Direct contribution of axial impact compressive load to anterior tibial load during simulated ski landing impact.
Anterior tibial loading is a major factor involved in the anterior cruciate ligament (ACL) injury mechanism during ski impact landing. We sought to investigate the direct contribution of axial impact compressive load to anterior tibial load during simulated ski landing impact of intact knee joints without quadriceps activation. Twelve porcine knee specimens were procured. Four specimens were used as non-impact control while the remaining eight were mounted onto a material-testing system at 70 degrees flexion and subjected to simulated landing impact, which was successively repeated with incremental actuator displacement. Four specimens from the impacted group underwent pre-impact MRI for tibial plateau angle measurements while the other four were subjected to histology and microCT for cartilage morphology and volume assessment. The tibial plateau angles ranged from 29.4 to 38.8 degrees . There was a moderate linear relationship (Y=0.16X; R(2)=0.64; p<0.001) between peak axial impact compressive load (Y) and peak anterior tibial load (X). The anterior and posterior regions in the impacted group sustained surface cartilage fraying, superficial clefts and tidemark disruption, compared to the control group. MicroCT scans displayed visible cartilage deformation for both anterior and posterior regions in the impacted group. Due to the tibial plateau angle, increased axial impact compressive load can directly elevate anterior tibial load and hence contribute to ACL failure during simulated landing impact. Axial impact compressive load resulted in shear cartilage damage along anterior-posterior tibial plateau regions, due to its contribution to anterior tibial loading. This mechanism plays an important role in elevating ACL stress and cartilage deformation during impact landing.
Department of Orthopaedic Surgery, NUS Tissue Engineering Programme, Office of Life Sciences, National University of Singapore, Singapore 117510.
C H
CH
Yeow
P V S
PV
Lee
J C H
JC
Goh
D000818:Animals; D016118:Anterior Cruciate Ligament / Q000473:pathology / Q000503:physiopathology; D000070598:Anterior Cruciate Ligament Injuries; D001265:Athletic Injuries / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D001696:Biomechanical Phenomena; D019245:Compressive Strength; D006801:Humans; D066298:In Vitro Techniques; D007718:Knee Injuries / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D023421:Models, Animal; D008954:Models, Biological; D012865:Skiing / Q000502:physiology*; D013314:Stress, Mechanical; D034421:Sus scrofa; D013977:Tibia / Q000503:physiopathology*; D055114:X-Ray Microtomography