OBJECTIVETo investigate the effect of rupture and reconstruction of the posterior cruciate ligament (PCL) on the degeneration of rabbit knee joint.

METHODSThirty-three mature New Zealand white rabbits were divided into 3 groups. In experiment group I, the PCL of the right knees in 21 rabbits were resected, the contralateral joints as control group, in which only a medial arthrotomy was performed. In experiment group II, the PCL of the right knees in 12 rabbits were immediately reconstructed after PCL were resected. In experiment group I and control group the rabbits were respectively killed 6, 12 and 26 weeks after the operation. In experiment group II the rabbits were respectively killed 12, 26 weeks after the operation. The methods of ink staining, histology, immunohistochemistry and SEM were used to analyze the changes of articular cartilage of the joints.

RESULTSIn experiment group I, the knee joints had obvious degeneration of articular cartilage at 26 weeks. The quantitative analysis of the results of the ink staining method showed the degeneration of knee articular cartilage was more serious at 26 weeks than that at 26 weeks in control group. Histological results demonstrated: the large area of fibrosis of cartilage could be seen in the medial condyle at 26 weeks; the fibrosis was deep into the deep layer of cartilage and the number of cells decreased; the average Mankin's score was 7.7. At 26 weeks, type I and III collagen were detected in fibrotic cartilage, while the staining of type II collagen was slight. In experiment group I, the injuries of cartilage in medial condyle could be seen at every stage through SEM, while the surface of cartilage demonstrated disorder in control group through SEM. In experiment group II, only a few specimens had mild injuries of cartilage, the degeneration of cartilage in medial condyle and trochlea were slighter at 26 weeks than that in experiment group I.

CONCLUSIONSPCL rupture can result in articular cartilage degeneration, which develops as time goes on. The degeneration of articular cartilage is more serious in medial compartment and patellofemoral joint than those in other positions. Immediate reconstruction of PCL can effectively prevent articular cartilage degeneration.