Pain on the bottom of the foot at the base of the great toe is characteristic of sesamoiditis. Symptoms usually originate from excessive, repetitive loading to this area of the foot. Often patients will have a higher arched foot. Treatment involves avoiding activities that aggravate symptoms; inserts that offload the involved area; comfort shoes; anti-inflammatory medications if tolerated; and possibly corticosteroid injections. Patience is required as it often takes time to successfully manage the symptoms of sesamoiditis.
Sesamoiditis is characterized by pain on the bottom of the foot along the base of the great toe (Figure 1). Sesamoiditis is a general term for painful inflammatory symptoms associated with either one or both of the seasmoid bones, which are located beneath the first metatarsal head as it forms part of the great toe. Symptoms can originate from a variety of pathologies that affect the sesamoid bones, but discomfort is usually associated with excessive loading of this area of the foot (Figure 2). Patients who present with this problem will often have a history of some recent event or series of events which resulted in increased stress to this area. They often describe a recent increase in repetitive weight-bearing activities that suddenly overload this joint, and a large percentage of these patients will recall ramping up some form of athletics, a sudden change in shoe wear, an increased exercise or training regimen, or, especially, an increase in their running training when queried in the physician’s office. Rarely is a major acute traumatic event the cause for the problem, although it certainly can be. Usually these patients have unwittingly subjected themselves to gradually increased or changed activity levels. Pain from this area is usually described as sharp and severe at times, and most patients can pinpoint the location with one finger (ie, the sesamoid itself). The discomfort they experience often leads to a restriction of activities, changes in shoe wear, and possibly even a limp. Patients will often find it uncomfortable to walk with barefeet or on hard surfaces. The actual symptoms can stem from a variety of causes, including: local overload of the soft-tissues in this area with resulting chronic tissue injury, stress fracture of one of the sesamoids or a sesamoid which never heals (nonunion) after injury, and cartilage damage (arthritis) between the sesamoid and the first metatarsal head. Another common injury to the great toe area is a “turf toe” injury, which is usually identified after acute trauma, and can also present with pain on the bottom of the ball of the foot beneath the big toe.
The most common forms of sesamoiditis, by far, present with a slow, steady onset of patterned pain beneath an otherwise normal looking big toe, which is worse with weightbearing and better with offloading activity. Patients can almost always point right to the site of discomfort, which is directly beneath one, or both, of the sesamoids. These structures sit on the inside (medial) and outside (lateral) part of the base of the great toe (1st metatarsophalangeal joint, beneath the 1st metatarsal head) —which these bones are designed to support. Patients are typically tender to palpation directly beneath one or both of the sesamoids, at the plantar base of the big toe.
It is also common for patients who suffer from sesamoiditis to have high arched feet, since this type of foot predisposes to this problem by concentrating excess load underneath the great toe, along the ball of the foot (Figure 2). Range of motion of the great toe is often normal, although there may be pain at the extremes of motion, particularly when the toe is bent upwards (dorsiflexed), because this puts axial strain on the tissues that attach to the sesamoids below (Figure 3). Marked loss of motion of the big toe, or pain on the top of the great toe is more consistent with a diagnosis of hallux rigidus and progressive arthritis.
Plain x-rays of the foot are always indicated to both help diagnose this problem, as well as rule out other potential problems in this region of the foot. They permit proper assessment of the entire forefoot region, and, in particular, are designed to look at the two sesamoids and how they sit anatomically beneath the great toe joint (1st metatarsophalangeal joint). Fractures, subluxations, dislocations, osteochondrosis, or avascular necrosis affecting the sesamoid(s) can usually be diagnosed on these plain x-rays. Sometimes people are born with sesamoids that are naturally in several pieces, called bipartite (two pieces) or multipartite (many pieces) sesamoids. While the normal sesamoid is a singular roundish bone the size of a pea, these types almost look like the bone has been broken. They are simply a normal variant, however, and need to be carefully distinguished from true fractures. Bipartite or multipartite sesamoids are common and, while they can cause pain in certain circumstances, they are usually asymptomatic. The best way to make this diagnosis is to get x-rays of the opposite side, since bipartitie sesamoids are often bilateral whereas a true fracture is usually not.
When an accurate diagnosis cannot be made and certain possible problems still cannot be ruled out, an MRI or even a CT scan can usually accurately differentiate between these various pathologies. MRI is probably the most preferred test, but both can be very helpful and may need to be ordered in order to assess whether there is evidence of joint damage (ex. arthritis) in the great toe, a capsular injury (turf toe), an areas of dead bone (avascular disease or osteochondrosis), or a stress fracture of one of the sesamoids.
While sesamoiditis can be a chronic, aggravating condition that is recalcitrant to treatment, fortunately most cases can be effectively treated with various forms of offloading and inflammation control. Management first requires ensuring that the symptoms are not caused by a fracture or nonunion of the sesamoid, or by an injury to the joint capsule of the great toe known as turf toe, however, since these conditions are usually treated somewhat differently and often respond differently to care. Straightforward cases of uncomplicated sesamoiditis are typically treated by off-loading the area, modifying activities in the short-term to decrease repetitive injury to the sesamoids, and possibly taking anti-inflammatory medication or icing to improve symptoms. Specific treatments include: