Total Knee Replacement Research
  • What are the indications for primary total knee replacement (TKA)?
  • What patient characteristics affect the outcomes achieved?
  • What are the indications for revision total knee replacement (TKAR)?

These are among the questions answered by a systematic review of research on total knee replacements. The review was prepared for the Agency for Healthcare Research and Quality (AHRQ) and released in December 2003. Of the 611 studies included in the analysis (dating from 1995 to 2003), 62 studies reported pre-and post-TKA functional data.

TKA and TKAR were found to be associated with improved functional outcomes on long-term followup. However, there may be selection bias in both the type of patients referred for TKA and those reported in the literature. Several different functional measures were used in the studies, but the Knee Society scale and the Hospital for Special Surgery scale were used most often.

TKA patients had an average age of 70 years, two-thirds were female, one-third was obese, and nearly 90% had osteoarthritis. Age, gender, and obesity were not significantly correlated with TKA outcomes. Patients with rheumatoid arthritis showed more improvement than those with osteoarthritis, but this may be a result of their greater potential for improvement because of poorer functional status at the time of surgery. Other patient characteristics have either not been studied or studied only in a few studies. The complication rate for TKA was 7.6% of knees operated on with 2% of total knees operated on requiring revision within 5 years or more. The majority of complications involved the knee itself or deep venous thrombosis.

The authors concluded that the research done to this point "does not provide a strong basis for making clinical recommendations regarding indications for outcomes from TKA. As pressures mount for more discrimination in identifying subjects for elective surgery, better information will be needed" (AHRQ, 2003, p. 8). For more of the findings and conclusions, use the link to the Summary report provided below.

Total Knee Replacement. Summary, Evidence Report/Technology Assessment: Number 86, AHRQ Publication Number 04-E006-1, December 2003. Agency for Healthcare Research and Quality, Rockville, MD. http://www.ahrq.gov/clinic/epcsums/kneesum.htm.