Cruciate Ligament Rupture. Experimental Study, The Effects Of Patellar Biomechanics

The injuries of posterior Curciate Ligament are very common in sport injuries. The injuries mainly effect the stabilization of knee joint. The PCL injury did effect the patella or not is unknown, there is few literature report it. This research intend to use biomechanic method observe the biomechanic change of patella after PCL complete rupture or incomplete rupture, provide the theory evidence of pathological changes in patella after PCL rupture.Objective:To investigate the biomechanical influences of partial and total PCL rupture on the patella.Methods:6 fresh cadaveric knees from adult human beings were divided into PCL intact group(6 samples),PMB broken group(3 samples),ALB broken group(3 samples) and PCL total broken group(6 samples). The knees were applied with 200N-800N axial loading force when they flexed 0°,30°,60°,90°.The strain on the patella was measured and analysed.Results:1. In PCL intact group:①In 0°position, the strain of all 4 test place of patellar were the smallest, and the differences among the parts were not significant (P>0.05).②In 30°positions, the inferior of patellar was compressive strain, the superior of patellar was tensile strain, the absolute value of strain was increased with the load increased. In 60° positions, the strain of inferior and superior of patellar were tensile strain, the absolute value of strain was increased with the load increased. In90°positions, the superior of patellar was compressive strain, the inferior of patellar was tensile strain, the absolute value of strain was increased with the load increased.The differences among the parts were all significant (P<0.05).③In 30°,60°,90°positions, the medial and lateral of patellar were compressive strain, the absolute value of strain was increased with the load increased. The differences among the parts were all significant (P<0.05).2. In ALB broken group:①In 0°position, the strain of all 4 test place of patellar were the smallest, and the differences among the parts were not significant (P>0.05).②In 30°positions, the superior of patellar was tensile strain, the inferior of patellar was compressive strain, the absolute value of strain on the superior and inferior of patellar was increased with the load increased. In 60°and 90°positions, the superior and inferior of patellar was tensile strain, and the absolute value of strain was increased with the load increased. The differences among the parts were all significant (P<0.05).③In 30°,60°,90°positions, the medial and lateral of patellar were compressive strain, the absolute value of strain was decreased with the load increased. The differences among the parts were all significant (P<0.05).3. In PMB broken group:①In 0°position, the strain of all 4 test place of patellar were the smallest, and thedifferences among the parts were not significant (P>0.05).②In 30° positions, the strain of superior of patellar were tensile strain, the inferior of patellar was compressive strain, the absolute value of strain on the superior and inferior of patellar was increased with the load increased. In 60°and 90°positions, the superior and inferior of patellar was tensile strain, the absolute value of strain was increased with the load increased. The differences among the parts were all significant (P<0.05).③In 30°,60°,90°positions, the medial and lateral of patellar were compressive strain, In 30°positions, the absolute value of strain was increased in first, then decreased with the load increased. In 60°,90°positions,the absolute value of strain was decreased with the load increased. The differences among the parts were all significant (P<0.05).4. In PCL total broken group:①In 0°position, the strain of all 4 test place of patellar were the smallest, and the differences among the parts were not significant (P>0.05).②In 30°positions, the strain of superior of patellar were tensile strain, the inferior of patellar was compressive strain. In 60°,90°positions, the superior and inferior of patellar were tensile strain, the absolute value of strain was increased with the load increased. The differences among the parts were all significant (P<0.05).③In 30°positions, the strain of medial of patellar were tensile strain, the lateral of patellar was compressive strain. In 60°,90°positions, the medial and lateral of patellar were compressive strain, the absolute value of strain was decreased with the load increased. The differences among the parts were all significant (P<0.05).Conclusion:1. PCL total rupture may cause abnormal load on the patellar in all the positions.2. ALB rupture may cause abnormal load on the patellar in 30°,60°,90°positions.3. PMB rupture not cause abnormal biomechanical change on patella in 0°position and 200N,400N loaded in 30°position.4. PCL total rupture can cause the strain of medial of patellar was larger than lateral of patellar, which need to be further explored.