Orthopedic pitfalls in the ED: radiographically occult hip fracture

Hip effusions or iliopsoas hematomas on ultrasound in identifying hip fractures in the emergency department

OBJECTIVE

We evaluated the sensitivity, specificity, predictive values, and likelihood ratios of hip effusion and/or iliopsoas hematoma on point-of-care ultrasound (POCUS) performed by ultrasound fellows and fellowship trained emergency providers to identify hip fractures in emergency department (ED) patients with a high suspicion of hip fracture.

METHODS

This was a prospective observational study of a convenience sample of patients with high suspicion of hip fracture at two academic EDs between 2018 and 2021. Patients with negative x-rays who did not receive further imaging with magnetic resonance imaging (MRI) or computed tomography (CT) were excluded. Sonographers were blinded to clinical data and ED imaging results. At the primary site, 8 ultrasound fellows and 4 emergency ultrasound fellowship-trained emergency providers performed the ultrasonographic examinations. At the secondary site, 2 ultrasound fellows, 4 emergency ultrasound-fellowship trained physicians, and 1 sports medicine fellowship-trained emergency provider performed the ultrasonographic examinations. A positive ultrasound was defined as either the presence of a hip effusion or iliopsoas hematoma on the affected extremity. The primary outcome measures were sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (LR+), and negative likelihood ratio (LR-) of POCUS findings for identification of a hip fracture compared with a ranked composite reference standard consisting of x-ray, CT, or magnetic resonance imaging (MRI); the highest-level test performed for each patient was used for comparison.

RESULTS

Among 213 patients analyzed, all 213 received an x-ray, 116 received a CT scan, and 14 received an MRI; 113/213 x-rays (53.1%), 35/116 CT scans (30.2%), and 7/14 MRIs (50.0%) were positive for a hip fracture. A total of 123 patients were diagnosed with a hip fracture (57.7%). There were 13 false negative x-ray results. Overall, compared with the reference standard of x-ray, CT, or MRI, POCUS had a sensitivity of 97% (95% CI: 94%, 100%), specificity of 70% (95% CI: 61%, 79%), PPV of 82% (95% CI: 75%, 88%), and NPV of 94% (95% CI: 88%, 100%) in the identification of hip fractures; with a positive likelihood ratio of 3.22 (95% CI: 2.35, 4.43) and negative likelihood ratio of 0.05 (95% CI: 0.02, 0.12).

CONCLUSION

In a convenience sample of ED patients with high clinical suspicion for hip fracture, the presence of a hip effusion and/or iliopsoas hematoma on POCUS performed by expert emergency ultrasonographers showed high sensitivity in diagnosing patients with a hip fracture.

Cost-Effective Analysis of Dual-Energy Computed Tomography for the Diagnosis of Occult Hip Fractures Among Older Adults

OBJECTIVE

Early and accurate diagnosis of hip fractures minimizes morbidity and mortality. Although current guidelines favor magnetic resonance imaging (MRI) for the diagnosis of occult hip fractures, a new technology called dual-energy computed tomography (DECT) seems an effective alternative. This article investigates a potentially cost-effective strategy for the diagnosis of occult hip fractures in older adults in Singapore.

METHODS

A decision tree model was developed to compare costs from a payer's perspective and outcomes in terms of quality-adjusted life-years (QALYs) of different imaging strategies for diagnosing occult hip fracture, comparing MRI with DECT supplementing single-energy computed tomography (SECT) and SECT alone. Model inputs were obtained from local sources where available. Sensitivity analyses are performed to test the robustness of the results.

RESULTS

The MRI strategy was dominated by the DECT strategy, whereas DECT supplementing SECT provided 0.30 more QALYs at an incremental cost of SGD106.41 with an incremental cost-effectiveness ratio of SGD352.52 per QALY relative to SECT alone. DECT seemed a cost-effective strategy at a willingness-to-pay threshold of SGD50 000 per QALY.

CONCLUSION

DECT supplementing SECT is a cost-effective imaging strategy to diagnose occult hip fractures among older adults in Singapore and should be included in clinical pathways to expedite timely treatment and considered for reimbursement schemes.

External Validation of Deep Learning Algorithm for Detecting and Visualizing Femoral Neck Fracture Including Displaced and Non-displaced Fracture on Plain X-ray

This study aimed to develop a method for detection of femoral neck fracture (FNF) including displaced and non-displaced fractures using convolutional neural network (CNN) with plain X-ray and to validate its use across hospitals through internal and external validation sets. This is a retrospective study using hip and pelvic anteroposterior films for training and detecting femoral neck fracture through residual neural network (ResNet) 18 with convolutional block attention module (CBAM) +  + . The study was performed at two tertiary hospitals between February and May 2020 and used data from January 2005 to December 2018. Our primary outcome was favorable performance for diagnosis of femoral neck fracture from negative studies in our dataset. We described the outcomes as area under the receiver operating characteristic curve (AUC), accuracy, Youden index, sensitivity, and specificity. A total of 4,189 images that contained 1,109 positive images (332 non-displaced and 777 displaced) and 3,080 negative images were collected from two hospitals. The test values after training with one hospital dataset were 0.999 AUC, 0.986 accuracy, 0.960 Youden index, and 0.966 sensitivity, and 0.993 specificity. Values of external validation with the other hospital dataset were 0.977, 0.971, 0.920, 0.939, and 0.982, respectively. Values of merged hospital datasets were 0.987, 0.983, 0.960, 0.973, and 0.987, respectively. A CNN algorithm for FNF detection in both displaced and non-displaced fractures using plain X-rays could be used in other hospitals to screen for FNF after training with images from the hospital of interest.

Emphasizing the Diagnostic Value of Digital Tomosynthesis in Detecting Hip Fractures

Our institution recently implemented the use of digital tomosynthesis (DTS) to workup emergency room patients with suspected hip fractures after initial negative or indeterminate radiographs. Our purpose is to evaluate the diagnostic accuracy of DTS for hip fracture detection. We performed a retrospective review of all DTS studies over a 17-month period (July 2017 to November 2018). The results of the radiographs and DTS were recorded as either positive or negative for fracture based on the radiology report. Our reference standard for a fracture was either confirmation on subsequent CT or MRI from the same visit or documentation of clinical findings supportive of a fracture in the patient’s electronic medical record. For patients with negative DTS who did not undergo subsequent cross-sectional imaging, a missed fracture was excluded if they did not return within 30 days with a confirmed fracture. Among 91 patients, there were 34 confirmed fractures—sites including, 7 femoral necks, 10 pubic rami, and 7 greater trochanters. DTS was positive for fracture in 29 patients; 28 of these fractures were true positives, 6 confirmed on cross-sectional imaging, and 22 confirmed clinically. One false positive was observed in a patient with no clinical evidence of a fracture. Six fractures were not detected by tomosynthesis but confirmed on CT/MRI. The sensitivity and specificity of DTS are 82% and 98%, respectively, compared to that of radiographs alone at 47% and 96%, respectively. DTS is a promising adjunct to radiographs for hip fracture detection in an emergency department.

Femoral neck fracture detection in X-ray images using deep learning and genetic algorithm approaches

Objectives

This study aims to detect frontal pelvic radiograph femoral neck fracture using deep learning techniques.

Patients and methods

This retrospective study was conducted between January 2013 and January 2018. A total of 234 frontal pelvic X-ray images collected from 65 patients (32 males, 33 females; mean age 74.9 years; range, 33 to 89 years) were augmented to 2106 images to achieve a satisfactory dataset. A total of 1,341 images were fractured femoral necks while 765 were non-fractured ones. The proposed convolutional neural network (CNN) architecture contained five blocks, each containing a convolutional layer, batch normalization layer, rectified linear unit, and maximum pooling layer. After the last block, a dropout layer existed with a probability of 0.5. The last three layers of the architecture were a fully connected layer of two classes, a softmax layer and a classification layer that computes cross entropy loss. The training process was terminated after 50 epochs and an Adam Optimizer was used. Learning rate was dropped by a factor of 0.5 on every five epochs. To reduce overfitting, regularization term was added to the weights of the loss function. The training process was repeated for pixel sizes 50x50, 100x100, 200x200, and 400x400. The genetic algorithm (GA) approach was employed to optimize the hyperparameters of the CNN architecture and to minimize the error after testing the model created by the CNN architecture in the training phase.

Results

Performance in terms of sensitivity, specificity, accuracy, F1 score, and Cohen’s kappa coefficient were evaluated using five- fold cross validation tests. Best performance was obtained when cropped images were rescaled to 50x50 pixels. The kappa metric showed more reliable classifier performance when 50x50 pixels image size was used to feed the CNN. The classifier performance was more reliable according to other image sizes. Sensitivity and specificity rates were computed to be 83% and 73%, respectively. With the inclusion of the GA, this rate increased by 1.6%. The detection rate of fractured bones was found to be 83%. A kappa coefficient of 55% was obtained, indicating an acceptable agreement.

Conclusion

This experimental study utilized deep learning techniques in the detection of bone fractures in radiography. Although the dataset was unbalanced, the results can be considered promising. It was observed that use of smaller image size decreases computational cost and provides better results according to evaluation metrics.

