Sesamoiditis: Irritation of the sesamoid bones.
Irritation, imbalance, or fracture of two small bones—sesamoids—near the big toe is a forefoot problem that may cause pain in some individuals. These two sesamoid bones, located on the underside of the foot, directly below the first metatarsal bone—the long, thin bone that’s positioned between the ankle bones and the big toe—are approximately the size of corn kernels and act like pulleys. The sesamoid bones function like a kneecap (another type of sesamoid bone) for the big toe joint.
The sesamoid bones provide a smooth surface over which the toe flexor tendons slide, and they improve the ability of these tendons to transfer force from the lower leg muscles to the proximal phalynx, or bone, of the big toe. The sesamoid bones under the base of the big toe also help bear some of the bodyweight, reducing the stress on other forefoot structures. Sesamoid bones, like other bones in the body, can break, and the tendons that pass over these structures can cause soft tissue irritation and inflammation. Sesamoiditis is most commonly seen in runners, baseball catchers, and ballet dancers.
Special grooves on the bottom of the first metatarsal bone accommodate the sesamoid bones. The sesamoid bones may move out of their special grooves and begin wearing away cartilage and bone in individuals with flat feet, flexible feet, or bunions, or if the feet have undergone some of the other anatomical changes that can result from long-term conventional footwear use. Feet that are imbalanced or too flexible may place excessive pressure on the sesamoid bones and cause them to fracture.
Sesamoiditis may cause a person to limp or walk on the outside aspect of his or her foot to help remove pressure from the painful area. Gait changes are a problematic compensation for this health problem, as they may cause pain and disability in one of the other lower extremity joints, such as the knee or hip.
Signs & Symptoms
Sesamoiditis usually involves a dull pain under the big toe joint that fails to resolve over time. Sesamoiditis-related pain is usually intermittent and may be worse when wearing certain shoes or participating in certain activities.
Some of the most common signs and symptoms associated with sesamoiditis include:
- Swelling and bruising
- Impaired ability to bend or straighten the big toe
- Pain in the affected area that develops gradually
- Pain focused under the big toe, on the ball of the foot
Sesamoiditis is an overuse injury that involves chronic, or long-term, inflammation of the sesamoid bones and the tendons that act on these bones. In some cases, a sudden and excessive upward bending force on the big toe may cause sesamoiditis. Wearing high heels and experiencing certain types of foot trauma may also lead to sesamoiditis.
Conventional footwear plays a prominent role in aggravating the sesamoids and their surrounding structures. Shoes with tapering toe boxes and toe spring can cause the sesamoids to become dislocated, causing dysfunction (click here for a video demonstration of this phenomenon). When the hallux, or big toe, is properly aligned with the first metatarsal bone, the sesamoids are also properly aligned in their grooves and function as nature intended.
Injured or inflamed sesamoid bones can take a long time to heal, as they bear almost continuous pressure with standing or walking. Conservative care methods that may be helpful in resolving sesamoiditis include:
Shoe Therapy: Adopting men’s and women’s footwear that allows proper toe splay—and therefore a more even distribution of bodyweight across the forefoot—can help.
Correct Toes: Wearing Correct Toes toe spacers helps enable optimal toe splay and bodyweight distribution across the forefoot.
Immobilization: Temporarily placing the affected foot in a conventional cast or a removable walking cast can help the injured or irritated tissues rest and recover. Crutches can help reduce the amount of force on the sesamoids and may be helpful in some cases.
Taping or Strapping: Taping or strapping the involved toe may help reduce tension on the sesamoid bones.
Padding: Adding a special pad inside the shoe can help cushion the sesamoid bones. This pad, called a metatarsal pad, helps return the forefoot fat pad to a position that supports and protects the sesamoids.
Physical Therapy (PT): PT is an important treatment measure for sesamoiditis, especially following immobilization. Range-of-motion exercises and ultrasound therapy are among the most commonly used PT modalities for this health purpose.
Anti-inflammatory medication, cortisone injections, and certain types of surgery are more aggressive approaches for treating sesamoiditis, though they may be necessary in some individuals. A foot care professional may recommend surgery, including sesamoid bone removal, if conservative care measures fail to resolve this health problem.