A sesamoid is a bone embedded in a tendon. Sesamoids are found in several joints in the body. The largest sesamoid bone in the body is the patella, or ‘knee cap’. In the foot, the sesamoids are two pea-shaped bones located in the ball of the foot, beneath the big toe joint.
Acting as a pulley for tendons, the sesamoids help the big toe move normally and provide greater ‘push off’ strength during walking and running. The sesamoids also serve as a weight-bearing 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.
Injuries to the sesamoids can involve the bones, tendons, and/or surrounding tissue in the joint—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. Frequently wearing high-heeled shoes can also be a contributing factor.
There are three types of sesamoid injuries in the foot:
Turf toe. This is an injury of the soft tissue surrounding the big toe joint. It usually occurs when the big toe joint is extended beyond its normal range. Turf toe causes immediate, sharp pain and swelling. It usually affects the entire big toe joint and limits the motion of the toe. Sometimes a “pop” is felt at the moment of injury.
Fracture. A fracture (break) in a sesamoid bone can be either acute or chronic.
- An acute fracture is caused by trauma—a direct blow or impact to the bone. An acute sesamoid fracture produces immediate pain and swelling at the site of the break, but usually does not affect the entire big toe joint.
- A chronic fracture is a stress fracture—a hairline break usually caused by repetitive stress or overuse. A chronic sesamoid fracture produces longstanding pain in the ball of the foot beneath the big toe joint. The pain, which tends to come and go, generally is aggravated with activity and relieved with rest.
Sesamoiditis. This is an overuse injury involving chronic inflammation of the sesamoid bones and the tendons involved with those bones. Sesamoiditis is caused by increased pressure to the sesamoids. Often, sesamoiditis is associated with a dull, longstanding pain beneath the big toe joint. The pain comes and goes, usually occurring with certain shoes
Diagnosis a sesamoid injury involves a good history and standard orthopaedic examination of the foot, focusing on the big toe joint. The surgeon will press on the big toe, move it up and down, and may assess the patient’s walking and evaluate the wear pattern on the patient’s shoes. X-rays are ordered, and in some cases, additional imaging studies—such as a bone scan or MRI—may also be needed.
Non-surgical treatment for sesamoid injuries of the foot may include one or more of the following options, depending on the type of injury and degree of severity:
- Padding, strapping, or taping. A pad may be placed in the shoe to cushion the inflamed sesamoid area, or the toe may be taped or strapped to relieve that area of tension.
- Immobilization and non-weightbearing. The foot may be placed in a cast or removable walking cast
- Oral medications. Nonsteroidal anti-inflammatory drugs (NSAIDs) are often helpful in reducing the pain and inflammation.
- Physical therapy. Sometimes the rehabilitation period following immobilization includes physical therapy, such as exercises (range-of-motion, strengthening, and conditioning) and ultrasound therapy.
- Orthotic devices. Inserts that fit into the shoe may be prescribed for long-term treatment of sesamoiditis to remove pressure placed on the ball of the foot.
Surgery is generally reserved for the most severe sesamoid injuries in which a complete tendon tear has occurred or where the sesamoid was fractured and completely displaced, particularly in an athlete. Other indications include patients who fail to respond to non-surgical treatment over a long period of time. Surgery can involve repairing tendons or the joint capsule, or, excising or shaving the sesamoid.