What the heck is a sesamoid? Or what’s that white circle on my x-ray by my big toe joint? These are probably the two most common questions asked in my office when people are diagnosed with a sesamoid injury.
A sesamoid bone is a bone embedded in a tendon. In your foot, the sesamoids are two M&M shaped bones located in the ball of your foot, beneath the great toe joint. These act as pulley mechanism for the tendons and help you push off with your big toe when walking or running. They also serve as the weightbearing surface for the first metatarsal absorbing the impact placed on the ball of the foot when walking, running and jumping.
Sesamoid injuries which can involve the bones, tendons and/or surrounding tissue in the joint are often associated with activities requiring increased pressure on the ball the foot, such as running, basketball, football, golf, tennis and ballet. In addition, people with high arches are risk for developing sesamoid problems. Frequently wearing high heel shoes can also be contributing factor.
There are three different kinds of sesamoid injuries in your foot.
Turf toe: Turf toe is an injury of the soft tissue around the big toe joint. It usually occurs when the big toe joint is extended beyond its normal range of motion or hyperflexed. This is very common in football, soccer and tennis. This is a completely soft tissue injury but can involve the cartilage of the joint.
Fracture: A sesamoid fracture occurs when a sesamoid bone breaks. This can be either acute or chronic. An acute fracture is caused by a direct blow and you usually will have immediate pain and swelling. A chronic fracture is usually a stress fracture or hairline break caused by repetitive stress. These are common in runners, golfers and ballet dancers. A chronic stress fracture of the sesamoid causes a long-standing pain in the ball the foot and is aggravated by activity and relieved with rest.
Sesamoiditis:Sesamoiditis is basically an overuse injury with chronic inflammation, but without fracture. Sesamoiditis is actually tendinitis of a tendon that has a sesamoid in it. Sesamoiditis is caused by increased pressure to the sesamoids and is usually a dull, long-standing pain beneath the big toe joint. This pain usually comes and goes.
Diagnosis of sesamoid injuries
In order to diagnose a sesamoid injury, physical exam and imaging is necessary. There is pain upon palpation of the ball of the foot and there maybe swelling and bruising. X-rays are taken focusing on the great toe joint. Often times a stress fracture will not be revealed on a plain film x-ray and an MRI, bone scan or orthopedic ultrasound maybe more helpful.
Conservative treatment for sesamoid injuries may include one of the following options depending on the type of injury and the severity.
Sesamoid injuries are unfortunate because they often take a long time to heal and have long-term consequences. Nonunion of sesamoid fractures (meaning they either take a long time to heal or never heal) are not uncommon due to the decreased blood supply to the sesamoid, because it is within a tendon. Bone stimulator’s can be helpful to try to avoid surgery. Even surgery is not an awesome option because it can destabilize the joint; and it’s difficult for some people to get back to running, jumping and playing with the other kids on a regular basis. If you suspect that you have a sesamoid injury please seek treatment early, because long-term consequences occur with prolonged inflammation causing joint dysfunction.