EARLY DEATHS FOLLOWING KNEE REPLACEMENT

Abstract

Total knee arthroplasty represents one of the greatest advances in modern orthopaedic surgery and remains one of the safest and most effective interventions for the treatment of crippling arthritis of the knee. It does, however, carry significant risk including death. Conventional studies have compared the incidence of death following knee arthroplasty to standardised mortality ratios of age and sex matched populations. This often raises aberrant results suggesting that knee arthroplasty is protective to health in the immediate post operative phase, attributed to the observation that patients undergoing surgery suffer fewer co morbidities than the population in general.

In an attempt to remove this “well patient effect”, we compared the incidence of death in the first 30 and 90 days following primary total knee arthroplasty to the incidence of death in a comparable population added to a waiting list for the same procedure.

All primary total knee arthroplasties undertaken, and all patients added to a waiting list for the same procedure, in a single unit between 2000 and 2007 were recorded. Death rates at 30 and 90 days of those on the waiting list were compared to death rates after surgery.

The 30 and 90 day mortality following primary total knee arthroplasty were 0.295% and 0.565% respectively. This compares to a 30 and 90 day mortality of 0.055% and 0.316% seen in a population of patients awaiting operation. When stratified for age, surgery conferred an excess surgical mortality in all age groups over the age of 60. Factors associated with an increased mortality following operation include male gender and increasing age.

Previous studies, where incidence of death is compared to standardised mortality ratios, have erroneously suggested that arthroplasty is associated with a decreased risk of death. This study demonstrates an increased risk of death associated with surgery in comparison to a similar population deemed fit enough to undergo operation. Primary total knee arthroplasty carries an excess surgical mortality of 0.24% at 30 days and 0.25% at 90 days, a 5.36 and 1.79 times greater risk of death respectively when compared to patients awaiting the same procedure.

This information will greatly assist orthopaedic surgeons when counselling patients as to the risks of surgery.