Detection and localisation of hip fractures on anteroposterior radiographs with artificial intelligence: proof of concept

AIM

To investigate the feasibility of applying a deep convolutional neural network (CNN) for detection/localisation of acute proximal femoral fractures (APFFs) on hip radiographs.

MATERIALS AND METHODS

This study had institutional review board approval. Radiographs of 307 patients with APFFs and 310 normal patients were identified. A split ratio of 3/1/1 was used to create training, validation, and test datasets. To test the validity of the proposed model, a 20-fold cross-validation was performed. The anonymised images from the test cohort were shown to two groups of radiologists: musculoskeletal radiologists and diagnostic radiology residents. Each reader was asked to assess if there was a fracture and localise it if one was detected. The area under the receiver operator characteristics curve (AUC), sensitivity, and specificity were calculated for the CNN and readers.

RESULTS

The mean AUC was 0.9944 with a standard deviation of 0.0036. Mean sensitivity and specificity for fracture detection was 97.1% (81.5/84) and 96.7% (118/122), respectively. There was good concordance with saliency maps for lesion identification, but sensitivity was lower for characterising location (subcapital/transcervical, 84.1%; basicervical/intertrochanteric, 77%; subtrochanteric, 20%). Musculoskeletal radiologists showed a sensitivity and specificity for fracture detection of 100% and 100% respectively, while residents showed 100% and 96.8%, respectively. For fracture localisation, the performance decreased slightly for human readers.

CONCLUSION

The proposed CNN algorithm showed high accuracy for detection of APFFs, but the performance was lower for fracture localisation. Overall performance of the CNN was lower than that of radiologists, especially in localizing fracture location.

Use of Multislice CT for Investigation of Occult Geriatric Hip Fractures and Impact on Timing of Surgery

Introduction:

The National Institute of Health and Clinical Excellence guidelines in the United Kingdom recommend magnetic resonance imaging (MRI) as the first-line investigation for radiographically occult hip fractures, if available within 24 hours. In our department, however, multislice computerized tomography (MSCT) is instead used as a first-line investigation due to significant delays associated with obtaining MRI. Our aim was to determine the validity and practicality of MSCT for diagnosis of occult hip fractures and its impact on timing of surgery.

Materials and Methods:

We retrospectively analyzed medical records and imaging for consecutive patients who underwent MSCT to investigate occult hip fractures between January 2014 and October 2016. We reviewed subsequent imaging and reattendances for patients with negative MSCT to exclude initially missed fractures.

Results:

Two hundred six patients underwent MSCT to investigate occult hip fracture during the study period. Hip fractures were identified in 59 patients, comprising 35 (59.3%) subcapital, 12 (20.0%) intertrochanteric, 8 (13.6%) transcervical, and 4 (6.8%) basicervical fractures. One missed hip fracture was identified: a patient with a negative MSCT was further investigated with MRI that demonstrated acute subcapital hip fracture. Multislice computerized tomography was obtained within 24 hours of initial radiograph in 145 (70.4%) patients. A total of 44.5% of occult hip fractures had surgery within the nationally recommended 36 hours of admission (hospital average for all hip fractures was 76.4% over the same period).

Discussion and Conclusions:

Multislice computerized tomography is a pragmatic approach to investigate the majority of occult hip fractures in a timely manner and minimize associated delay to surgery. However it cannot completely exclude the diagnosis, especially in abnormal anatomy. The lack of a true gold standard comparison (ie, MRI) means a true sensitivity and specificity cannot be calculated, although can be cautiously estimated by lack of subsequent reattendance or investigation. Further prospective randomized CT versus MRI trials are required.

NHSLA litigation in hip fractures: Lessons learnt from NHSLA data

Hip fractures are a major cause of trauma related death, usually occurring in vulnerable elderly patients. There are an estimated 70,000 hip fractures in the UK per year with numbers set to rise. The estimated annual cost to the healthcare economy is in the region of £2 billion. A 17-year review examining litigation related to hip fractures was undertaken. Under a freedom of information request, data was obtained relating to all orthopaedic claims made to the NHS Litigation Authority (NHSLA) between 1995 and 2012. Data was filtered to identify cases involving hip fractures examining litigation trends related to this specific area. 10263 NHSLA orthopaedic cases were identified, of which 13.3% (n=1364) cases related to the hip and femur. Hip fractures made up 16.7% (n=229). The total cost of hip fracture litigation was over £7 million with an average cost per case of £32,700. The commonest reasons for litigation were diagnostic errors (30.6%), issues with care (24.9%) alleged incompetent surgery (15.7%) and development of pressure sores (5.7%). This study highlights the main causes of litigation in patients sustaining hip fractures, with diagnosis in the emergency department and ward presenting a significant problem. In addition, the data identifies a range of care related issues, as well as several surgical factors and highlights the importance of pressure area care. We discuss these and make suggestions on how to improve practice in this area with the aim of improving patient care and reducing litigation.

