INTRODUCTION — Sesamoid bones are found embedded in the tendons near many joints. They function to protect the tendon and enhance its mechanical effect. Most sesamoid bones are small and resemble grains of sesame; the meaning of the word's greek root is "shaped like a sesame." The two largest sesamoids in the foot reside near the first metatarsophalangeal (MTP) joint and are susceptible to fracture.
This topic review will discuss sesamoid fractures of the foot in adults. Other foot fractures are discussed elsewhere. (See "Toe fractures in adults" and "Stress fractures of the metatarsal shaft" and "Metatarsal shaft fractures".)
CLINICAL ANATOMY — There are two relatively large sesamoids adjacent to the first metatarsophalangeal (MTP) joint (image 1). Injuries to these sesamoids comprise 12 percent of injuries to the great toe complex . Small sesamoids are occasionally seen elsewhere in the foot, most notably beneath the fifth MTP joint (image 2A-C). These smaller sesamoids are rarely of clinical significance (figure 1A-C).
The sesamoids of the first MTP joint are embedded within the tendon of the flexor hallucis brevis and allow for increased dorsiflexion of the MTP. They are also involved in shock absorption, reduction of friction, and protection of tendons . The medial (ie, tibial) sesamoid is thought to bear greater force during the normal gait cycle and is more commonly fractured from either direct force or cumulative stress [3,4]. The lateral (ie, fibular) sesamoid is injured much less often.
It is important to recognize that sesamoids are sometimes "partite," ie, one sesamoid is made up of two or three separate pieces (image 3). A study of 35 cadaveric feet found the incidence of partite sesamoids to be 11.1 percent . This finding is comparable to other studies. Partite sesamoids are frequently bilateral. Hence, bilateral comparison views are sometimes helpful in distinguishing a partite from a fractured sesamoid. (See 'Partite sesamoids' below.)
EPIDEMIOLOGY AND MECHANISM OF INJURY — Direct blows and forced hyperdorsiflexion can lead to acute sesamoid fractures. However, stress fractures are more common  (see "Overview of stress fractures").
One study found sesamoid injuries occur most commonly in long distance running and in sports that require rapid acceleration and deceleration, such as tennis, racquetball, football, soccer, and volleyball . Dancers are also at risk [6,7]. A five-year retrospective review of 58 patients between the ages of 9 and 21 with sesamoid fractures found that these injuries occurred far more often in girls . Dance, running, and gymnastics were the most common associated activities. A chart review involving 683 young athletes with sesamoid injury found that while sesamoiditis was the most common diagnosis, 16.6 percent had a sesamoid stress fracture and 7.3 percent had an acute sesamoid fracture .
CLINICAL PRESENTATION AND EXAMINATION — Patients with a sesamoid stress fracture usually complain of poorly localized pain around the first metatarsophalangeal (MTP) joint for several weeks. Swelling is not generally seen until the injury has progressed. Erythema is typically absent.
Often, the patient is unable to localize the pain until the examiner directly palpates the injured sesamoid. Passive dorsiflexion of the first MTP joint can elicit pain in sesamoid fractures. If this movement does not produce pain and a fracture is suspected, some suggest holding the MTP in maximal dorsiflexion and deeply palpating the suspected area, while the patient tries to plantar flex the great toe .
A presumptive diagnosis of sesamoiditis is made if the following conditions are met :
●Focal pain is present over a sesamoid
●Pain with passive dorsiflexion of the MTP is present
●No swelling or redness is present
●Radiographs show no fracture is present
However, if rest from activity and shoe orthoses do not resolve pain in two to four weeks, other diagnoses, such as a subtle sesamoid fracture, should be entertained.
Approach to imaging — Standard anteroposterior (AP), oblique, and lateral views of the foot are generally sufficient to demonstrate sesamoid fractures (image 4A-B). Dedicated sesamoid views, such as lateral oblique (which shows the fibular sesamoid), medial oblique (which shows the tibial sesamoid), and axial (image 5) views can be obtained if standard plain radiographs are negative but there remains a high index of suspicion.
Fractures of the sesamoids are usually transverse (image 4A-B) . Like scaphoid fractures, sesamoid fractures may not be apparent on initial radiographs. Plain radiographs should be repeated after two weeks of presumptive therapy if a fracture is strongly suspected but initial studies are negative.
If the cause of symptoms remains unclear, magnetic resonance imaging (MRI) may be needed to make a definitive diagnosis. MRI is the modality of choice after plain radiographs. Sagittal and coronal planes are most helpful for evaluating the sesamoids. However, MRI findings can be nonspecific and thus difficult to interpret. Bone marrow edema may suggest a stress fracture, but sesamoiditis may cause similar findings . Another option is ultra-high-resolution computed tomography (CT). CT is best for imaging trabecular and cortical bone .
Partite sesamoids — Partite sesamoids, a normal variant, may be confused with fractured sesamoids. Fracture lines of sesamoids usually have irregular edges (image 4A-B), in contrast to the smooth borders of a partite sesamoid (image 3). In addition, partite sesamoids usually demonstrate even cortication around their entire circumference (image 6), whereas the fracture line of a sesamoid will lack cortication (image 4A-B).
