We reviewed the records of 1257 patients having 1625 total knee arthroplasties; all had pre-operative and postoperative perfusion lung scans and postoperative venograms which were classified as showing no thrombi, calf thrombi or proximal thrombi. Patients with calf thrombi were found to have a significantly greater risk for both symptomatic and asymptomatic pulmonary embolism compared with patients with no venographic thrombi. There were positive lung scans in 6.9% of patients with calf thrombi compared with 2.0% of patients with negative venograms (p < 0.001). Symptomatic pulmonary embolism occurred in 1.6% of patients with calf thrombi compared with 0.2% of patients with negative venograms (p = 0.034). The risk of pulmonary embolism was not significantly different between patients with treated proximal thrombi, and those with calf thrombi. Patients who develop deep-vein thrombosis despite prophylaxis are at increased risk for pulmonary embolism; these patients should receive treatment, or undergo follow-up studies to detect proximal propagation.

The survivorship method of analysis has been used to compare the failure rate and overall success of 1,430 cemented primary total knee arthroplasties performed at The Hospital for Special Surgery over a 15-year period. There were 224 total condylar prostheses with a polyethylene tibia, 289 of the posterior stabilised type with an all polyethylene tibia, and 917 posterior stabilised with a metal-backed tibial component. There were 12 failures in the total condylar series, giving an average annual failure rate of 0.65% and a 15-year success rate of 90.56%. The posterior stabilised prosthesis with a polyethylene tibia showed an average annual failure rate of 0.27% and a 10-year success rate of 97.34%, and this prosthesis with a metal-backed tibial component gave an annual failure rate of 0.19% and a seven-year success rate of 98.75%. The overall survival rate was not influenced by sex or age, diagnosis or the percentage of ideal body weight. No metal-backed tibial components have yet needed revision for loosening. It seems that infection will be the major cause of failure.