Starring the Marvellous Meniscus
By Bernie Clark
April 20, 2023
The pain kept getting stronger. Burning. Oooowwwch! But, you know – no pain, no gain. So, I stayed. It was winter of 1999. I started doing asana practice in the spring of 1997 but then I found power yoga and through that, Ashtanga. I was keen to master the deeper postures. My feet were snuggled up high upon my thighs in as tight a Lotus pose as I could manage. After about two minutes of the pain, I had had enough. I slowly, stiffly, unfolded my legs and straightened them out. The burning feeling in both inner knees didn’t go away very quickly. In fact, it did not go away at all. I had crushed the medial menisci in both knees. The burning pain would be my companion for several years. I learned the hard way that Lotus pose, also called Padmasana, was not the destroyer of all disease, as promised in the Hatha Yoga Pradipika, but rather Lotus pose was a weapon which in the wrong hands became the destroyer of knees.
I have always been a type A personality. Pushing through obstacles was de rigueur, a way of life. It is understandable that this same drive would show up in my yoga practice. And, in hindsight, it was obvious that I was a prime candidate for yoga injuries caused, not by the postures themselves, but by how I approached and used them. My intention was always to master a pose by looking good in it. I was driven by aesthetics and had no clue that there was an alternative, functional approach to the practice. When the knee pain wouldn’t stop, I looked for solutions, but first I had to understand what had happened. Why did Lotus pose destroy my knees?
The Anatomy of the Knee
To understand the problem, it is useful to understand the basic anatomy of the knee. Figure 2 shows the structure of a right knee and the soft tissues around and within it. The focus for this discussion is on the collateral ligaments on the outside and inside of the knee (the lateral collateral ligament and the medial collateral ligament) as well as the two C-shaped cartilaginous gaskets called the lateral and medial meniscus. These menisci are shown in more detail in figure 3.
Figure 2: The anatomy of the knee. Take special note of the medial collateral ligament and how close it is to the medial meniscus. They are connected and continuous. Image from Shutterstock.
Figure 3: The menisci are C-shaped cartilaginous gaskets that help the bottom of the femur and the top of the tibia form a more congruent fit. Notice, again, how the medial collateral ligament is joined to the medial meniscus. Image from Shutterstock.
The femur has two very rounded bumps at the end, called condyles; the top of the tibia is relatively flat. These two surfaces are not very congruent. The femur is like a ball on the flat table of the tibia. Moving the knee would be risky if it were not for the presence of the menisci. The exact function of the menisci is not certain, but they probably act as shock absorbers, and they help to make bones fit better, like putting a ball in a shallow bowl.[1] They are thicker at the outer edges than in the middle, which helps to create the bowl shape in which the rounded femoral condyles fit. As a shock absorber, the meniscus flattens out when a load bears down upon it, distributing the stress radially. The composition of its collagen fibers and their orientation help to distribute the multidirectional forces to which the knee is subjected. The menisci may also help to reduce the amount of slipping and sliding that the femur can do across the top of the tibia. In addition, menisci help spread lubrication within the joint, spread weight over a broader surface and protect the surfaces of the bones’ cartilage.
When we walk, our knees are subjected to compressive forces equal to three times our body’s weight; when we run, this can become four to eight times our weight. The menisci bear 40–70% of this stress.[2] How much the meniscus can handle depends upon its size, shape and thickness, which is, not surprisingly, quite variable and can change as we age. Exercise, loads or other forms of compressive stress can make it thicker and stronger, but too much stress can make it thinner.
As we age, we lose blood flow to the inside of the menisci.[3] Due to the lack of vascularization within the knee joint and the position of blood vessels outside of the joint capsule, damage to the menisci is very hard to heal. Close to the outer edge of the menisci there is blood flow to them, but by the time we are adults, the inner two-thirds of the menisci have no vascularization at all.[4] That is exactly where my tears were; to the inner menisci.
