Fractures easily missed by conventional radiographic diagnosis]

Although conventional radiography is the mainstay for diagnosing fractures, there are multiple conditions in which a fracture can be overlooked by the radiologist. This report focuses on the radiographic findings of various presentations of fractures including (1) minimally displaced fractures, (2) avulsion fractures, (3) stress fractures, (4) incomplete fractures and physeal injuries in children, and (5) occult fractures complicated with overt injury. Radiologists need to be familiar with these relatively common entities and aware of the limitations of radiography for fracture diagnosis; there are cases that can be diagnosed clinically without radiographic findings of cortical disruption. Repeated radiographic examination, CT, or MRI may be indicated depending on the clinical situation. The involvement of radiologists in the routine interpretation of conventional radiographs in trauma settings is encouraged to improve the detection of subtle fractures.     

Magnetic resonance imaging of para-acetabular insufficiency fractures in patients with malignancy

AIM: To describe the characteristic magnetic resonance imaging (MRI) findings of para-acetabular insufficiency fractures in patients with malignancy, and compare the MRI appearance of these fractures with that of metastatic bone disease. MATERIALS AND METHODS: MRI examinations were reviewed in 16 patients with a known malignant tumour and severe hip pain that raised the possibility of local recurrence or metastatic disease. Six patients had received pelvic irradiation, and three patients were receiving steroid medication. RESULTS: The total number of fractures detected was 21: a solitary fracture was present in 11 patients and five patients had bilateral para-acetabular fractures. Two patients had associated sacral insufficiency fractures, and one of them had stress fractures involving both acetabular columns. Conventional radiography allowed the diagnosis of 14 (67%) fractures; six (28%) radiographic examinations were negative; and one (5%) examination was equivocal for fracture. Available scintigraphic and computed tomography (CT) studies revealed typical findings of fracture. Using MRI, insufficiency fractures appeared as linear regions of low signal intensity on T1- and T2-weighted images. Marked marrow oedema was evident in all cases. Fractures characteristically were parallel to the superior acetabulum in a curvilinear fashion in 18 (86%) instances, and were oblique in three (14%) instances. The fractures demonstrated considerable enhancement after intravenous gadolinium administration. No associated soft tissue masses were documented. CONCLUSION: Para-acetabular insufficiency fractures are a cause of hip pain, which may mimic skeletal metastasis in the patient with malignancy and pelvic irradiation. Recognition of the characteristic MRI findings of these fractures can preclude misdiagnosis and unnecessary bone biopsy.     

MRI demonstration of radiographically occult fractures: what have we been missing?

During the course of MRI examinations of the knee for possible internal derangement, the hip for avascular necrosis, and the shoulder for rotator cuff tears, we have encountered many examples of unsuspected fractures of the tibial plateau, femoral condyles, pelvis, hip and proximal humerus. These fractures were either radiographically inapparent or demonstrated very subtle abnormalities that were missed on prospective interpretation. In addition, a large number of patients have been found to demonstrate evidence of intraosseous trabecular disruption, or edema and hemorrhage of medullary bone, or stress type injuries, all of which are radiographically occult. The clinical significance of these osseous abnormalities varies and is dependent upon the degree of injury. It is believed that an awareness of these osseous abnormalities will improve the accuracy of MRI interpretation, will heighten an appreciation of the subtle radiographic abnormalities that may be present, and will improve patient evaluation and management.     

Magnetic resonance imaging features of fractures using the short tau inversion recovery (STIR) sequence: correlation with radiographic findings

The MRI characteristics of fractures have been described on the basis of spin echo (SE) images emphasizing T1 and T2 contrast. These previous studies were carried out for injuries in which radiographic proof was often lacking. In comparison with SE images, short tau inversion recovery (STIR) images have been shown to provide superior contrast between normal and abnormal marrow. To determine the MRI characteristics of fracture using STIR pulse sequences, we reviewed 28 patients who had radiographic evidence of fracture and were examined with T1-weighted SE and STIR sequences. MRI marrow signal abnormalities were demonstrated at all fracture sites ranging in age from less than 24 h to 8 weeks. The extent of marrow signal abnormalities exceeded the size of corresponding radiographic findings of fracture in all cases. The MRI features of fractures on T1-weighted SE images consisted of irregular intramedullary zones of hypointensity. On STIR images a corresponding zone of hyperintensity extended to the outer cortical margin. Intramedullary lines of hypointensity extending to the inner cortical margin were identified within the hyperintense marrow abnormality on STIR images in 64% of the fractures. The results of this study show that MRI using T1-weighted SE and STIR sequences can consistently demonstrate prominent signal abnormalities at fracture sites including those in which radiographic signs are subtle.     

