bone stress injuries account for approximately 8.2% of all injuries in elite track and field athletes .
stress fractures are a result of accelerated physiologic change from excessive loading applied to a normal bone .
this is the sequelae of high intensity , duration of training , nutrition , and biomechanical , muscular , and hormonal imbalance .
differential diagnosis includes fracture of the tibia , muscle sprain or contusion , periostitis , bur - sitis , medial tibial stress syndrome , and compartment syndrome .
the diagnosis of tibia stress fractures requires high level of clinical suspicion , and confirmation is needed with imaging .
plain radiographs have often times yielded negative results until 3  weeks to 3  months when bone callus is formed .
the criterion standard for diagnosis of stress fractures is magnetic resonance imaging ( mri ) or bone scan scintigraphy .
the high cost of these 2 imaging modalities has paved way for research into other less diagnostic tests such as ultrasonography .
ultrasonography has been shown to be beneficial in the diagnosis of lower extremity stress fractures , primarily in metatarsal bones and ankle malleoli .
the diagnosis of tibia stress fractures with ultrasound has only been reported in a few cases .
the purpose of this case report is to contribute to the limited evidence in literature regarding the diagnosis of tibia stress fractures with ultrasonography .
the patient was an otherwise healthy 19-year - old white female division 1 collegiate mid - distance runner who came to the office complaining of left shin pain .
she had been an athlete throughout high school and recollected having pain in the same area for several months . however , 3  weeks prior to coming to the office
she described the pain as a sharp pain and initially rated it as a 3/10 in intensity ( measured by visual analog scale of 1 - 10 , where 10 is worst pain ) .
the pain , however , had progressed to a 9/10 in intensity prior to being seen in clinic .
patient s examination revealed tenderness on the left mid - shaft of the tibia along the anterior border .
after a trial of conservative management with rest , ice , and nonsteroidal anti - inflammatory drugs , plain radiography of the left lower extremity was performed and was unremarkable ( figure 1 ) .
ultrasound of the left tibia showed focal hyperechoic elevation of periosteum with irregularity over the left distal tibia measuring about 3  cm with a positive doppler over the area ( figures 2 and 3 ) .
an mri was ordered that confirmed periosteal reaction consistent with stress fracture over the distal tibia with no fracture line ( figure 4 ) .
normal x - ray findings of the left lower extremity in the posterior anterior view .
longitudinal view of the anterior tibia showing discontinuity of hyperechoic line representing disruption of bony cortex ( green arrow ) and periosteal edema ( yellow arrows ) . on the left - hand side
t2 coronal ( left ) image shows a lucent appearance at site of pain , and axial ( right ) image reveals marrow edema ( green arrow ) and periosteal edema ( yellow arrows ) of the tibia .
on 3  weeks of follow - up , the patient was doing well without any significant symptoms ( figure 5 ) .
follow - up longitudinal view at 3  weeks shows callous formation at site of injury which signifies healing .
it is important to diagnose stress fractures early to prevent bone remodeling , nonunion injuries , and loss of function
. the sensitivity of standard radiography which can miss fractures in the early stages of stress fractures due to the absence of callus formation can be as low as 10% .
bone scan with technetium tc 99 m diphosphonate allows for early diagnosis but is coupled with high costs , lengthy procedure times , and exposure to ionizing radiation .
magnetic resonance imaging provides a noninvasive method of detecting stress fractures with good sensitivity , but its high cost and poor accessibility in some rural areas prevent routine use .
both are highly sensitive and provide optimal depiction of bone marrow edema , periosteal inflammation , and cortical fractures .
although these modalities have become the standard for diagnosis , ultrasonography is becoming more accepted as a first - line imaging modality for soft tissues , muscles , and tendon pathologies .
cortical irregularities and hypertrophic changes may be visualized before they are seen on plain radiographs or mri . in stress fractures ,
its sensitivity and specificity compared with mri remain inferior despite its 81.8% sensitivity and 66.6% specificity of ultrasound in the diagnosis of metatarsal stress fractures .
hallmark findings are present in the diagnosis of stress fractures using ultrasound and were likewise found in this case report .
these findings include the following : hyperechogenicity of the surrounding soft tissue which indicates soft tissue edema and inflammatory reaction ; thickening of the periosteum ; increased periosteal color doppler flow .
widespread use of the ultrasound in stress fractures varies by circumstance and is still an area of ongoing research .
its major drawback is that it is heavily operator dependent , requiring skill to recognize normal anatomy and pathology .
given its small field of view , nearby anatomical structures are often unavailable . however ,
the current imaging modalities are cost intensive , poorly accessible , and invasive and are linked with increased patient discomfort .
continued improvements in ultrasound resolution quality have increased its clinical utility . in the hands of a skilled technician ,
ultrasound can provide real - time unparalleled images to detect stress fractures in a safe and portable manner .
this case emphasizes that in cases where there is suspicion of stress fracture , diagnostic ultrasound can provide a good alternative .
 stress fractures are a frequent cause of lower extremity pain in athletes , and especially in runners . 
 plain imaging has a low sensitivity . magnetic resonance imaging ( mri ) or 
 bone scan scintigraphy is the criterion standard , but expensive . 
 we present the case of a young female distance runner with left shin pain . 
 plain radiography was unremarkable . 
 ultrasound showed focal hyperechoic elevation of the periosteum with irregularity over the distal tibia and increased flow on doppler . 
 these findings were consistent with a distal tibia stress fracture and confirmed by mri . examination of our case will highlight the utility of considering an ultrasound for diagnosis of tibial stress fracture . 
Introduction
Case Presentation
Discussion