tibial Eminence Dimensions for the Clinical Evaluation of ACL-Injured Knees: A Comparison between CT and MRI

“…15 26 27 In the setting of an ACL-insufficient knee, the MTE seems to play a larger role in tibiofemoral stability, with lower MTE volumes being correlated with increased anterior tibial translation. 15 Therefore, while ACL injuries in young patients are often treated operatively, in a subgroup of older individuals with decreased posterior tibial slopes, large MTE dimensions, and no excessive anteroposterior laxity, the increased tibiofemoral stability resulting from these geometric factors may permit successful nonoperative management. To our knowledge, this is the first study to validate a reproducible method to measure MTE height and width and compare the MTE measurements between CT and MRI.…”

“…As a result, decreased volumes of the MTE may lead to less bony contact with the notch, placing greater demand on ligamentous restraints and other soft tissues, such as the menisci. 15,26,27 In the setting of an ACL-insufficient knee, the MTE seems to play a larger role in tibiofemoral stability, with lower MTE volumes being correlated with increased anterior tibial translation. 15 Therefore, while ACL injuries in young patients are often treated operatively, in a subgroup of older individuals with decreased posterior tibial slopes, large MTE dimensions, and no excessive anteroposterior laxity, the increased tibiofemoral stability resulting from these geometric factors may permit successful nonoperative management.…”

“…[10][11][12][13][14] In a cadaveric study, Wang et al demonstrated that increased volume of the MTE, as measured on computed tomography (CT), may be associated with decreased tibiofemoral stability during axial loading in ACL-injured knees. 15 A larger MTE may contribute to increased tibiofemoral stability by abutting the intercondylar notch and preventing increased anterior tibial translation and internal tibial rotation in the absence of an ACL. Therefore, similar to the manner in which tibial slope is utilized in the clinical setting, 16 measurements of MTE dimensions may help predict knee stability after ACL injury as well as graft forces after ACL reconstruction.…”