With high-resolution contrast-enhanced MRI at 7.1T the time course of gross pathologic changes in rabbit knees with surgically induced OA can be monitored. Still insufficient spatial resolution and image contrast of the applied 2D protocols limit the sensitivity and prohibit detection of articular cartilage contour abnormalities. However, signal alterations in the cartilage layer indicate alterations of tissue composition at a very early stage of OA development. When used with 3D protocols, contrast-enhanced MRI offers a promising tool for qualitative and quantitative in vivo monitoring of OA in rabbit models.

Summary: Damage to the meniscus can lead to posttraumatic osteoarthritis. Early markers of joint injury and tissue disease may be useful in developing and administering clinical treatmenl. We investigated the effects of total medial meniscectomy on biomarkers measurcd serially in synovial lavage fluid each month for 3 months. Following meniscectomy in dogs, four biomarkers were evaluated: cartilage oligomeric matrix protein, keratan sulfate epitope (5D4). the 3R3(-) neoepitope of chondroitin-(,-sulfate, and the 3B3(+) chondroitinasegenerated epitope of chondroitin-6-sulfate. Meniscectomy led to statistically significant elevations of all four biomarkers, with levels peaking at 4 weeks. By 12 weeks. the level of thc SD4 epitopc returned to the prcoperative baseline level whereas that of cartilage oligomeric matrix protein. 3B3(-), and 3B3(+) remained above the baseline. Concentrations of these biomarkers in the knees not operated on did not change significantly from the baseline. The levels of cartilage oligomeric matrix protein and 3B3(-) relativc to 3B3(+) rcrnained constant in all knees. In contrast. the level of SD4 relativc to 3B3(+) declined over time in the knee operated on but remained constant in the knee not operated on. These results demonstrate a quantitative change in the molecular componenls of synovial fluid after meniscectomy. as well as a qualitative change evinced by an alteration in the relative proportions of these epitopes. Extensive analyses showed a strong correlation between serum levcls of 3B3( -) from thc femorai and cephalic veins; however, serum 3B3(-) was not correlated with synovial h i d 3B3( -). These findings support the hypothesis that the conccntrations of select cartilage biomarkers in synovial fluid are altered following meniscectomy and are promising tools for objectively monitoring the induction of osteoarthritis in this model system.The menisci have been shown to be critical for normal function and health of the knee joint (42,78), serving crucial roles in load transmission (3), shock absorption (86), joint congruence (59) and stability (63), and likely proprioception (26,31,80,112). Meniscal injury is quite common (12), second in frequency only to ligamentous strain (9,32,48,56,93). It is the most common injury sustained by athletes (100) and i s the predominant injury associated with chondral damage beyond the third decade of life (29). Observations of the natural history of meniscal damage reveal deleterious long-term consequences. As many as 20-60% of patients with an isolated injury of the meniscus had radiographic signs of joint degeneration (32.94). Knee injury may occur at an early age, with the first radiographic signs of osteoarthritis ensuing, on average,

No abstract

In this rabbit model of medial meniscectomy, levels of type II collagen fragments in SF appear to provide a useful marker of the early degenerative changes.

No abstract