The current practice of total knee replacement that is performed in the United States has minimal effects on quality of life among patients with knee osteoarthritis, according to a study published in the BMJ.

Bart S Ferket, MD, PhD, from Icahn School of Medicine at Mount Sinai, and colleagues conducted a marginal structuring modeling and cost effectiveness analysis to evaluate the impact of total knee replacement on quality of life among patients with knee osteoarthritis and to estimate the differences in lifetime costs and quality adjusted life years (QALYs).

The analysis included 4,498 participants from the Osteoarthritis Initiative (OAI) with or at high risk for knee osteoarthritis between 45 and 79 years of age. The participants had no previous knee replacement and were followed for up to 9 years. A validation cohort included 2,907 participants from the Multicenter Osteoarthritis Study (MOST) who were followed for 2 years.

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At baseline, the 1,327 OAI participants with knee osteoarthritis had worse SF-12 physical component summary (PCS), SF-6D, and osteoarthritis-specific quality of life scores than the 3,171 participants at high risk for knee osteoarthritis.

In OAI participants, the main treatment effects of total knee replacement comprised an absolute improvement of 1.70 points on SF-12 PCS. For osteoarthritis-specific measures of quality of life, the procedure’s main effects improved the Western Ontario and McMaster Universities arthritis index score by 10.69 and the knee injury and osteoarthritis outcome score quality of life subscale by 9.16 points.

The researchers noted that the most economic strategy for total knee replacement was performing the procedure in patients with an SF-12 PCS <35, assuming a cost effectiveness threshold of $200,000 per QALY.

The findings were reproduced in the knee osteoarthritis patients from the MOST cohort. The investigators also found that total knee replacement would become cost effective in patients with SF-12 PCS scores ≤40 if the hospital admission costs decreased below $14,000, given a cost effectiveness threshold of $200,000 per QALY.

“Given its limited effectiveness in individuals with less severely affected physical function, performance of total knee replacement in these patients seems to be economically unjustifiable,” the study authors concluded. “Considerable cost savings could be made by limiting eligibility to patients with more symptomatic knee osteoarthritis.”


  1. Ferket BS, Feldman Z, Zhou J, Oei EH, Bierma-Zeinstra SMA, Mazumdar M. Impact of total knee replacement practice: cost effectiveness analysis of data from the Osteoarthritis Initiative. BMJ. 2017. doi:10.1136/bmj.j1131