Added value of interpreter experience in occult and suspect hip fractures: a retrospective analysis of 254 patients

The influence of experience in categorizing suspect and occult fractures on radiography compared to MRI and clinical outcome has not been studied. The aim of this study is to evaluate the importance of experience in diagnosing normal or suspect hip radiographs compared to MRI. Primarily reported normal or suspect radiography in 254 patients with low-energy hip trauma and subsequent MRI was re-evaluated by two experienced reviewers. Primary readings and review were compared. The prevalence of fractures among normal and suspect radiographic studies was assessed. Clinical outcome was used as reference. At review of radiography, 44 fractures (17 %) were found. Significantly more fractures were found among suspect cases than among normal cases. At MRI, all 44 fractures were confirmed, and further 64 fractures were detected (25 %). MRI detected all fractures with no missed fractures revealed at follow-up. There were a significantly higher proportion of fractures at MRI among the suspect radiographic diagnoses for both the primary report and at review than among occult cases. The more experienced reviewers classified radiography examinations with higher accuracy than primary reporting general radiologists. There was almost complete agreement on MRI diagnoses.     

Prevalence of exclusively and concomitant pelvic fractures at magnetic resonance imaging of suspect and occult hip fractures

Pelvic fractures may occur together with hip fractures as a result of low energy trauma. It is unclear whether they do require special attention. There are conflicting results in the literature about the prevalence of both concomitant hip and pelvic fractures as well as exclusive pelvic fractures. It has been reported that hip fractures and obturator ring fractures are mutually exclusive. To retrospectively analyze the prevalence of exclusively pelvic as well as concomitant hip and pelvic fractures in patients examined with MRI after low-energy trauma in elderly. During 9 years, 316 elderly patients had been examined with MRI for suspected or occult hip fracture after a fall. A fracture was diagnosed when MRI showed focal signal abnormalities in the subcortical bone marrow, with or without disruption of adjacent cortices. One observer reviewed all studies. A second observer verified all studies with hip fractures. Follow-up was available for all but two patients that died prior to hip surgery. The prevalence of concomitant pelvic and femoral neck or trochanteric fractures was statistically compared using chi-squared test for categorical variables. Hip fractures were found in 161 (51 %) patients of which 29 (9 %) had concomitant pelvic fractures. There were exclusively pelvic fractures in 82 (26 %) patients of which 65 (79 %) were on the traumatized side only. In 73 patients, there were no fractures. Occult or suspected hip fractures are not infrequently associated with pelvic fractures. Exclusively pelvic fractures are not uncommon.     

Ankle and foot injuries: analysis of MDCT findings

OBJECTIVE: The purpose of our study was to assess MDCT findings and the advantages of MDCT compared with radiography in patients referred to a level 1 trauma center for diagnostic evaluation of acute ankle and foot trauma. MATERIALS AND METHODS: During a period of 37 months, 388 patients underwent MDCT of the ankle and foot due to an acute trauma. Imaging studies (MDCT and radiography) were retrospectively reevaluated with respect to fracture location, fracture type, and mechanism of injury, and findings from the primary radiographs of the ankle and foot were compared with MDCT findings. RESULTS: Of the 388 patients, 344 (89%) had one or more fractures in the ankle or foot. A total of 517 fractures were found in all anatomic regions: ankle, calcaneus, talus, midfoot, and forefoot. The three most common occult fractures in the ankle not detected on primary radiography were isolated fractures of the posterior and medial malleolus and Tillaux fractures. The calcaneus was the most commonly fractured bone, and the sensitivity of radiography in the detection of calcaneal fractures was 87%. The sensitivity of radiography in the detection of talar fractures was 78%, whereas it was only 25-33% in the detection of midfoot fractures. A Lisfranc fracture-dislocation was not detected on primary radiography in five (24%) of 21 cases. The three main injury mechanisms were falling from a height (164 patients [48%]), a simple fall (68 patients [20%]), and a traffic accident (47 patients [14%]). CONCLUSION: In patients with injuries from high-energy polytrauma and in those with complex ankle and foot fractures, the sensitivity of radiography is only moderate to poor; in these cases, MDCT is recommended as the primary imaging technique.     