Both menisci are connected to the tibia by coronal ligaments, to each other by the transverse ligament and to the patella by the patellomeniscal ligaments.[5] The medial meniscus is connected to the medial collateral ligament, to both the anterior and posterior cruciate ligament, and to the semimembranosus hamstring muscle. Unlike the medial meniscus, the lateral meniscus is not connected to a collateral ligament and thus has more mobility.[6] It is also larger than the medial meniscus.
When the knee flexes, the menisci slide backwards, pushed by the femoral condyles and pulled by the attached tendons and ligaments.[7] When the knee extends, they slide forward. In rotation, the menisci also move but in opposite directions: in external (lateral) rotation of the tibia, the lateral meniscus moves forward as the lateral femoral condyle slides forward over the tibia; in internal (medial) rotation, the medial meniscus moves forward. The lateral meniscus is better able to slide out of the way of strong shearing forces than the medial meniscus, which is more fixed in position. For these reasons it is rarer to tear the lateral meniscus and far more common to tear the medial one.
External Rotation at the Hip Socket
Figure 4: Most seated postures require external rotation of the femur in the hip socket. If this movement is limited, stress starts to build up in the knees, especially in the medial side (the inner knee).
The reduced ability of the medial meniscus to slide, compared to the lateral meniscus, is the reason that yoga students, like me, who have forced their knees into Lotus pose may have torn their medial meniscus; it wasn’t able to slide out of the way and was crushed between the medial femoral condyle and tibia.
Lotus pose requires a lot of external rotation of the femur in the hip socket (called the acetabulum). In seated postures, external rotation helps to turn the leg so that the foot comes in towards or passed the mid-line of the body, as shown in the postures in figure 4: Lotus pose on the left and sitting cross-legged on the right. However, if a student is limited in the amount of external rotation available at the hip socket (often due to the shape, size and orientation of the acetabulum and femur), then trying to lift the foot onto the thigh in Lotus pose requires a twist at the knee.
Compare the two students in figure 4: the one on the left has a lot of external rotation available and can easily bring her feet onto the opposite thighs in Lotus pose. However, notice how high the knees are of the student on the right. She is restricted in how much external rotation she has and there is no way for her to lower her knees to the floor.[8] If she tried to bring a foot onto the opposite thigh, all the movement would have to come from her knees. The result for her may well be a sharp, burning pain in her inner knee.
Prognosis and Prescriptions
Figure 5: Vajrasana or Hero pose is sitting on the heels. Options include sitting on a block or two between the feet, as the middle student is doing, and tucking a folded towel or wooden dowel behind the back of the knees.
Since the menisci effectively triple the surface area of the tibia to help distribute the weight of the femur, if they are damaged, or have to be surgically removed, the stress on the tibia can increase by over 200%.[9] Over time, this can lead to degeneration of the articulating cartilage and to osteoarthritis. It is a very good idea to not damage our meniscus, and the body, being very wise, will warn us before that happens. The warning sign is pain. Since I had the mindset that “no pain” meant “no gain”, I made the natural, and in hindsight, ridiculous decision to ignore the warning. I later learned another attitude: “no pain, no pain!”
If the meniscus is torn, ruptured or crushed, sometimes the only recourse is surgery to snip out the damaged portion. However, most doctors prefer to wait a while before opting for surgery. Range of motion enhancement and gentle stresses are often recommended (such as cycling), but full weight bearing is delayed until the acute phase of the injury has been resolved. After this stage, some rehabilitation has been achieved by stressing the knees passively through periods of sitting on the heels (in yoga, this is called Hero Pose—Vajrasana as shown in figure 5), or by placing doweling or rolled up washcloths behind the knees while sitting on the heels. Another option is to pull a folded strap or rolled up wash cloth behind the back of the knee whenever you are sitting in a cross-legged or externally rotated position. I tried many variations of these yoga recommendations, but none of them ended the pain. In 2001, I opted for the arthroscopic surgery, starting with my right knee which was damaged the most.[10]
Despite my surgeon saying that it would take three months, it took about six months to regain my pre-operation range of motion. But the pain was gone and I was pleased with that. The surgeon had warned me, however, that cushioning provided by the meniscus was reduced through the surgery and thus the cartilage at the ends of the femur and tibia would eventually start to wear away. Not quickly, but he did tell me to expect arthritis to develop in that knee over the next five to ten years. That was the downside to surgery. I did not like that prediction and vowed to make sure that would not happen.
