Adult acquire flatfoot is unfortunately a relatively common problem. There are some people that have lived with flatfeet their entire lives with no problems and others that have noticed a recent change in the anatomy of their feet with debilitating pain.
There are many causes of AAFD, and one of the most common involves injury to the posterior tibial tendon, a tendon on the inside of the foot/ankle. This tendon’s main function is essentially to pull or hold up the arch on the inside of the foot. With damage to this tendon, the arch will collapse. Injury is more common in women, especially over the age of 40, and those patients that are overweight, have diabetes and even high blood pressure. Patients that participate in high impact sports like football, basketball, and soccer, have a higher risk of injuring this tendon.
Another cause of AAFD is arthritis, more commonly inflammatory arthritis like rheumatoid. The inflammation attacks cartilage in joints as well as ligaments and tendons. Those ligaments and tendons that are injured may not be able to hold up the arch any more, causing the flatfoot deformity.
Specific injury to the ligaments, or even bones of the midfoot, can cause arch collapse. This can be from a fall from a height, crush injuries, motor vehicle accidents, sports injuries, etc. If not repaired properly, injuries to the midfoot or ‘Lisfranc’ injuries will cause lifelong debilitation.
With the growing overweight population, we increasingly see arch collapse with diabetics, or Charcot Foot. The loss of normal sensation to the feet leads to more severe foot deformities because these patients do not typically feel pain. Not only are the ligaments connecting the bones together affected, but the bones themselves can fracture and disintegrate, and develop into a very deformed foot.
Adult acquired flatfoot can present with many symptoms other than just ‘fallen arches.’ Depending on the cause of this deformity, patients can present with pain and swelling on the inside of the foot and ankle where the posterior tibial tendon courses. Pain is usually associated with activity, with running, climbing up and down stairs, and even walking and standing, but is typically relieved by rest. Other patients with advanced deformity, may experience sharp pain on the outside of the ankle when standing, from impingement or ‘pinching’ of the joint or bones here.
Treatment of AAFD is primarily dependent on the cause. Acute fractures and dislocations of the midfoot should be surgically repaired to prevent deformity. Flatfeet secondary to damage to the posterior tibial tendon or arthritis should be initially treated conservatively with shoe orthotics and maybe even bracing if severe. Orthotics that can hold up the fallen arch can provide significant pain relief, and can include full length medial arch supports orthotics, UCBL orthotics, and Arizona braces. If this fails, the patient may require surgical reconstruction of the foot to restore the fallen arch and eliminate pain. Those patients with severe diabetes or neuropathy that caused the deformity, should be treated conservatively with custom shoe wear, and occasionally surgery to prevent or treat foot ulcers.