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 his tologic cartilage evaluation in a rabbit meniscectomy model of the early st age 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 nonoperated knees and five knees in which the meniscus had been removed immediately before the evaluations served as control specimen s. Overall, the joint space of the peripheral part of the medial knee compa rtment 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 ca rtilage changes were seen at the joint surface area of contact on radiograp hs than in the sham-operated knees (P < 0.0015). Indeed, the area of contac t had cartilage changes similar to those in the whole medial compartment. H owever, there was no correlation between the degree of histologic cartilage change and the corresponding joint space measurements. Joint space width a s measured on weightbearing radiographs is reduced after meniscectomy in th e rabbit, but it does not reflect the degree of cartilage damage of the loa ded joint surfaces in early stages of osteoarthrosis.