Flat feet (pes planus) are common but do not always cause pain or symptoms. However, they can shift stress to other parts of the lower leg, ankle, knee and hip, leading to problems over time.
A physical exam observing how the foot looks when standing is the first step to diagnosing flat feet. Your doctor may take X-rays of your foot while you are weightbearing to check for changes in the shape of the arch and to look for other conditions that can lead to flatfoot.
Symptoms
Patients with painful flat feet experience pain when they walk, particularly for extended periods of time. The pain is typically felt along the inside of the ankle and foot where the posterior tibial tendon lies. The pain is also often felt when the patient is attempting to push off with or stand on their toes. The pain and weakness will generally get worse with activity and may be aggravated by certain types of shoes such as high heels or those that are tight around the toes.
Flatfoot can be diagnosed by visual inspection of the foot and ankle as well as weight bearing x-rays and magnetic resonance imaging (MRI) scans when necessary. MRI scans provide detailed images of soft tissue such as tendons and ligaments. They are often used to check for inflammation or tearing of the posterior tibial tendon or other structures in the foot and ankle.
Progressive collapsing flatfoot deformity, or adult acquired flatfoot is most commonly caused by dysfunction of the posterior tibial tendon. The posterior tibial tendon attaches the calf muscles to the small bones on the inside of the foot and provides stability for the arch. When this tendon becomes inflamed or torn it is no longer able to support the arch and the arch collapses. The condition can develop slowly over a long period of time or can be the result of a specific injury.
Diagnosis
In most cases, flat feet are diagnosed with a physical examination of the foot and ankle. The examiner can observe a flat arch when looking at the foot from behind, or notice that more than two toes can be seen from the back of the foot (known as the “too many toes sign“). The person may also have pain and other problems when walking or standing on the foot.
Your doctor will take a history of your health problems and symptoms, including any that have occurred recently. Then your doctor will examine the feet and ankles, both while you’re standing and while you’re not. Your doctor might take X-rays of your feet to look for changes in the shape of your arch. They might also order an MRI scan to get better pictures of soft tissue structures like tendons and ligaments.
Most people with flexible flatfoot get better with orthotics and physical therapy, especially when the flatness is mild to moderate. When the condition is severe and the underlying cause, such as arthritis in key ankle joints, causes pain that does not respond to treatment, surgery might be needed. The surgeon might perform a procedure called fusion (arthrodesis) to remove the cartilage from one or more ankle joints and fix the bones in a corrected position. This eliminates the joint and reduces pain.
Treatment
The most important factor in the diagnosis of flat foot is a detailed clinical examination. The physical exam helps distinguish flexible versus rigid flat foot and identifies common mimics. X-rays are important for determining deformities and measuring progression. Imaging studies such as MRI provide excellent detail of soft tissues such as tendons and ligaments. The MRI scan can help differentiate the type of flat foot and determine whether other pathology such as a tarsal coalition, an accessory navicular bone or congenital vertical talus is contributing to the problem.
Nonsurgical treatment options can help to reduce symptoms, provide foot support and relieve pain. These include limiting weight bearing, using orthotic devices in shoes, activity modification, use of nonsteroidal anti-inflammatory drugs (NSAIDs) and physical therapy.
For a more severe type of flat foot surgery may be needed to restore a good arch shape. This can involve a combination of techniques including osteotomies (cutting bones to re-align them) and fusion of joints, tendon lengthening or transfer procedures as well as implanted devices to help maintain the corrected position.
For example, in stage 3 acquired adult flat foot a procedure known as double or triple arthrodesis may be required to correct the collapse of the hindfoot. This involves fusing two or three joints in the hindfoot, and can be combined with the transfer of a tendon from the foot to the shin.