Acquired Flatfoot Deformity


Symptoms

Pain and fatigue along the inside and bottom of the ankle and foot are the most common signs of an early Posterior Tibial Tendon Dysfunction (PTTD). Mild swelling and changes in the shape of the foot are also findings in earlier stages of PTTD. As the condition worsens, the pain often shifts to the outside of the foot where the fibula is now contacting and impinging on the calcaneus do to the loss of arch height and eversion of the hindfoot

The acquired flatfoot deformity is a relatively common condition although it is often overlooked. The deformity is caused by a dysfunction to the Tibialis Posterior Tendon (TPT) and/or muscle which is responsible for maintaining proper medial foot arches. The muscle arises from the proximal posterior aspect of the tibia and fibula as well as the interosseous membrane that joins the two bones. Distally, the muscle becomes tendinous and passes behind the medial malleolus before it inserts into the navicular, medial cuneiform and the inferior joint capsule of the medial naviculocuneiform joint.

Function

The role of the tibialis posterior muscle during gait is to stabilize the midtarsal joints via locking the calcaneocuboid and talonavicular joints. This ensures that the forward propulsive forces developed by the calf muscles (Gastrocs and soleus) are transmited to the metatarsal heads and results in a stable base for push-off during gait. If the tibialis posterior muscle fails to lock the midtarl joints, the forward propulsive forces are now distributed to the midfoot and as a result stresses the medial longitudinal arch and eventual collapse of the arch with rearfoot valgus and subtalar joint eversion.

Anatomically the tendon is supplied by two arteries, one that supplies the proximal tendon and one that supplies the distal tendon. This pattern of blood supply leaves a region of hypovascularity that may be more susceptible to injury and degenerative changes.


Who’s at risk?

There are two primary groups of people who present with PTTD. The first are people around 30 years of age who may have a history of systemic inflammatory conditions. The second group is older (around 55 years of age) who have acquired the dysfunction from chronic overuse. The rate of TPT rupture has been noted to be highest among overweight middle-aged women, patients with hypertension or diabetes, and those who have had oral and/or injected corticosteroids.

Stages of Injury

Posterior Tibial Tendon Dysfunction has been categorized into four stages as listed below:

Stage 1: Tenosynovitis:

• This stage is characterized by mild to moderate symptoms due to swelling located in the synovial sheath that surrounds the TPT. Pain and swelling are localized to the medial aspect of the foot with only minimal weakness and dysfunction present.

Stage 2: Elongation or Tearing of the TPT

• Visible deformity is present as the midfoot pronates and forefoot abducts resulting in loss of the medial ach height. Increased weakness is present with the patient being unable to stand on tip toe on the affects leg.

Stage 3: More severe deformity

• More severe deformity is present then in stage 2. A fixed hind foot is also characteristic of this stage.

Stage 4: Ankle degeneration

• Hindfoot valgus deformity is present at rest and early bony generative changes are visualized on X-Ray.

Treatment

Treatment options are dependent upon the stage of PTTD present. The early stages can be managed conservatively while the later stages with actual structural deformity may require surgical intervention.

Conservative therapy for functional PTTD includes a period of modified activity levels which may include a removable walking below the knee boot or cast. The cast is recommended for 1-3 weeks followed by using custom-fit orthotics to help alleviate tendon sheath swelling and pain. After a three to six month trial, many patients will have recovered and will no longer need orthotic inserts. However, despite treatment, some patients will need to continue with orthotic use and some may progress to more advanced stages of PTTD. If after the 3-6 month trial period the patient is still experiencing pain, other forms of orthotic inserts should be prescribed such as a medial posted UCBL device or an ankle-foot orthosis. If after another 3-6 month trail no improvements are noticed, a surgical consult is recommended.

To increase the success rate of conservative treatment, it is necessary to have the muscle and tendon treated directly. Several soft-tissue treatment methods have been very successful in treating this condition. Some of these treatments include ART®, Graston®, and medical acupuncture. They help to restore the proper blood supply to the muscle, break-up any scar tissue adhesions and restore function to the muscle. This helps the muscle become more efficient and thereby decreases the time to full recovery. Be sure to talk to your sports therapist about PTTD and how to get it treated effectively so you can get back to pain free activities!

* Note: local corticosteroid injections have been shown to progress a PTTD and are therefore contra-indicated as they may predispose the tendon to rupture.