Acute elbow trauma in children: spectrum of injury revealed by MR imaging not apparent on radiographs

Diagnostic accuracy of fat pad sign, X-ray, and computed tomography in elbow trauma: implications for treatment choices-a retrospective study

Introduction

Identifying skeletal injuries significantly impacts patient outcomes in trauma cases. This study aims to compare the diagnostic accuracy of X-ray (XR) and computed tomography (CT) in detecting elbow fractures among patients presenting at the emergency department (ED). Additionally, the study assesses the potential contribution of the fat pad sign to enhancing the diagnostic accuracy of XR images in identifying elbow fractures. The secondary aim focused on evaluating the precision of XR imaging in determining the necessity for surgical intervention among patients presenting with elbow trauma.

Methods

Conducted retrospectively at an ED within a secondary hospital, this study included patients with elbow trauma between January 1, 2017, and January 1, 2020, who underwent both XR and CT imaging of the elbow joint. Following the application of exclusion criteria, the analysis comprised 183 patients based on remaining image data.

Results

When comparing XR to CT for fracture detection, XR exhibited a sensitivity of 46.9%, specificity of 85.9%, positive predictive value (PPV) of 79.3%, negative predictive value (NPV) of 58.4%, area under the curve (AUC) of 0.664. Considering the fat pad sign in XR as a fracture indicator, the sensitivity is 60.2%, specificity is 81.2%, PPV is 78.7%, NPV is 63.9% and AUC is 0.707. A significant difference was found when comparing the AUCs obtained with and without considering the fat pad sign (p = 0.039). Regarding surgical treatment decision-making, XR showed a sensitivity of 50%, specificity of 100%, PPV of 95%, NPV of 100%, and an AUC of 0.750 when compared to CT.

Conclusion

The findings indicate that XR alone is insufficient for detecting elbow fractures and determining the need for surgical treatment. Incorporating the fat pad sign improves the diagnostic accuracy of XR. In cases where suspicion of fracture is high, considering CT imaging is crucial to avoid missed diagnoses, prevent complications, and guide treatment decisions effectively.

Prospective Evaluation of Magnetic Resonance Imaging Features of Magnesium-Based Alloy Screw Resorption in Pediatric Fractures

BACKGROUND

The resorption of magnesium-based alloy bioabsorbable screws results in the release of hydrogen gas, which can mimic infection and enter the growth plate. The screw itself and the released gas may also affect image quality.

OBJECTIVE

The evaluation of magnetic resonance imaging (MRI) findings during the most active phase of screw resorption is the objective, with particular focus on the growth plate and to assess for the presence of metal-induced artifacts.

MATERIAL AND METHODS

In total, 30 prospectively acquired MRIs from 17 pediatric patients with fractures treated with magnesium screws were assessed for the presence and distribution of intraosseous, extraosseous, and intra-articular gas; gas within the growth plate; osteolysis along the screw; joint effusion; bone marrow edema; periosteal reaction; soft tissue edema; and metal-induced artifacts.

RESULTS

Gas locules were found in the bone and soft tissues in 100% of the examinations, intra-articular in 40%, and in 37% of unfused growth plates. Osteolysis and the periosteal reaction were present in 87%, bone marrow edema in 100%, soft tissue edema in 100%, and joint effusion in 50% of examinations. Pile-up artifacts were present in 100%, and geometric distortion in 0% of examinations. Fat suppression was not significantly impaired in any examination.

CONCLUSIONS

Gas and edema in the bone and soft tissues are normal findings during the resorption of magnesium screws and should not be misinterpreted as infection. Gas can also be detected within growth plates. MRI examinations can be performed without metal artifact reduction sequences. Standard fat suppression techniques are not significantly affected.

Nonunion of humeral medial condyle fracture caused by excessive functional exercise: a case report and review of the literature

Background

Medial epicondyle fractures are one of the more common humerus fractures, but humeral medial condyle fracture (HMCF) is rare. Nonunion of medial humeral condyle fractures due to functional exercise is less common.

