Sesamoiditis

Sesamoiditis refers to overuse injury involving chronic inflammation of the sesamoid bones and the tendons involved with those bones. These tendons surround small disc-shaped bones called the sesamoids, found in the ball of your foot. Sesamoiditis is caused by increased pressure on the sesamoid bones. Often, sesamoiditis is associated with a dull, longstanding pain beneath the big toe joint. The pain comes and goes, usually occurring with certain shoes or certain activities.

A sesamoid is a bone embedded in a tendon. Sesamoids are found in several joints in your body. In the normal foot, the sesamoids are two pea-shaped bones located in the ball of the foot, beneath the big toe joint. The sesamoid bones help to strengthen the tendons, assisting with running and with keeping the big toe joint stable (1st metatarsophalangeal joint). Acting as a pulley for tendons, the sesamoids help the big toe move normally and provide leverage when the big toe pushes off during walking and running. The sesamoids also serve as a weightbearing surface for the first metatarsal bone (the long bone connected to the big toe), absorbing the weight placed on the ball of the foot when walking, running and jumping.

The pain of sesamoiditis is beneath the head of the 1st metatarsal (the big toe), with or without inflammation or fracture. The pain is usually made worse by walking and may be worse when wearing flexible thin-soled or high-heeled shoes. Occasionally, inflammation occurs, causing mild warmth and swelling or occasionally redness that may extend medially and appear to involve the 1st metatarsophalangeal joint. Sesamoid fracture can also cause pain, moderate swelling, and possibly inflammation.

Sesamoiditis diagnosis is usually clinical.

Sesamoiditis is a relatively common cause of foot pain and is treated with modification of footwear and orthotics, anti-inflammatory medication, rest and ice.

Sometimes, the sesamoid bones can get broken usually a stress or hairline fracture – in this case, you may need to stay off your foot (non-weight-bearing) to rest the sesamoid bone and allow it to heal. The treatment for a broken sesamoid bone will vary depending on you and how severe the fracture is, however in some cases crutches are needed for 6 weeks.

It’s helpful to see your family doctor as they can examine your foot and decide if you need X-rays to look for other causes of your foot pain. They can also refer you to an orthotist, physiotherapist or an orthopaedic surgeon for specialised treatment.

Simply not wearing the shoes that cause pain may be sufficient. If symptoms of sesamoiditis persist, shoes with a thick sole and orthotics are prescribed and help by reducing sesamoid pressure. If fracture without displacement is present, conservative therapy may be sufficient and may also involve immobilization of the joint with the use of a flat, rigid, surgical shoe.

Nonsteroidal anti-inflammatory drugs (NSAIDs) and injections of a corticosteroid/local anesthetic solution can be helpful. Although surgical removal of the sesamoid may help in recalcitrant cases, it is controversial because of the potential for disturbing biomechanics and mobility of the foot. If inflammation is present, treatment includes conservative measures plus local infiltration of a corticosteroid/anesthetic solution to help reduce symptoms.

Sesamoiditis key points

• Dancers, joggers, and people who have high-arched feet, wear high heels, or have bunions can develop pain at the sesamoids beneath the head of the 1st metatarsal.
• Pain is worse when weight-bearing, particularly when wearing certain shoes.
• Diagnosis based on clinical findings; exclude infection with synovial fluid analysis when swelling is present and exclude suspected fracture with x-rays.
• Prescribe new, thick-soled shoes, orthotics that decrease pressure on the sesamoids, or both.

Figure 1. Sesamoid bones foot

Sesamoiditis causes

Sesamoid injuries can involve the bones, tendons and/or surrounding tissue in the joint. They are often associated with activities requiring increased pressure on the ball of the foot, such as running, basketball, football, golf, tennis and ballet. In addition, people with high arches are at risk for developing sesamoid problems. Frequent wearing of high-heeled shoes can also be a contributing factor.

Sesamoiditis is a common cause of metatarsalgia. The 2 semilunar-shaped sesamoid bones aid the foot in locomotion. The medial bone is the tibial sesamoid, and the lateral bone is the fibular sesamoid. Direct trauma or positional change of the sesamoids due to alterations in foot structure (eg, lateral displacement of a sesamoid due to lateral deviation of the great toe) can make the sesamoids painful. Sesamoiditis is particularly common among dancers, joggers, and people who have high-arched feet or wear high heels. Many people with bunions have tibial sesamoiditis.

