M u s c u l o s k e l e t a l I m a g i n g • R ev i ew Ha et al. Pitfalls in Radiography of Lower Extremity Trauma
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Musculoskeletal Imaging Review
Alice S. Ha1 Jack A. Porrino Felix S. Chew Ha AS, Porrino JA, Chew FS
Radiographic Pitfalls in Lower Extremity Trauma OBJECTIVE. Radiography remains the imaging standard for fracture detection after trauma. However, fractures continue to be the most common type of missed injuries. In this article, we describe common radiographic pitfalls in lower extremity trauma and describe strategies for dealing with them. CONCLUSION. Pitfalls include insufficient views, improperly positioned or technically imperfect radiographs, nondisplaced fractures, commonly missed locations, small avulsions portending large injury, sesamoid injuries, satisfaction of search, incomplete or faulty reasoning, and periprosthetic fractures.
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Keywords: fracture, lower extremity, pitfalls, radiography DOI:10.2214/AJR.14.12626 Received January 30, 2014; accepted after revision April 23, 2014. 1
All authors: Department of Radiology, University of Washington, Box 354755, 4245 Roosevelt Way NE, Seattle, WA 98105. Address correspondence to A. S. Ha ([email protected]).
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adiography remains the initial modality to detect or exclude the presence of a fracture. According to the American Academy of Orthopaedic Surgeons [1], 7,310,000 physician visits and 3,148,000 emergency department visits were related to extremity fractures in 2003, leading to 867,000 hospitalizations. Pitfalls for the radiologist that may result in a missed or delayed diagnosis abound in this circumstance. Failure to diagnose is the most common error alleged in medical malpractice suits against radiologists, and extremity fractures are the second most frequently missed diagnosis (after breast cancer) [2]. Although some missed fractures may be related to perceptual errors that appear to be avoidable in retrospect, others are related to anatomic, technical, and physiologic factors that are out of the interpreting radiologist’s control. In a recent study of 3081 confirmed fractures in emergency department patients, 115 fractures were initially missed [3]. Fifty-three percent of missed fractures occurred in the lower extremities, with the foot being the most missed location. Postulated reasons for these errors included subtle fractures (37%) and radiographically occult fractures (33%). Leeper et al. [4] showed that, of missed injuries at a level I trauma center (15%), 70% were fractures. In this article, we identify several common radiographic pitfalls in lower extremity trauma and describe strategies for dealing with them.
Pitfalls Pitfall 1: Insufficient Views Many fractures are visible on only a single view. If that view is not obtained, then the examination will be interpreted as falsely negative. Most radiology departments follow protocols that call for orthogonal views in frontal (anteroposterior or posteroanterior) and lateral projections for the long bones. For the hip, knee, ankle, and foot, various additional views may also be obtained (Table 1). At the knee, fractures of the patella may not be evident unless an axial patellar view is obtained (Fig. 1). The lack of weight-bearing views can lead to false-negative radiographic findings in Lisfranc or Chopart joint injuries [5, 6]. Stress views may be necessary to show injury to the ankle mortise or syndesmotic diastasis. When there is high clinical suspicion for a fracture despite initial negative radiographic findings, obtaining extra radiographic views in an attempt to identify a fracture may not be the most efficient or cost-effective course [7–10]. Instead, when available, CT or MRI may be a better option. MRI is better at identifying soft-tissue injuries that may have clinical importance. Pitfall 2: Improperly Positioned or Technically Imperfect Radiographs When a fracture is present, the best chance of seeing it on radiographs is with multiple views that are properly positioned and technically adequate. With digital radiography,
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Pitfalls in Radiography of Lower Extremity Trauma insufficient tube current (milliamperes) will result in an underexposed radiograph that will have less information than a properly exposed radiograph. However, because the display settings may present the image with the expected gray scale, contrast, and brightness, the radiograph may appear to be properly exposed. We present an example in which fractures were obvious on a properly positioned and exposed radiograph but were not apparent on an improperly positioned and underexposed follow-up radiograph obtained several days later (Fig. 2). Other pitfalls with modern radiography that may impede the diagnosis of fractures include the use of image compression and the use of substandard or handheld displays. Although radiologists using a PACS should not encounter these issues, for clinicians without U.S. Food and Drug Administration–approved display monitors, subtle and even not-so-subtle abnormalities may be overlooked if displays do not have the appropriate luminance, contrast, bit depth, and image enhancement tools. For clinicians working in brightly lit spaces, glare and reflections may further reduce the information available from a radiograph [11]. Pitfall 3: Nondisplaced Fractures Even with properly positioned and technically excellent radiographs, some fractures are undetectable on radiographs because they are nondisplaced. These fractures are symptomatic and have the appropriate clinical findings