Background: As an elective procedure, total knee arthroplasty is
under scrutiny to evaluate its cost-effectiveness. In this review, we examined
the available literature on total knee arthroplasty to assess the evidence
regarding factors associated with better functional outcomes.
Methods: A structured literature search of English-language
databases was performed to identify studies of the functional outcomes of
total knee arthroplasty that had been published between 1995 and April 2003.
Inclusion criteria were a study of primary total knee arthroplasty, more than
100 knees in the study, provision of baseline data and rating of postoperative
outcomes with a standardized symptom scale, and an experimental or
quasi-experimental study design. The abstracting form included a list of
potential prognostic factors, including comorbidities, radiographic evidence
of joint destruction, bone loss, integrity of the extensor mechanism, range of
motion, alignment, tibiofemoral angle, and ligament integrity, as well as the
characteristics of the operating surgeon, such as procedure volume and
Results: Sixty-two studies met the criteria and were reviewed. Total
knee arthroplasty was found to be associated with substantial functional
improvement, with the effect sizes varying with the measure that was used.
Physician-derived measures showed effect sizes of 2.35 and 3.91, whereas
patient-derived measures showed smaller effect sizes (1.27 and 1.62). Few
investigators used multivariate models to identify associations between
outcomes and patient characteristics.
Conclusions: Total knee arthroplasty is a generally effective
procedure, but the current English-language literature does not support
specific recommendations about which patients are most likely to benefit from
Level of Evidence: Prognostic Level II. See Instructions
to Authors for a complete description of levels of evidence.