Cartilage Lesions In Knee Joints Research Articles

Quantitative Analysis of Collagen Network Structure and Fibril Dimensions in Cartilage Repair with Autologous Chondrocyte Transplantation

Objective: The aim of this study was to undertake a stereological analysis to quantify the dimensions of the collagen network in the repair tissue of porcine joints after they had been subjected to autologous chondrocyte transplantation (ACT). Method: ACT was used to repair cartilage lesions in knee joints of pigs. Electron-microscopic stereology, immunostaining for type II collagen, and quantitative polarized-light microscopy were utilized to study the collagen fibrils in the repair tissue 3 and 12 months after the operation. Results: The collagen volume density (V_V) was lower in the repair tissue than in normal cartilage at 3 months (20.4 vs. 23.7%) after the operation. The collagen surface density (S_V, 1.5·10^–2 vs. 3.1·10^–2 nm²/nm³) and V_V increased with time in the repair tissue (20.4 vs. 44.7%). Quantitative polarized-light microscopy detected a higher degree of collagen parallelism in the repair tissue at 3 months after the operation (55.7 vs. 49.7%). In contrast, 1 year after the operation, fibril parallelism was lower in the repair tissue than in the control cartilage (47.5 vs. 69.8%). Conclusion: Following ACT, V_V and S_V increased in the repair tissue with time, reflecting maturation of the tissue. One year after the operation, there was a lower level of fibril organization in the repair tissue than in the control cartilage. Thus, the newly synthesized collagen fibrils in the repair tissue appeared to form a denser network than in the control cartilage, but the fibrils remained more randomly oriented.

Polychrome sequential labeling of subchondrial bone tissue in early and advanced stages of gonarthrosis in male STR/IN-mice

Polychrome sequential labeling is used to study the dynamic of subchondral bone sclerosing during developing osteoarthrotic cartilage lesions in knee joints of male STR/1N-mice. The applied technique gives detailed information about site and time of new bone formation in the subchondral tissue using four different colored vital markers. Whereas control animals show regular bone deposition with a circumferential, concentric arrangement of fluorochromes along the various trabeculae, STR/1N-mice with osteoarthrotic cartilage lesions displayed fluorescence bands arranged eccentrically around the marrow cavities always pointing towards the cartilage lesions. The results also demonstrate, that the linear separation between the first label and the anatomic surface of the bone marrow cavity varies considerably in the individual experimental groups. Compared to control knee joints, which show appositional bone growth rates of 25 to 50 microns per 70 days, osteoarthrotic mice reveal increased bone growth rates during developing osteoarthrosis. In early osteoarthrotic cartilage lesions distances between the individual bands are distinctly larger in comparison to distances in advanced lesions. In both cases the rate of appositional bone growth exceeds bone formation in control animals 3 to 4 times.

Detection of Posttraumatic Cartilage Lesions using Magnetic Resonance Imaging (MRI): An experimental Study on Canines

Purpose: The investigation of cartilage lesions in knee joints after knock injuries with Magnetic Resonance Imaging (MRI) over a time period of six months. Materials and Methods: A controlled force form a drop-tower was applied to one knee of 12 normal adult beagle dogs to produce a subchondral bone bruise and soft tissue compression without visible bone fracture. MR images of both knees were acquired at a magnetic field strength of 1.5 T immediately after this defined knock-trauma and again after six months. The images were based on sagittal T1-weighted spin-echo sequence, a T2-weighted turbo-spin-echo sequence with spectral fat-suppression, and a fat suppressed 3D spoiled gradient echo sequence (FLASH®, SPGR). The traumatized joints underwent an arthroscopy immediately after the second MR examination and biopsies of the cartilage were performed. The biopsies were scored histologically (Mankin score of degenerative cartilage lesions). Results: Six months after trauma, ten out of the twelve canines had circumscribed cartilage lesions in the traumatized area of the affected knee joint and nearly all dogs had joint effusions in the affected knee joints. Furthermore, the knees with the most extending bone marrow edema developed high-grad cartilage lesions. All control scans and cartilage biopsies of the contralateral knee joints showed normal findings. Conclusion: Joint trauma causes focal cartilage defects. The described animal model supports the hypothesis that subchondral traumatic lesions such as bone bruises are an important risk factor for early development of osteoarthritis in (knee) joints. Within a few months, severe osteoarthritis could be induced by subchondral bone bruises. Potential etiogenic mechanisms are the damage of subchondral nutrition of hyaline cartilage or changes in the biochemical composition or biomechanic properties of the cartilage.