and mechanism of injury, but they are not evident on radiographs. In essence, the radiograph findings are falsely negative, because the method itself is insufficient to reveal the fracture. The detection of acute fractures on radiographs generally requires that they be displaced to some degree. With a high clinical index of suspicion, further evaluation with additional imaging is typically required, particularly if the results of this imaging will affect clinical management. An example of this is the older or elderly adult with hip pain after a groundlevel fall, coupled with an inability to bear weight. Osteoporosis often further adds to the difficulty of detecting nondisplaced fractures. Radiograph findings may be negative or equivocal because diffuse loss of bone mineral makes nondisplaced fracture lines less conspicuous. Because the management of a proximal femur fracture is usually surgical, when the pretest probability of fracture is high according to the clinical presentation, further evaluation with CT or MRI is
TABLE 1: Standard Trauma Radiographs Performed at the University of Washington Body Part
Standard Views
Hip
Anteroposterior and crosstable or frogleg lateral of affected hip
Femur
Anteroposterior and lateral
Knee
Anteroposterior, lateral, and both obliques
Tibia and fibula
Anteroposterior and lateral
Ankle
Anteroposterior, oblique (ankle mortise), and lateral
Foot
Anteroposterior, oblique, and lateral
Calcaneus
Lateral, Harris-Beath (axial)
typically performed. Although the American College of Radiology [12] recommends MRI (rating 9) in favor of CT (rating 6) or radionuclide bone scan (rating 4) for middle-aged or elderly patients whose radiographs show negative or indeterminate findings, there is mixed opinion in the literature regarding the diagnostic superiority of CT versus MRI to exclude the presence of a radiographically occult hip fracture [13]. CT may provide the best option if MRI is unavailable or the patient has a contraindication to MRI. However, MRI is superior at detecting bone marrow edema (Fig. 3). Bone scans have been applied to the initial diagnosis of radiographically occult fractures [14] but have minimal use in our practice because of the ubiquitous availability of CT. Bedside sonography has recently been studied as a modality for detecting fifth metatarsal fractures, essentially as an extension of the physical examination, and shows some promise when compared with radiographs [15]. However, sonography performed less well than radiography in a polytrauma screening situation [16]. Pitfall 4: Common Locations of Errors Prior analyses have stratified common locations for missed fractures [1, 3, 17]. A study of overlooked fractures in the emergency department found that 51.4% of missed fractures involved the ankle or foot [18]. In a study by Wei et al. [3], missed fractures of the lower extremity involved, in descending order, the foot, the knee, the hip, and the ankle. In our experience, site-specific anatomic issues may be troublesome. For example, an anteroposterior view of the pelvis is taken with the leg in approximately 15° of internal rotation in an effort to obtain the most optimal view of the proximal femur. However, because nonresponsive patients with highenergy trauma often present with the femur in external rotation, a Judet view with 40° of
angulation of the pelvis is often performed to offset this conundrum [12]. Rotated, and therefore foreshortened, views of the proximal femurs should be considered equivocal or indeterminate if no actual fracture is seen. At the knee, avulsion fractures may occur at the various surfaces of the femur, tibia, fibula, and patella, where soft-tissue structures attach; these are often obscured by overlying bones. Tibial plateau fractures, when nondepressed, may be difficult to see unless the x-ray beam happens to be directed along the plane of the fracture. The presence of a lipohemarthrosis would indicate the presence of an intraarticular fracture and, if no fracture is seen, should trigger consideration for CT or MRI. At the ankle, one must be alert to the possibility of proximal fibular fractures, beyond the FOV (Fig. 4), and of foot fractures. For example, Maisonneuve fracture is a pronation-external rotation injury with concomitant distal tibiofibular syndesmotic disruption and proximal fibular fracture [19]. Understanding the fracture pattern with the associated pattern of injury mechanism is crucial, especially in the ankle [20]. The foot itself has some of the most complex bony anatomy in the body, with multiple oddly shaped bones that overlap with one another. The subtle nature of some foot fractures and the complex anatomy may result in an increased propensity to missed fractures of the foot. Small osteochondral fractures of the talar dome or small avulsion fractures around the hindfoot and midfoot may be difficult to find [21]. The anatomy of the hindfoot and midfoot makes it challenging to identify fractures, particularly of the talus [22] (Fig. 5), cuboid (Fig. 6), cuneiforms [23–25], anterior process of the calcaneus [26], and Lisfranc joint [27]. Lisfranc and Chopart joint injuries can be subtle or occult on non-weight-bearing radiographs. Delayed diagnosis of fractures can lead to nonunion,
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Ha et al. secondary osteoarthritis, avascular necrosis, pseudoarthrosis, and even neuropathic joints [5, 6, 28]. Calcaneal fractures may be associated with lumbar spine fractures. The radiologist should be aware of locations in which fractures are commonly missed and pay special attention to these regions. We typically use CT or MRI for problem-solving in regions of complex anatomy.
