Pathological flat foot is caused by 2 types of diseases:
- Neuromuscular diseases are the ones related to nerve or muscle injury.
- Birth defects are generally bony abnormalities, like an extra bone or fused bones.
Congenital Vertical Talus is a birth defect in which the ankle bone – talus is more vertically oriented. This causes the joints of the other ankle bones to get locked in an awkward position. There is complete loss of flexibility of the foot, with a resultant flattening of the arch of the foot. The treatment is a corrective surgery.
Tarsal Coalition is a complete or partial fusion of 2 or more ankle bones, which are called tarsals. This reduces the ankle mobility and hampers the flexibility of the foot. Thus, the plantar aponeurosis is unable to pull the front and back of the foot together, and the result is flat feet. The treatment is surgical or medical depending on the severity of the symptoms.
Accessory Navicular is an additional ankle bone which is present along with the navicular bone. This bone is normally not symptomatic but sometimes it can cause swelling and fullness along the inner edge of the foot. This compromises the arch of the foot and results in a flatfoot. The condition is temporary and does not require any special treatment. Painkillers and anti-inflammatory medications along with rest gives relief from the symptoms.
Hypermobile flatfoot is a condition in which the joints of the foot are extremely lax, along with decreased tone in foot muscles. Thus, the foot muscles do not have adequate power to pull the front foot and back foot together. This results in failure of the arch of foot and so a flat foot. The treatment is medical as well as surgical. Physical therapy to improve the tone of the foot muscles along with orthotics play an important role in the treatment.
Z-foot or Skew foot is a birth defect in which the foot is highly deformed. The front foot is deviated inwards and the back foot is deviated outwards, giving the foot a shape like the letter “z”. Hence, the name z-foot or skew foot. This is a very complicated type of flat foot. Treatment consists of multiple surgeries, which aim at bringing normal alignment of the foot to some extent. Wedges of bone are removed from the heel bone and some ankle bones to re-align the foot. Post-op orthosis and physical therapy are needed for complete recovery which takes from 6 months to 1 year.
Peroneal Spastic foot is a neuromuscular cause of flat feet. The muscles along the lateral part of the leg are called peroneal muscles, which are attached to the medial (inner) part of the foot. A spasm of the peroneal muscles can occur because of nerve injury due to various diseases, like poliomyelitis, leprosy, and so on. This causes the inner part of the foot to be pulled outwards and downwards, thus, flattening the arch of the foot. The treatment consists of surgical release of the tight muscles, to restore the arch in its functional place.
Tight Achilles Tendon is a neuromuscular cause of flat feet. The achilles tendon is attached at the back of the heel bone. A tight achilles tendon pulls the heel bone in a direction opposite to the plantar aponeurosis. Thus, the aponeurosis is unable to form the arch of the foot by pulling the front foot and back foot together. The treatment consists of a surgery called Z-plasty or V-Y plasty, which increases the length of the achilles tendon.