Tibial plateau geometry influences lower extremity biomechanics during landing.

BACKGROUND: Intersubject differences in lateral and medial posterior tibial plateau slope, coronal tibial slope (CTS), and medial tibial plateau depth (MTD) may influence one's susceptibility for anterior cruciate ligament (ACL) injury. Understanding how these structural characteristics influence hip and knee joint biomechanics during weightbearing activity may advance our understanding of how tibial plateau geometry influences one's injury risk potential. Purpose/ HYPOTHESES: To determine the extent to which tibial plateau geometry is associated with frontal and transverse plane hip and knee joint biomechanics during the initial landing phase of a double-legged drop landing. Greater lateral tibial slope combined with lower medial/lateral tibial slope ratio would predict greater tibial internal rotation motion and moments. Lower CTS would predict greater hip adduction and knee valgus motion and reduced internal peak varus moments. These associations would be stronger when combined with a shallower MTD. STUDY
DESIGN: Descriptive laboratory study.
METHODS: Magnetic resonance scans of the knee were obtained on 23 female participants who were also assessed for hip and knee joint biomechanics during the initial landing phase of double-legged drop jumps.
RESULTS: Once controlling for the respective initial hip flexion or initial knee flexion angle at ground contact, lower CTS consistently predicted greater initial and peak hip adduction and knee valgus angles (R (2) range, .212-.427, P < .027). Greater coronal and lateral tibial slope predicted greater hip internal rotation (femur relative to pelvis) at initial contact (R (2) = .504) and greater CTS and lower medial/lateral tibial slope ratio predicted greater knee internal rotation (tibia relative to femur) excursions (R (2) = .594, P = .001). Joint geometry was not associated with hip or knee peak joint moments.
CONCLUSION: These data confirm substantial intersubject differences in tibial condylar geometry that are associated with intersubject differences in hip and knee motion patterns when landing from a jump. CLINICAL RELEVANCE: The current findings may partially explain a female's greater likelihood of demonstrating combined motion patterns of knee valgus and external rotation during landing. Although tibial geometry cannot be modified through training, these associations suggest that tibial geometry may have a substantial influence on tibiofemoral joint biomechanics when the knee is subjected to external loads and deserves further study in our understanding of ACL injury.