Extension corner avulsion fracture of the cervical spine

The purpose of this study was to determine the radiographic findings and clinical significance of the extension corner avulsion fracture (ECAF) of the cervical spine and to defined the role of the plain radiography, computed tomography (CT), and magnetic resonance imaging (MRI) in the evaluation of this injury in order to establish a radiographic protocol. Imaging studies of the cervical spine (including plain radiographs, CT scans, and MRI examinations) and medical records of 31 patients from two major trauma centers were reviewed retrospectively. Twentyeight (90%) of 33 ECAFs occurred at C2. Two patients (7%) had ECAF at more than one level. Ten patients (32%) had additional cervical injuries. Traumatic spondylolisthesis of C2 was the most common associated cervical injury (10%). Seven patients (23%) had associated thoracolumbar injuries. Although all available sagittal reformations demonstrated characteristic fracture, axial CT images failed to demonstrate the fracture in three cases, but, in one patient, they revealed other clinically insignificant fractures not appreciated on plain radiographs. MRI was noncontributory in cases of isolated ECAF. Five patients (16%) had neurologic deficits, with three localized to the cervical region. ECAF occurs most commonly at C2, typically does not result in direct neurologic injury, and is characterized radiographically by a triangular-shaped anteroinferior corner fracture fragment with associated soft tissue swelling. In most cases, ECAF can be adequately assessed by plain radiography. CT and MRI should be reserved for patients with complex fracture patterns or neurologic symptoms.     

Magnetic resonance imaging in pediatric elbow fractures

Purpose: Magnetic resonance imaging (MRI) evaluation of pediatric elbow trauma with or without a visible fracture on radiography.

Material and Methods: MRI was performed in the acute phase in 25 children with an elbow injury. Nine patients with an elbow effusion only on radiographs and 16 with a fracture or luxation seen on radiographs underwent subsequent MRI. No sedation was used.

Results: MRI revealed eight occult fractures (89%) in seven out of nine patients who had only an effusion on radiographs. Based on MRI findings, septic arthritis was suspected in one patient. Two patients out of five with a supracondylar fracture on the radiograph had a cartilage lesion in the humerus. MRI depicted a 3-mm gap on the articular surface in two patients with a lateral condyle fracture, a more accurate fracture location in two patients than the radiographs, and an additional occult fracture in two patients. MRI showed a fracture not seen on radiographs in two of three patients with prior luxation.

Conclusion: MRI is a sensitive and accurate method in the diagnosis of pediatric elbow injuries, especially when only an effusion is present on radiographs. Occult fractures are more common in pediatric patients with elbow injury than reported earlier.     

Imaging findings in symptomatic patients with femoral diaphyseal stress injuries

Purpose: To assess the imaging findings seen in symptomatic patients with stress injuries of the femoral diaphysis.

Material and Methods: Seven patients (5 F, 2 M, age range 16 to 56 years, mean 38 years) underwent imaging evaluation of the symptomatic lower extremity due to an insidious onset of thigh or groin pain unrelated to trauma. Imaging studies included radiography and magnetic resonance imaging (MRI) in seven patients, bone scintigraphy in five, and computed tomography (CT) in three.

Results: Radiographs depicted three frank fractures in two patients, and revealed findings of stress injury in six patients. Available scintigraphic and CT findings were abnormal. On MR images, a solitary fracture was seen in two patients; two patients presented with bilateral stress fractures of the femoral diaphysis; and all seven patients had the imaging features of stress injury. Femoral diaphyseal stress fractures (n = 6) appeared as linear regions of T1- and T2-weighted low signal intensity, surrounded by diffuse bone marrow edema. Three of the six frank fractures, with an evident fracture line, were longitudinal and parallel to the cortical surface.

