Severe destruction of menisci and articular cartilage are the main characteristics that occurred during rheumatoid arthritis of the knee, as evident from a study published in the Journal ‘Orthopaedic Surgery.’

Xianghong Meng and colleagues conducted a prospective study to assess features of knee rheumatoid arthritis (RA) on MRI and histological examination to determine pathogenesis related to knee joint devastation during RA. 

A total of 22 patients whose 26 knee joints went through total knee arthroplasty (TKA) to treat RA was selected. The two radiologists categorized the stages of knee joints on the basis of bone erosion, synovial thickening and bone marrow edema occurrence along with menisci and articular cartilage destruction using MRI. The Mann-Whitney U-test and Analysis of variance with a post-hoc test were used to compare the severity of damage of articular cartilage of medial and lateral tibial plateaus, femoral condyles, menisci and bone. The samples of menisci, synovia, cartilage and subchondral bone for histological examination were taken from the resected specimens of the knee during TKA. The histological assessment was done using immunohistochemistry and microscopy. Further, the Mann-Whitney U-test was also used to assess histological differences between areas of bone erosion and bone marrow edema.

The articular damage of medial and lateral tibial plateaus and the medial and lateral femoral condyles were classified as grade 4 with an average demolition grade of 3.6 (P = 0.002). The lateral femoral condyle assessed with the least amount of destruction. Twenty-one out of 26 patients were at stage three and rested four at stage four. The cartilage found with severe pathological changes like hyperplasia, fibrosis and related thinning & destruction. Out of total 26 specimens, 68 areas of bone erosion and 36 regions of bone marrow edema were found along with pathological changes like lymphocyte infiltration, fibrosis and mosaic structure of bone.

Further, both medial and lateral menisci showed grade 4-meniscus destruction with an average 3.85 destruction rate (P = 0.039). The medial menisci found with the highest degree of destruction.  Most severe pathological findings were noticed were engulfing calcified debris and fibrosis. All the 26 specimens were found to have synovitis with plasma cell infiltration, hyperplasia of intima cells and lymphocyte. As per results, menisci and cartilage damage is the major, whereas the bone erosion and bone marrow edema are the less significant features of knee RA.