Knee arthroscopy: Should this common knee surgery be performed less often?

Imagine you’re walking along and suddenly experience excruciating knee pain. Though it initially seems stuck in one position, after a minute or two you can limp along home, but just barely. At your doctor’s visit, an x-ray is normal but symptoms continue for weeks. An MRI is performed and now you have an explanation: a torn meniscus. (Two menisci — rubbery cartilage pads that act as shock absorbers — separate the bottom of your knee bone from the top of your shin bone.) A month later, you’re no better despite rest, pain medicines, and physical therapy. It’s time for surgery to fix it, right? Maybe not.

Knee arthroscopy is among the most common surgeries performed

If you went ahead with surgery, you’d be in good company. Each year, an estimated 750,000 arthroscopic knee operations are performed in this country at a cost of $4 billion. Among the most common reasons for this surgery is a torn meniscus that causes intermittent and severe pain, catching, or locking.

During arthroscopy, an orthopedist inserts a hollow-tubed instrument with a camera and light on the end into an anesthetized knee. After examining the inside of the knee, instruments can be passed through the hollow tube to remove debris, smooth ragged edges, and cut away cartilage that is impairing knee function.

Many people have both a torn meniscus and osteoarthritis (the age-related, wear-and-tear type of arthritis). The combination is common, not only because these conditions become more common with age, but also because a meniscal tear is a risk factor for developing osteoarthritis. And arthroscopic surgery itself (often performed to treat a meniscal tear) may also promote osteoarthritis.

We already know that arthroscopy for osteoarthritis doesn’t help most people. But how good is it for the combination of osteoarthritis and a meniscal tear?

A new study re-evaluates the usefulness — and risk — of knee arthroscopy for meniscal tears

Past studies (such as this one) have raised the possibility that surgery provides little advantage over nonsurgical approaches for many people with meniscal tears, at least over the short run. A more recent study followed people with meniscal tears and osteoarthritis for five years  and compared how well they did with arthroscopic surgery or more conservative treatment, such as physical therapy and pain medications.

The study was published in Arthritis and Rheumatology and enrolled 351 people age 45 and older who had

• knee pain for at least a month with symptoms that seemed related to a meniscal tear (such as intermittent, sudden pain or catching)
• little or no improvement despite taking medications, limiting activity, and/or physical therapy
• osteoarthritis (confirmed by x-rays or MRI scan) and a meniscal tear demonstrated by MRI scan.

Half were randomly assigned to have arthroscopic surgery followed by physical therapy, while the other half received physical therapy for 12 weeks.

Arthroscopy has questionable benefits, many risks

Within the first few weeks and months, pain and function improved about the same amount in both groups, and at a similar rate.

But nearly 40% of the study subjects assigned to receive physical therapy “crossed over” into the arthroscopic surgery group due to lack of improvement. In addition, more study subjects receiving arthroscopy required knee replacement surgery during the study period.

Some study subjects (7% of the total) underwent knee replacement surgery during this study, including 9% of those assigned to arthroscopy and 5% of the nonsurgical group. This difference was not considered statistically significant. But a significant difference was noted when the cross-over subjects (those who were assigned to physical therapy but switched into the surgery group) were included in the surgery group: 10% of the arthroscopy group versus 2% in the physical therapy group had knee replacement.

While the numbers were too small to be confident about a true difference, these results raise the concern that arthroscopy increases the chances that arthritis will progress and knee replacement will be needed.

Additional downsides of surgery are well known, and include:

• pain, risk of bleeding, and risk of infection (as with any surgical procedure)
• cost — while prices and insurance coverage vary, the cost of arthroscopic knee surgery in the US commonly ranges from $5,000 to $10,000
• a recovery period that lasts weeks to months
• the possibility that the operation will cause arthritis to advance more rapidly than it would have, which could lead to the need for knee replacement.

The bottom line

Together with previous findings, this study suggests that among middle-aged and older adults with meniscal tears and osteoarthritis, nonsurgical treatment should be the preferred option over arthroscopic meniscal repair. Of course, the question remains: how long should you give nonsurgical treatments before giving up on them and scheduling surgery, especially if symptoms are severe?

Undoubtedly, there are people who are helped by arthroscopic knee surgery: someone whose knee is locked, or who cannot walk at all due to pain or catching, may need surgery sooner than later.

But if you don’t fall into this category, and if arthroscopic knee surgery is recommended to you, ask your surgeon about this study and whether it applies to your situation. The better plan may be to put surgery off for at least a while longer.

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