I need help with rehab of posterior tibialis tendon break, calcaneus realignment. The injury is 18 months old. The physio says it's as good as it gets, and it's time to start functional exercise loads. Other than the obvious, any suggestions?
The posterior tibialis is a critically important muscle as it is a major factor in deceleration of pronation of the subtalar joint. Its origin is the interrosseus membrane, posteromedial fibula and posterolateral tibia. It inserts at the navicular tuberosity, medial cuneiform and 2-4 metatarsals. It isolated function is plantar flexion and inversion of the foot. In the open chain, this is true. However in gait, we have to think of not the foot action in isolation but of the tibia moving over the foot. When viewing the posterior tibialis action from this perspective, it must first eccentrically load as it lengthens. During the loading phase, the calcaneus is everting, and navicular is moving medially in relation to the talus. Additionally, the forefoot is abducting in relation to the mid and rear foot. This action lengthens the posterior tibialis, therefore causing it to be recruited to decelerate pronation of the foot. Likewise, during this phase, it is assisting to decelerate dorsiflexion as it slows the forward momentum of the tibia moving over the foot.
As the swing leg passes the stance leg and the heel of the stance leg begins to leave the ground, the posterior tibialis assists to create external rotation of the tibia and supination of the subtalar joint. Weakness of the posterior tibialis can cause the foot to remain in pronation too long and result in overuse of other tissues to facilitate supination.
With these actions in mind, the goal of training the posterior tibialis is to allow it to go through tri-plane loading (i.e., the need to decelerate dorsiflexion, tibial internal rotation and calcaneal eversion). When deciding which exercise to select for your client, find the plane of motion where they are most successful (most stability, least symptoms, greatest fluidity of motion) and then integrate upper or lower extremity reaches or body angles to create the reaction required to work the posterior tibialis. Examples of exercises to explore are below:
- Far Left: Forward (sagittal plane) lunge with medial reach of the arm
- Middle: Sagittal plane lunge with medial reach
- Far Right: Single leg squat with lateral, anterior and medial reach
As the client becomes stronger, you can add an Airex mat or Dyna disc to simulate an unstable surface. If these toys are not available, have the client try doing the above movements in sand or on a folded towel. Be cautious not to progress them too quickly before commencing with unstable surfaces.
If you notice, the above exercises are integrated and work synergistically with the gluteal complex. One of the primary functions of the gluteals is to decelerate internal rotation of the lower extremity, dorsiflexion and frontal plane action of the foot. Therefore, one of the many friends of the posterior tibialis is the gluteal complex. If the gluteals are weak, this can cause overuse of the muscles of the lower leg, especially the posterior tibialis.