Progressive Flat Foot

Tendons connect muscles to bones and stretch across joints, enabling you to bend that joint. One of the most important tendons in the lower leg is the posterior tibial tendon. This tendon starts in the calf, stretches down behind the inside of he ankle and attaches to bones in the middle of the foot.

The posterior tibial tendon helps hold your arch up and provides support as you step off on your toes when walking. If this tendon becomes inflamed, over-stretched or torn, you may experience pain on the inner ankle and gradually lose the inner arch on the bottom of your foot, leading to flat foot.

Signs and Symptoms

  • Pain and swelling on the inside of the ankle
  • Loss of the arch and the development of a flat foot
  • 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

Progressive flat foot often occurs in women over 50 years of age and may be due to an inherent abnormality of the tendon. However, there are several other risk factors, including:

  • Obesity
  • Diabetes
  • Hypertension
  • Previous surgery or trauma, such as an ankle fracture on the inner side of the foot
  • Local steroid injections
  • Inflammatory diseases such as Reiter's syndrome, rheumatoid arthritis, spondylosing arthropathy 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 a physical examination. Your physician may ask you to stand on your bare feet facing away from him/her 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 have "too many toes" showing.

You may also be asked to stand on your toes or to do a single heel rise: stand with your hands on the wall, lift the unaffected foot off the ground, and raise up on the 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, an ultrasound or a magnetic resonance image (MRI) of the foot.

*Source:  American Orthopaedic Foot & Ankle Society® http://www.aofas.org

*This material was codeveloped by the American Academy of Orthopaedic Surgeons

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