The sensitivity of ct scans in diagnosing occult femoral neck fractures

Non-displaced hip fractures can be difficult to diagnose on plain film radiographs. When there is ongoing clinical suspicion of an occult fracture, further imaging is obtained. We investigated the sensitivity of computed tomography (CT) scans in detecting these fractures and the delays to surgery that three-dimensional imaging causes. We identified 78 CT scans performed for possible hip fractures over the past 3 years with the presence and absence of a fracture recorded. Based on subsequent imaging, the accuracy of CT scans was determined. CT scanning yielded sensitivity was 86% and specificity 98% for occult hip fracture (OHF). The median delay to definitive diagnosis was 37h. Our results demonstrate that CT scan does not bear sufficient sensitivity to detect all OHFs. We therefore recommend that MRI should be offered when a fracture is suspected. CT scans should be reserved for when MRI is not available, but a negative scan should be confirmed with subsequent MRI.

Commonly missed injuries in the accident and emergency department

Accident and emergency (A&E) medicine is a high-risk speciality in which the majority of patients are managed by junior doctors with limited clinical experience. A review of the literature identified that the rate of missed injury ranges from 0.4 to 65%. Missed injuries are by definition preventable and have multiple implications for patients and health-care workers. This article reviews the types of injury that are commonly missed in A&E departments and identifies the errors that have been made in the past, with recommendations for management strategies to reduce the incidence of missed injury.

Accuracy of a modified axiolateral radiographic hip projection in suspected cases of hip fracture: experience and results from a regional trauma centre

Conventional radiographs play an important role as a first line imaging modality in the assessment for suspected hip fractures in the majority of trauma centres. The routinely performed radiographic projections in our emergency department for patients with clinically suspected hip fractures include antero-posterior (AP) and cross-table lateral views of the affected hip. Certain clinical scenarios which include the presence of significant pain of the injured lower limb, a large patient habitus, as well as pre-existing patient morbidity which would limit the range of motion of the lower limbs, for example the presence of prior joint replacement surgery or lower limb contractures, may however preclude proper positioning of the patient to obtain an optimal cross-table lateral view of the affected hip. The objective of this study is to investigate whether a modified axiolateral hip projection would be a feasible alternative to the cross-table lateral projection in the initial radiographic assessment of suspected cases of hip fracture.

Bilateral occult hip fracture

One of the most common acute injuries seen in the emergency department is the hip fracture. This injury is usually diagnosed by plain radiographs, however these fractures are sometimes not obviously apparent. Occult hip fractures present a pitfall for emergency department physicians. We present a case of a patient who sustained bilateral occult hip fractures. We review the epidemiology of the condition, examine what diagnostic studies are available that may help the physician avoid missing the occult hip fracture and what the literature tells us about the utility of each of these modalities. The prognosis of the occult hip fracture along with options for treatment is also discussed.

Is the Patellar Pubic Percussion Test useful to diagnose only femur fractures or something else? Two case reports

In the literature, the utility of the Patellar Pubic Percussion Test (PPPT) to diagnose occult fractures of the femur is well described. However, up to now there are no studies demonstrating the efficacy of this test in recognizing fractures of the pelvis. In this two case report a positive PPPT allowed the therapist to recognize clinical conditions requiring caution, protecting patients from a potentially unsuitable treatment. Both patients had a negative pelvis and femur x-ray after a fall, but the clinical findings and a positive PPPT lead the physiotherapist to suggest further examinations. In these two cases the PPPT seemed to be a useful diagnostic tool to identify periacetabular, ileo-pubic and ischio-pubic ramus fractures. These findings suggest that PPPT could be positive even for a bone lesion in any of the transit points of the vibration, from the patella to the pubic symphysis.

Easily Missed Fractures in the Lower Extremity

As long as radiography remains cheap and provides value in patient care, it will continue to be widely used as a front-line imaging technique. There are limitations to what a radiograph can depict, however. It is imperative to understand the limitations of radiography to avoid pitfalls owing to the overlap of numerous osseous structures. This article reminds the reader of the association between certain radiographic abnormalities and the anatomic relevance in the patient. Although interpretive errors occur in fast-paced, high-volume emergency settings, meticulous attention to changes in the cortex and medullary bone may help to keep errors to a minimum.

