Clinical meaning
Total knee arthroplasty (TKA) replaces the damaged articular surfaces of the knee joint with prosthetic components. Osteoarthritis, the primary indication, involves progressive degradation of hyaline cartilage from mechanical stress and enzymatic destruction. Chondrocytes release matrix metalloproteinases (MMPs) and aggrecanases that degrade the collagen-proteoglycan matrix. Loss of cartilage exposes subchondral bone, which undergoes sclerosis and osteophyte formation. The synovial membrane becomes inflamed, producing excess synovial fluid with inflammatory mediators (IL-1, TNF-alpha) that further accelerate cartilage destruction. In TKA, the femoral condyles are resurfaced with a cobalt-chromium component, the tibial plateau with a titanium baseplate and polyethylene insert, and often the patellar surface with a polyethylene button. Cemented fixation uses polymethyl methacrylate (PMMA) that generates an exothermic reaction during curing. Post-operatively, the inflammatory response and surgical tissue disruption create risk for deep vein thrombosis due to venous stasis, endothelial injury (Virchow triad), and hypercoagulability.