Bilateral comparison plain radiographs or MRI can be obtained to distinguish a partite sesamoid from a fracture when plain films are unclear. Fracture is unlikely if tenderness is minimal and comparison radiographs demonstrate a partite sesamoid with similar appearance. One should bear in mind, however, that partite sesamoids can sustain fractures. Such fractures generally demonstrate modest point tenderness until healing is underway.
Radiographic pitfalls — Clinicians commonly mistake sesamoids and accessory bones for avulsion fractures on plain radiographs. To avoid this error, it is helpful to know the location of the most common sesamoids and accessory bones. In the foot, the most common sesamoids lie in the area of the first and fifth MTP joints (see 'Clinical anatomy' above). The most common accessory bones are found proximal to the base of the fifth (ie, small) metatarsal (os vesalianum), adjacent to the cuboid in the peroneus longus tendon (os peroneum), adjacent to the navicular (os tibiale externum), and posterior to the talus (os trigonum) (figure 1A-C). A detailed discussion of accessory bones is found separately. (See "Ankle pain in the active child or skeletally immature adolescent: Overview of causes".)
DIAGNOSIS — A definitive diagnosis of sesamoid fracture is made with diagnostic imaging, most often plain radiographs. Sesamoid fracture occurs most commonly in long distance runners and participants in sports requiring rapid acceleration and deceleration. The diagnosis is suspected clinically in patients complaining of poorly localized pain around the first metatarsophalangeal (MTP) joint for several weeks. Most often pain stems from a stress fracture and is of gradual onset; fracture due to forced hyperdorsiflexion causes acute pain. Often, the patient is unable to localize the pain until the examiner directly palpates the injured sesamoid. Passive dorsiflexion of the first MTP joint can elicit pain.
DIFFERENTIAL DIAGNOSIS — The differential diagnosis of sesamoid fractures includes the following conditions:
●Flexor hallucis brevis tendinopathy
●Medial plantar digital nerve entrapment
●Metatarsophalangeal (MTP) arthritis 
●First MTP joint sprain (turf toe)
●Proximal phalanx fracture
●Distal metatarsal fracture
History and examination alone are not sufficient to distinguish sesamoid fractures from sesamoiditis, bursitis, osteonecrosis, and flexor hallucis brevis tendinopathy. Medial plantar nerve entrapment presents with proximal medial arch pain that may radiate to the toes. First MTP joint sprain, synovitis, and MTP arthritis may present with an effusion of the first MTP joint. Proximal phalanx and distal metatarsal fractures present acutely with diffuse swelling and ecchymosis of the great toe or forefoot.
Radiographic studies are necessary to distinguish the conditions listed above from a sesamoid fracture. If plain radiographs are unrevealing but a fracture is suspected on clinical grounds, advanced imaging may be necessary to establish a diagnosis. The differential diagnosis and approach to patients with forefoot pain is reviewed in detail separately. (See "Evaluation, diagnosis, and select management of common causes of forefoot pain in adults".)
INDICATIONS FOR SURGICAL CONSULTATION OR REFERRAL — Open fractures require urgent referral. Displaced sesamoid fractures, which are rare, should also be referred. Early referral should also be considered for athletes, dancers, and other patients who are anxious to return to full activity.
For nondisplaced fractures, referral is advised if healing has not occurred by four to six months (nonunion) or if symptoms are still bothersome after four to six months. Patients requiring referral can be sent to either a podiatrist or an orthopedist, depending on local availability and expertise. Podiatrists often have more experience in both conservative and operative care of sesamoid injuries, with the exception of orthopedists who specialize in the foot and ankle.
INITIAL TREATMENT — Clinicians can treat sesamoid fractures in several ways. Abstaining from the activity thought to have caused the fracture is common to all approaches. In addition, some type of padding or bracing footwear is used, including [4,8]:
●C- or O-shaped padding around the sesamoid to unload it
The severity of symptoms often dictates which approach is chosen. If the patient is pain-free with weight-bearing, some treat with a molded orthosis for six to eight weeks . With acute traumatic fractures or highly symptomatic stress fractures, some recommend casting for three to four weeks followed by a firm-soled shoe and padding . Others recommend no weight-bearing during the initial three to four weeks, but this level of protection is unnecessary in most cases .
The optimal treatment remains controversial. Some authors claim prolonged conservative treatment with immobilization is ineffective in treating sesamoid fractures [2,15]. Nonetheless, before pursuing surgery, conservative treatment using one of the approaches described above seems prudent. We recommend using the least intrusive and least expensive intervention that achieves satisfactory pain control during ambulation. Often, treatment with C or O pads and a stiff-soled shoe yields satisfactory results.
Nonopioid analgesics may be used to help control pain. While some authors recommend nonsteroidal antiinflammatory drugs (NSAIDs) to treat pain from stress fractures , others have questioned their use . The effects of NSAIDs upon fracture healing is discussed separately. (See "Nonselective NSAIDs: Overview of adverse effects", section on 'Healing of musculoskeletal injury'.)
