Objective: To investigate the effect of the anterior cruciate ligament (ACL) rupture on the biomechanics of the lateral collateral ligament (LCL).
Methods: The specimens in this experiment were knee joints from 6 normal fresh adult male cadavers which was donated voluntarily, aged of 26-35 years with an average of 31.4 years. The knee joints were dissymmetry with 3 in left and right sides respectively. At first, all the 6 specimens lying on the self-made movement tooting, whose LCL straining were measured by strain gauges at different angles (0, 30, 60 and 90 degrees) under axial loads of 400 N by e-testing machine for simulation of the normal knee joint force, were regarded as the intact ACL group. Then, the ACL in all 6 specimens were cut off completely as the deficiency group and did the same step.
Results: The strain of the LCL were as follows at 0, 30, 60 and 90 degrees: (0.00 +/- 1.63), (-17.2 +/- 8.57), (-24.00 +/- 4.80) and (26.50 +/- 4.65) mu epsilon in intact ACL group; (0.75 +/- 8.22), (-52.75 +/- 3.33), (24.30 +/- 4.99) and (26.30 +/- 4.27) mu epsilon in deficiency group. There was no significant difference at 0 degree and 90 degrees flexion (P > 0.05), but significant difference at 30 degrees and 60 degrees flexion (P < 0.05) between the two groups.
Conclusion: The rupture of the ACL has significantly effect on the strain of the LCL which suffering abnormal load in the state at 30 degrees and 60 degrees flexion. At 30 degrees flexion the relaxation of the LCL increased, which means the possibility of the injury of the LCL is rare; and at 60 degrees flexion the LCL become very tense and thereby at the high risk of instability.