Case presentation

We report a 5-year-old patient with a nonunion HMCF due to excessive functional exercise, who bruised the elbow 1 year ago and had no positive findings on all imaging studies. On this physical examination, there was a snapping and palpable lump in the elbow joint during movement, but the patient did not feel any discomfort and the range of motion of the joint was normal. X rays and computed tomography (CT) showed that the left HMCF was discontinuous, the broken ends were dislocated, and the joint alignment was poor. Open reduction (OR) and screw fixation was used during the operation, and the patient recovered well at 3-month follow-up.

Conclusions

The rarity and low radiographic appearance of displaced HMCF are easily overlooked and can eventually lead to nonunion HMCF, especially when radiographically difficult to visualize before age 5 years. Therefore, regardless of whether there are signs or imaging abnormalities in the growth process of adolescents, they should be vigilant, shorten the time interval for re-examination, and early detection and timely treatment can avoid some complications caused by this.

Occult Fractures in Children with a Radiographic Fat Pad Sign of the Elbow: A Meta-Analysis of 10 Published Studies

BACKGROUND

A radiographic fat pad sign after an elbow injury in children may indicate an occult fracture. Different incidences and locations of occult fractures have been reported. The primary objective of this meta-analysis was to assess the overall rate of occult fractures in children with a positive fat pad sign from the data of original studies. Secondary objectives were to assess the fracture types and to identify risk factors for sustaining an occult fracture.

METHODS

A systematic literature search of the Embase, MEDLINE, and Cochrane databases was performed according to PRISMA guidelines. Studies on pediatric populations with a positive fat pad sign identified using a lateral elbow radiograph and with follow-up imaging were included in this meta-analysis. Included studies were assessed for risk of bias with use of the MINORS (Methodological Index for NOn-Randomized Studies) instrument.

RESULTS

Ten studies with a total of 250 patients, of whom 104 had an occult fracture, were included. Accounting for heterogeneity between the studies, the overall occult fracture rate was 44.6% (95% confidence interval: 30.4% to 59.7%). The most common fracture locations were the supracondylar humerus (43%), proximal ulna (19%), proximal radius (17%), and lateral humeral condyle (14%). Definitions of a positive pad fad sign were not uniform among studies, and the follow-up imaging modality also varied (radiography, magnetic resonance imaging, or computed tomography). The average MINORS score was 10.1 for the 7 noncomparative studies and 18.7 for the 3 comparative studies, with both averages classified as moderate quality. We were not able to identify risk factors for an occult fracture in the presence of a positive fat pad sign.

CONCLUSIONS

The occult fracture rate was 44.6% in pediatric elbow injuries with a positive fat pad sign. Supracondylar humeral fractures were the most frequently encountered type. The findings of this meta-analysis underline the potential clinical relevance of a positive fat pad sign in children and denote the opportunity for future studies to create evidence-based guidelines.

LEVEL OF EVIDENCE

Level II. See Instructions for Authors for a complete description of levels of evidence.

Resumption of school after lockdown in COVID-19 pandemic: Three case reports

BACKGROUND

Students in the 9^th grade of junior high school in Changsha were under a 75 d lockdown due to the coronavirus disease 2019 (COVID-19) pandemic. After the resumption of school post-lockdown, the 9^th grade students in Changsha faced the entrance physical examination test for senior high school.

CASE SUMMARY

We report on 3 cases of occult fracture on the same site in adolescents of the same grade since resumption of school after the lockdown from the COVID-19 pandemic. Three students in the 9^th grade of junior high school who were facing the physical examination in 2 wk were diagnosed with an occult fracture of the distal femur.

CONCLUSION

It is recommended that the students, parents, education providers and policy makers should all pay attention to the physical exercise of students when the resumption of school after lockdown occurs and they should be aware of occult fractures when the adolescents have pain after physical exercise.

Pediatric Imaging of the Elbow: A Pictorial Review

The elbow is a complex joint, subject to a wide range of traumatic, inflammatory, metabolic and neoplastic insults. The pediatric elbow has several diagnostic pitfalls due to the normal developmental changes in children. Knowledge of these normal variants is essential for both diagnosis and management of their elbow injuries. Radiography remains the first imaging modality of choice. Magnetic resonance imaging is excellent in evaluating lesions within the bone and soft tissues. In this pictorial essay, we provide insights into pediatric elbow imaging, show a range of entities specific to the pediatric elbow, and discuss diagnostic pitfalls that result from normal elbow growth in children.

