Abstract
Osteoarthritis (OA) is one of the most common causes of knee pain in the aging population and presents with higher odds with increased BMI. Total knee arthroplasty (TKA) has become the standard of care for the treatment of OA. Over “719,000 TKA's were performed in 2010 in the USA alone, with dramatic economic burden- costing 16,000 USD per TKA” (CDC 2012). Over the past two decades, this cost was compounded by the unknown increasing rate of primary TKA and cannot be explained by the expanding population or worldwide obesity epidemic. These facts raise two key questions: are patients' quality of life expectations higher and driving the TKA rate up, or have surgeons changed their indications and started to operate on less disabled people? Our study aimed to determine the average functional profile for patients undergoing TKA using patient reported Outcome Measure (SF-36), to document if preoperative SF-36 scores have changed over the past two decades, and lastly to asses if patient pre-operative SF-36 scores are lower in in the USA vs the rest of the world.
A literature search of Medline, Embase and Cochrane databases was performed extracting data from publishing year 1966 to 2016 with a search date of Dec 12, 2016. Two independent reviewers revised the abstracts and excluded articles with: no TKA, revision TKA, no pre-op SF-36, no SF-36 reported, incomplete scores to calculate SF-36, duplicates, review article, meta-analysis, letter to the editor, conference proceeding or abstract, disagreements were resolved with a third reviewer. All languages were included to maximize the catchment of data. All remaining articles were independently read and excluded if they did not provide data required for our study. Included articles were analyzed for data including: for year of patient enrollment, location (USA vs. non-USA), pre-operative SF-36 mental (MCS) and physical (PCS) component summary, level of evidence. Recorded data was compared post completion to assess inter-observer accuracy as per PRISMA guidelines for meta-analysis.
After applying all the exclusion criteria on 923 selected abstracts, a total of 136 articles of which 30 were randomized control trials, were completely reviewed and included in our study. A total of 56,713 patients' physical component scores were analyzed and revealed an overall pre-operative SF-36 physical component score 31.93. When stratifying the data, it was revealed that patients operated in the USA had an average score of 32.3 whereas Non-US countries were 31.7, with no statistical significance. No statistical difference between SF36 scores was seen over time amongst studies of all nations.
Based on the results of this study, we have shown that orthopaedic surgeons are performing TKA universally at the same pre-operative scores, independent of country of origin or year of surgery. The indications thus have remained consistent for two decades regardless of the advances in technology. Functional profiles of patients appear similar among US and Non-US countries. Further, we infer that based on pre-operative SF-36 PCS scores, the optimal time to undergo a TKA is when PCS is 31.9 +/−3.
