Current status of total knee arthroplasty.

Total knee arthroplasty has become an acceptable method of surgical management for severe, disabling gonarthropathy. The three major biomechanical classifications of total knee prostheses are minimally constrained, partially constrained, and fully constrained. The major indication for total knew arthroplasty is pain, followed in a much lower frequency by instability, loss of motion, and deformity. The principal contraindications for the various types relate solely to the residual or restorable ligamentous stability of the knee and the degree of bone loss. In general, the greater the instability and bone loss, the more constrained the prosthesis must be Theoretically, loosening rates increase with increasing shear stresses, which are generally highest with the most constrained prostheses. The major complications are sepsis, loosening, and instability. Various prostheses have incorporated patellofemoral resurfacing as the final dimension in producing a total knee arthroplasty. Knee arthroplasty is very effective in preserving functional knee motion, with relief of pain as an alternative to arthrodesis.