The use of computed tomography in identifying radiologically occult hip fractures in the elderly

INTRODUCTION

Fractured neck of femur (NOF) is a cause of significant morbidity and mortality. Approximately 4% of patients with an initial normal hip x-ray in the emergency department (ED) will in fact have an occult fracture. In cases where there is ongoing clinical suspicion of NOF fracture despite a normal hip x-ray, alternative imaging should be used. Although available evidence supports the use of magnetic resonance imaging (MRI) for this, it is often not readily accessible from the ED. In our department, it is common practice to request computed tomography (CT).

METHODS

A historical review was undertaken of all patients who presented between October 2007 and January 2011 who had CT requested by ED staff. Patients included in the study were those who presented following low impact trauma in whom fractured NOF was suspected despite a normal x-ray.

RESULTS

Of the 65 included patients, fractures (pelvic and hip) were identified in 38 patients on CT. Fractured NOFs were found in 13 patients. Acetabular fractures were found in nine patients, five of whom required further orthopaedic management. One patient went on to have MRI to confirm the diagnosis of an impacted NOF fracture, suspected both on x-ray and CT. Further review was undertaken of the medical notes of discharged patients to identify any who reattended or required further imaging. No such cases were found.

CONCLUSIONS

This review has shown the use of CT to be a practical approach to improving the care of patients with occult hip fractures.

Investigation of occult hip fractures: the use of CT and MRI

Aim. At present there is no data looking at modern multislice computerised tomography (CT) in the investigation of occult hip fracture. The aim of this study was to retrospectively compare the reports of patients sent for magnetic resonance imaging (MRI) or CT with negative radiographs and a clinical suspicion of a fractured neck of femur. Methods. All patients presenting to the hospital with a clinical suspicion of a hip fracture but initial negative radiographs over a three-year period were included. Patients were either investigated with an MRI scan or CT scan. The presence of a fracture, the requirement for surgery, and any further requirement for imaging were recorded. Results. Over three years 92 patients were included of which 61 were referred for a CT and 31 for an MRI. Thirty-four patients were found to have a fracture. Of these, MRI picked up a fracture in 36% and CT in 38% of referrals. Discussion. Up to 10% of proximal femur fractures may be missed on initial radiographs. Current guidelines state patients should be offered MRI if hip fracture is suspected despite negative hip radiographs. Our findings show that modern multislice CT may be comparable with MRI for detecting occult fracture.

Garden type I fractures myth or reality? A prospective study comparing CT scans with X-ray findings in Garden type I femoral neck fractures

The Garden type I femoral neck fracture is defined as an incomplete fracture of the neck of the femur as seen on the antero-posterior (AP) radiograph of the injured hip. The diagnosis of incomplete femoral neck fractures has decreased in recent years with the development of improved radiographic imaging. We hypothesized that incomplete femoral neck fractures seen on radiographs are in fact complete fractures on computed tomography (CT). The study aims to test this hypothesis by comparing CT scan images to X-ray findings in patients diagnosed with Garden type I femoral neck fractures. From January 2008 to October 2010, our management of femoral neck fractures included a CT scan of the injured hip for all Garden type I fractures. CT findings were reported by a musculoskeletal radiologist. A classification of the fracture was performed by an orthopedic surgeon. Eight hundred and twenty five femoral neck fractures were admitted during the study period. Seventeen of these fractures (2.1%) were considered incomplete based on radiographic evaluation. In 17 cases (100%), the CT scan demonstrated a complete fracture extending through the medial cortex. Subsequently, all 17 fractures were fixed with standard cannulated screw technique on a fracture table. Secondary displacement occurred in one patient prior to fixation. All fractures healed well and no avascular necrosis was noted. In summary, our study shows that incomplete femoral neck fractures identified on X-rays are actually complete fractures based on CT scans. If confirmed by a larger study population, our findings can simplify the Garden classification by eliminating an inaccurate subcategory. The clinical implications are that Garden type I fractures should all likely be fixed with cannulated screws and with an effort to prevent displacement during treatment.

