Sesamoiditis – The Clinical Syndrome
Sesamoiditis is being seen with increasing frequency in clinical practice because of the increased interest in jogging and long-distance running. The sesamoid bones are small, rounded structures embedded in the flexor tendons of the foot and are usually in close proximity to the joints. These sesamoid bones decrease friction and pressure of the flexor tendon as it passes in proximity to a joint. Sesamoid bones of the first metatarsal occur in almost all patients, with sesamoid bones being present in the flexor tendons of the second and fifth metatarsals in many patients.
Although the sesamoid bone associated with the first metatarsal head is affected most commonly, the sesamoid bones of the second and fifth metatarsal heads also are subject to the development of sesamoiditis. Sesamoiditis is characterized by tenderness and pain over the metatarsal heads. The patient often feels as if he or she is walking with a stone in the shoe. The pain of sesamoiditis worsens with prolonged standing or walking for long distances and is exacerbated by improperly fitting or padded shoes. Sesamoiditis most often is associated with pushing-off injuries during football or repetitive microtrauma from running or dancing.
What are the Symptoms of Sesamoiditis
Pain can be reproduced on physical examination by pressure on the affected sesamoid bone. In contrast to metatarsalgia, in which the tender area remains over the metatarsal heads, with sesamoiditis, the area of maximal tenderness moves along with the flexor tendon when the patient actively flexes his or her toe. A patient with sesamoiditis often exhibits an antalgic gait in an effort to reduce weight bearing during walking. With acute trauma to the sesamoid, ecchymosis over the plantar surface of the foot may be present.
How is Sesamoiditis diagnosed?
Plain radiographs are indicated in all patients with sesamoiditis to rule out fractures and identify sesamoid bones that may have become inflamed. Based on the patient’s clinical presentation, additional tests, including complete blood cell count, erythrocyte sedimentation rate, and antinuclear antibody testing, may be indicated. Magnetic resonance imaging (MRI) and ultrasound imaging of the metatarsal bones is indicated if joint instability, occult mass, or tumor is suspected as well as to help confirm the clinical diagnosis. Radionucleotide bone scanning may be useful in identifying stress fractures of the metatarsal bones or sesamoid bones that may be missed on plain radiographs of the foot.
Differential Diagnosis
Primary pathological processes of the foot, including gout and occult fractures, may mimic the pain and disability associated with sesamoiditis. Entrapment neuropathies such as tarsal tunnel syndrome may confuse the diagnosis, as may bursitis and plantar fasciitis of the foot, both of which may coexist with sesamoiditis. Metatarsalgia is another common cause of forefoot pain and may be distinguished from sesamoiditis by the fact that the pain of metatarsalgia is over the metatarsal heads and does not move when the patient actively flexes his or her toes, as is the case with sesamoiditis. Primary and metastatic tumors of the foot also may manifest in a manner analogous to arthritis of the midtarsal joints.
Treatment
Initial treatment of the pain and functional disability associated with sesamoiditis should include a combination of nonsteroidal antiinflammatory drugs (NSAIDs) or cyclooxygenase-2 (COX-2) inhibitors and physical therapy. Local application of heat and cold may be beneficial. Avoidance of repetitive activities that aggravate the symptoms and short-term immobilization of the midtarsal joint also may provide relief. For patients who do not respond to these treatment modalities, injection of the affected sesamoid bone with a local anesthetic and steroid may be a reasonable next step. Ultrasound guidance may improve the accuracy of needle placement and decrease the incidence of needle-related complications.
Complications and Pitfalls
The major complication of injection of sesamoiditis is infection. This complication should be exceedingly rare if strict aseptic technique is followed. Approximately 25% of patients report a transient increase in pain after injection of sesamoid bones, and patients should be warned of this possibility. Another potential risk of this injection technique is trauma to the tendon from the injection.
Clinical Pearls
Pain emanating from the forefoot is a common problem encountered in clinical practice. Sesamoiditis must be distinguished from stress fractures of the metatarsal bones, metatarsalgia, Morton neuroma, and fractures of the sesamoid bones. Although the previously mentioned injection technique provides palliation of the pain of sesamoiditis, the patient often also requires shoe orthoses that include padded insoles to help remove pressure from the affected sesamoid bones. Coexistent bursitis and tendinitis also may contribute to metatarsal pain and may require additional treatment with more localized injection of an anesthetic and depot steroid. The use of physical modalities, including local heat and gentle range-of-motion exercises, should be introduced several days after the patient undergoes this injection technique for sesamoiditis pain. Vigorous exercises should be avoided because they would exacerbate the patient’s symptoms. Simple analgesics and NSAIDs may be used concurrently with this injection technique.
