Total Knee Replacements in Knee OA Are Not Performed at Optimal Times

A substantial number of patients with knee osteoarthritis (OA) undergo total knee replacement either prematurely or belatedly, according to results of a new study.

“As the number of surgeries rises, we need to make sure the timing is optimal for patients to obtain the most benefit and to keep health care costs down,” lead study author Hassan Ghomrawi, PhD, MPH, an associate professor of surgery at the Northwestern University Feinberg School of Medicine, said in a press release.2 “Because knee replacement is an elective procedure, the timing of surgery is susceptible to not just clinical factors, but also demographic, socioeconomic and sociocultural ones. We need to develop a better understanding of these factors to improve timing of surgery.”


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To analyze the timeliness of total knee replacement, the researchers analyzed data from 2 multicenter cohort studies. The authors of these studies had longitudinally tracked demographic, patient-reported, radiographic, clinical examination, and total knee replacement utilization information on 8002 participants who had or were at risk for knee OA. The participants had been observed for up to 8 years.

Based on validated total knee replacement appropriateness criteria, the researchers of the new study classified the participants as being either potentially appropriate or likely inappropriate for total knee replacement.

Among all the participants, 3417 knees met the inclusion and exclusion criteria. The researchers classified these knees into 3 utilization categories based on the timing of the total knee replacement:

  1. Timely: The patient had total knee replacement within 2 years after the procedure had become potentially appropriate (n=290 knees). Knees in this group composed 8% of the total and 9% of the knees for which replacement was potentially appropriate.
  2. Potentially appropriate, but knee not replaced: The knee had remained unreplaced for more than 2 years after the procedure had become potentially appropriate (n=2833 knees). Knees in this group composed 83% of the total and 91% of those for which replacement was potentially appropriate. Of the knees in this group, 1204 (42.5%) had severe symptoms.
  3. Premature: The procedure was likely inappropriate but had been performed (n=294). Knees in this group composed 9% of the total knees and 26% of the 1114 total knee replacements performed.

Black participants were more likely to be classified as being potentially appropriate for but not undergoing total knee replacement. Meanwhile, participants with a body mass index greater than 25 kg/m2, as well as those with depression, were less likely to have a premature total knee replacement.

Undergoing total knee replacement too early may result in little or no benefit while exposing the patient to the risks of a major operation, whereas waiting too long may cause limitations in physical activity that, in turn, increase the risk of additional disability and chronic disease,” the researchers wrote. 

—Colleen Murphy


1. Ghomrawi HMK, Mushlin AI, Kang R, et al. Examining timeliness of total knee replacement among patients with knee osteoarthritis in the U.S.: results from the OAI and MOST longitudinal cohorts [published online January 13, 2020]. J Bone Joint Surg Am. doi:10.2106/JBJS.19.00432.

2. Knee replacement timing is all wrong for most patients [press release]. Chicago, IL: Northwestern University; January 13, 2020. Accessed January 14, 2020.