The posterior tibial tendon is the strongest tendon that supports the arch on the inner side of the ankle/foot. As we age, the tendon can degenerate (tendinosis), partially tear or rupture leading to a flatfoot compared to the opposite foot. The underlying spring ligament can also stretch out.
This typically occurs in patients in their 50s, but can present at a later age. It may be triggered by a traumatic episode, but often there is no obvious trauma that the patient can recall. This is because it is a degenerative condition as we age. The pain and swelling starts on the medial or inner part of the ankle/foot. The tendon is weak and the arch starts to collapse/flatten which may lead to pain on the lateral or outer part of the ankle/foot from impingement.
The initial treatment is to have the patient try to stay in a “pain free zone” with activity modification. Immobilization is usually required and takes the form of a walking boot or brace. Physical therapy is then instituted and the patient transfers into a pair of over-the-counter or custom insert/orthotics. This nonoperative treatment can be successful in a significant number of patients but may be prolonged and take more than six months. A success is defined as the symptoms being either completely or near fully resolved allowing them to return to all or a majority of their activities. The arch does not restore and remains flat, but the patient functions well.
A patient fails nonoperative treatment when the symptoms persist despite the treatment. They usually have chronic pain and dysfunction on a regular basis that affects their activities. Unfortunately, a simple repair of the posterior tibial tendon has not been shown to be effective due to the degenerative tearing. The surgery can be divided into two components. The soft tissue component involves transferring the flexor digitorum longus tendon, repairing a portion of the posterior tibial tendon if possible and shortening/imbricating the spring ligament. A lengthening of the Achilles tendon or calf muscle may also be indicated. The bony component involves a osteotomy or bone cut which is determined by the degree of the flatfoot deformity. It is an outpatient procedure under general or regional anesthesia. The patient will be placed in a nonremovable splint and will be nonweightbearing with crutches. At two weeks, the stitches are removed and the patient is placed in a removable boot. The patient is still on crutches for weeks three and four. Partial weight-bearing in the boot will begin at four weeks and physical therapy at six weeks. The patient transitions from the boot to a lighter brace as they become stronger over the next one month. They are then fitted for custom orthotics as the return to their activities.
The flatfoot deformity may become rigid as opposed to flexible. In this case, the flatfoot is stiff and stuck in this position. It is usually a more severe deformity with associated arthritis. The nonoperative treatment involves custom orthotics or bracing. If this is unsuccessful, the surgical treatment is a triple or hindfoot fusion to correct the deformity to “lock it in place.” There was stiffness prior to surgery which will remain postoperatively, but the foot is in a better position. Please note that this is a hindfoot fusion of the joints below the ankle. It is not an ankle fusion. The idea of a hindfoot fusion may be a significant concern to patient thinking that they will have no motion of the foot and ankle. While they do lack most side to side motion and some up-and-down motion, the ankle/foot is pain free or significantly less painful. It also provides a stable foot in a better position to walk and function. It is an outpatient procedure under general or regional anesthesia. The patient will be placed in a nonremovable splint and will be nonweightbearing with crutches. At two weeks, the stitches are removed and the patient is placed in a removable boot. The patient is still nonweightbearing on crutches to about the 8 to 10 week mark. Partial weight-bearing in the boot will then begin for about four weeks. The patient transitions from the boot to a lighter brace as they become stronger over the next one month.