Q: I have been having kneecap pain for years. My doctor ordered an MRI and it showed that I have some arthritis in my knee and a cartilage tear. I was surprised to hear that I did not need surgery for my cartilage tear. Are these cartilage tears a benign problem?
A: Osteoarthritis is a condition where the smooth cartilage lining a joint begins to wear down and extra bone (spurs) can appear. The thigh bone meets the leg bone to form the knee joint and each side has cartilage to allow for smooth, pain-free movement. The kneecap is also part of the knee joint and it has cartilage lining as well. The leg bone side has thicker cartilage, known as menisci, providing cushioning and support for the knee. When osteoarthritis strikes, the cartilage thinning leads to pain from the rough surfaces in contact. The thinning cartilage can also tear without trauma.
About 85 per cent of the Canadian population has osteoarthritis by the age of 70. So far, we know that genetics, previous injury, increasing age and obesity are important causes of knee osteoarthritis. Osteoarthritis of the knee is more common in women than in men and the gender difference widens once women reach menopause.
Discovery of cartilage tears
Most patients with knee cartilage tears have obvious signs of this problem and do not require an MRI for diagnosis. Usually, they have pain, swelling and a tight knee that can sometimes catch or lock. In patients without osteoarthritis, there is often a history of injury. Patients with osteoarthritis of the knee also have pain, stiffness and swelling and if they have signs of a cartilage tear on examination, it can be difficult to distinguish how much of their pain is from the cartilage tear and how much is from the osteoarthritis. Active tears either improve with conservative treatment or may benefit from a surgical scope procedure.
Are "silent" tears a concern?
When a cartilage tear is discovered incidentally on an MRI scan, the patient may have no symptoms or signs related to the tear. This is referred to as a '"silent" tear. Some studies have shown that more than 50 per cent of individuals with osteoarthritis have these tears on MRI. Of course, the abnormal finding can be very concerning for the patient but not every finding needs an intervention, or does it?
An interesting research study published in the journal Osteoarthritis and Cartilage, done by Lange and colleagues in Australia, looked at these "silent" tears in a group of 41 women with knee osteoarthritis. The researchers compared characteristics such as age, weight, pain, balance and walking ability in those with tears compared to those without. The patients did not have a history of joint injury. The results showed that women with findings of a "silent" tear on MRI were not able to walk as far in a six-minute walk test as those without a tear. They also found that balance on a platform was better in those without a tear compared to those with a tear.
Research studies looking at multiple factors can be complex and challenging to conduct. Before we assume it is time to order MRIs for those with knee osteoarthritis, it is important to look at possible reasons for the results found. First of all, the study size was small and differences found were statistically on the weak side. A larger study could show more pronounced, convincing differences between the groups. Secondly, a key difference between the groups was age. The group with tears was on average, five years older. So, it is important to ask, how much of the difference in balance and walking was related to older age? It is possible that something other than a cartilage tear is responsible for the results. Finally, although pain ratings were similar between the groups, we do not know whether the tear group had more severe osteoarthritis or if some of their pain was due to the tear, which would make the tear not truly "silent."
Although, the study mentioned had some pitfalls, this is typical of most research and not every project will have a clear and stunning result. However, the best part about research is that we can often discover important new questions to be asked in future studies based on the findings in the original study. "Silent" cartilage tears in osteoarthritis have largely been ignored in medicine and perhaps, it would be wise to take a further look at this issue. Our ability to help patients improves as our body of knowledge grows, using the powerful combination of clinical experience, patient feedback and research findings to make healthy decisions.
Overall, those with osteoarthritis have no need to worry about proper treatment whether they have a "silent" tear or not. The approach to treatment for osteoarthritis has become more comprehensive in recent years, with sport medicine physicians, physiotherapists and other health professionals routinely recommending aerobic exercise and balance as part of therapy for osteoarthritis. No doubt, additional helpful advice is yet to come.