Analysis of initial injury radiographs of occult femoral neck fractures in elderly patients: a pilot study

Diagnosis of occult hip fractures by initial radiographs remains challenging in the emergency department. Previously, the gold standard for accurate diagnosis of occult hip fractures was magnetic resonance imaging. This study used initial radiographs obtained in the emergency department to evaluate specific signs and measurements as diagnostic references for occult femoral neck fractures in elderly patients.Initial negative radiographs were reviewed for 2 groups of patients: a group with occult femoral neck fractures (n=16) and a group without fractures (n=32). Reviews of initial radiographs and all imaging studies were performed by a senior orthopedist (C-C.C.) and a radiologist (H-T.W.). Diagnostic signs included lateral, medial, anterior, and posterior signs; measurements included elevation of the fat pad and external rotation of the femur. The prevalence of occult femoral neck fracture was 3.3%. Initial radiographs of occult femoral neck fractures were not routinely negative; 14 (87.5%) of 16 patients with fractures had at least 1 radiographic sign. Using the positive lateral or posterior sign as the diagnostic reference, the sensitivity was 0.875 and the specificity was 0.906. When elevation of the fat pad was ⩾1.5 mm, the sensitivity was 0.867 and the specificity was 0.857 for the diagnosis of occult femoral neck fracture.The lateral and posterior signs and elevation of the fat pad ⩾1.5 mm on initial radiographs are recommended as diagnostic references for occult femoral neck fracture. These references are clearly defined and may offer important information for all clinicians and radiologists in the emergency department.

Bone bruise, lipohemarthrosis, and joint effusion in CT of non-displaced hip fracture

BACKGROUND

A suspected occult hip fracture after normal radiography is not uncommon in an elderly person after a fall. Despite a lack of robust validation in the literature, computed tomography (CT) is often used as secondary imaging.

PURPOSE

To assess the frequency and clinical utility of non-cortical skeletal and soft tissue lesions as ancillary fracture signs in CT diagnosis of occult hip fractures.

MATERIAL AND METHODS

All fracture signs (cortical and trabecular fractures, bone bruise, joint effusion, and lipohemarthrosis) were recorded in 231 hip low-energy trauma cases with CT performed after normal or equivocal radiography in two trauma centers.

RESULTS

There were no fracture signs in 110 patients. Twelve of these had a joint effusion. In 121 patients with 46 cervical hip fractures and 75 trochanteric fractures one or more fracture signs were present. Cortical fractures were found in 115 patients. Bone bruise was found in 119 patients, joint effusion in 35, and lipohemarthrosis in 20 patients.

CONCLUSION

Ancillary signs such as bone bruise and lipohemarthrosis can strengthen and sometimes indicate the diagnosis in CT of occult hip fractures. Joint effusion is a non-specific sign.

Role of MRI in hip fractures, including stress fractures, occult fractures, avulsion fractures

MR imaging plays a vital role in the diagnosis and management of hip fractures in all age groups, in a large spectrum of patient groups spanning the elderly and sporting population. It allows a confident exclusion of fracture, differentiation of bony from soft tissue injury and an early confident detection of fractures. There is a spectrum of MR findings which in part is dictated by the type and cause of the fracture which the radiologist needs to be familiar with. Judicious but prompt utilisation of MR in patients with suspected hip fractures has a positive therapeutic impact with healthcare cost benefits as well as social care benefits.

Acute hip pain and inability to ambulate: a rare presentation for perirectal abscess

A patient with acute hip pain out of proportion to physical findings and inability to weight bear despite negative plain films warrants further in-depth evaluation. Correctly diagnosing the cause of hip pain, a common emergency department (ED) complaint, may be a challenge in the geriatric population (Perron A, Miller M, Brady W. Orthopedic pitfalls in the ED: radiographically occult hip fracture. Am J Emerg Med 2002; 20: 234-7; Cannon J, Silvestri S, Munro M. Imaging choices in occult hip fracture. J Emerg Med 2009; 37: 144-52; Kiu A, Khan S. Radiology of acute hip and femoral injuries. Br J Hosp Med (London) 2010; 71: M22-M24; Zacher J, Gursche A. Regional musculoskeletal conditions: hip pain. Best Pract Res Clin Rheumatol 2003; 17: 71-85). A perirectal abscess as a cause of acute hip pain and inability to ambulate, with gluteus muscle inflammation but no evidence for bone or joint infection, has not been described, to the authors' knowledge. An 82-year-old woman with a history of diabetes, previously ambulatory, presented to the ED after being found on her apartment floor by a visiting health aide, complaining of acute pain in her left hip. Pain was exacerbated by palpation and range of motion testing, and she was unable to bear weight. There was no report of fever, rectal or abdominal pain, bleeding, or painful defecation. Plain films were negative for fracture or lytic lesion. Computerized tomography (CT) of the hip and pelvis was then obtained, which was negative for boney abnormality but revealed a 5-cm ischiorectal abscess with inflammation of the adjacent gluteus muscle. This case illustrates the potentially subtle nature of a deep perirectal abscess in an elderly patient. The CT imaging, useful for investigating the possibility of occult femoral neck fracture, was fortuitous in leading to the diagnosis. One must consider the possibility of visceral processes causing referred pain, when evaluating the patient with an acutely painful hip (Perron A, Miller M, Brady W. Orthopedic pitfalls in the ED: radiographically occult hip fracture. Am J Emerg Med 2002; 20: 234-7; Zacher J, Gursche A. Regional musculoskeletal conditions: hip pain. Best Pract Res Clin Rheumatol 2003; 17: 71-85).