[31]. Accessory ossicles can be confusing without a thorough understanding of where they typically occur. The ankle is a proverbial hot spot for accessory bones, as are the metatarsal phalangeal joints. Although these ossicles should not be confused with displaced fracture, these small bones should not be taken for granted, because they too can be fractured [32, 33].
Pitfall 5: Little Avulsion Fractures, Big Trauma Small avulsion fractures may be easy to overlook. Sometimes they portend major injuries. For example, posterior malleolar avulsion fractures of the ankle usually occur when the distal fibula is laterally displaced away from the tibia by forceful abnormal movement of the talus, rupturing the syndesmosis and the anterior tibiofibular ligament [17] (Fig. 7A). The strong posterior tibiofibular ligament remains intact but avulses off the posterior tibia where it attaches. If the fracture is reduced before radiographs are obtained, the injury may be overlooked [21]. Another classic example would be the Segond fracture (Figs. 7B and 7C). This fracture occurs along the lateral tibia and appears to be the result of avulsion of the lateral knee joint capsule. There have been numerous studies showing a high association of the Segond fracture with major soft-tissue injury, including the anterior cruciate ligament and the menisci [29, 30]. Other frequent sites of avulsion fractures include the medial and lateral femoral condyles, the median eminence of the tibia, the fibular head, the medial and lateral malleoli of the ankle, the anterolateral margin of the distal tibia, the dorsal neck of the talus, the anterior process of the calcaneus, and the bases of the second and fifth metatarsals. When a small avulsed fracture fragment is present, the radiologist should consider the underlying soft-tissue ramifications by determining which soft-tissue structure attaches to the bone fragment.
Pitfall 7: Satisfaction of Search When radiologists interpret radiographs with multiple abnormalities and find some but not all of the abnormalities, satisfaction of search may be invoked as the cause. Satisfaction of search occurs when the detection of one abnormality somehow interferes with the recognition of others; in other words, abnormalities are missed because other abnormalities are found. This phenomenon was initially studied in chest radiographs in which simulated lung nodules were added to an experimental set of cases as distractors but were omitted in the control set [34]. Berbaum et al. [34] found that radiologists performed more poorly with respect to finding the nonsimulated abnormalities in the experimental set than in the control set, confirming a substantial satisfaction-of-search effect. In various ways, this finding has been replicated in extremity radiographs. In a series of experiments, Bernbaum et al. [35, 36] created multiimage musculoskeletal cases in which they were able to test whether an abnormality detected in the first image interfered with detection of abnormalities on the subsequent images with ROC analysis; they found that the initial finding of nondisplaced fractures evoked satisfaction-of-search errors but that the initial finding of a severe fracture with high morbidity did not. Ashman et al. [37] simply studied radiologists’ performance on skeletal radiographs with two or more abnormalities and considered that a satisfaction-of-search error had occurred whenever there was a failure to find all of the abnormalities (Fig. 9). Fleck et al. [38] found that satisfaction of search is affected by the relative frequency of types of abnormalities, time pressure, and expectations about the frequency of abnormalities. Their work suggests that, when observers look for a particular abnormality and find it, they become less likely to find a perceptually different abnormality that is less common. In their study of gaze dwell times, Berbaum et al. [39] suggested that satisfaction-of-search effects were not the result of faulty visual
