Degenerative Meniscal Tears: Osteoarthritis Increases Risk
As many of us come to realize when we get older, the adage that time heals all wounds is a fallacy when it comes to age-related wear and tear on our knees. The meniscus—made up of fibrous cartilage that acts as a shock absorber between the bones of the knee—commonly thins and weakens as we age, which can eventually result in a tear in the cartilage.
An age-related, or degenerative, tear is different from an acute meniscal tear, which is the result of a single traumatic injury. An acute tear typically causes sudden sharp pain and is a common sports injury. A degenerative meniscal tear develops gradually as repeated everyday movements wear down the cartilage. A weak meniscus can tear with no or minimal trauma, such as when standing up or getting out of a car—actions that could include an awkward turn of a bent knee while the other foot is planted. Degenerative tears are also common in people who have osteoarthritis.
Finding symptom relief
Not everyone with a degenerative meniscal tear has symptoms. In fact, you might not realize you've torn your meniscus when it happens. And symptoms, if any, might not appear until weeks later. Symptoms can include painful knee clicking, popping, locking, and catching as well as a feeling of instability as if your knee is going to give out. When symptoms do strike, it's usually during activities when the knee is bending and straightening, such as when walking up and down stairs.
If knee problems persist after conservative treatment, such as physical therapy, doctors may recommend a surgical procedure called an arthroscopic partial meniscectomy (APM) to repair the tear. APM involves removing torn meniscal fragments and trimming away damaged areas of cartilage.
A growing body of evidence, however, has found little to no benefit for such surgery for most degenerative meniscal tears. In one recent study, published in February 2018 in the Annals of the Rheumatic Diseases, Finnish researchers reported that APM offers no benefit over sham (fake) surgery in relieving symptoms of knee locking.
In the study, researchers randomly assigned 146 patients, ages 35 to 65, to either an APM or a sham surgery. During both interventions, surgeons inserted an arthroscope (a small, flexible tube) into the knee area, but they performed a partial meniscectomy only during the real surgery. The participants who underwent the procedures had prior knee pain but no evidence of osteoarthritis. Neither the patients nor their primary care doctors were told whether they had real or simulated surgery; only the orthopedic surgeon and surgery staff knew. Two years after the procedures, both groups had nearly identical improvements in knee function, and most patients reported that their knees felt better. However, critics of the study contend that the insertion of an arthroscope and flushing the joint space with fluid, which was done during both the sham surgery and APM, might account for improvement and similar outcomes.
A 2016 study in the journal BMJ also suggested that APM had no benefit for degenerative meniscus tears. The researchers reported that APM improved pain and function no better than exercise therapy. In addition, supervised exercise resulted in improved thigh-muscle strength.
Arthroscopic surgery of the knee is considered a low-risk procedure. Potential adverse effects include those typically associated with most surgeries but are uncommon: blood clots, infection, and, rarely, death. A downside to APM is a prolonged recovery period of two to six weeks with limited mobility. Generally, patients can't bear full weight on their leg the first week after surgery, and driving and physical activity are limited for two to three weeks. They may also experience pain and swelling.
Reinforcing the belief that APM rarely has any long-term benefit for degenerative meniscal tears is a clinical practice guideline on arthroscopic surgery developed last year by an international panel of experts and published in the BMJ. The panel attributed any change for the better after arthroscopy to natural improvement over time or to the placebo effect. The experts suggested that "almost everyone would prefer to avoid the pain and inconvenience of the recovery period after arthroscopy, since it offers only a small chance of a small benefit."
The bottom line
Physical therapy that strengthens and stabilizes the muscles around the knee should be your first line of treatment if you have a degenerative meniscal tear. If you also have osteoarthritis, a steroid injection may help. But if your symptoms don't improve with conservative methods, consider consulting an orthopedic surgeon. He or she may discuss the possibility of surgery with you if you can't extend your knee completely and motion is restricted, or the tear is large and complex. Carefully weigh the risks and benefits, and keep in mind that symptom improvement isn't guaranteed after an APM.