Study Shows Timing Of Knee Replacement Critical To Outcome

F.J. Thomas

Chicago, IL ( – The best outcome for an injured worker having a knee replacement is largely dependent on when the surgery occurs, according to a study from Chicago’s Northwestern University School of Medicine.

The study, published in The Journal of Bone and Joint Surgery, was funded by grants from the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) and was gleaned from the Osteoarthritis Initiative and Multicenter Osteoarthritis multicenter trials.

The authors believe their study is the first of its kind to closely look at the overall timing of knee replacement surgery due to osteoarthritis. Previous studies have evaluated timing of surgery, but only in patients who had already had surgery and the data pool was much smaller than the data reviewed in this particular study.

An algorithm developed in 2003 in Europe but further developed in a later study in 2014 was applied. The 2014 study, which reviewed around 200 patients, found that one-third had undergone the surgery too early.

A total of 8,002 patients who either had osteoarthritis or were at risk for developing OA were followed for up to 8 years. Of them,3,417 knees qualified and were classified into three categories:

  • Timely – Knee replacement within 2 years after the replacement would have been appropriate
  • Potentially appropriate – Knee was not replaced within 2 years of replacement being appropriate
  • Premature – Knee replacement was most likely not appropriate at that time but procedure was performed

A total of 290 knees were classified as timely; 2,833 knees classified as potentially appropriate; and a total of 294 were classified as premature.

Of the knees that were classified as potentially appropriate but were not replaced, 1,204 or 42.5 percent had severe symptoms. Additionally, the data showed that fewer African Americans had timely knee replacement surgery. Those with a higher body mass index and diagnoses of depression were less likely to have a premature knee replacement.

In a report by Northwestern EDU, lead investigator and associate professor of surgery at Northwestern University Feinberg School of Medicine, Hassan Ghomrawi, believes that people are waiting to have their knees replaced, due mainly to cost, and because the potential impacts of waiting are huge. “The osteoarthritis causes deterioration of their function,” Ghomrawi said. “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.”

Ghomrawi believes that pain, joint function, radiographic assessment and age are all factors that must be strategically taken into consideration for the best outcome. Additionally, he credits outside factors as having an impact. “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,” he said. “We need to develop a better understanding of these factors to improve timing of surgery.”

The full study is available on the Journal of Bone and Joint Surgery’s website.

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