Effect of Posterior Cruciate Ligament Rupture on Biomechanical and Histological Features of Lateral Femoral Condyle

Feasibility study of core training in knee injury recovery

Objectives

This study aims to investigate the effects of core and routine training on joint function, anterior tibia translation and balance in patients with knee joint injury.

Patients and methods

Between March 2021 and March 2022, a total of 70 patients (49 males, 21 females; mean age: 31.2±5.3 years; range, 17 to 44 years) with knee ligament injury or meniscus injury were included. The patients were divided into core training group (n=35) and conventional training group (n=35) by matching method. During the recovery process, the regular training group performed routine training, whereas the core training group engaged in core training. Both groups were trained for a total of eight weeks. After training, the Visual Analog Scale (VAS), knee Lysholm score, KT-2000 tibial anterior translation, and the star excursion balance test (SEBT) results were collected.

Results

The mean VAS scores in both groups were decreased from baseline values. The mean Lysholm score increased from baseline data; the degree of tibial anterior translation decreased compared with baseline data (p<0.05). The mean SEBT scores showed significant improvement over baseline data. In contrast with the routine training group, the mean VAS score of core training was lower and the total score of Lysholm was higher (p<0.05). When bending the knee at 90°, the mean tibial anterior translation was 3.87±1.23 mm in the core training group, significantly lower than in the regular training group (p<0.05). The SEBT results showed that, after eight weeks of training, healthy and injured legs in core training group exceeded those of the regular training group in the farthest distance (p<0.05).

Conclusion

Our study results indicate that core training is more successful than regular training in reducing pain, and it can ameliorate the dynamic balance stability of patients with knee injury.

The effects of posterior cruciate ligament rupture on the biomechanical and histological characteristics of the medial collateral ligament: an animal study

Background

To investigate the effect of complete rupture of the posterior cruciate ligament (PCL) on the biomechanics and histology of the medial collateral ligament (MCL).

Materials and methods

Seventy-two male rabbits were randomly divided into two groups: the ruptured group was treated with complete PCL amputation, while the intact group was only subjected to PCL exposure without amputation. Eighteen rabbits were randomly sacrificed at 8, 16, 24, and 40 weeks after the operation, and their specimens were processed for mechanical tensile testing, nano-indentation experiments, hematoxylin-eosin (HE) staining, and picrosirius-polarization staining.

Results

There was no significant difference in the length and maximum displacement of the MCL between the ruptured group and the intact group at each time point. The maximum load of the ruptured group was significantly smaller than that of the intact group at 40 W. The elastic modulus and micro-hardness of the ruptured group increased significantly at 24 W and decreased significantly at 40 W. At 16 W and 24 W after PCL rupture, the number of type I collagen fibers and type III collagen fibers in the MCL of the ruptured group was significantly increased compared with that of the intact group. While the type I collagen fibers of the ruptured group were significantly decreased compared with the intact group at 40 W, there was no significant difference in type III collagen fibers between the ruptured group and the intact group.

Conclusion

PCL rupture has no significant effect on the mechanical and histological properties of MCL in a short period of time under physiological loading, but the histological and mechanical properties of MCL decrease with time.

The morphology and histology study on rabbit degenerated medial meniscus after posterior cruciate ligament rupture

The morphology and histology changes in the medial meniscus after posterior cruciate ligament (PCL) rupture are poorly understood. Forty-eight rabbits were divided into matched mode pairs; each rabbit had an experimental side, in which the PCL was transacted, and a control side. At the 4, 8, 16 and 24 weeks after the PCL transection, each of the 12 rabbits was killed. Histology was performed to detect the expression of the tissue inhibitors of metalloproteinases-1 (TIMP-1), matrix metalloproteinase (MMP)-1 and MMP-13 in the medial meniscus. We found that medial meniscus displayed significant degenerative characteristics in morphology. The histological evaluation of the degeneration found that the expression levels of TIMP-1, MMP-1 and MMP-13 in the medial meniscus were higher in the experiment side than those in the control side (P<0.05). The expression of both TIMP-1 and MMP-13 was initially elevated and then decreased. The MMP-1 expression reached its peak swiftly and then maintained a relatively high level. There were clear time-dependent degenerative changes in the histology of the medial meniscus after PCL rupture. The high expression of TIMP-1, MMP-1 and MMP-13 in the cartilage may be responsible for the degeneration, and PCL rupture may trigger meniscus degradation and ultimately osteoarthritis.