Case of chronic Tibialis Posterior dysfunction with a partial tear
I thought this would be an interesting case to share with you as it outlines all of the classic signs of chronic tibialis posterior dysfunction. Because this case also involved a partial tendon tear, the findings are even more prevalent and thus easy to see.
The Tibialis Posterior (TP) muscle originates on the posterior aspect of the tibia, fibula, and the interosseous membrane. As part of the deep compartment of the leg, it courses deep to the soleus muscle and inferiorly parallel to the flexor digitorum (FD) medially and flexor hallucis longus (FHL) laterally. At approximately the distal 1/3 of the tibia it crosses anterior to the FD to become the first muscle posterior to the medial malleolus on the medial side of the foot. The medial malleolus serves to change the direction of pull on the tendon as it continues anteriorly to insert into the undersurface of the midfoot via various insertion points. This acute change in direction is believed to increase the stresses on the tendon as rupture usually occurs in this area (as it did in this case).
In a closed kinetic chain, the function of the TP is to support the medial arch in order to control the rate of pronation during gait. With chronic dysfunction/weakening of this muscle the rate of pronation remains unchecked thus causing the entire force of the body transfer to the ground. Due to Newtons 2nd law (for every action there is an equal and opposite reaction) this results in a an equal ground reaction force (GRF) that must then be absorbed by the tissues = INJURY.
A more detailed explanation of this injury can be found in the following article by Functional Anatomic Palpation Systems © instructor Dr. Scott Howitt. Although the patient demonstrated in the video and pictures does not match the profile of the one discussed by Dr. Howitt, a good review of this condition is provided:
Conservative treatment of a tibialis posterior strain in a novice triathlete: a case report – Journal of the Canadian Chiropractic Association 2009; 53(1)
Below I have added some of the physical findings observed in my patient along with a description of an exercise used to strengthen this muscle.
Figure 1: Dysfunction of the tibialis posterior causing acquired adult flatfoot deformity (AFFD)
Figure 2: The common “too many toes” sign – typically the physical examination of patients with tibialis posterior dysfunction reveal flatfoot deformity consisting of flattening of the medial arch, hindfoot valgus, and abduction of the midfoot. The abduction allows more toes to be seen when standing behind the patient leading to the “too many toes” sign. All of these findings are seen in this picture.
Video: The tibialis posterior muscle initiates the process of inversion of the hindfoot during gait bringing it into a neutral position. The loss of inversion force found with dysfunction of the tibialis posterior, or in this case a partial rupture, explains why patients with tibialis posterior tendon injuries have a limited ability, or are completely unable to rise onto their toes from a position of single leg stance. In the video, the patient is able to rise onto the toes with difficulty in bipedal posture (first half of the video); however she is completely unable to do so when asked to rise on the symptomatic side only.
Figure 3: “Heels Up” Raise – one of the best exercises to strengthen the tibialis posterior is demonstrated here. With a tennis ball placed between the calcaneii the patient is instructed to perform calf raises while promoting inversion by asking them to squeeze the ball during the motion