Posttraumatic painful hip: sonography as a screening test for occult hip fractures

OBJECTIVE

Nondisplaced hip fractures may be radiographically occult and require magnetic resonance imaging (MRI) or bone scintigraphy for diagnosis. Both examinations are expensive and are not readily available in many hospitals. Our objective was to evaluate sonography as a screening tool for occult hip fractures in posttraumatic painful hips in elderly patients.

METHODS

We prospectively evaluated 30 patients (mean age, 73 years), who were admitted for painful hips after having low-energy trauma with nondiagnostic hip radiographs. After inclusion, patients underwent sonography of both hips for signs of injury. After completion of the sonographic examination and analysis of the results, patients underwent MRI of both hips. The sonographic findings were compared with the MRI findings, which served as the reference standard for accurate detection of a hip fracture.

RESULTS

Ten hip fractures were diagnosed by MRI. Sonography showed trauma-related changes in all of those patients and in 7 additional patients, 3 of whom had pubic fractures. Sonography correctly identified 13 patients without hip fractures. The sensitivity of sonography was found to be 100%, whereas the specificity for hip fractures was 65%.

CONCLUSIONS

Sonography for posttraumatic hip pain with negative radiographic findings did not result in a single missed hip fracture. Therefore, sonography may serve as an effective screening tool, mandating MRI only for cases with positive findings, whereas patients with negative sonographic findings need no further investigation. Sonography may therefore be very useful in hospitals around the world, where MRI may not be readily affordable or available.

Digital image enhancement improves diagnosis of nondisplaced proximal femur fractures

Today most emergency room radiographs are computerized, making digital image enhancement a natural advancement to improve fracture diagnosis. We compared the diagnosis of nondisplaced proximal femur fractures using four different image enhancement methods using standard DICOM (Digital Imaging and Communications in Medicine) after window-leveling optimization. Twenty-nine orthopaedic residents and specialists reviewed 28 pelvic images consisting of 25 occult proximal femur fractures and three images with no fracture, using four different image filters and the original DICOM image. For intertrochanteric fractures, the Retinex filter outperforms the other filters and the original image with a correct fracture type diagnosis rate of 50.6%. The Retinex filter also performs well for diagnosis of other fracture types. The Retinex filter had an interobserver agreement index of 53.5%, higher than the other filters. Sensitivity of fracture diagnosis increased to 85.2% when the Retinex filter was combined with the standard DICOM image. Correct fracture type diagnosis per minute for the Retinex filter was 1.43, outperforming the other filters. The Retinex filter may become a valuable tool in clinical settings for diagnosing fractures.

LEVEL OF EVIDENCE

Level I, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Use of the patellar-pubic percussion test in the diagnosis and management of a patient with a non-displaced hip fracture

This case report describes the diagnosis and subsequent medical and physical therapy management of a 68-year-old patient with an undiagnosed non-displaced hip fracture. Initial plain film radiographs and a computed tomography (CT) scan of the involved hip were both interpreted as negative. One of the findings on the physical examination included a positive patellar-pubic percussion test (PPPT). This finding in a female patient of this age raised the suspicion of an occult hip fracture and she was referred back to her primary care physician. Repeat radiographs revealed a non-displaced hip fracture and the patient was treated surgically. The PPPT is an easy-to-implement clinical examination tool that may be extremely useful in physical therapy practice to guide the decision-making process for patients with suspected hip fractures. The utilization of the PPPT by the treating physical therapist for the patient in this case report contributed to a timely diagnosis, potentially preventing the disabling sequelae associated with a displaced femoral fracture.

Imaging choices in occult hip fracture

BACKGROUND

Hip fracture is a common injury, with an incidence rate of > 250,000 per year in the United States. Diagnosis is particularly important due to the high dependence on the integrity of the hip in the daily life of most people.

OBJECTIVES

In this article we review the literature focused on hip fracture detection and discuss advantages and limitations of each major imaging modality.

DISCUSSION

Plain radiographs are usually sufficient for diagnosis as they are at least 90% sensitive for hip fracture. However, in the 3-4% of Emergency Department (ED) patients having hip X-ray studies who harbor an occult hip fracture, the Emergency Physician must choose among several methods, each with intrinsic limitations, for further evaluation. These methods include computed tomography, scintigraphy, and magnetic resonance imaging.

