Medial and lateral menisci vascularization level in advanced osteoarthritis of the knee

Osteoarthritis of the knee is a disease widespread across the world, which leads to disability. The vascularization of the menisci is usually divided into three zones, but it can be vascularized in each zone, which is linked with the regenerative potential of the menisci. It was hypothesized, that the degree of the vascularization of the lateral and medial menisci, quantified using the Bonar score system, will be differentiated. This study also aimed to investigate the vascularization of degenerated menisci and the correlation between vascularization and preoperative pain level. This study included consecutive patients who underwent total knee arthroplasty for symptomatic end-stage knee osteoarthritis. The inclusion criteria were the presence of severe unilateral idiopathic arthritis (Ahlback score II or more) and informed consent from the patient. The following exclusion criteria were selected: secondary OA, previous surgical procedures within the affected knee, severe deformity (> 15 deg. valgus > 20 deg. varus), advanced OA in other joints, diabetes, and advanced atherosclerosis of lower limbs. During the surgery, the menisci were completely dissected to preserve their original shapes. The samples were prepared using the hematoxylin and eosin (H&E) staining method and the Alcian blue protocol and were examined under light microscopy. The extent of histopathological changes was assessed based on the Bonar score. Immunohistochemical examination of vascularization was performed using anti-CD31 and anti-CD34. The mean Bonar score was 8.2 points in the valgus knee population and 8 points in the varus knee population (p = 0.8777). The vascularization of the medial and lateral menisci was comparable in both groups (p = 0.1138). There were no statistically significant differences between the VAS score and vascularity scores in both knee deformity groups (p = 0.8046). The vascularization of both menisci, in both knee deformity group, is similar with high scores of vascularization in the advanced osteoarthritis. Moreover, there was no correlation between VAS score and meniscus vascularization. The vasculature of menisci is important in tissue regeneration, and also despite advanced degenerative process in osteoarthritis, is still at high level.