INJURY & REHAB: why you need to address tibialis posterior when managing plantar fasciitis
With a range of foot-related problems resulting from tibialis posterior dysfunction, there’s a clear need to assess the function of this muscle.
A full assessment of a client presenting with plantar fasciitis (pain in the heel and underside of the foot) needs to take into account the client’s hip, knee, ankle and foot function, as well as all the muscles of importance, such as the gluteals, peroneals, hamstrings, quadriceps, tricep surae, tibilias anterior and tibialis posterior.
The functionality of the joints and relevant muscles is assessed in order to understand the contributing biomechanical dysfunction and allow an appropriate treatment plan to be established. Here, we examine one of the muscles which is often seen in clinical practice to contribute to the pain and biomechanical dysfunction in clients with plantar fasciitis, namely the tibialis posterior.
The tibialis posterior is a vital muscle of the lower leg because of its numerous insertions, support of the leg, foot and ankle, and its relationship with normal foot pronation. Inhibition of the tibialis posterior often results in knee pain, foot pain, and ankle pain, as well as overpronation, which can defer excess shock to the rest of the body during impact. Problems such as shinsplints, plantar fasciitis, bunions, hammer toes, and neuromas are often a result of tibialis posterior dysfunction.
The tibialis posterior’s main action is to invert and plantar flex the ankle joint (i.e. push and pull the foot up and down), as well as stabilise the medial aspect of the ankle. It is also the major muscle that supports the medial arch of the foot and, along with many of the insertions throughout the plantar aspect of the foot, the tibialis posterior is responsible for the actual strength and health of the foot itself.
Origins and insertions
The tibialis posterior originates at the medial portion of the proximal posterior tibia and the medial two-thirds of the proximal posterior fibula. The interosseous membrane binds the tibia and fibula together, and forms much of the origin of the tibialis posterior, along with the deep fascia of the lower leg. The tibialis posterior inserts into the navicular tuberosity, three cuneiforms, cuboid and bases of the second through to fourth metatarsal bones. This makes the tibialis posterior very important in the stability of the lower leg, support of the medial arch, and normal pronation.
Who is prone to suffer plantar fasciitis?
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Plantar fasciitis can be experienced by a person displaying either lower- or higher-arched feet. Clients with lower arches have conditions resulting from too much motion, whereas clients with higher arches have conditions resulting from too little motion. In both of these instances the tibialis posterior is affected by inhibition. With the increased motion experienced by the clients with lower arches, the tibialis posterior is overused through its support of the medial arch during excess motion – in turn becoming hypertonic and inhibited. In terms of the higher-arched clients, the tibialis posterior is continually engaged in contraction to assist in supporting the medial arch height.
In assessing a client presenting with plantar fasciitis, the tibialis posterior needs to be examined in order to, firstly, rule out tibialis posterior tendinopathy and, secondly, gauge the contribution of the tibialis posterior to the client’s pain and biomechanical dysfunction.
The assessment of the tibialis posterior should involve manual muscle testing and palpation of (i.e. using the hands to examine) the muscle and the tendon. A personal trainer can undertake this assessment. To manual muscle test, have the client supine with the leg in lateral rotation and the foot inverted with plantar flexion at the ankle joint. The practitioner supports the leg above the ankle and applies pressure on the medial plantar surface of the foot in the direction of dorsiflexion of the ankle and eversion of the foot. If the flexor hallucis longus and flexor digitorum longus are being substituted, the toes will be strongly flexed as pressure is applied. A weakness will show in decreased ability to invert the foot and plantar flex the ankle.
The practitioner should palpate the entire muscle and tendon. If there is sensitivity in the area of insertion in the bottom of the foot, the tendon behind the medial malleolus and muscle belly should be palpated. The insertion tenderness can often be mistaken for plantar fasciitis. Releasing any adhesions found within the muscle belly will decrease the tenderness at the insertion.
If during the assessment the tibialis posterior is found to be inhibited, the muscle should be released and lengthened through soft tissue work and stretching. Strengthening exercises should then be provided. These can include inversion exercises, isometric, active, and resistance band inversion.
The client should seek professional advice before attempting any rehabilitation exercises. A thorough examination of the client’s biomechanics of the lower limb should be undertaken by an allied health professional to ascertain why the tibialis posterior was inhibited initially. By doing so, the health practitioner can determine what appropriate action should be undertaken to ensure the tibialis posterior is not inhibited.
Sandra Steel, DC is the principal chiropractor at Total Body Fusion n Morningside, QLD. She employs a number of chiropractic techniques, dry needling, Active Release Technique, Functional Movement Screening and corrective exercises to achieve client functionality. totalbodyfusion.com.au