Conclusion: Femoral diaphyseal stress fractures are often inconspicuous with conventional radiography. MRI depicts the changes of stress injury in the femoral diaphysis, and is particularly useful in documenting the presence, morphology, and extent of fracture(s), information valuable for definitive diagnosis and appropriate management.     

Radionuclide bone imaging in spondylolysis of the lumbar spine in children

Bone scintigraphy and radiography were performed in seven children with back pain. Six of the children with radiographic evidence of a pars interarticularis defect also had abnormal scintigrams. Increased uptake of the bone imaging agent occurred at six of the ten sites of radiographic pars interarticularis defects, implying increased bone metabolic activity. However, the location of scintigraphic abnormalities did not correspond to the location of radiographic abnormalities in several cases. Possible explanations for the discordant findings are: (a) normal bone metabolism at the site of an old spondylolysis and (b) radiographically inapparent stress fractures. Measurements of absorbed radiation dose indicate that plain radiography, including oblique views where appropriate, has a lower absorbed radiation dose than scintigraphy or tomography and should be performed prior to these studies.     

Acetabular stress fractures in military endurance athletes and recruits: incidence and MRI and scintigraphic findings

OBJECTIVE: To evaluate the incidence and the MRI and scintigraphic appearance of acetabular stress (fatigue) fractures in military endurance athletes and recruits. DESIGN AND PATIENTS: One hundred and seventy-eight active duty military endurance trainees with a history of activity-related hip pain were evaluated by both MRI and bone scan over a 2-year period. Patients in the study ranged in age from 17 to 45 years. They had hip pain related to activity and had plain radiographs of the hip and pelvis that were interpreted as normal or equivocal. The study was originally designed to evaluate the MRI and scintigraphic appearance of femoral neck stress fractures. Patients had scintigraphy and a limited MRI examination (coronal imaging only) within 48 h of the bone scan. Twelve patients demonstrated imaging findings compatible with acetabular stress fractures. RESULTS: Stress fractures are common in endurance athletes and in military populations; however, stress fracture of the acetabulum is uncommon. Twelve of 178 patients (6.7%) in our study had imaging findings consistent with acetabular stress fractures. Two patterns were identified. Seven of the 12 (58%) patients had acetabular roof stress fractures. In this group, two cases of bilateral acetabular roof stress fractures were identified, one with a synchronous tensile sided femoral neck stress fracture. The remaining five of 12 (42%) patients had anterior column stress fractures, rarely occurring in isolation, and almost always occurring with inferior pubic ramus stress fracture (4 of 5, or 80%). One case of bilateral anterior column stress fractures was identified without additional sites of injury. CONCLUSIONS: Stress fractures are commonplace in military populations, especially endurance trainees. Acetabular stress fractures are rare and therefore unrecognized, but do occur and may be a cause for activity-related hip pain in a small percentage of military endurance athletes and recruits.     

Adequacy of plain radiography in the diagnosis of cervical spine injuries

Our hypotheses were (1) that plain radiography of the cervical spine in the evaluation of low risk patients with minor blunt trauma is accurate and (2) that computed tomography (CT) of the cervical spine in the evaluation of low risk patients is unnecessary. This study evaluates those hypotheses. We prospectively recorded findings of all patients with blunt trauma who underwent imaging over a period of 70 days. Injury status was determined by review of all radiographic studies obtained on each patient. Chart reviews were performed to determine mechanism of injury and neurological status. Patients were divided into three groups: very low risk, low risk, and high risk. Study end point was fracture. The study included 219 patients. The very low risk group had 107 patients, none of whom had fractures found on CT (projected specificity of plain radiography: 100%). The low risk group contained 78 patients who had no fractures seen on plain radiography or CT (specificity of plain radiography and CT: 100%). The high risk group consisted of 34 patients; 15 had fractures demonstrated on CT. Plain radiography missed one fracture out of 15. In low risk patients, plain radiography is an efficient diagnostic exam with a specificity of 100%. In high risk patients, plain radiography is a good adjunctive screening exam in conjunction with CT scan, with a sensitivity of 93.3% and specificity of 95%.     