Proximal radius fractures in children: evaluation of associated elbow fractures

BACKGROUND

Additional fractures occur in association with proximal radius fractures, but the extent of these secondary injuries has not been systematically assessed.

OBJECTIVE

To ascertain the frequency and nature of additional fractures associated with proximal radius injuries in a large pediatric cohort.

MATERIALS AND METHODS

Radiographs meeting search criteria for proximal radius fracture during a 5-year period were reviewed. Fracture characteristics and the coexistence of additional elbow fractures were recorded and analyzed. The retrospective review was compared with initial interpretation and a blinded review by two pediatric musculoskeletal radiologists.

RESULTS

Four hundred ninety-four proximal radius fractures were included. The radial neck was the most common fracture site (89%). Neck fractures occurred in younger patients (mean: 7.3 years) than head fractures (mean: 13.3 years) (P<0.001). Additional elbow fractures occurred in 39%, most commonly at the olecranon (22%). Additional fractures occurred in younger patients (mean: 7.2 years) than isolated proximal radius fractures (mean: 8.5 years) (P<0.001). Elbow joint effusion and complete or displaced radius fractures were each associated with additional elbow fractures (P<0.001). When compared with initial interpretation, 25% of additional fractures were not identified on initial radiographs, of which 44% were occult retrospectively. Fracture identification demonstrated excellent inter-reader reliability (interclass correlation coefficient [ICC]: 0.88, 0.94), but joint effusion interobserver agreement was only fair (ICC: 0.52, 0.41).

CONCLUSION

Proximal radius fractures in children often occur in association with other elbow fractures, most commonly involving the olecranon. Enhanced awareness of these fracture patterns, especially in the setting of joint effusion or complete and displaced radius fractures, may improve detection to guide appropriate management.

Using the Medial and Lateral Humeral Lines as an Adjunct to Intraoperative Elbow Arthrography to Guide Intraoperative Reduction and Fixation of Distal Humerus Physeal Separations Reduces the Incidence of Postoperative Cubitus Varus

BACKGROUND

Distal humerus physeal separations are rare pediatric elbow fractures that are often misdiagnosed and difficult to treat. Adequate reduction is often technically challenging and up to 71% of children develop postoperative cubitus varus. We propose using the medial and lateral humeral lines as an adjunct to elbow arthrography in order to guide intraoperative fixation of distal humerus physeal separations to reduce the incidence of postoperative cubitus varus.

METHODS

From 2009 to 2014, all pediatric patients under the age of 3 diagnosed with a distal humerus physeal separation and treated surgically at our institution were included for analysis. Two senior pediatric orthopaedic surgeons separately reviewed the preoperative, intraoperative, and postoperative images of all patients and measured the position of the ulnar axis relative to the medial and lateral humeral lines. The medial and lateral humeral shafts were defined as parallel lines drawn along the medial and lateral humeral diaphysis. Adequate reduction was defined by reduction of the ulnar axis within the boundaries of the medial and lateral humeral lines. Patients were assessed at latest follow-up for cubitus varus and any other surgical complications.

RESULTS

Thirteen patients fulfilled the inclusion criteria and were on average 1.70 years old, ranging from 0.62 to 3 years old. Intraoperatively and immediately postoperatively, all 13 patients (100%) were noted to have adequate reduction of the ulnar axis within the boundaries medial and lateral humeral lines. None of the patients required intraoperative arthrography (0%). At the date of latest follow-up, 12 patients (92.3%) had no angular deformities compared with the contralateral limb and 1 patient (7.7%) had developed cubitus varus. No surgical complications were noted (0%).

CONCLUSION

Intraoperative reduction of the ulnar axis within the boundaries of the medial and lateral humeral lines is associated with a lower incidence of postoperative cubitus varus in the treatment of distal humerus physeal separations in children.

LEVEL OF EVIDENCE

Level IV.

