With Total Knee Arthroplasty, Timing Is Everything

    Nearly 1 million total knee arthroplasty (TKA) procedures are performed in the US each year, with projections of a rapid increase by 2030.

    The surgery can effectively provide pain relief and restore function, but the timeliness of the procedure is critical: Patients with knee osteoarthritis (OA) who keep putting off surgery may end up with so much joint degeneration that they do not experience significant improvement when they finally undergo TKA, while those who have the procedure prematurely may see only minimal benefit.

    How many candidates for TKA are missing the “sweet spot” for surgery? Too many, according to a new study from Northwestern Medicine published online ahead of print by the Journal of Bone & Joint Surgery. Using data from 2 multicenter trials – the Osteoarthritis Initiative and Multicenter Osteoarthritis – they found that 90% of candidates delayed the procedure well beyond the time it could benefit them most, while about 25% who do not yet need TKA underwent the procedure prematurely.

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    This is believed to be the first study to prospectively examine the timeliness of TKA among a large number of patients with knee OA who could benefit from the surgery. Few prior studies have quantified timeliness of surgery but only among patients who already had knee replacement, and these studies generally were in smaller cohorts of patients.

    More than 8000 participants in the Osteoarthritis Initiative and Multicenter Osteoarthritis trials were at risk for knee OA and had been followed for up to 8 years. Of those, 3417 met the study authors’ inclusion and exclusion criteria and were included in the Northwestern study.

    The researchers divided the study participants into 3 categories based on TKA utilization:

    • Timely. These patients (n=290 knees) underwent TKA within the 2 years after surgery was deemed to be potentially appropriate.
    • Potentially appropriate but knee not replaced. These patients (n=2822 knees, 1204 with severe symptoms) were candidates for TKA but they had not undergone the procedure in the more than 2 years after it became potentially appropriate.
    • Premature. These patients (n=294 knees) underwent TKA before it was potentially appropriate.

    “When people wait too long [for TKA], 2 things happen,” said lead investigator Hassan M.K. Ghomrawi, PhD, MPH, associate professor of surgery at Northwestern University Feinberg School of Medicine.

    “The osteoarthritis causes deterioration of their function. Some of them wouldn’t be able to straighten out their legs, affecting their walking and mobility. When you can’t get exercise, you can start to develop other health problems such as cardiovascular problems. You may also become depressed. The overall impact can be huge.”

    The second problem with delaying surgery is less benefit. “You don’t get as much function back when you wait too long; your mobility is still reduced versus somebody who had it in a timely fashion,” Dr. Ghomrawi said.

    The ideal timing of knee replacement surgery is based on an algorithm that factors in pain, joint function, radiographic assessment, and age to determine if a person will benefit from surgery.

    Undergoing TKA too early based on the algorithm means patients are having major surgery with a risk of complications and experiencing minimal benefit. They may also need a revision later in life, which is a much more difficult surgery with poorer outcomes than the index procedure.

    “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 healthcare costs down,” Dr. Ghomrawi said.

    “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.”


    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. J Bone Joint Surg Am. 2020 Jan 13. doi: 10.2106/JBJS.19.00432. [Epub ahead of print]