Significant pain during ambulation can be reduced by maximizing the use of physical interventions such as orthoses. Pain during rest can be reduced using medications other than NSAIDS, such as acetaminophen.
FOLLOW-UP CARE — Padding, use of a firm-soled shoe, or immobilization should be continued for six to eight weeks . Follow-up is performed one to two weeks after diagnosis and monthly thereafter. It is not uncommon for sesamoid fractures to remain painful for several months.
Overall, outcomes are generally good, especially in young athletes. Observational data suggests that conservative care leads to good outcomes in approximately 90 percent of young athletes, with 85 percent returning to their sport, although many months may be needed .
If pain persists and the fracture does not heal, the goal of treatment changes from bone healing to pain reduction. This can involve partial excision of the sesamoid. It is unclear when this change in treatment priorities should be made. Some diagnose permanent nonunion of the sesamoid bone if no healing has occurred six months after the fracture . Referral is therefore recommended if significant symptoms remain four to six months after diagnosis.
Surgical options include partial sesamoidectomy, bone grafting, or complete sesamoidectomy in cases involving avascular necrosis . Total excision of both sesamoids is not recommended, as this can lead to disabling deformity (the so-called "cock-up toe") .
RETURN TO WORK AND SPORTS — After the initial six to eight week treatment period, patients may return to activities as their symptoms permit. Mild persistent pain can be treated with a pad to unload the sesamoid. Patients should be told to increase their activities by no more than 10 percent per week. Rapid increases in the volume or intensity of activity can lead to recurrence of stress fractures. The patient should cut back on activities immediately if symptoms increase and seek reevaluation if they persist.
ADDITIONAL INFORMATION — Several UpToDate topics provide additional information about fractures, including the physiology of fracture healing, how to describe radiographs of fractures to consultants, acute and definitive fracture care (including how to make a cast), and the complications associated with fractures. These topics can be accessed using the links below:
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Lower extremity (excluding hip) fractures in adults" and "Society guideline links: Acute pain management".)
SUMMARY AND RECOMMENDATIONS
●Epidemiology, anatomy, and mechanism – Sesamoid fractures are a common cause of pain near the first metatarsophalangeal (MTP) joint. The majority of these fractures are stress fractures that can be managed nonsurgically.
The two relatively large sesamoids adjacent to the first MTP joint are the most frequently injured sesamoids. Of these, the medial (tibial) sesamoid is thought to bear more force during gait and is more commonly fractured. Sesamoids are sometimes "partite" (one sesamoid comprised of two or three separate pieces). (See 'Clinical anatomy' above.)
Stress fractures are the most common type of sesamoid fracture. (See 'Epidemiology and mechanism of injury' above.)
●Physical examination – Patients with a sesamoid fracture usually complain of poorly localized pain around the first MTP joint for several weeks. Swelling is not generally seen until the injury has progressed. Erythema is typically absent. Direct palpation of the sesamoid and passive dorsiflexion of the first MTP joint can elicit and localize pain in sesamoid fractures. (See 'Clinical presentation and examination' above.)
●Diagnostic imaging – Standard anteroposterior (AP), oblique, and lateral views of the foot are generally sufficient to demonstrate sesamoid fractures, but they may not appear on early radiographs. Transverse sesamoid fractures are most common. Lack of cortication and irregular borders help distinguish fracture lines (image 4A) from partite sesamoids (image 3). Sesamoid and accessory bones are commonly mistaken for avulsion fractures. Special views, bilateral comparison views, and magnetic resonance imaging (MRI) can be helpful when the diagnosis remains unclear. (See 'Diagnostic imaging' above.)
●Indications for referral – Open fractures (generally following significant trauma) require urgent referral. Displaced sesamoid fractures, which are rare, should also be referred. For nondisplaced fractures, referral is advised if healing has not occurred by four to six months (nonunion), or if symptoms remain bothersome after four to six months. (See 'Indications for surgical consultation or referral' above.)
●Treatment – Treatment is controversial. Abstaining from the activity thought to have caused the fracture is common to all approaches. In addition, some type of padding or bracing footwear is used, including: C or O-shaped padding around the sesamoid to unload it; a molded orthosis; a wooden-soled shoe; or a short leg cast. The severity of symptoms often dictates which approach is chosen. Nonopioid analgesics may be used. (See 'Initial treatment' above.)
Padding, use of a firm-soled shoe, or immobilization should be continued for six to eight weeks. Initial follow-up is performed one to two weeks after diagnosis and monthly thereafter. (See 'Follow-up care' above.)
●Return to activity – After the initial six to eight-week treatment period, patients may return to activities as their symptoms permit. Patients should be told to increase their activities by no more than 10 percent per week. Rapid increases in the volume or intensity of activity can lead to recurrence. Prolonged symptoms are not uncommon and may necessitate referral for possible surgery. (See 'Return to work and sports' above.)
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