Q: I started practicing yoga about six months ago to help with a shoulder problem. The shoulder got better but I noticed my knee started acting up. Could the yoga positions caused this. Any idea?
A: Activities associated with an positions such as squatting and the Lotus position have been considered potential risk factors for medial meniscal tears of the knee. As you now know, in assuming the Lotus position, the feet are placed on the opposing thighs. It is a posture commonly used for meditation in the Hindu Yoga and Buddhist traditions. The position is said to resemble a lotus flower to encourage proper meditative breathing.
But it is an extreme position for some people -- especially those who did not grow up doing this type of movement and who are starting yoga later in life. The posterior root of the medial meniscus describes the back corner of the meniscus. And specifically on the side of the knee closest to the other knee. This type of meniscal tear results in a piece of cartilage that is separated into two pieces but only attached to the bone (tibia) at one end.
Because of its location, the stress placed on this part of the meniscus could conceivably be greatest when the knee is in the extreme positions of flexion required in the squatting position. The same goes for the flexion and rotation required by the Lotus position.
But as it turns out, a recent study was done comparing patients with medial meniscus posterior root tears (MMPRTs) with patients who had other types of meniscal tears. The patients were all Asian from Korea and had been using these positions all their lives. The results showed that these two positions did not increase the risk for MMPRTs.
What they found was that it's mostly intrinsic factors (not lifestyle) that make a difference. The four intrinsic risk factors with the greatest impact on MMPRTs included: increased age (older than 50 years of age), female sex, being overweight (higher BMI), and lower level of sports activity. The mechanical angle of the knee (as seen on X-rays) was one anatomic feature that also increased the risk of MMPRTs.
The fact that positions often used by Oriental people did not contribute to the posterior corner tears of the medial meniscus may be because the knee structure adapt to these positions when used from an early age on. We do not know yet if this type of injury occurs more often in those individuals like you who begin using these positions later in life.
Reference: Byoung-Yoon Hwang, MD, et al. Risk Factors for Medial Meniscus Posterior Root Tear