The foot is a very highly balanced part of the anatomy and is comprised of numerous bones, tendons and muscles.  Tendons connect muscles to bones and stretch across joints, enabling you to bend the joint.  One of the most important tendons in the lower extremity is the posterior tibial tendon.  This tendon originates in the calf, and travels down the inside of the ankle to attach to the bones in the middle of the foot. 
The posterior tibial tendon helps to support the arch, and locks the foot as a rigid lever so that when the heel is lifted off the ground, the foot is stable enough to walk forward on.  If the tendon becomes inflamed, overstretched or torn, you may experience pain around the inner side of the ankle, and gradually lose the inner arch of the foot, leading to a flatfoot deformity.
 
Signs and symptoms of posterior tibial tendon dysfunction

• Pain and swelling on the inside of the ankle
• Loss of the arch and development of a flatfoot
• Gradually developing pain on the outer side of the ankle or foot
• Weakness and an inability to stand on the toes
• Tenderness over the midfoot, especially when under stress during activity

Risk factors
Posterior tibial tendon dysfunction most often occurs in women over 50 years of age and may be due to an inherent abnormality of the tendon.  But there are several other risk factors, including:

• Obesity
• Diabetes
• Hypertension
• Previous surgery or trauma, such as an ankle fracture
• Local steroid injections
• Inflammatory diseases such as Reiter's syndrome, rheumatoid arthritis, ankylosing spondylitis and psoriasis

Athletes who are involved in sports such as basketball, tennis, soccer or hockey may tear the posterior tibial tendon.  The tendon may also become inflamed if excessive force is placed on the foot, such as when running on a banked track or road.

Diagnosis
The diagnosis is based on both a history and physical examination performed by a trained foot and ankle specialist.  Your physician may ask you to stand on your bare feet facing away from him to view how your foot functions.  As the condition progresses, the front of the affected foot will start to slide to the outside.  From behind, it will look as though you will have "too many toes" showing.  You may also be asked to stand on your toes or do a single heel rise;  stand with your hands supported, lift the unaffected foot off the ground, and raise up on your toes of the other foot.  Normally, the heel will rotate inward; the absence of this sign indicates posterior tibial tendon dysfunction.  Your doctor may request x-rays, or an MRI of the ankle for further evaluation.
 
Treatment
Without treatment, the flatfoot that develops from posterior tibial tendon dysfunction eventually becomes rigid.  Arthritis develops in the hindfoot.  Pain increases and spreads to the outer side of the ankle.  The way you walk may be affected and wearing shoes may be difficult.  The treatment your doctor recommends will depend on how far the condition has progressed.  One can liken the posterior tibial tendon's relationship to the maintenance of the arch of the foot to the wooden slat of a swing suspended by 2 ropes in your backyard.  If one of the ropes frays, the seat tilts.  If the posterior tibial tendon tears or becomes dysfunctional, the arch of the foot will collapse causing the larger joints of the middle and back part of the foot to tilt inward.  To remedy the broken swing, one needs to "level the seat", or "swing a new rope".  In a sense this equates to conservative and surgical treatments.  In the early stages, posterior tibial tendon dysfunction can be treated with rest, non-steroidal anti-inflammatory drugs and immobilization of the foot and ankle for 6 to 8 weeks with a rigid below-knee cast or boot to prevent overuse.  After the cast is removed custom made orthotics will be used to "level the seat".  If the condition is advanced, your doctor may recommend that you use a custom made ankle-foot-orthosis (AFO).
If conservative treatments don't work, your doctor may recommend surgery.  Several procedures can be used to treat posterior tibial tendon dysfunction, and often more than one procedure is performed at the same time.  Your doctor will suggest a specific course of treatment based on your individual case.  The surgeons of Cambridge foot and ankle have expertise in the surgical treatment of this condition, and have performed numerous reconstructive and salvage procedures for patients. 

Surgical options include:

• Tenosynovectomy:  In this procedure, the surgeon will clean away (debride) and remove (excise) any inflamed tissue surrounding the tendon.
• Osteotomy:  This procedure changes the alignment of the heel bone (calcaneus), in effect "leveling the seat".  A screw is placed across the bone cut to hold it together while it heals
• Tendon transfer:  This procedure involves transferring another tendon that lies next to the posterior tibial tendon (the flexor digitorum longus FDL-tendon) and helps to bend the toes, to repair the damaged tendon.

FDL tendon transfer

• Lateral column lengthening:  In this procedure, the surgeon places a small wedge of bone into a cut in the outside of the calcaneus.  This helps to realign the bones and recreate the arch.
• Arthrodesis:  This procedure welds (fuses) one or more bones together, eliminating movement in the joint.  This stabilizes the hindfoot and prevents the condition from progressing further.