CONCLUSION

We present an evidence-based algorithm for the evaluation of a patient suspected to have an occult hip fracture in the ED. Also outlined are future directions for research to distinguish more effective techniques for identifying occult hip fractures.

MRI and CT of insufficiency fractures of the pelvis and the proximal femur

OBJECTIVE

Pelvic and proximal femur insufficiency fractures are of increasing significance in our aging population, and cross-sectional imaging is challenging. The aims of this study were to compare the sensitivity of CT and MRI in detecting insufficiency fractures; to analyze the typical location, morphology, and combinations thereof in these fractures; to analyze imaging morphology; and to analyze associated clinical findings.

MATERIALS AND METHODS

MRI studies obtained at 1.5 T were analyzed in 145 patients with pelvic insufficiency fractures. In 64 of 145 patients, MRI and multidetector CT (MDCT) findings were compared. Imaging studies were analyzed by two radiologists; combined clinical history, findings from all imaging studies, and follow-up imaging studies served as the standard of reference.

RESULTS

In the subgroup undergoing both imaging techniques, MRI detected 128 of 129 (99%) fractures in 63 of 64 (98%) subjects, whereas CT detected only 89 of 129 (69%) fractures in 34 of 64 (53%) subjects. In particular, fractures at the femoral head and acetabulum were better detected with MRI. In the complete population, two or more fractures were found in 70.3% (102/145) of patients, and 89.2% (33/37) of patients with pubic insufficiency fractures had concomitant fractures at other locations. In 63 of 145 (43.4%) patients, a previous malignancy was found; in only 93 of 145 (64.1%) patients, the leading symptom responsible for the MRI examination was pain.

CONCLUSION

This study showed that MRI was substantially better than CT in detecting insufficiency fractures. In addition, two or more insufficiency fractures were frequently present, typical fracture combinations were found, and insufficiency fractures were frequently associated with malignant disease.

Occult fractures of extremities

Recent advances in cross-sectional imaging, particularly in CT and MR imaging, have given these modalities a prominent role in the diagnosis of fractures of the extremities. This article describes the clinical application and imaging features of cross-sectional imaging (CT and MR imaging) in the evaluation of patients who have occult fractures of the extremities. Although CT or MR imaging is not typically required for evaluation of acute fractures, these modalities could be helpful in the evaluation of the occult osseous injuries in which radiographic findings are equivocal or inconclusive.

The advantages of MRI in the detection of occult hip fractures

While the displaced hip fracture can be visualized easily by plain radiography, the non-displaced fracture may be radiographically occult and require different imaging modalities, e.g., MRI for proper visualization. The accuracy of readers and cost advantages of utilizing MRI have not been assessed. Therefore, we undertook a study of these factors. The medical records of all patients who had visited the emergency room from June 2002 until May 2003 with a clinically suspected hip fracture, negative or equivocal plain film and subsequent MRI examination were retrospectively reviewed. Two senior and two junior radiologists independently evaluated both the MR images and radiographs of all 33 patients in a blinded study. One of three possible evaluations was described for the images of each modality: absence, presence or possibility of fracture. The economic consequences of using MRI in the detection of occult hip fractures were calculated. For all four doctors participating in this study, MRI proved to be far more sensitive and specific in the detection of occult hip fractures than radiography. Using the MR images, the senior radiologists identified the occult hip fracture patients with 100% accuracy and were in complete agreement. The agreement between junior and senior radiologists was high (average kappa=0.75). MRI also detected soft tissue injuries in 39% of the patients that could not be identified with radiography. Adoption of the new protocol using MRI saves hospitals from Euro 242 to 627 per patient. By shortening the time to diagnosis and permitting a superior visualization of both bone and soft tissue injuries, MR imaging prevents unnecessary hospitalization and delays in definitive treatment. MR images should be assessed by senior radiologists.

Occult trauma in high-risk populations

Several groups of patients are at increased risk for traumatic injury that is "occult," or not apparent on initial presentation. Perhaps the most notorious are those who abuse alcohol, but other groups include the elderly, coagulopathic, those with neurological disease, and the mentally ill. Moreover, traumatic injury can coexist with (or be masked by) medical pathology, resulting in the disposition of injured patients to nonsurgical services where surveillance for traumatic injury diminishes. Because delays or failures in diagnosis might result in unnecessary pain, morbidity, and mortality, it is important for the emergency physician to identify occult presentations of trauma before disposition. This review highlights commonly missed traumatic injuries in adult patients.