Four Diagonally Laid Tunnels Reconstruction Of Posterior Cruciate Ligament And Anatomic Reconstruction Of Posterolateral Complex: An Experimental Study

Objective:Posterior cruciate ligament(PCL) and posterolateral complex(PLC) provides static and dynamic stability to the knee prevent excessive hyperextension, varus angulation, and tibial external rotation.The purpose of this study was to compare reconstruction of posterior cruciate ligament with four diagonally laid tunnels with the single-bundle PCL reconstruction and double-bundle PCL reconstruction,and make sure that This four diagonal angle tunnel technique be a new method for anatomic PCL reconstruction; then the knees were tested in the intact, PLC-deficient, and PLC-reconstructed conditions using a biomechanical torsion test machine, make sure a new anatomic PLC reconstruction technique.Methods: The 6 fresh-frozen human knee speciments were tested with CSS-44020 load cell in the PCL intact, the PCL dissected, and the PCL reconstructed knee. The single bundle PCL reconstruction was performed. secondly,the single tibial tunnel double-bundle femoral tunnel ("Y"shaped) PCL reconstruction was performed. At last,four diagonal angle tunnel PCL reconstruction was performed.While 134N posterior load was applied to the proximal part of the tibia,tibial posteror translation were measured as the knee was flexed at 0°,30°,60°,90°,120°.Analysis and comparation were done to the three reconstruction methods.Then tibia external rotation degrees were tested in the intact, PLC-deficient, and PLC-reconstructed conditions using a biomechanical torsion test machine as the knee was flexed at 0°,30°,60°,90°.Results:1 When the proximal part of the tibia was applied a 134N posterior load, posterior tibial translation of the intact PCL knee was greatest (7.37±1.04mm) at 30°and least (3.78±0.37mm) at 120°of flexion. Then in the PCL dissected, the tibial translation increased significantly , was greatest (16.33±0.83mm) at 90°and least (9.68±1.39mm) at 0°of flexion(P<0.05). After the single bundle PCL reconstruction,posterior tibial translation was decreased and greatest (8.12±0.62mm) at 30°of flexion. After the single tibial tunnel double-bundle femoral tunnel ("Y"shaped) PCL reconstruction, the posterior tibial translation was decreased significantly, greatest (7.43±0.63mm) at 30°and least (4.72±0.62mm) at 120°of flexion(P>0.05).After four diagonal angle tunnel PCL reconstruction,the posterior tibial translation was decreased significantly, greatest(7.40±0.48mm)at 30°and least(3.82±0.46mm) at 120°of flexion ,which were similar to that of the intact PCL knee(P>0.05).2 After external rotation torques of 5Nm were given to the tibia of the intact knees , The degree of external tibial rotation was least (9.15±0.29°) at 0°and greatest (21.95±1.73°) at 90°of flexion . The sectioning of the PLC result in a significant increase in external rotation at all degree of flexion,The degree of external tibial rotation was least (34.33±1.35°) at 0°and greatest (46.89±0.93°) at 90°of flexion(P<0.05).After reconstruction of LCL,PT( tibial tunnel of PT is from the Gerdy tubercle to the point 20 mm inferior to the posterior joint line and at lateral of the inferolateral corner of the PCL) and PFL,external tibial rotation values were not significantly different from those for the intact knee at any angle tested,The degree of external tibial rotation was least 9.79±0.59°) at 0°and greatest (22.54±1.26°) at 90°of flexion(P>0.05).Conclusion:1 Single bundle PCL reconstruction can restore the posterior tibial translation, which is greatest at 30°;single tibial tunnel double-bundle femoral tunnel ("Y"shaped) PCL reconstruction can restore the posterior tibial translation, but can not keep PCL fiber and attachment isn't similar to the anatomically intact PCL.And four diagonal angle tunnel PCL reconstruction can restore the posterior tibial translation and the attachment is similar to the anatomically intact PCL. This four diagonal angle tunnel technique keeps more PCL fiber and better protects bone bridge between tunnels and restore anterior-Posterior laxity of normal knee effectively across the full range of flexion.2 The tibial tunnel of PT is from at the point 20 mm inferior to the posterior joint line and at lateral of the inferolateral corner of the PCL, which is similar to the intact PT and easily find through arthroscopic.3 Reconstruction of LCL, PT and PFL was anatomically similar to intact PCL, restore tibial external rotation of normal knee across the full range of flexion effectively.