Knee surgery shows no benefit for people with mild osteoarthritis

A new study indicates that there is no apparent benefit to arthroscopic knee surgery for age-related tears of the meniscus in comparison with nonsurgical or sham treatments. The study, published in CMAJ (Canadian Medical Association Journal), provides evidence that middle-aged or older patients with mild or no osteoarthritis of the knee may not benefit from the procedure.

As people age, the meniscus in the knee thins and becomes less flexible and more susceptible to tearing. When the meniscus tears, it can cause pain and mechanical symptoms. Arthroscopic knee surgery (meniscal débridement) is one of the most common orthopedic surgical procedures, with more than 4 million performed each year around the world. This surgical technique is commonly used to address degenerative meniscus tears. The procedure involves making small (keyhole-type) incisions to remove the torn fragments from the damaged meniscus. Although the surgery is minimally invasive, there may still be complications; these risks must be weighed against benefits to the patient.

Two previous studies showed that for patients with severe knee arthritis, arthroscopic knee surgery is not effective for long-term symptom relief.

To determine whether arthroscopic knee surgery for degenerative meniscal tears would provide relief to patients with mild or no osteoarthritis, researchers analyzed seven randomized controlled trials.

The sample total was 811 knees in 805 patients with a mean age of 56 years. In four trials, there was no short-term pain relief in the first six months after surgery for patients with some osteoarthritis, nor was there improvement in long-term function up to two years later in five trials.

What happens to a knee with osteoarthritis?

When your knee has osteoarthritis its surfaces become damaged and it doesn’t move as well as it should do. The following happens:

- The cartilage becomes rough and thin - this can happen over the main surface of your knee joint and in the cartilage underneath your kneecap.
- The bone underneath the cartilage reacts by growing thicker and becoming broader.
- All the tissues in your joint become more active than normal, as if your body is trying to repair the damage.
- The bone at the edge of your joint grows outwards, forming bony spurs called osteophytes.
- The synovium may swell and produce extra fluid, causing the joint to swell - this is called an effusion or sometimes water on the knee.
- The capsule and ligaments slowly thicken and contract.

These changes in and around your joint are partly the result of the inflammatory process and partly an attempt by your body to repair the damage. In many cases your body’s repairs are quite successful and the changes inside your joint won’t cause much pain or, if there is pain, it’ll be mild and may come and go.