Adult acquired flatfoot deformity or posterior tibial tendon dysfunction is a gradual but progressive loss of ones arch. The posterior tibial muscle is a deep muscle in the back of the calf. It has a long tendon that extends from above the ankle and attaches into several sites around the arch of the foot. The muscle acts like a stirrup on the inside of the foot to help support the arch. The posterior tibial muscle stabilizes the arch and creates a rigid platform for walking and running. If the posterior tibial tendon becomes damaged or tears the arch loses its stability and as a result, collapses causing a flatfoot. Adult flatfoot deformity can occur in people of all ages and gender however, it occurs most commonly in sedentary middle aged to elderly females. There are several risk factors for posterior tibial tendon dysfunction that include: obesity, steroid use, systemic inflammatory diseases such as rheumatoid arthritis, trauma, being born with a low arch, and diabetes. It occurs most commonly in one foot however, it can occur in both feet especially in people with systemic diseases such as diabetes and rheumatoid arthritis.
There are four stages of posterior tibial tendon dysfunction. In the first stage the posterior tibial tendon is inflamed but has normal strength. There is little to no change in the arch of the foot. In stage two the tendon is partially torn or shows degenerative changes and as a result loses strength. There is considerable flattening of the arch without arthritic changes in the foot. Stage three results when the posterior tibial tendon is torn and not functioning. As a result the arch is completely collapsed with arthritic changes in the foot. Stage four is identical to stage three except that the ankle joint also becomes arthritic.
Surgical correction is dependent on the severity of symptoms and the stage of deformity. The goals of surgery are to create a more functional and stable foot. There are multiple procedures available to the surgeon and it may take several to correct a flatfoot deformity.
Stage one deformities usually respond to conservative or non-surgical therapy such as anti-inflammatory medication, casting, functional orthotics or a foot ankle orthosis called a Richie Brace. If these modalities are unsuccessful surgery is warranted. Usually surgical treatment begins with removal of inflammatory tissue and repair of the posterior tibial tendon. A tendon transfer is performed if the posterior tibial muscle is weak or the tendon is badly damaged. The most commonly used tendon is the flexor digitorum longus tendon. This tendon flexes or moves the lesser toes downward. The flexor digitorum longus tendon is utilized due to its close proximity to the posterior tibial tendon and because there are minimal side effects with its loss. The remainder of the tendon is sutured to the flexor hallucis longus tendon that flexes the big toe so that little function is loss.
Stage two deformities are less responsive to conservative therapies that can be effective in mild deformities. Bone procedures are necessary at this stage in order to recreate the arch and stabilize the foot. These procedures include isolated fusion procedures, bone grafts, and/or the repositioning of bones through cuts called osteotomies. The realigned bones are generally held in place with screws, pins, plates, or staples while the bone heals. A tendon transfer may or may not be utilized depending on the condition of the posterior tibial tendon.
Stage three deformities are better treated with surgical correction, in healthy patients. Patients that are unable to tolerate surgery or the prolonged healing period are better served with either arch supports known as orthotics or bracing such as the Richie Brace. Surgical correction at this stage usually requires fusion procedures such as a triple or double arthrodesis. This involves fusing the two or three major bones in the back of the foot together with screws or pins. The most common joints fused together are the subtalar joint, talonavicular joint, and the calcaneocuboid joint. By fusing the bones together the surgeon is able to correct structural deformity and alleviate arthritic pain. Tendon transfer procedures are usually not beneficial at this stage.
Stage four deformities are treated similarly but with the addition of fusing the ankle joint.
Time off work depends on the type of work as well as the surgical procedures performed. . A patient will be required to be non-weight bearing in a cast or splint and use crutches for four to twelve weeks. Usually a patient can return to work in one to two weeks if they are able to work while seated. If a person's job requires standing and walking, return to work may take several weeks. Complete recovery may take six months to a full year.
Complications can occur as with all surgeries, but are minimized by strictly following your surgeon's post-operative instructions. The main complications include infection, bone that is slow to heal or does not heal, progression or reoccurrence of deformity, a stiff foot, and the need for further surgery. Many of the above complications can be avoided by only putting weight on the operative foot when allowed by your surgeon.
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