US versus conventional radiography in the diagnosis of sternal fractures

Purpose: To investigate the value of ultrasonography (US) in the diagnosis of sternal fractures.Material and Methods: Twenty-three patients (mean age 35.4 years) with a clinical suspicion of sternal fracture after blunt chest trauma were retrospectively reviewed. At admission, a.p. and lateral chest radiographies and sternal US were obtained. Sternal fractures were classified as nondisplaced or displaced. US and conventional radiographic findings were compared.Results: In 3/23 (13.0%) of the patients, no fracture was found by radiography or by US. Both radiography and US demonstrated sternal fractures in 16/23 (69.6%) of the patients. Sternal fractures were detected only by US while the conventional radiography was negative in 2/23 (8.7%) cases. Also in 2/23 (8.7%) of the patients with US positive for fracture, radiographies were suspicious. In 2 patients, the degree of fracture displacement on US was lesser than that found by radiography.Conclusion: US was better than lateral radiography to diagnose sternal fractures; however, conventional radiography remains the standard means of demonstrating grade of displacement.     

膝关节骨与韧带急性损伤的MRI研究

目的:探讨MRI检查中急性膝关节骨损伤与韧带损伤之间的合并关系以及临床应用价值。方法:38例急性膝部骨损伤病人,行MRI重点观察STIR序列的损伤情况。骨损伤分为显性骨折(X线检查可见)与隐性骨损伤(X线检查未见异常),韧带损伤包括撕裂与完全断裂。结果:38例共45处骨损伤,包括显性骨折28处(73%)、隐性骨损伤(骨挫伤)17处(44%)。84%病例的骨损伤累及胫骨。86%的病例合并多韧带损伤,最常累及内侧副韧带、前交叉韧带与后交又韧带,74%的损伤韧带非邻近骨损伤部位。结论:急性膝部骨损伤最常累及腔骨,常合并多韧带损伤,但韧带损伤多不靠近骨损伤部位。MRI脂肪抑制序列能直观地显示韧带的撕裂与完全断裂,且能发现相当多的隐性骨损伤病例。     

Sublabral sulcus at the posteroinferior acetabulum: a potential pitfall in MR arthrography diagnosis of acetabular labral tears

OBJECTIVE: Our study correlated findings on hip MRI and MR arthrography with hip arthroscopy to assess the location, prevalence, and potential pitfall of a normal acetabular sublabral sulcus. MATERIALS AND METHODS: We retrospectively collected 58 hip MRI studies along with surgical reports in 58 patients who underwent hip arthroscopy over a 5-year period. Intraoperative photography (n = 23), radiography (n = 56), unenhanced MRI (n = 13), and MR arthrography (n = 54) studies were available for review. Two radiologists described hip anatomy on radiology studies with agreement by consensus. RESULTS: A normal posteroinferior sublabral groove was confirmed on available arthroscopy photographs in four (17.4%) of 23 hips. In each of these four patients, the anatomic sublabral groove correlated with apparent partial labral detachment on MR arthrography. On review of all studies, 13 hips (22.4%) without a posterior labral tear at surgery had imaging findings of a sublabral sulcus. The sulcus was not associated with acetabular dysplasia, which was radiographically noted in 12 cases (21.4%). Preoperatively, the sulcus was misdiagnosed as a tear in two cases. Labral tears were anterior or anterosuperior in 51 patients. CONCLUSION: A posteroinferior sublabral groove is a relatively common normal anatomic hip variation. If not recognized as normal, the sulcus may serve as a diagnostic pitfall on MR arthrography. Its location is distinct from most labral tears. We did not discover a sublabral sulcus at the anterior or anterosuperior acetabulum, the most common sites of labral injury.     