Pitfall 6: Bipartite Sesamoid Versus Fracture Sesamoid bones and accessory ossicles pose a unique challenge for the radiologist. Sesamoid bones are often multipartite; therefore, distinguishing fracture from normal anatomic variations can be difficult (Fig. 8). The radiologist must rely on the clinical picture and knowledge of the more predictable appearance of the normal multipartite sesamoid bone. Special attention should be paid to possible sesamoid injury (stress reaction or fracture) in runners with forefoot pain
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scanning of the remaining images after the first abnormality was found. Whether Rogers’ [40] suggested strategy of paying better attention can systematically reduce satisfaction-of-search errors is unknown, but in our opinions, it is well worth trying. Pitfall 8: Faulty Reasoning Once fractures have been identified, the radiologist should characterize them so that further management can be planned. However, there may be more information that the radiologist can provide beyond the scope of a simple fracture description. Fractures of particular anatomic sites are often more frequent at particular ages and typically occur as a result of a specific mechanism. Identification of a fracture that is atypical for site, age, and mechanism should lead to further investigation. For example, fractures of the proximal femoral shaft (subtrochanteric or intertrochanteric-subtrochanteric) typically occur in healthy adults as a result of a major traumatic event, such as a motor vehicle crash or a fall from a height. Proximal femoral shaft fractures may occur as a result of a ground-level fall in very elderly populations with skeletal fragility or in those with some underlying condition that predisposes the bone to fracture. Therefore, the finding of a proximal femoral shaft fracture in a young or middle-aged adult as a result of a ground-level fall should trigger immediate suspicion of an underlying predisposing condition. There are often clues to the underlying pathophysiology on the initial trauma radiographs. Thickening of the lateral femoral cortex, especially if there is a triangular peaked appearance, has been recognized as characteristic for a bisphosphonate-associated insufficiency fracture [41] (Fig. 10). The presence of bone destruction, either permeated or geographic, may indicate the presence of a tumor or of osteomyelitis. The proximal femur is the most common site of bone metastasis [42]. In particular, the presence of a lesser trochanteric femur fracture in an adult should elicit strong clinical concern for pathologic fracture due to metastatic disease [43, 44]. This information is valuable to the clinician in tailoring treatment. Pitfall 9: Fractures After Hardware Placement Fracture evaluation can be challenging in patients after hardware placement, such as that seen with fracture fixation or joint replacement, for various reasons [45, 46]. Dense overlapping metallic densities can limit visualization of hardware fractures or periprosthetic bone frac-
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Pitfalls in Radiography of Lower Extremity Trauma tures. Oblique views are often helpful. Crosssectional imaging, such as CT or MRI, can be limited by metal artifacts and should be performed with modified metal artifact reduction protocols when available. Hardware implants alter the stresses on the host bone, resulting in chronic bone loss where stress-shielding occurs and bony hypertrophy where stresses are concentrated. When subjected to trauma, forces tend to concentrate where there is an abrupt interface between implant and bone. Fractures often begin at those interfaces and then propagate away from the point of concentration. For example, femoral fractures in patients with hip implants usually pass through the tip of the femoral stem (Fig. 11). Fractures through bones with internal fixation tend to pass through the cortex at the end of the plate. Conclusion Most fractures that are missed on radiographs are the result of errors in perception. Many of these misses occur in predictable locations where the radiographic anatomy is complex. Specific attention to these anatomic sites may increase fracture detection. Double reading of radiographs may avoid some of these errors but may not be practical or cost effective [47]. The precise correlation of physical examination findings—site of maximal pain and tenderness—with radiographs may be