Inhibition of Anterior Tibial Translation or Axial Tibial Rotation Prevents Anterior Cruciate Ligament Failure during Impact Compression

Abstract

Background Anterior cruciate ligament injury is prevalent in activities involving large and rapid landing impact loads. Hypothesis Inhibition of anterior tibial translation/axial tibial rotation forestalls the ligament from failing at the range of peak compressive load that can induce ligament failure when both factors are unrestrained. Study Design Controlled laboratory study. Methods Sixteen porcine knee specimens were mounted onto a material testing system at 70° of flexion and were divided into 4 test groups: impact compression without restraint (IC), anterior tibial translation restraint (ICA), axial tibial rotation restraint (ICR), and combination of both restraints (ICC). Compression was successively repeated with increasing actuator displacement until ligament failure or visible bone fracture was observed. During compression, rotational and translational joint data were obtained using a motion capture system. Results The IC group underwent ligament failure via femoral avulsion; the peak compressive force during failure ranged from 1.4 to 4.0 kN. The ICA, ICR, and ICC test groups developed visible bone fracture with the ligament intact; the peak compressive force during fracture ranged from 2.2 to 6.9 kN. Posterior femoral displacement and axial tibial rotation for the ICA and ICR groups, respectively, were significantly lower relative to the IC group ( P < .05). Both factors were substantially reduced in the ICC group, but peak compressive force was higher compared with the IC group ( P < .05). Conclusion Substantial inhibition of these factors in an impact setup, which can induce ligament failure with the factors unrestrained, was able to prevent failure. Clinical Relevance Adequate inhibition of anterior tibial translation and axial tibial rotation by knee bracing during injurious impact is necessary for effective ligament protection.