Two years later, I had my left knee operated on. I expected another six-month recovery period but I had also booked a Thai Yoga Massage Therapy advanced training course with Saul David Raye. The 10-day training was scheduled four weeks post op. Thai massage is done on the floor, which required me to be sitting on my heels a lot. Even four weeks post op, my knee was so swollen that there was no way I could do that, but I did not want to miss the course so I went anyway. Funny thing happened at the course: at the start of the day, my knee was so stiff that I could only stand on my knees. I couldn’t sit on my heels. But, by the end of the first day I realized that I was, indeed, sitting on my heels. The next morning, my knee was swollen again but by the end of the training, all my knee stiffness had vanished. It turns out that some stress is required to accelerate healing.
Whenever I came across a senior yoga teacher at conferences and trainings, teachers like Eric Schiffman and Richard Freeman, I asked for their ideas of how to heal a torn meniscus. They all frowned sympathetically but couldn’t offer much. David Life did suggest Vajrasana. He said it had helped his knee issues. It was the owner of City Yoga in Vancouver, Mike Dennison, who told me about Vajrasana with doweling. Vowing to avoid the predicted arthritis, I started to sit on my heels with doweling tucked tightly behind the knees. Mike also loaned me his wobble-board to help me rebuild my leg strength and balance.[11] Squats, working with weights, and riding a bike also helped to strengthen the knees.
I have described the use of doweling in an article I wrote eight years post op, Yin Yoga for the Knees, so I won’t repeat it here.[12] Knowing that hip tightness can also lead to problems in the knees I also worked on enhancing my external rotation range of motion in the hip socket. It was in 2003, just after my second surgery, that I discovered Yin Yoga and began to modify my type A yangster approach to asana practice. I no longer went into any pose or stayed if there were any painful sensations. Little tweaks became a one-way ticket out of the posture. To enhance my hip’s external rotation, I spent a lot of time in the Yin Yoga version of Pigeon, called Sleeping Swan, Winged Dragons and Shoelace. Out of fear of arthritis, I followed my surgeon’s advice and stopped doing sports that create a lot of dynamic, compressive stresses in the knee. No more running. I stopped playing tennis.
It has been 20 years since my operations. There is no sign of arthritis in either knee and my mobility is good. I recently started playing pickleball, a safer version of tennis and easier on the knees, and occasionally run sprints to maintain endurance. Usually, however, I ride a recumbent bike or climbs stairs to keep my heart rate elevated. I am aware that my knees do need to bear loads and undergo stress, but not too much. I still sit on my heels every day (it is my morning meditation posture) and still use the doweling once in a while. But, I also make sure that I spend lots of time every day grounded (see this article on Earthing for more on that), eat and sleep well and lead an overall healthy life, which of course include yoga and meditation. Which part of all of this has really helped my knees? I don’t really know; and I don’t really care. As long as my knees are happy, I don’t feel so kneedy.
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[1] See Henry Gray, Susan Standring, and B.K.B. Berkovitz, eds., Gray’s Anatomy, 39th ed. (London: Elsevier, 2005), 110.
[2] See K.Y. Zhang, A.E. Kedgley, C.R. Donoghue, D. Rueckert, and A.M. Bull, “The Relationship between Lateral Meniscus Shape and Joint Contact Parameters in the Knee: A Study Using Data from the Osteoarthritis Initiative,” Arthritis Research and Therapy 16 (2014): R27, doi:10.1186/ar4455.
