Radiographic joint space narrowing and histologic changes in a rabbit meniscectomy model of early knee osteoarthrosis

The purpose of this study was to compare weightbearing radiographs with histologic cartilage evaluation in a rabbit meniscectomy model of the early stage of osteoarthrosis. Fifteen rabbits had a medial meniscectomy performed in one knee and a sham operation in the other knee. Five rabbits each were sacrificed at 13, 25, and 40 weeks after surgery. Radiographic joint space width and histologic cartilage changes of the medial knee compartment were quantified. Five non-operated knees and five knees in which the meniscus had been removed immediately before the evaluations served as control specimens. Overall, the joint space of the peripheral part of the medial knee compartment was narrower in knees operated on for meniscus removal than in sham-operated knees (P < 0.003). In the knees with the meniscus removed, more cartilage changes were seen at the joint surface area of contact on radiographs than in the sham-operated knees (P < 0.0015). Indeed, the area of contact had cartilage changes similar to those in the whole medial compartment. However, there was no correlation between the degree of histologic cartilage change and the corresponding joint space measurements. Joint space width as measured on weightbearing radiographs is reduced after meniscectomy in the rabbit, but it does not reflect the degree of cartilage damage of the loaded joint surfaces in early stages of osteoarthrosis.