Useful Plain Radiographic Findings in Diagnosis of Pediatric Olecranon Fracture Complicated With Proximal Radial Fracture

OBJECTIVE

The aim of this study was to verify the use of initial plain radiographs, specifically the presence of a longitudinal crack on the olecranon, for diagnosing olecranon occult fractures in children.

METHODS

We retrospectively reviewed all patients younger than 16 years who were diagnosed with proximal radial fractures treated at our hospital between April 1, 2006 and September 31, 2014. We included 22 patients (9 boys and 13 girls) with a mean age of 8.5 years. Three hand surgeons were blinded to each other's results after examining all the initial radiographs of the injured elbows. To diagnose the fracture, we evaluated computed tomography scans in 9 cases and follow-up radiographs in the other 13 cases. Finally, we classified the fractured olecranon into 3 types: medial crack, posterior flat, and posterior crack.

RESULTS

Twelve cases (54.5%) had associated olecranon fractures. According to the fracture type of the olecranon, 3 cases were a medial crack, 5 were a posterior flat, and 3 were a posterior crack. Each type of fracture had characteristic findings on plain radiographs. The mean value for sensitivity was 97.2% (range, 91.7%-100%), and the specificity was 90.0% (90.0%).

CONCLUSIONS

Our data indicated that this easy, noninvasive use of plain radiographs for checking whether a longitudinal crack exists on the olecranon benefits the patient by preventing missed diagnoses of pediatric olecranon fractures.

MRI for occult physeal fracture detection in children and adolescents

BACKGROUND

Conventional radiography has limitations in the detection of physeal fractures before the closure of the physis occurs. Fracture detection may be improved by using magnetic resonance imaging (MRI).

PURPOSE

To evaluate the usefulness of MRI for the detection of occult fractures involving the physis when radiography results are negative.

MATERIAL AND METHODS

In this prospective study, 24 children (age range, 3-15 years; mean age, 10.7 years) received MRI if they met the following criteria: acute joint trauma, swelling and tenderness around the joint, limitations in bearing weight, an open physis, and negative radiography results for fractures. Fractures revealed by the MRI were classified according to the Salter-Harris classification system. Joint effusion, bone marrow edema, and periosteal alterations were graded on a three-point scale. The non-parametric Wilcoxon test and Fisher's exact test were used for the statistical evaluation.

RESULTS

From a total of 24 MR data-sets, 23 were evaluated (one patient was excluded due to poor MR image quality). Elbow injuries were present in 10 patients (43.5%), distal tibia injuries in 10 patients (43.5%), and distal femur injuries in three patients (13%). MRI results excluded physeal fractures in 15 (65.2%) of the 23 children. An occult physeal fracture was detected with MRI in eight (34.8%) patients; of these, five (21.7%) had fractures of the elbow, two (8.7%) had fractures of the distal tibia, and one (4.3%) had a fracture of the distal femur. All of the patients with fractures and 11 of the 15 patients without fractures demonstrated bone marrow edema.

CONCLUSION

The frequency of occult fracture, as detected by MRI, was 34.8%. Thus, MRI is a useful additional imaging method for the detection of occult fractures when radiography is negative.

The role of fat pad sign in diagnosing occult elbow fractures in the pediatric patient: a prospective magnetic resonance imaging study

In 1954, Norell described the 'fat pad sign' for the first time. This refers to the radiological visualization of the elbow fatty tissue. This is a prospective study with the aim of clarifying the relation between the presence of a positive fat pad sign on the lateral radiograph and the type of injury verified on MRI. From January to December 2010, 31 children were diagnosed primarily with a positive fat pad sign. An above-the-elbow cast was applied and all patients were referred for an MRI within a few days. All patients were recommended a clinical follow-up and informed about the MRI results. After revision, five patients were found to have a negative fat pad sign and were excluded. This resulted in a total of 26 patients, 10 men and 16 women, mean age 10±2.62 years. The time between the injury and the initial radiological examination was 0.8±0.27 days and the MRI was obtained on an average of 6.6±3.84 days. A total of 12 patients had an injury of the left side and 14 of the right side. The MRI showed a posterior positive sign in all except five cases and six occult fractures, which accounts for 23%. Nineteen patients (73%) had a bone bruise. All patients except one had a normal range of movement with no pain on the last clinical examination after 2-3 weeks. The presence of a positive fad pad sign is not synonymous with occult fractures. Finding occult fractures on MRI does not alter the final treatment of these patients. On the basis of this study and review of other similar studies, pediatric patients who presented with elbow effusion verified on conventional radiographs could be treated with a cast for 2-3 weeks and extra clinical or radiological controls did not seem to be indicated.