[3] See A.J. Fox, A. Bedi, and S.A. Rodeo, “The Basic Science of Human Knee Menisci: Structure, Composition, and Function,” Sports Health 4.4 (2012): 340–51, doi:10.1177/1941738111429419.
[4] Ibid.
[5] See P.K. Levangie and C.C. Norkin, “The Knee,” in Levangie and Norkin, eds., Joint Structure and Function: A Comprehensive Analysis, fifth ed., Philadelphia, PA: F.A. Davis Company, 2001, 399–443
[6] The lateral meniscus is joined to the medial femoral condyle by a posterior meniscofemoral ligament and is also connected to the popliteal tendon.
[7] See V. Vedi et al., “Meniscal Movement: An In-Vivo Study Using Dynamic MRI,” Journal of Bone and Joint Surgery, British volume 81.1 (1999): 37–41.
[8] Admittedly, I am speculating here. I don’t know this student and I would have to ask her what she experiences in this posture and when she tries to lower her knees to the floor. However, after years of seeing students adopt this position of the knees when sitting cross-legged, it is almost always the case that bony compression between the neck of the femur and the rim of the acetabulum prevents further external rotation. Yoga will not change this. If it is tension in the capsular ligaments that is preventing her from lowering her knees, then over time, and with a lot of hip work, she may increase her range of motion here. But, only until she ultimately reaches the point of compression.
[9] See Donald A. Neumann and A. Joseph Threlkeld, “Basic Structure and Function of Human Joints,” in Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation, ed. Donald A. Neumann (St. Louis, MO: Mosby, 2010), 142.
[10] In the years after my surgeries, I came across several studies that showed knee surgeries for torn menisci or knee arthritis are no better than placebos. One study found that almost 30% of men my age had meniscal tears but were asymptomatic: they had no pain at all. This implies that a torn meniscus may not be the cause of knee pain. I am sure this is all true, and quite fascinating, but for me, I know how and when I tore my menisci and I know that was what was causing my pain. Would they have healed on their own? I doubt that because I did wait two years before having the first surgery and four years before the second. The pain was not resolving on its own. The studies that showed the surgeries were no better than placebo still involved surgery. In the control cases, it was a sham surgery, where incisions were made, but no trimming of the meniscus or washing out of the synovial fluid (lavage) was done. This showed that neither the cutting of the meniscal tear or the flushing of the joint was what stimulated healing, but it may well be that the incisions into the knee were enough to create an inflammation response and it is possible that that was what healed the knees. Whatever is the real reason, I do know that my knees felt better after the surgeries.
For the studies on the placebo nature of knee surgeries start with this summary at Pain Science: https://www.painscience.com/biblio/fascinating-landmark-study-of-placebo-surgery-for-knee-osteoarthritis.html .
For a study on asymptomatic meniscal tears, see Horga LM, Hirschmann AC, Henckel J, Fotiadou A, Di Laura A, Torlasco C, D’Silva A, Sharma S, Moon JC, Hart AJ. Prevalence of abnormal findings in 230 knees of asymptomatic adults using 3.0 T MRI. Skeletal Radiol. 2020 Jul;49(7):1099-1107.
Recent advances in regrowing cartilage through stem cells seeded into artificial scaffolds hold out the hope that one day, replacement menisci may be grown for transplant within the knee. See B.B. Mandal, S.H. Park, E.S. Gil, and D.L. Kaplan, “Stem Cell-Based Meniscus Tissue Engineering,” Tissue Engineering. Part A 17.21–2 (2011: 2749–61.
[11] A wobble board or balance board is a flat, circular board with a rounded bottom. There are many variations and are relatively inexpensive. The challenge is to stand and balance on the board and this require coordination and core strength.
[12] See Bernie Clark, “Yin Yoga for the Knees,” Yin Yoga Newsletter (July 2011), https://yinyoga.com/yin-yoga-for-the-knees.