There are two bones on the ball of the foot underneath the 1st metatarsal, behind the big toe joint. These bones are called sesamoids. They act to take on the pressure from the ground as one pushes off the ground when walking. This area of the foot takes on most of the pressure and forces from the ground and needs the added support from these bones. They are incorporated in the flexor tendon of the big toe (the tendon that flexes the tendon down). Many times one or both of these bones can become injured and cause pain. This can lead to inflammation and disruption of the bones called sesamoiditis.
Most patients will describe a deep achy and sharp pain in the ball of the foot behind the big toe with every step taken. It will be difficult to perform many weight bearing activities. Most patients do not have pain when at rest.
|X-ray showing the two sesamoids underneath and behind the big toe joint.|
Injury is the main cause of sesamoiditis. This is usually from overuse and extra pressure through the area. It can be caused by hyperextension injury of the big toe as well. Often times a stress fracture or full fracture can occur in the bone from overuse or a fall. These bones have a very limited blood supply and are difficult to heal when not treated early. High heels are often a contributing factor because they stretch the flexor tendon and place the sesamoids in a more vulnerable and weight bearing position under the foot. Without treatment, every step after the initial injury will cause continued injury to the bone. This can lead to chronic pain and inflammation of the bone. Continued aggravation of the bone or extensive fracture can lead to the bone loosing blood supply and dying (avascular necrosis).
Clinical examination consists of how much pain there is on palpation of the bone. This will also help identify which of the two bones or if both are involved. Plain x-ray evaluation is important to evaluate the extent of the injury to the bones. In some cases an MRI of the foot is needed to evaluate if the bone is viable or if it has lost its blood supply (avascular necrosis).
|X-ray showing fractured sesamoid.|
Conservative treatment consists of taking pressure off the foot in the area of the sesamoids. Initially the doctor may recommend a period of immobility of the foot by placing the foot in a special boot to take all the weight off the bones. Some patients will need to be on crutches in acute injuries. Patients will need to rest the foot and use proper cushioned shoes. Any exercise program should be delayed during the healing process. Anti-inflammatory can also be used to reduce the inflammation in the bones. Physical therapy can be used to bring increased circulation to the area and limit inflammation and pain over long the long term. Functional orthotics with special accommodation is used to take the pressure off the ball of the foot. In some cases, cortisone injections can be used to reduce the inflammation around the bones. Sesamoiditis can usually be controlled and improved with conservative treatment. Surgery is infrequently needed to treat this condition. Surgery is indicated when conservative treatments fail. Surgery usually involves removal of part or all of the sesamoid.
|X-ray showing removed sesamoid.|