LEVEL OF EVIDENCE

Level III, development of diagnostic criteria on the basis of consecutive patients.

The predictive value of a normal radiographic anterior fat pad sign following elbow trauma in children

OBJECTIVE

The purposes of this study were to describe the characteristics of a normal anterior fat pad (AFP) and to determine the association between a normal AFP and the absence of fracture.

METHODS

A prospective cohort of children aged 1 to 18 years with elbow trauma underwent radiographic examination. All patients received standard orthopedic management and follow-up 7 to 14 days after injury. A pediatric radiologist evaluated all radiographs for the presence or absence of fracture and documented whether the AFP was normal or abnormal on the lateral view. The radiologist also recorded specific measurements of the AFP including the apical angle, which is formed by the intersection of the humerus and the superior aspect of the AFP. The interpretation of the AFP on the initial lateral radiograph was compared with the final patient outcome (fracture/no fracture).

RESULTS

Two hundred thirty-one patients had elbow radiographs; 34 patients (15%) were lost to follow-up. A total of 56 fractures were identified: 49 (87%) on the initial radiograph and an additional 7 (13%) on follow-up radiographs. This latter group was defined as occult fractures. Among the 197 patients available for analysis, 113 (57%) had a normal AFP on the initial radiograph. Of these, 2 children had a final diagnosis of fracture. The sensitivity of a normal AFP was 96.4% (95% confidence interval, 86.6%-99.4%), and the negative predictive value was 98.2% (95% confidence interval, 93.1%-99.7%). There was a significant difference in mean AFP angle when the AFP was read as normal (14.7 [SD, 3.3] degrees) compared with when it was read as abnormal (27.0 [SD, 6.8] degrees) (P < 0.01).

CONCLUSIONS

Our data suggest that a normal AFP is highly associated with absence of elbow fracture and that the determination of a normal AFP can be aided by measuring the apical angle of the AFP.

Elbow extension test to rule out elbow fracture: multicentre, prospective validation and observational study of diagnostic accuracy in adults and children

OBJECTIVE

To determine whether full elbow extension as assessed by the elbow extension test can be used in routine clinical practice to rule out bony injury in patients presenting with elbow injury.

DESIGN

Adults: multicentre prospective interventional validation study in secondary care. Children: multicentre prospective observational study in secondary care.

SETTING

Five emergency departments in southwest England.

PARTICIPANTS

2127 adults and children presenting to the emergency department with acute elbow injury.

INTERVENTION

Elbow extension test during routine care by clinical staff to determine the need for radiography in adults and to guide follow-up in children.

MAIN OUTCOME MEASURES

Presence of elbow fracture on radiograph, or recovery with no indication for further review at 7-10 days.

RESULTS

Of 1740 eligible participants, 602 patients were able to fully extend their elbow; 17 of these patients had a fracture. Two adult patients with olecranon fractures needed a change in treatment. In the 1138 patients without full elbow extension, 521 fractures were identified. Overall, the test had sensitivity and specificity (95% confidence interval) for detecting elbow fracture of 96.8% (95.0 to 98.2) and 48.5% (45.6 to 51.4). Full elbow extension had a negative predictive value for fracture of 98.4% (96.3 to 99.5) in adults and 95.8% (92.6 to 97.8) in children. Negative likelihood ratios were 0.03 (0.01 to 0.08) in adults and 0.11 (0.06 to 0.19) in children.

CONCLUSION

The elbow extension test can be used in routine practice to inform clinical decision making. Patients who cannot fully extend their elbow after injury should be referred for radiography, as they have a nearly 50% chance of fracture. For those able to fully extend their elbow, radiography can be deferred if the practitioner is confident that an olecranon fracture is not present. Patients who do not undergo radiography should return if symptoms have not resolved within 7-10 days.

