That’s right. The calf muscles can cause pain behind your knee! It’s mostly from the two-headed gastrocnemius you see bulging when athletes go up on their toes, but the soleus muscle makes a contribution. If you have calf cramps at night, then the “gastroc” could be the cause of your knee pain.
This one is pretty easy to understand. The tendons of the two heads of the gastrocnemius muscle attach separately above the knee on the back sides. When a muscle crosses a joint, it acts on it mechanically to increase joint pressure (which can cause pain). The “gastroc” is no exception, but unlike other joint-crossers that are active in moving the joint, the gastroc only assists in bending the knee. It helps stabilize it, but it’s action is mainly to point the toe from it’s lower attachment to the heel.
Since I’m a Neuromusclular Therapist (Boston area), I have to place the Trigger Points from the gastrocnemius muscle as it’s most important contribution to knee pain. Of the four identified TrPs, the ones nearest to the knee are most likely to cause knee pain. 1) From a functional standpoint, a tight gastroc muscle with an active TrP can pull on it’s tendon at the knee to cause localized pain. 2) The attachment Trigger Points” that form where muscle and tendon fibers come together (musculotendinous junction) to connect to the bone have radiating pain to the back of the knee.
The soleus muscle, underneath the gastrocnemius, has one Trigger Point near the knee that can cause some pain behind the knee, but most soleus TrPs refer locally in the calf and downward.
Trigger Points in the calves are activated or perpetuated by several factors, but mostly by overload like from sports or walking uphill or in high heels, or from prolonged shortening like from having the toes pointed downward in bed or driving long distances pressing on the gas pedal or sitting on a bar stool with the heels hooked on a rung. They can also be activated by deconditioning or immobility as when in a walking cast, or perpetuated by bending forward like at the sink. Compression like from tight knee socks can impede blood flow and cause ischemia and pain. Excess cooling like from an air conditioner can aggravate TrPs as can viral infections.
The last three posts include those muscles most involved with knee pain, the quads, hammies, pops, and gastrocs. There are other muscles that therapists should think about when solving a knee pain puzzle. Look for posts to follow on Knee pain: Tips for therapists and one on Knee pain: The best stretches.