Your sesamoids are two small bones under the base of your big toe that help provide leverage for normal toe biomechanics. Every time the ball of your foot strikes the ground, weight is transferred through your sesamoids. Functioning like your kneecap, your sesamoids enable your toe joint to bend with more strength and stability. Overuse of your big toe typically causes a sesamoid disorder. Runners, cyclists, and people who abruptly increase their training regimen are at an increased risk of suffering a sesamoid disorder if they overuse the muscles and tendons that bend their big toes.
Loss of blood supply in your sesamoids is rare, but it can be caused whenever damage in the tissue surrounding the sesamoids decreases their blood supply. If the blood supply to these small bones is compromised, a diagnosis known as Avascular necrosis (AVN) can ensue. AVN of the sesamoid is pathology of the medial or lateral hallucal sesamoid resulting in pain under the first metatarsophalangeal joint often presenting in young female athletes. There is overlap of stress fracture, nonunion, and AVN that makes defining the diagnosis difficult but the treatment and outcomes are similar. Often advanced imaging such as CT scan, bone scan or MRI is necessary to make the exact diagnosis. Nonoperative modalities are designed to offload the sesamoid. Boot immobilization and a non-weightbearing protocol can be effective in the acute sages of deformity. Use of a bone stimulator daily can help physiological healing of the bones. Transition into a special orthotic with a cutout modification for these bones can be very effective to reduce symptoms and allow for pain-free gait. AVN that is advanced can lead to fragmentation and atrophy of the sesamoids. The only operative treatment used for AVN of the sesamoid is excision of the involved bone, which results most commonly in complete patient satisfaction. Please schedule a timely evaluation if you feel sharp pain under the great toe to determine if your sesamoids are the cause!