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a 29-year - old woman presenting with lower - extremity pain and walking difficulties was referred by the department of neuropsychiatry to our clinic . her pain , which was in the toes ,
was described as continuous , throbbing , crushing , and burning , and its intensity was registered as 8 on the 11-point numeric rating scale ( nrs ) . at night , her pain was severe enough to wake her frequently . according to her medical history , these symptoms had arisen 9 months previously ( 3 months postpartum ) and were accompanied by postpartum depression .
orthopedic , neurologic , rheumatologic , and endocrinologic examinations had been unable to reveal the cause of her pain .
eventually , she had been referred to a psychiatrist for a somatoform disorder and then admitted to the psychiatric ward . at the hospital , she had been treated for painful legs and moving toes ( plmt ) syndrome , but the symptoms had persisted . as time passed , her depression had steadily worsened .
the patient had then been scheduled for consultation with a pain specialist . as a last resort
we reevaluated her problem , taking special note of the directionality of her pain , which originated at the great toes and extended to her calves ( fig .
1 ) . on physical examination , there was tenderness at the base of the great toes bilaterally , and this tenderness increased , becoming pain , particularly during dorsiflexion .
on the basis of an ultrasonographic foot evaluation , we found sesamoid bones on each interphalangeal joint of the hallux under the flexor hallucis longus tendon ( fig .
, in a dynamic examination involving the application of a usg probe and passive extension and flexion of the hallux , we were able to diagnose the influence of symptomatic interphalangeal sesamoids on the flexor hallucis longus tendon .
the patient was treated through an ultrasound - guided injection of 1 ml of 0.125% levobupivacaine ( chirocaine , abbott , elverum , norway ) mixed with 10 mg of triamcinolone acetonide between the sesamoid bone and flexor hallucis longus tendon at each site .
the following day , the patient reported no pain and , with her doctor 's permission , went shopping .
subsequently , she was discharged in a state of complete remission . from that day to the present , her depression has also greatly improved .
the accessory ossicles and sesamoid bones of the ankle and foot are anatomic variants that usually remain asymptomatic . interestingly
, radiographic findings on the hallucal interphalangeal sesamoid bones suggest that race may have a strong predisposing effect : similarly high prevalence rates of 89.3% and 91% have been reported among korean and japanese subjects , respectively , whereas the rates are only 13% among north american , 3.9% among bahraini , 2% among turkish , and 0% among black african subjects [ 2 - 5 ] .
even so , it should be noted that such differences may reflect factors other than race ( e.g. technical variations in radiography leading to underestimation and/or variability in the degree of sesamoid ossification ) . in any event ,
asymptomatic sesamoids are present in a large percentage of the korean population and can become symptomatic ( i.e. , painful ) with degenerative changes resulting from undue pressure , overuse , or trauma . for imaging evaluation , conventional radiography ( i.e. , lateral and dorsoplantar views of the foot and a special axial projection of the sesamoids ) is initially recommended .
in addition , because sesamoid bones are small , oval , rough , convex in shape , and composed mainly of bone , cartilage , and fibrous tissue , their contours on radiographs often are obscured by the opacity of the larger bones .
thus , when patients suffer from foot pain of unknown origin , the hallucal interphalangeal sesamoid bones need to be considered as a possible differential diagnosis , especially when radiographs are inconclusive . in such cases ,
scintigraphy , computed tomography ( ct ) , or magnetic resonance ( mr ) imaging can be used .
indeed , misdiagnosis remains the most serious problem in cases of hallucal interphalangeal sesamoid bones .
patients often are falsely suspected of having a somatoform disorder , which itself can lead to depression and anxiety .
the depression and anxiety can become more severe over time as the pathology continues to be invisible and/or overlooked on radiographs or misdiagnosed upon examination .
therefore , physicians should practice detailed history - taking and conduct thorough examinations when seeking to identify the causes of pain .
differential diagnoses of sesamoid pain include sprain , fracture , osteonecrosis , degenerative joint disease , chronic bursitis , and neural entrapment , among others .
ultrasound is particularly effective in the diagnosis of a variety of musculoskeletal disorders ; hallucal interphalangeal sesamoids , as a kind of sesamoid , are characterized with regard to location , contour , echogenicity , and shadowing . moreover , good results can be obtained in the treatment , for example , of tenosynovitis through usg - guided injections of small doses of local anesthetics mixed with steroids between the interphalangeal sesamoid bone and the flexor hallucis longus .
the purpose of management is to eliminate inflammation and predisposing factors . in cases where conservative therapy is ineffective
although excision undoubtedly provides the most effective relief , less invasive methods for treating symptomatic sesamoid bones need to be considered prior to surgical intervention .
the present case , involving a 29-year - old woman who presented to our clinic with lower - extremity pain and walking difficulties , demonstrates that careful history - taking and symptom provocation technique during physical examination are essential for the proper diagnosis of hallucal interphalangeal sesamoid bones and , thus , effective pain management .
additionally , this case confirms that dynamic usg , especially in the digital area , is useful for both diagnosis and treatment .
the hallucal interphalangeal sesamoid bone is usually asymptomatic , but it is not uncommon for it to be symptomatic in cases of undue pressure , overuse , or trauma . even in symptomatic cases , however , patients often suffer for extended periods due to misdiagnosis , resulting in depression and anxiety that can steadily worsen to the extent that symptoms are sometimes mistaken for a somatoform disorder . 
 dynamic ultrasound - guided evaluations can be an effective means of detecting symptomatic sesamoid bones , and a simple injection of a small dose of local anesthetics mixed with steroids is an easily performed and effective treatment option in cases , for example , of tenosynovitis .