Most bones in the human body are connected to each other at joints. But there are a few bones that are not connected to any other bone. Instead, they are connected only to tendons or are embedded in muscle. These are the sesamoids. The kneecap (patella) is the largest sesamoid. Two other very small sesamoids (about the size of a kernel of corn) are found in the underside of the forefoot near the great toe, one on the outer side of the foot and the other closer to the middle of the foot.

Sesamoids act like pulleys. They provide a smooth surface over which the tendons slide, thus increasing the ability of the tendons to transmit muscle forces. The sesamoids in the forefoot also assist with weightbearing and help elevate the bones of the great toe. Like other bones, sesamoids can break (fracture). Additionally, the tendons surrounding the sesamoids can become irritated or inflamed. This is called sesamoiditis and is a form of tendinitis. It is common among ballet dancers, runners and baseball catchers.

Sesamoiditis symptoms

Most patients experiencing sesamoiditis identify the following symptoms:

• Sharp stabbing pain that is focused under your big toe on the ball of your foot. With sesamoiditis, pain may develop gradually; with a fracture, pain will be immediate.
• Swelling and bruising may or may not be present.
• Inability to put body weight on the ball of your foot.
• The pain causes you to walk differently.
• Pain in the area even when not standing.
• The pain is made worse with activity.
• You may experience difficulty and pain in bending and straightening the big toe.

Depending on severity, these symptoms may eventually resolve with rest. However, when patients return to activity there is a high rate of reoccurrence. Left untreated, sesamoiditis can progress to stress fractures, leading to long layoffs from sport or activity.

Sesamoiditis diagnosis

During the examination, your doctor will look for tenderness at the sesamoid bones. Your doctor may manipulate the bone slightly or ask you to bend and straighten the toe. He or she may also bend the great toe up toward the top of the foot to see if the pain intensifies. With the foot and 1st (big) toe dorsiflexed, your doctor inspects the metatarsal head and palpates each sesamoid. Tenderness is localized to a sesamoid, usually the tibial sesamoid. Hyperkeratotic tissue may indicate that a wart or discrete callus is causing pain.

Your physician will request X-rays of the forefoot to ensure a proper diagnosis and to exclude fracture, osteoarthritis, or displacement. In many people, the sesamoid bone nearer the center of the foot (the medial sesamoid) has two parts (bipartite). Sesamoids separated by cartilage or fibrous tissue (bipartite sesamoids) may appear fractured on x-rays. Because the edges of a bipartite medial sesamoid are generally smooth, and the edges of a fractured sesamoid are generally jagged, an X-ray is useful in making an appropriate diagnosis. Your physician may also request X-rays of the other foot to compare the bone structure. If the X-rays appear normal, the physician may request a bone scan or an MRI may also be done.

If inflammation causes circumferential swelling around the 1st big to joint (metatarsophalangeal joint), arthrocentesis is usually indicated to exclude gout and infectious arthritis.

Sesamoiditis treatment

Sesamoiditis treatment is generally nonoperative. However, if conservative measures fail, your physician may recommend surgery to remove the sesamoid bone.

Sesamoiditis treatment include:

• Stop the activity causing the pain.
• Take aspirin or ibuprofen to relieve the pain.
• Rest and ice the sole of your feet. Do not apply ice directly to the skin, but use an ice pack or wrap the ice in a towel.
• Wear soft-soled, low-heeled shoes. Stiff-soled shoes like clogs may also be comfortable.
• Use a felt cushioning pad to relieve stress.
• Return to activity gradually, and continue to wear a cushioning pad of dense foam rubber under the sesamoids to support them. Avoid activities that put your weight on the balls of the feet.
• Tape the great toe so that it remains bent slightly downward (plantar flexion).
• Your doctor may recommend an injection of a steroid medication to reduce swelling.
• If symptoms persist, you may need to wear a removable short leg fracture brace for 4 to 6 weeks.

Fracture of the sesamoid

• You will need to wear a stiff-soled shoe or a short, leg-fracture brace.
• Your physician may tape the joint to limit movement of the great toe.
• You may have to wear a J-shaped pad around the area of the sesamoid to relieve pressure as the fracture heals.
• Pain relievers such as aspirin or ibuprofen may be recommended.
• It may take several months for the discomfort to subside.
• Cushioning pads or other orthotic devices are often helpful as the fracture heals.