[Click! Health] "Why Does the Sole Hurt?"... Exploring Causes of Sole Pain

When the soles of the feet hurt, people often think of 'plantar fasciitis' first, but it is often not the actual cause. The pain may originate from the sole itself or from other conditions such as gout, diabetes, vascular abnormalities, or spinal diseases. Together with Professor Jeong Deok-hwan of the Department of Orthopedics at Gangdong Kyung Hee University Hospital, we take a closer look at diseases according to the location of foot sole pain.

Jung Deok-hwan, Orthopedic Surgery Department, Gangdong Kyung Hee University Hospital. [Image source=Gangdong Kyung Hee University Hospital]

◆Pain at the back of the sole that worsens in the morning: 'Plantar Fasciitis' = Plantar fasciitis occurs when the plantar fascia, which is attached in an arch shape from the toes to the heel on the sole, is continuously irritated, causing some degenerative and inflammatory changes. Plantar fascia irritation can occur due to congenital abnormalities, but it usually results from excessive use of the foot. According to the Health Insurance Review and Assessment Service, the number of plantar fasciitis patients increased by about 77% over 10 years, from 153,285 in 2013 to 271,850 in 2022. Symptoms include pain at the back of the sole, the center of the heel, or slightly inward, and if the pain worsens when starting to walk or in the morning, plantar fasciitis can be suspected. Professor Jeong Deok-hwan explained, "The plantar fascia, which contracts during sleep at night, tears and stretches again when walking in the morning," adding, "Therefore, plantar fasciitis causes the most severe pain when getting up and starting to walk in the morning."

Plantar fasciitis is often confused with other diseases. Middle-aged women sometimes mistake it for a stress fracture of the heel bone or confuse it with atrophy of the plantar fat pad. Since accurate diagnosis is often difficult with just physical examination and medical history, detailed tests such as MRI may be performed if necessary. Once diagnosed with plantar fasciitis, conservative treatment is first implemented. Most patients improve with lifestyle changes and shoe replacement. The most effective treatment is stretching. Stretching that stimulates the heel, calf, and arch of the sole is helpful.

◆Big toe bending outward: 'Bunion (Muji Oebanjeung)' = If there is pain at the front part of the sole where the big toe meets the sole, it may be a bunion. Bunion is a condition where the big toe bends outward due to genetic factors or acquired causes such as wearing uncomfortable shoes. When the balance of the tendons and ligaments on the inside and outside holding the big toe is disrupted, deformation begins and continues once it occurs. Even if those who develop it later switch to comfortable shoes, the deformation progresses. Conservative treatment includes wearing comfortable shoes with a wide toe box and low heels. However, if pain occurs when the protruding part touches the shoe, or if there is deformation of the second and third toe joints, severe calluses on the sole causing discomfort, or a risk of arthritis, surgery is performed.

◆Pain and swelling under the big toe: 'Sesamoiditis' = If the area under the big toe hurts when walking and appears swollen even at rest, it may be sesamoiditis. It is more likely to occur in people with high arches (pes cavus), those who suddenly increase exercise, or those who wear high heels. The sesamoid bones bear the most pressure when stepping, and if the arch is high, the pressure on the sesamoid bones increases. When the pressure on the sesamoid bones intensifies, pain and swelling occur in that area.

◆Pain and numbness at the front of the sole: 'Morton's Neuroma (Jigan Sin-gyeong-jong)' = Foot sole pain can also be caused by nerve problems. There are nerve junctions between the third and fourth toes or between the second and third toes on the sole. When these nerves thicken due to continuous irritation, causing pain, it is called Morton's neuroma. Pain occurs when the sole is pressed or when stepping forward compresses the nerve. Symptoms include pain and numbness at the front of the sole. Professor Jeong Deok-hwan said, "Morton's neuroma is as common as plantar fasciitis," adding, "The pain is caused by nerve swelling, not a true tumor."

Foot sole pain can also arise from causes other than problems with the foot itself. For example, gout causes severe pain and swelling at the junction of the big toe and sole, similar to sesamoiditis. Therefore, there are steps to follow to accurately identify the cause of foot sole pain.

First, it is advisable to rest for a few days after the pain occurs to check if it is due to recent overuse or strain. Next, it is necessary to determine whether the foot sole pain is caused by systemic diseases. If it is due to other conditions such as diabetes, gout, vascular diseases, or neurological disorders, conservative treatment for foot sole pain will be ineffective. Finally, it is important to distinguish the exact location of the pain on the sole. This is because conservative treatments differ for each condition, from plantar fasciitis to Morton's neuroma.

Professor Jeong Deok-hwan said, "Many patients who visit with foot sole pain actually have systemic diseases as the cause rather than foot problems," adding, "Confirming the absence of other diseases helps to more accurately identify the cause of foot sole pain, provide precise conservative treatment, and also relieve patients' anxiety."