helpful, even if it requires that the radiologist examine the patient. With PACS and teleradiology, the radiologist may be at some distance from the patient, and communication with the provider who has examined the patient may be the best that the radiologist can do. Further imaging may be necessary when the results are likely to change management. Although splinting and obtaining follow-up radiographs are sensible options for the upper extremity, because the lower extremities are weight-bearing, the associated morbidity for a patient with an undiagnosed fracture or dislocation is often greater. CT is an excellent immediate option; however, MRI often provides a more comprehensive evaluation for soft-tissue injuries and may allow the identification of a nondisplaced radiographically and CT-occult fracture. Some researchers have reported that sonography may have a role in fracture diagnosis as well, but perhaps more for screening at the point of care [48] rather than problem solving for radiographically occult fractures. References 1. Weisel BB, Saunders, RA, Weisel SW. Chapter 23: physical impairment ratings for fractures. In:
Browner BD, Jupiter JB, Levine AM, Trafton PG, Krettek C, eds. Skeletal trauma: basic science, management, and reconstruction, 4th ed. Philadelphia, PA: Elsevier, 2009 2. Whang JS, Baker SR, Patel R, Luk L, Castro A 3rd. The causes of medical malpractice suits against radiologists in the United States. Radiology 2013; 266:548–554 3. Wei CJ, Tsai WC, Tiu CM, Wu HT, Chiou HJ, Chang CY. Systematic analysis of missed extremity fractures in emergency radiology. Acta Radiol 2006; 47:710–717 4. Leeper WR, Leeper TJ, Vogt KN, Charyk-Stewart T, Gray DK, Parry NG. The role of trauma team leaders in missed injuries: does specialty matter? J Trauma Acute Care Surg 2013; 75:387–390 5. van Rijn J, Dorleijn DM, Boetes B, Wiersma-Tuinstra S, Moonen S. Missing the Lisfranc fracture: a case report and review of the literature. J Foot Ankle Surg 2012; 51:270–274 6. van Dorp KB, de Vries MR, van der Elst M, Schepers T. Chopart joint injury: a study of outcome and morbidity. J Foot Ankle Surg 2010; 49:541–545 7. Dorsay TA, Major NM, Helms CA. Cost-effectiveness of immediate MR imaging versus traditional follow-up for revealing radiographically occult scaphoid fractures. AJR 2001; 177:1257–1263 8. Brooks S, Cicuttini FM, Lim S, Taylor D, Stuckey SL, Wluka AE. Cost effectiveness of adding magnetic resonance imaging to the usual management of suspected scaphoid fractures. Br J Sports Med 2005; 39:75–79 9. Blackmore CC, Mann FA, Wilson AJ., Helical CT in the primary trauma evaluation of the cervical spine: an evidence-based approach. Skeletal Radiol 2000; 29:632–639 10. Theocharopoulos N, Chatzakis G, Damilakis J. Is radiography justified for the evaluation of patients presenting with cervical spine trauma? Med Phys 2009; 36:4461–4470 11. Krupinski EA, Williams MB, Andriole K, et al; ACR; AAPM; Society for Imaging Informatics in Medicine. Digital radiography image quality: image processing and display. J Am Coll Radiol 2007; 4:389–400 12. American College of Radiology. ACR appropriateness criteria: acute hip pain—suspected fracture. American College of Radiology website. www.acr.org/~/media/ACR/Documents/AppCriteria/Diagnostic/AcuteHipPainSuspectedFracture. pdf. Published 2013. Accessed May 15, 2014 13. Gill SK, Smith J, Fox R, Chesser TJ. Investigation of occult hip fractures: the use of CT and MRI. ScientificWorldJournal 2013; 2013:830319 14. Lewis SL, Rees JI, Thomas GV, Williams LA. Pitfalls of bone scintigraphy in suspected hip fractures. Br J Radiol 1991; 64:403–408 15. Yesilaras M, Aksay E, Atilla OD, Sever
