This muscle is a very important stabilizer of the the whole lower extremity. It attaches to all 8 bones in the arch of the foot. It primary job is to absorb shock by slowly letting the foot and arch flatten which is also known as pronation. Every step we take whether we are walking or running the arch of the foot partially flattens to absorb shock and the tibialis posterior is the muscle that eccentrically contracts( this means it slowly un contracts).We sometimes call this the negative part of an exercise. As another example, if we we are bench pressing and the weight is all the way up in the air and our elbows are extended and we let it come down to our chest this is also a negative exercise. We do want to train it eccentrically(negatively) see my youtube video on the exercise and anatomy. Because the whole leg, pelvis and lumbar spine all move when we over pronate our foot, the shock absorption now happen in other places. The improper movement caused by a weak or inhibited tibialis posterior muscle can cause problems in the foot like neuroma, bunion, or stress fractures. The problem can affect the knee by causing or irritating meniscus injuries, kneecap pain and alignment. It also commonly affects the hip with bursitis and low back pain and disc injury. If the posterior tibialis tendon is inflamed we will have pain behind our ankle bone(Medial Malleolus) but this not always will be present when we have the disfunction. It also responds to Active Release Techniques Therapy
in addition to the rehabilitation exercises.