Irritation, imbalance, or fracture of two small bones—sesamoids—near your big toe is a forefoot problem that may cause pain in some individuals. These two sesamoid bones, located on the underside of your foot, directly below your first metatarsal bone, are approximately the size of corn kernels and act like pulleys. Your sesamoid bones function like a kneecap—another type of sesamoid bone—for your big toe joint.
Your sesamoid bones provide a smooth surface over which your toe flexor tendons slide, and they improve the ability of these tendons to transfer force from your lower leg muscles to the proximal phalynx, or bone, of your big toe. The sesamoid bones under the base of your big toe also help bear some of your body weight, reducing the stress on other forefoot structures. Sesamoid bones, like the other bones in your 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 your first metatarsal bone—the long, thin bone that connects your ankle bones to your big toe—accommodate your sesamoid bones. Your sesamoid bones may move out of their special grooves and begin wearing away cartilage and bone if you have flat feet, flexible feet, or bunions, or if your feet have undergone some of the various anatomical changes that can result from long-term conventional footwear use. Feet that are imbalanced or too flexible may place excessive pressure on your sesamoid bones and cause them to fracture.
Sesamoiditis may cause you to limp or walk on the outside aspect of your foot to help remove pressure from your painful involved area. Gait changes are a problematic compensation for this health problem, as they may cause pain and disability in one of your other joints, such as your knee, hip, or low back joints or some other part of your foot. You should always seek treatment as soon as possible if you suspect you have sesamoiditis.
Causes and Symptoms
Sesamoiditis is an overuse injury that involves chronic, or long-term, inflammation of your sesamoid bones and the tendons that act on these bones. In most cases, a sudden and excessive upward bending force on your big toe causes sesamoiditis, although wearing high heels and experiencing certain types of foot trauma may also contribute to your sesamoiditis.
Conventional footwear plays an important role in aggravating your sesamoids and their surrounding structures. Shoes with tapered toe boxes and toe spring can cause the sesamoids to become dislocated, causing dysfunction. (Click here for a video demonstration of this phenomenon). When your hallux, or big toe, is properly aligned with your first metatarsal bone, your sesamoids are also properly aligned and function as they’re intended to.
Sesamoiditis commonly involves a dull pain under your big toe joint that fails to resolve over time. Sesamoiditis-related pain is usually intermittent, or comes and goes, 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:
- Pain focused under your big toe, on the ball of your foot
- Pain in your affected area that develops gradually
- Swelling and bruising
- Impaired ability to bend or straighten your big toe
Injured or inflamed sesamoid bones can be difficult to heal, as you put almost continuous pressure on these structures every time you stand or walk. Conservative care methods may be helpful in resolving your sesamoiditis. Conservative treatment techniques include:
- Shoe therapy: Footwear that allows proper toe splay can help. For footwear suggestions, see our list of recommended shoes. Toe splay can be enabled with our toe spacing device, Correct Toes.
- Immobilization: Your affected foot may be placed in a cast or removable walking cast to help rest your injured or irritated tissues. Crutches can help reduce the amount of force on your sesamoids.
- Taping or strapping: Your involved toe may be taped or strapped to help reduce tension on your sesamoid bones.
- Padding: A special pad may be placed inside your shoe to help cushion your sesamoid bones. A metatarsal pad helps return the fat pad in the ball of your foot to a place where it will protect your sesamoids.
- Physical therapy (PT): PT is an important treatment measure for this health problem, 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 treatment measures for treating your sesamoiditis and may be necessary in some individuals. Your doctor may recommend surgery, including sesamoid bone removal, if conservative care measures fail to resolve your health problem.
-Dr. Ray McClanahan, DPM, NW Foot & Ankle