M, Kalenderer O. The accuracy of bedside ultrasonography as a diagnostic tool for the fifth metatarsal fractures. Am J Emerg Med 2014; 32:171–174 16. Bolandparvaz S, Moharamzadeh P, Jamali K, et al. Comparing diagnostic accuracy of bedside ultrasound and radiography for bone fracture screening in multiple trauma patients at the ED. Am J Emerg Med 2013; 31:1583–1585 17. Jibri Z, Mukherjee K, Kamath S, Mansour R. Frequently missed findings in acute ankle injury. Semin Musculoskelet Radiol 2013; 17:416–428 18. Er E, Kara PH, Oyar O, Ünlüer EE. Overlooked extremity fractures in the emergency department. Ulus Travma Acil Cerrahi Derg 2013; 19:25–28 19. Levy BA, Vogt KJ, Herrera DA, Cole PA. Maisonneuve fracture equivalent with proximal tibiofibular dislocation: a case report and literature review. J Bone Joint Surg Am 2006; 88:1111–1116 20. Okanobo H, Khurana B, Sheehan S, Duran-Mendicuti A, Arianjam A, Ledbetter S. Simplified diagnostic algorithm for Lauge-Hansen classification of ankle injuries. RadioGraphics 2012; 32:E71–E84 21. Prokuski LJ, Saltzman CL. Challenging fractures of the foot and ankle. Radiol Clin North Am 1997; 35:655–670 22. Dale JD, Ha AS, Chew FS. Update on talar fracture patterns: a large level I trauma center study. AJR 2013; 201:1087–1092 23. Eraslan A, Ozyurek S, Erol B, Ercan E. Isolated medial cuneiform fracture: a commonly missed fracture. BMJ Case Rep 2013; 2013:bcr2013010093 24. Olson RC, Mendicino SS, Rockett MS. Isolated medial cuneiform fracture: review of the literature and report of two cases. Foot Ankle Int 2000; 21:150–153 25. Kou JX, Fortin PT. Commonly missed peritalar injuries. J Am Acad Orthop Surg 2009; 17:775–786 26. Renfrew DL, el-Khoury GY. Anterior process fractures of the calcaneus. Skeletal Radiol 1985; 14:121–125 27. Gupta RT, Wadhwa RP, Learch TJ, Herwick SM. Lisfranc injury: imaging findings for this important but often-missed diagnosis. Curr Probl Diagn Radiol 2008; 37:115–126 28. Sherief TI, Mucci B, Greiss M. Lisfranc injury: how frequently does it get missed? And how can we improve? Injury 2007; 38:856–860 29. Hess T, Rupp S, Hopf T, Gleitz M, Liebler J. Lateral tibial avulsion fractures and disruptions to the anterior cruciate ligament: a clinical study of their incidence and correlation. Clin Orthop Relat Res 1994; 303:193–197 30. Gottsegen CJ, Eyer BA, White EA, Learch TJ, Forrester D. Avulsion fractures of the knee: imaging findings and clinical significance. RadioGraphics 2008; 28:1755–1770 31. Kindred J, Truby C, Simons SM. Foot injuries in
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Ha et al. runners. Curr Sports Med Rep 2011; 10:249–254 32. Smith JT, Johnson AH, Heckman JD. Nonoperative treatment of an os peroneum fracture in a high-level athlete: a case report. Clin Orthop Relat Res 2011; 469:1498–1501 33. Tang JY, Mulcahy H, Chew FS. High energy fracture of the fabella. Radiol Case Rep 2010; 5:454 34. Berbaum KS, Franken EA Jr, Dorfman DD, et al. Satisfaction of search in diagnostic radiology. Invest Radiol 1990; 25:133–140 35. Berbaum KS. Satisfaction of search in osteoradiology. AJR 2001; 177:252–253 36. Berbaum KS, El-Khoury GY, Ohashi K, et al. Satisfaction of search in multitrauma patients: severity of detected fractures. Acad Radiol 2007; 14:711–722 37. Ashman CJ, Yu JS, Wolfman D. Satisfaction of search in osteoradiology. AJR 2000; 175:541–544 38. Fleck MS, Samei E, Mitroff SR. Generalized “satisfaction of search”: adverse influences on dual-target search accuracy. J Exp Psychol Appl
2010; 16:60–71 39. Berbaum KS, Brandser EA, Franken EA, Dorfman DD, Caldwell RT, Krupinski EA. Gaze dwell times on acute trauma injuries missed because of satisfaction of search. Acad Radiol 2001; 8:304–314 40. Rogers LF. Keep looking: satisfaction of search. AJR 2000; 175:287 41. Porrino JA Jr, Kohl CA, Taljanovic M, Rogers LF. Diagnosis of proximal femoral insufficiency fractures in patients receiving bisphosphonate therapy. AJR 2010; 194:1061–1064 42. Jacofsky DJ, Haidukewych GJ. Management of pathologic fractures of the proximal femur: state of the art. J Orthop Trauma 2004; 18:459–469 43. Rouvillain JL, Jawahdou R, Labrada Blanco O, Benchikh-El-Fegoun A, Enkaoua E, Uzel M. Isolated lesser trochanter fracture in adults: an early indicator of tumor infiltration. Orthop Traumatol Surg Res 2011; 97:217–220 44. Phillips CD, Pope TL Jr, Jones JE, Keats TE, MacMillan RH 3rd. Nontraumatic avulsion of the
