Study Eases Fears: Knee Surgery Surge Not Linked to Premature Intervention

Kerry Dooley Young

November 16, 2023

A meta-analysis appears to allay concerns that surgeons might be performing total knee arthroplasties (TKA) on healthier patients.

"Both the total number [of surgeons performing primary TKA] and the number of surgeons per capita have been generally increasing," wrote Peter Dust, MD, of McGill University, Montreal, Quebec, Canada, and co-authors. "Reassuringly, however, our results suggest that despite the increasing number of surgeons, the indications for surgery are not being eroded by operating on healthier patients to fill operating room time."

The study was published October 24 in the Canadian Journal of Surgery.

Rising Demand

In the paper, Dust and colleagues noted that there was a 162% increase in volume of total knee arthroplasties among people enrolled in the US Medicare program between 1991 and 2010.

Unrelated to the study, the Canadian Institute for Health Information (CIHI) has also reported similar trends. In 2018-2019, about 75,000 knee replacements were performed in Canada; an increase of 22.5% over the previous 5 years. The numbers dropped in 2020-2021 during the pandemic due to limited access to medical facilities during that time, but then rebounded between April and September 2022 to close to pre-pandemic numbers. However, about 50% of patients were waiting longer during that time than the recommended 6 months (182 days) for their surgery.

So, What’s Happening?

The trends for rising numbers of knee surgeries cannot be fully explained by population growth and increasing rates of obesity, Dust and colleagues wrote in the paper. That led them to ask whether some patients were undergoing surgery with a higher level of preoperative function compared with the past.

They conducted a systematic review and meta-analysis of the MEDLINE, Embase and Cochrane databases with the aim of determining the effect of time, age, and sex on preoperative functional status. A total of 149 studies were ultimately included in the study, with data from 257 independent groups and 57,844 patients recruited from 1991 to 2015.

The analysis revealed that patients are undergoing TKA with a level of preoperative function similar to that in the past. Also, patient age, sex, and location did not influence the functional status at which patients were considered for surgery.

Jasvinder Singh, MD, professor of medicine and epidemiology at University of Alabama at Birmingham, who was not involved with the research, offered another suggestion to Medscape Medical News to explain the trend: people today are more familiar with knee replacement surgery and thus find it a less daunting option.

"Everybody knows somebody who has had a knee done or a hip done," Singh said."People are a lot more familiar with these things than they were 30 years ago."

Subjective Criteria Persists

In the paper, Dust said that he and his colleagues had hoped this study might reveal a target physical component summary (PCS) score, used to assess functional status, based on which patients could be considered for surgery. Their findings, however, did not enable such a recommendation to be made.

Dr Claudette Lajam

In an interview with Medscape, Claudette Lajam, MD, a spokesperson for the American Academy of Orthopedic Surgeons (AAOS), agreed that there does not appear to be a trend toward earlier intervention. Also, a precise number or score that can be used to determine when patients should undergo TKA still does not exist. Lajam is a professor of orthopedic surgery and system chief for orthopedic quality and risk at NYU Langone Health, New York City.

The "sweet spot time" for TKA is still not clear based on available metrics, Lajam said. Physicians need to consider not only patient level of function before surgery, but also when to intervene so they will get the most benefit from these procedures.

The knee has to be "bad enough to justify major surgery," she said, while waiting too long might lead to inferior outcomes.

In time, she thinks artificial intelligence (AI) could help in identifying when primary care clinicians should advise patients to seek specialist care for ailing knees.

AI could allow physicians and researchers to search for clues about the best timing for surgery by combing through millions of X-rays, a variety of functional scores used in assessing patients, and other sources of information, she explained. At this time, the PCS used by Dust and colleagues is just one of many measures used to assess patient level of function. AI might be able to bring these data together for scientists to review.

"AI can see patterns that I can’t see right now," Lajam said.

But she emphasized that any AI application would be an aid to physicians in counseling patients. Evaluation by an experienced surgeon, together with guidance from any AI tool, could provide a greater understanding of how TKA could help patients with arthritis of the knee.

"The physician sees intangibles that AI would not see because we actually talk to the patient," she explained.

Dust said there was no outside funding for the study and the authors and Lajam report no relevant financial relationships. Singh said he has received consulting fees from companies including AstraZeneca and institutional research support from Zimmer Biomet Holdings. He has also received food and beverage payments from Intuitive Surgical Inc./Philips Electronics North America, and owns stock options in companies including Atai Life Sciences. He is a member of the executive committee of Outcome Measures in Rheumatology (OMERACT).


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