Wrist injuries; diagnosis with multidetector CT

The aim of the study was to assess acute-phase multidetector CT (MDCT) findings in wrist injuries. We retrieved all emergency room MDCT requests processed in the period from August 2000 to May 2003. All patients with a wrist injury who underwent MDCT initially were included. Imaging studies were evaluated in relation to injury mechanism, fracture location, and fracture type. A total of 6422 MDCT examinations were performed during this 34-month period, and 38 patients (24 male, 14 female, age range 21–73 years, mean age 40 years) met the inclusion criteria. MDCT revealed 56 fractures and 7 dislocations in 29 patients. In 9 patients (24%) MDCT findings were normal. Eleven patients (29%) underwent surgical procedures. The main injury mechanism was a fall (58%). In 33 cases the primary radiograph was available. Compared to primary radiographs, MDCT revealed 9 occult fractures, mainly in small carpal bones. In 14 cases a suspected fracture (of the scaphoid in 7 cases) was ruled out by MDCT. Due to high-quality two-dimensional reformatting, MDCT examinations were not dependent on the wrists position in the CT gantry. In the comparison with radiography, MDCT detected occult fractures and ruled out suspected fractures, both mainly in the small carpal bones. High-quality two-dimensional reformats gave significant information about the fracture anatomy. MDCT provides fast and valuable information in assessing complex wrist fractures or when the primary radiograph is equivocal.     

Incomplete intertrochanteric fractures: imaging features and clinical management

PURPOSE: To present the imaging findings and treatment options for incomplete intertrochanteric fractures. MATERIALS AND METHODS: Among 31 patients with the magnetic resonance (MR) imaging diagnosis of incomplete intertrochanteric fracture, 30 also underwent radiography. MR and radiographic findings were compared. Note was made of fracture length and extent as depicted on the coronal and axial MR images, treatment (surgical vs conservative), and follow-up. RESULTS: Correlation between radiographic and MR findings was poor. Incomplete intertrochanteric fracture was the prospective radiographic diagnosis in only one case. Fracture in 18 patients was treated surgically and in 13 was managed conservatively. In both groups, the average age of the patients and length of the fractures and the percentage of separate fractures involving the greater trochanter and crossing the midline of the femur in the axial plane were the same. Fractures crossed the midline in the coronal plane in 50% of the surgical group but in only 23% of the nonsurgical group. Average time from injury to ambulation was 2 days less in the surgical group, but no difference in functional status was found subjectively between the two groups at clinical follow-up. CONCLUSION: Incomplete intertrochanteric fractures are a previously unrecognized subset of intertrochanteric fractures that are diagnosed unequivocally only with MR imaging.     

Fatigue fracture of the sacrum: a case report

We report a patient with a stress fracture in the sacrum. This may be a cause of hip or back pain. In contrast to typically bilateral insufficiency fractures, fatigue fractures are usually unilateral and the appearances are not diagnostic on scintigraphy. As the plain film findings may be subtle and overlooked, computed tomography is more specific in delineating a sclerotic vertical fracture parallel to the sacroiliac joint. Recognition of the characteristic radiographic pattern in sacral fatigue fractures can avoid incorrect diagnosis and unnecessary tests or treatment.     

Multidetector computed tomography of cervical spine fractures in ankylosing spondylitis

PURPOSE: To analyze multidetector computed tomography (MDCT) cervical spine findings in trauma patients with advanced ankylosing spondylitis (AS). MATERIAL AND METHODS: Using PACS, 2282 cervical spine MDCT examinations requested by emergency room physicians were found during a period of 3 years. Of these patients, 18 (16 M, aged 41-87, mean 57 years) had advanced AS. Primary imaging included radiography in 12 and MRI in 11 patients. RESULTS: MDCT detected one facet joint subluxation and 31 fractures in 17 patients: 14 transverse fractures, 8 spinous process fractures, 2 Jefferson's fractures, 1 type I and 2 type II odontoid process fractures, and 1 each: atlanto-occipital joint fracture and C2 laminar fracture plus isolated transverse process and facet joint fractures. Radiographs detected 48% and MRI 60% of the fractures. MRI detected all transverse and odontoid fractures, demonstrating spinal cord abnormalities in 72%. CONCLUSION: MDCT is superior to plain radiographs or MRI, showing significantly more injuries and yielding more information on fracture morphology. MRI is valuable, however, in evaluating the spinal cord and soft-tissue injuries. Fractures in advanced AS often show an abnormal orientation and are frequently associated with spinal cord injuries. In these patients, for any suspected cervical spine injuries, MDCT is therefore the imaging modality of choice.