Failure in total knee arthroplasty: mechanisms, revisions, and results.

Of 700 prosthetic knees inserted during the period from 1969 to 1978, 94 failed; 19 of the failures occurred due to infection. Other obvious mechanisms of failure were wear debris sy novitis, ligament rupture, and patellar dislocation. The majority of prosthetic loosenings occurred on the tibial side. There were five mechanical factors of such loosening: tilt and sink; compression; torsion; toggle; and a combination of these factors. Excluding those who died or were lost to follow-up, the results of revision were 37% good or excellent; 60% fair or poor; and 3% failure. To some extent the results were prosthesis dependent; the semiconstrained prosthesis had a good result in 48%, unlinked hinges a good result in 24%, and a true hinge a good result in 21%. The results in infected cases were poor; of five prosthetic revisions, only one was good. Fusion was found difficult to achieve; of 11 attempts, only six obtained solid fusion. Four amputations were performed, all for infection in hinged knee replacements.