Muscle knots in the Tibialis Posterior are typically located deep in the lower leg, just behind the shin and toward the inner side of the calf. These muscle knots often refer pain to the back of the lower leg, Achilles tendon, the heel, the inner ankle, and the sole of the foot, and into the the bottom of the big toe. This pain sometimes mimicks plantar fasciitis or posterior tibial tendonitis. People often feel discomfort when walking or standing for long periods, especially if they have fallen arches or overpronation, which can strain this muscle further.