Posterior tibial tendon dysfunction is a problem that occurs in one of the tendons on the inner side of the ankle.
A review of your anatomy is helpful in understanding how this occurs. The posterior tibial muscle attaches to the back of the shin bone; the posterior tibial tendon connects this muscle to the bones of the foot. It passes down the back of the leg, not far from the Achilles tendon, then turns under the prominence of the inner side of the ankle. It then attaches to the bone of the inner side of the foot, just adjacent to the arch of the foot.
Posterior tibial tendon problems usually occur just underneath the prominence of the inner side of the ankle, called the medial malleolus. The medial malleolus is the end of the shin bone (the tibia) and the posterior tibial tendon wraps just underneath the medial malleolus. This area of the tendon is particularly prone to developing problems because it lacks a robust blood supply to nourish and repair the tendon.
This part of the tendon exists in a "watershed zone," where the blood supply is weakest. So when the tendon becomes injured, as a result of trauma or overuse, the body has difficulty delivering the proper nutrients for healing.
The Link With AAFD
When left untreated, posterior tibial tendonitis can gradually progress to a problem called adult-acquired flatfoot deformity (AAFD).1 This condition typically begins with pain and weakness of the posterior tibial tendon, but as the condition progresses, the ligaments of the foot are affected and the foot joints can become malaligned and rigidly deformed. For this reason, most physicians prefer the early treatment before the later stages of AAFD.
Most commonly, patients with posterior tibial tendonitis complain of pain on the inner of the foot and ankle and occasionally have problems associated with an unsteady gait.2 Many patients report having had a recent ankle sprain, although some will have had no recent injury.
As posterior tibial tendonitis progresses, the arch of the foot can flatten and the toes begin to point outwards. This is the result of the posterior tibial tendon not doing its job to support the arch of the foot.
Diagnosis of posterior tibial tendonitis is commonly made by physical examination. Patients have tenderness and swelling over the course of the posterior tibial tendon. Usually, they have weakness inverting their foot (pointing the toes inward). Also common in patients with posterior tibial tendonitis is an inability to stand on their toes on the affected side.
When the examination is unclear, or if a patient is considering surgery, an MRI may be obtained. The MRI is an effective method to detect ruptures of the tendon, and it can also show inflammatory changes surrounding the tendon.
Posterior tibial tendon insufficiency can be classified according to the stage of the condition. The classification is from stage 1 through stage 4 with increasing deformity of the foot as the condition progresses.3
Stage 1: The earliest stage of posterior tibial tendon insufficiency is having pain and swelling along the tendon. The foot may appear completely normal, or people may notice their foot has a mild flatfoot deformity, probably something they feel they have always had.
Stage 2: As the condition progresses, the arch of the foot begins to collapse. While the arch of the foot can be corrected, when people stand the foot appears flat along its inner side.
Stage 3: Once into stage 3 of the condition, the foot cannot be easily corrected, a condition called a rigid flatfoot deformity.
Stage 4: Once in stage 4, not only is the foot involved but the adjacent ankle joint also become involved in the condition.
As these stages progress, the treatment to correct the problem becomes more invasive.
While nonsurgical treatment can be used at any stage, the likelihood of success with less invasive treatments may decrease as the condition progresses.
The initial treatment of posterior tibial tendonitis is focused on resting the tendon to allow for healing.4 Unfortunately, even normal walking may not adequately allow for the tendon to rest sufficiently. In these cases, the ankle must be immobilized to allow for sufficient rest. Options for early treatment include:
Shoe inserts and arch supports
By providing a stiff platform for the foot, shoe inserts and walking boots prevent motion between the midfoot and hindfoot. Preventing this motion should decrease the inflammation associated with posterior tibial tendonitis. Casts are more cumbersome but are probably the safest method to ensure the posterior tibial tendon is adequately rested.
Other common treatments for early-stage posterior tibial tendonitis include anti-inflammatory medications and activity modification.4 Both of these treatments can help to control the inflammation around the posterior tibial tendon.
Surgical treatment of posterior tibial tendonitis is controversial and varies depending on the extent of the condition. In the early stages of posterior tibial tendonitis, some surgeons may recommend a procedure to clean up the inflammation called a debridement.5 During a debridement, the inflamed tissue and abnormal tendon are removed to help allow for the healing of the damaged tendon.
In more advanced stages of posterior tibial tendonitis, the arch of the foot has collapsed and a simple tendon debridement may be insufficient to correct the problem. Reconstruction of the posterior tibial tendon is occasionally performed.
In reconstructive procedures, a neighboring tendon, called the flexor digitorum longus, is moved to replace the damaged posterior tibial tendon.6 This procedure is often combined with a bone reconstruction as well. Finally, in the most advanced cases of posterior tibial tendonitis, when the arch of the foot has become rigid, a fusion procedure is the preferred treatment.
A Word From Verywell
Posterior tibial tendon dysfunction and adult-acquired flatfoot deformity can be frustrating problems. Often, people feel their symptoms are ignored by a doctor who may not see much in the way of deformity, but people experience discomfort and instability of the ankle.
Once in the later stages, treatment can be invasive and limit in terms of the function of the foot. For these reasons, early efforts with noninvasive treatments, including footwear modifications and therapeutic activities, are the most preferred methods to control symptoms of the condition.