Importance of posterior tibial slope in joint kinematics with an anterior cruciate ligament-deficient knee

Aims To fully quantify the effect of posterior tibial slope (PTS) angles on joint kinematics and con-tact mechanics of intact and anterior cruciate ligament-deficient (ACLD) knees during the gait cycle. Methods In this controlled laboratory study, we developed an original multiscale subject-specific finite element musculoskeletal framework model and integrated it with the tibiofemoral and patel-lofemoral joints with high-fidelity joint motion representations, to investigate the effects of 2.5 degrees increases in PTS angles on joint dynamics and contact mechanics during the gait cycle. Results The ACL tensile force in the intact knee was significantly affected with increasing PTS angle. Considerable differences were observed in kinematics and initial posterior femoral trans-lation between the intact and ACLD joints as the PTS angles increased by more than 2.5 degrees (beyond 11.4 degrees). Additionally, a higher contact stress was detected in the peripheral posterior horn areas of the menisci with increasing PTS angle during the gait cycle. The maximum ten-sile force on the horn of the medial meniscus increased from 73.9 N to 172.4 N in the ACLD joint with increasing PTS angles. Conclusion Knee joint instability and larger loading on the medial meniscus were found on the ACLD knee even at a 2.5 degrees increase in PTS angle (larger than 11.4 degrees). Our biomechanical findings support recent clinical evidence of a high risk of failure of ACL reconstruction with steeper PTS and the necessity of ACL reconstruction, which would prevent meniscus tear and thus the development or progression of osteoarthritis.

Automated summary

This study aimed to investigate the effects of posterior tibial slope (PTS) angles on joint kinematics and contact mechanics of intact and anterior cruciate ligament-deficient (ACLD) knees. The results showed that increasing PTS angles significantly affected the tensile force on the ACL in the intact knee and led to differences in kinematics and increased loading on the medial meniscus.