Abnormal Knee MRI, But No Pain

Knee MRI by Becky Stern from Flickr

Here's a piece of surprising news for everyone. In this recently published paper I read, nearly all patients who had abnormalities on their knee MRI were asymptomatic, meaning no pain despite having an "abnormal" MRI.

The main inclusion criteria for this study were sedentary adults. They did not do at least 30 minutes of moderate intensity physical activity 5 days a week or 20 minutes of more intense activities 3 days a week. They did not have any knee pain, no current or previous history of knee injury and surgery.

The authors reviewed 230 knees of 115 uninjured inactive adults (51 males and 64 females). Median age was 44 years (range was 25-73 years) and all the subjects had bilateral MRI's (3.0 Tesla, high resolution) done.

Here's what they found. Brace yourself as you read on. MRI showed abnormalities in a whopping 97% of knees. 30% of knees showed tears in the meniscus. Horizontal tears were most common, while bucket handle tears least common.

Articular cartilage (57%) and bone marrow abnormalities (48%) were common in the patellofemoral (knee) joint. Moderate (19%) intensity articular cartilage lesions and severe (31%) were observed.

Grade 4 means bone rubbing on bone

Articular cartilage injuries is my area of interest since I did my postgraduate research in that area. It is interesting to note that a quarter (or 25%) of the subjects had Grade 4 changes (see picture above) visible on MRI but did not complain of pain. Perhaps this is important to remember when imaging the knee since there seems to be more visible findings here compared to the rest of the knee (articular cartilage wise).

Moderate intensity lesions were found in 21% of knee tendons while there were high grade tendonitis found in 6% of knees reviewed. The patella and quadriceps tendons being the most affected.

3% partial ligament ruptures were found, of which 2% were of the Anterior Cruciate Ligament (ACL).

The authors concluded that nearly all knees of asymptomatic adults they studied show abnormalities in at least one knee structure on MRI. Meniscal tears, articular cartilage and bone marrow lesions in the patellofemoral joint were the most common pathological findings. 

They also reported finding bucket handle and complex meniscal tears (both of which commonly operated on) in asymptomatic knees. This interesting to note as bucket handle tears (as well as complex tears) would often cause 'locking' in the knee and therefore require surgery.

There you have it, the subjects were sedentary adults who did no exercise so no one can say that it was running or exercise that "wore out" their joints. And some these very same adults had "terrible" or abnormal MRI's, but were asymptomatic or did not have any pain.

So don't fret if your MRI is abnormal. You may not need any surgical intervention, especially if you do not have any pain or if that pain is easily treated.

Maybe these abnormalities should be just described as "wrinkles" on the inside. 

Reference

Horga LM, Hirschman AC, Henckel J et al (2020). Prevalence Of Abnormal Findings In 230 Knees Of Asymptomatic Adults Using 3.0 T MRI. Skele Radiol 49: 1099-1107. DOI: 10.1007/s00256-020-03394-z