Knee arthroscopy has been a very popular operation for treating painful knees for more than 30 years. Unfortunately it doesn’t always work. Over the last few years a lot of research has been looking at which patients it works well in and which it doesn’t. From this we have figured out that there are two groups of patients with painful knees who get little or no benefit from knee arthroscopy. The first group is patients with osteoarthritis and the second group are atraumatic meniscal tears. I’ll go over both groups.
If you have osteoarthritis this means that the firm cartilage surface covering the bone in the knee has worn away. There may also be a torn meniscus cartilage in your knee (the meniscus is a softer cushion that sits between the surfaces). There may also be loose fragments of surface cartilage which have come loose and are floating inside your knee. The evidence tells us that performing a knee arthroscopy to remove the torn meniscus and loose fragments does not lead to a lasting benefit. This is because the cartilage covering the surface will still be missing and the pain comes from the exposed bone. There is no way to arthroscopically put a new surface over the exposed bone.
Occasionally a large fragment of loose bone forms inside an osteoarthritic knee and gets caught. This can cause the knee to intermittently jam up and stop moving. In these cases performing a scope will help remove those symptoms. This is an uncommon situation.
The only effective treatments for osteoarthritis are exercise and weight loss followed by knee replacement if the symptoms persist and become too severe.
The tricky situation is when there is a recent twisting injury which has caused pain in someone who had very few symptoms prior to the injury AND an MRI scan shows that they have the combination of a meniscal tear and some thinning of the articular surface. We still do not know exactly how much thinning of the surface cartilage and in which patterns is acceptable when we are considering an arthroscopy for a traumatic meniscal tear. These cases are considered on an individual basis for either conservative management with anti-inflammatories, exercise and weight loss or arthroscopy.
The second group is atraumatic meniscal tears. This is when there is no injury but the knee becomes painful and a subsequent MRI scan shows a torn meniscus. In the past these patients would be likely to have an arthroscopy. Recent studies have shown that many of them will improve without surgery. Again, they seem to do better with exercise, weight loss and anti-inflammatories. There are a group, probably about 30%, in whom symptoms persist and they eventually have surgery.
The end result is that we are doing less knee arthroscopies than we used to (I am doing half the number I was 5 years ago), and we are treating more patients non-operatively. There are still good reasons to perform for knee arthroscopy. It is a simple operation which generally leads to a quick recovery when we select the appropriate patients. If you have recently twisted your knee and have a torn meniscus or your knee is not improving despite an exercise program then you should get an opinion from a surgeon.
So the key points are:
- Meniscal tears in association with osteoarthritis usually do not need knee arthroscopy
- Meniscal tears without a history of injury often do not need surgery
- Many meniscal tears can be treated with exercise, anti-inflammatories and weight loss
- Knee arthroscopy is most effective when there has been a recent injury with an unstable meniscal tear and little or no osteoarthritis
If in doubt get an opinion from a surgeon who will spend some time explaining the pros and cons of surgery vs non-operative management.
This article and more patient information is available on my website
Alignment of Total Knee Replacements 