Background: We examined the long-term survivorship and
patient-reported outcomes at a minimum of ten years following primary total
knee arthroplasty. We hypothesized (1) that the survival rate would be at
least 90% at ten years; (2) that age, gender, body-mass index, and primary
diagnosis would not affect the survival rate; and (3) that the functional
status of patients would be comparable with that of an age and gender-matched
normal population.
Methods: A total of 407 patients (523 knees) who had had primary
total knee arthroplasty between January 1988 and April 1991 were identified.
The mean age of the patients at the time of surgery was sixty-nine years, and
68% of the patients were women. At ten years, 165 patients (211 knees) had
died; seven of these 211 knees had been revised before the time of death. Of
the remaining 242 patients, 208 (86%) completed a questionnaire, which
included the Western Ontario and McMaster University Osteoarthritis Index
(WOMAC), the Short Form-36 (SF-36), and questions regarding patient
satisfaction and revision surgery. In the group of patients who participated
in the study, ten patients (eleven knees) had had a revision before the
review.
Results: A total of eighteen knees were revised. Twelve knees were
revised because of aseptic failure and, of these, nine were revised because of
polyethylene wear. The probability of survival at ten years was 96.1% with
revision for any reason as the end point (and 97.2% when only aseptic failures
were considered). Because of the small number of failures, we were unable to
draw conclusions about associations between failure and age, gender,
diagnosis, and body-mass index. The mean WOMAC scores (and standard deviation)
at the time of the evaluation were 88 ± 17 for pain and 79 ± 20
for function. The SF-36 scores were similar to those for an age and
gender-matched normal population, with only the physical functioning score
being significantly lower (p < 0.001) and with the general health score
being significantly higher (p < 0.001). Patients generally were very
satisfied with all aspects of the outcome.
Conclusions: At ten years, the survival of the prosthesis was
excellent and the majority of patients were functionally independent, had very
little knee pain, and were very satisfied with the result. The health benefits
of this total knee arthroplasty were maintained after a minimum duration of
follow-up of ten years.
Level of Evidence: Therapeutic study, Level IV (case
series [no, or historical, control group]). See Instructions to Authors for a
complete description of levels of evidence.