What’s the best surgery for pain in aging knees -- arthroscopy or arthroplasty?

knee pain

By Dr. Pier Boutin, MD

As an orthopedic surgeon, the most common condition I see is knee pain — young or old, it doesn’t matter. Young people may have torn ligaments or cartilage, while people over forty more often show signs of degenerative changes in the knee joint. And while treatment in younger people is straightforward—typically observation, physical therapy, or arthroscopy—choosing the right treatment for older patients requires a little more thinking.

What causes knee pain?

The knee joint consists of three bones: the femur (thigh bone), the tibia (lower leg bone), and the patella (knee cap). The end of each bone is capped with cartilage, a smooth, resilient yet springy coating. Between the femur and tibia sit two semicircular rubbery pads called the menisci (singular: meniscus).

During sports, young athletes may twist or bend their knees in positions that the knees can’t support under the high stress of running or turning. The result can be a tear in either a meniscus or a ligament within the knee called the anterior cruciate ligament, or ACL. Both these injuries are best treated with arthroscopic surgery, a procedure in which a camera and surgical tools are inserted into the small spaces of the knee joint to evaluate and repair damage.

Older people, including aging athletes, develop knee pain without major trauma. They may have damage to the knee already, but it’s not enough to cause pain — it’s often just a softening of the cartilage and wearing of the menisci. Typically this begins slowly and remains unnoticed until a minor trauma, such as a slight twist of the knee while getting up from a chair, or repetitive bending while working in the garden, triggers inflammation in the joint. The menisci and cartilage become frayed, like the hem of jeans dragging on pavement. Eventually, the tattered pieces disintegrate and expose bare bone. Once bone is exposed, the joint deteriorates rapidly, causing arthritis (which simply means “inflamed joint”) and pain.

Patients age 40 and up often come to my office with a swollen knee that hurts when they bend it or walk. Since most of them had little or no pain prior to the incident, they expect results that will give them the knees they had when they were 20. But that’s not realistic, since the padding inside of the knee is tattered and friable as a result of age -- it was deteriorating before the injury. The protective cartilage has now disintegrated and is susceptible to further damage.

Why knee arthroscopy may not be the right choice for your knee pain

For many older people with knee pain, arthroscopy isn’t the best option. Here’s why:

Most older people develop tears that are degenerative or complex — meaning they aren’t going to be easy to put back together. If the initial assessment of the knee by MRI reveals cartilage damage or thinning, an arthroscopy to address a complex tear will not solve the problem; instead, it will more likely make matters worse. Arthroscopy is really best reserved for younger patients with mild degenerative changes who did not respond to other, more conservative therapy.

Why is arthroscopy OK for younger patients but not for older ones? Mostly, it has to do with changes to the tissue as we age. In adults over 40, the cartilage surfaces are very sensitive and brittle; contact with surgical instruments often causes fragments to flake off. When the frayed meniscus is removed, it leaves less padding between the bones — which not only reduces the lining but also often triggers inflammation after the surgery. The inflammation causes further deterioration and increased pain. That’s not what you want!

Arthroscopy is often described as a “minor” procedure. It is not. Many studies have shown that patients with cartilage deterioration who undergo arthroscopy for a meniscus tear will develop arthritis faster than patients treated with cortisone injection and physical therapy.

Despite all this evidence that it’s not the best or most helpful treatment, knee arthroscopy remains popular. I see at least 2 or 3 patients a week with swollen and painful knees 6-12 months after arthroscopy; their post-surgery x-rays show marked advancement in arthritis. These people will require a total knee replacement sooner than they would have, had they not had an arthroscopy.

For this reason, in 2017, an international group of specialists recommended conservative management rather than arthroscopic knee surgery for nearly all patients with degenerative joint disease. Conservative management includes cortisone injections to reduce inflammation in the joint, low-impact exercise (specifically a stationary bicycle, since this reduces stress on the knee), changes in how you perform certain activities that put strain on the joint, and above all, patience — conservative management doesn’t work overnight, and you need to give it some time to work before contemplating surgery.

Knee arthroscopy versus total knee replacement (arthroplasty)

For most over-40 patients with degenerative joint changes who don’t respond to conservative management, the best option is a knee replacement rather than arthroscopy. It’s important to know the difference between arthroscopy and arthroplasty — that is, knee replacement surgery.

The term knee replacement may sound frightening, but it’s misleading — your knee joint isn’t removed and replaced. What actually happens is that the ends of the femur and tibia and the underside of the patella (kneecap) are resurfaced with a layer of metal alloy (cobalt chrome) covered with polyethylene, which replaces the damaged and often disintegrated cartilage and menisci. The ligament structures and most of the bones remain intact. This success rate of knee replacement surgery is over 97%; while recovery from surgery may be as long as three months, the “new” knee generally lasts a lifetime.

So the general advice when your aging knees are aching is conservative management. Work with your doctor and physical therapist and see if that provides relief. There are so many natural and non-surgical steps that you can take to find relief! Only if conservative mangement fails to give you relief, explore surgical options and make the decision that’s best for you.

Last updated on 11/16/2019