MDCT of the Elbow in Pediatric Patients with Posttraumatic Elbow Effusions

OBJECTIVE

The purpose of this study was to determine the performance characteristics of MDCT in the detection of fractures in children with posttraumatic elbow effusions and to assess the effect of MDCT findings on clinical management.

SUBJECTS AND METHODS

Unenhanced MDCT of the elbow was prospectively performed without sedation on 31 children 20 months to 16 years old who had posttraumatic elbow effusions. Two blinded reviewers independently and in consensus characterized all MDCT scans as positive or negative for the presence of fracture. Level of interobserver agreement was determined with the kappa statistic. Sensitivity, specificity, positive predictive value, and negative predictive value of MDCT for fracture detection were determined for the consensus MDCT interpretations with follow-up radiographs as the reference standard. Patients were treated with casts and instructed to return in 2-3 weeks for clinical and radiographic follow-up unless a change in management was indicated on the basis of MDCT findings. The frequency of alteration of management was determined.

RESULTS

Both reviewers detected fractures in 15 (48%) of the patients individually and in 16 (52%) of the patients by consensus. Interobserver agreement for fracture detection with MDCT was excellent (kappa = 0.85). The sensitivity, specificity, positive predictive value, and negative predictive value of MDCT in the detection of fractures were 92%, 79%, 79%, and 92%, respectively. Four (13%) of the children had changes in management based on the MDCT findings.

CONCLUSION

MDCT is a sensitive means of evaluating for radiographically occult fractures in children with posttraumatic elbow effusions. It has a high negative predictive value and a high level of interobserver agreement. MDCT findings may lead to alteration of treatment of children with nondisplaced lateral condylar and radial head fractures.

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.

Are bone bruises a possible cause of osteochondritis dissecans of the capitellum? A case report and review of the literature

A 17-year old soccer-player sustained a fracture and dislocation of the ulnar epicondyle combined with a bone bruises at the radial head and the capitellum. An open reduction and internal fixation was performed using two K-wires. Initial recovery was uneventful. After the operation he was discharged home and reviewed on a regular basis. When bony union had occurred the two K-wires were removed. However, on follow up he continued to complain of pain on the radial aspect of the joint and did not regain his normal range of movement. A further MRI was performed. Now a grade II osteochondritis dissecans not visible on the previous MRI taken 12 weeks earlier was clearly visualised. Treatment was continued conservatively with physiotherapy but avoiding aggressive mobilisation. On final review 6 months later he was able to move painfree with residual limitation of movement (ROM 0-5-130 degrees). Another MRI taken now was assessed as normal.

Clinical diagnosis of fractures in a paediatric population

Diagnosing fractures in the paediatric population is a problematical process for which there are currently no accepted clinical criteria. We studied the physical signs sought by accident and emergency staff in 126 children with suspected fractures. We found a significant correlation between 'point tenderness' and fracture, as demonstrated by plain radiograph. 'Swelling' and 'redness' approached significance. These results correlate well with previous work in this area, but further research using a larger sample is required as confirmation.

Therapeutische Relevanz der Magnetresonanztomographie bei Gelenkverletzungen im Kindesalter

AIM

In this retrospective study, we assessed whether the use of MRI in children provides additional, therapeutically relevant information to assist in the diagnosis of joint injuries. In addition, we determined whether the usefulness of this approach is dependant on age of the child and localisation of the trauma.

METHOD

MRI of 45 children aged between 3 and 16 years were analysed independently by four different investigators (two radiologists, two trauma surgeons) and assessed for their therapeutic relevance.

RESULT

MRI of the knee (n=18) gave additional information in 11 patients (61%) and led to a change in the recommended therapy involving arthroscopy in seven patients (39%). MRI of the ankle (n=21) provided additional information in 12 patients (57%) and the decision for further therapy was influenced in six patients (29%), however, the indication for surgery was not influenced. The diagnosis of injuries of the elbow (n=6) was changed in four patients (67%), but the therapeutic decision was not influenced.

CONCLUSION

MRI additional to conventional x-ray provides relevant information on the therapeutic procedure to be used for the knee, whereas for the ankle and the elbow MRI it rarely delivers additional information relevant to therapeutic decision making.

Magnetic resonance imaging of the elbow. Part I: normal anatomy, imaging technique, and osseous abnormalities

Part I of this comprehensive review on magnetic resonance imaging of the elbow discusses normal elbow anatomy and the technical factors involved in obtaining high-quality magnetic resonance images of the elbow. Part I also discusses the role of magnetic resonance imaging in evaluating patients with osseous abnormalities of the elbow. With proper patient positioning and imaging technique, magnetic resonance imaging can yield high-quality multiplanar images which are useful in evaluating the osseous structures of the elbow. Magnetic resonance imaging can detect early osteochondritis dissecans of the capitellum and can be used to evaluate the size, location, stability, and viability of the osteochondritis dissecans fragment. Magnetic resonance imaging can detect early stress injury to the proximal ulna in athletes. Magnetic resonance imaging can detect radiographically occult fractures of the elbow in both children and adults. Magnetic resonance imaging is also useful in children to further evaluate elbow fractures which are detected on plain-film radiographs.

The Fat Pad Sign Following Elbow Trauma in Adults

OBJECTIVE

An elbow joint effusion with no fracture seen on radiographs after acute trauma has become synonymous with occult fracture. This study evaluates the incidence of fracture in such cases as determined by MR imaging and the predictive value of an elbow joint effusion.

METHODS

Twenty consecutive patients whose posttrauma elbow radiographs showed an effusion but no fracture and who were suitable for MR imaging were recruited. The elbow effusion size, represented by anterior and posterior fat pad displacement, was measured from the initial lateral elbow radiograph. Suitable candidates underwent MR imaging using a bone marrow sensitive sequence. The time between injury and MR imaging ranged from 0 to 12 days (mean 4 days).

RESULTS

Seventy-five percent of the 20 patients who underwent MR imaging had radiographically occult fractures identified. Some (86.6%) of these fractures were located in the radial head, 6.7% were in the lateral epicondyle, and 6.7% were in the olecranon. Ninety percent had evidence of bone marrow edema. Fifteen percent had collateral ligament disruption identified on MR imaging, and 5% had a loose body. There was no change in patient management as a result of the additional imaging. The anterior fat pad displacement ranged from 5 to 15 mm (mean 9.25), and the posterior fat pad was elevated from 1 to 6 mm (mean 3.2).

CONCLUSION

Our data using MR imaging suggests that fat pad elevation in the presence of recent trauma is frequently associated with a fracture. The size of the effusion, anterior/posterior fat pad elevation, or a combination of both does not correspond to the likelihood of an underlying fracture. MR imaging reveals a broad spectrum of bone and soft tissue injury beyond that recognizable on plain radiographs as demonstrated by all patients in this study.

Imaging of elbow injuries in the child and adult athlete

Because of the often complex and sometimes poorly remembered history of trauma to the elbow, imaging beyond conventional plain film radiographs is often needed. Usually, this consists of high-resolution MR imaging to evaluate the articular cartilage, supporting ligaments, and tendons about the elbow. Sonography, however, can also be used, especially when there is a targeted clinical question as to the presence of epicondylitis, or to provide guidance for diagnostic or therapeutic injections.

Elbow effusions in trauma in adults and children: is there an occult fracture?

OBJECTIVE

The purpose of this study was to evaluate whether a detectable abnormality was present on MR imaging without a visible fracture on conventional radiography in the setting of trauma. A recent retrospective study based on the presence or absence of periosteal reaction on follow-up radiographs concluded that fractures were not always present. The discrepancies in the literature over the usefulness of joint effusions as an indicator of fracture caused us to evaluate whether fractures were present more often than identified by conventional radiography. To do this, we used MR imaging.

MATERIALS AND METHODS

Thirteen consecutive patients (age range, 4-80 years; seven children and six adults), whose post-trauma elbow radiographs showed an effusion but no fracture, underwent screening MR imaging.

RESULTS

All patients showed bone marrow edema. Four of the seven children had fractures on screening MR imaging, and all adults had some identifiable fractures.

CONCLUSION

Preliminary data using screening MR imaging suggests that an occult fracture usually is present in the setting of effusion without radiographically visualized fracture.