lesser trochanter: a pathognomonic sign of metastatic disease? Skeletal Radiol 1988; 17:106–110 45. Schwarzkopf R, Oni JK, Marwin SE. Total hip arthroplasty periprosthetic femoral fractures: a review of classification and current treatment. Bull Hosp Jt Dis 2013; 71:68–78 46. Haidukewych GJ, Langford J, Liporace FA. Revision for periprosthetic fractures of the hip and knee. J Bone Joint Surg Am 2013; 95:368–376 47. Kung JW, Melenevsky Y, Hochman MG, et al. On-call musculoskeletal radiographs: discrepancy rates between radiology residents and musculoskeletal radiologists. AJR 2013; 200:856–859 48. Safran O, Goldman V, Applbaum Y, et al. Posttraumatic painful hip: sonography as a screening test for occult hip fractures. J Ultrasound Med 2009; 28:1447–1452 49. Mulcahy H, Chew FS. Foot (case 9–27): location 1636. In: Chew FS, Maldjian C, eds. Broken bones: the x-ray atlas of fractures. Seattle, WA: BareBonesBooks, 2009
Fig. 1—20-year-old man who sustained transient lateral patellar dislocation that spontaneously reduced on field of injury. Fractures were not visible on lateral and anteroposterior radiographs. Sunrise view shows multiple avulsion fragments (arrow) along medial margin of patella.
Fig. 2—19-year-old man after sports injury. A, Initial oblique radiograph shows incomplete second and third metatarsal shaft fractures. Reprinted with permission from [49]. B, Follow-up radiograph obtained 1 week later at outpatient office without radiologic technologists does not show metatarsal fractures because of underpenetration and improper tube angulation. Note lack of trabecular bone detail and poor visualization of tarsometatarsal and naviculocuneiform joints.
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Pitfalls in Radiography of Lower Extremity Trauma
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Fig. 3—65-year-old man after ground-level fall with nondisplaced fracture not seen on radiographs. A, Anteroposterior radiograph appears normal. Lateral view was also normal. Patient complained of right hip pain and was unable to bear weight or walk. B, Coronal T1-weighted MRI shows nondisplaced femoral neck fracture. C, Fracture was internally fixed with three compression screws.
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Fig. 4—28-year-old woman after ground-level fall. A, Oblique view of ankle shows syndesmotic widening and subtle medial malleolar avulsion fracture. B, Lateral view of proximal leg shows oblique proximal fibular shaft fracture, constituting Maisonneuve fracture.
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Ha et al. Fig. 5—53-year-old man with talus fracture. A and B, Anteroposterior (A) and lateral (B) radiographs show comminuted medial talar body fracture. C and D, Subsequent sagittal (C) and axial (D) CT images more comprehensively show additional oblique fracture (arrows) through talar body extending into subtalar joint.
Fig. 6—35-year-old woman with foot pain after fall. A, On radiographs, including lateral view, fracture is difficult to see even in retrospect. B, Intraarticular fracture of cuboid at fourth tarsometatarsal joint (arrow) is seen on this sagittal CT reformation.
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Pitfalls in Radiography of Lower Extremity Trauma
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Fig. 7—Two patients with avulsion fracture signaling underlying injury. A, 32-year-old man with ankle injury sustained in fall. Lateral radiograph shows minimally displaced posterior malleolar fracture (arrow), indicative of rupture of ankle syndesmosis. B and C, 30-year-old man after car-versus-pedestrian crash. Coronal (B) and sagittal (C) STIR MR images show acute Segond fracture at lateral tibial plateau (arrow, B) and full-thickness anterior cruciate ligament tear.
A Fig. 8—32-year-old woman who experienced foot injury while playing soccer. Anteroposterior radiograph shows bipartite medial sesamoid with separation extending diagonally across bone. At proximal aspect, there is transverse avulsion fracture (arrow), and sesamoid has retracted distally. Medial soft tissues are swollen. Diagnosis of turf toe was made.
B
Fig. 9—61-year-old woman who sustained polytrauma in motor vehicle crash. Multiple fractures and dislocations led to satisfaction of search. A and B, Initial evaluation of anteroposterior oblique (A) and lateral (B) radiographs of foot focused on multiple metatarsal and toe fractures and multiple metatarsophalangeal joint dislocations. Calcaneal fractures were initially overlooked.
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Ha et al. Fig. 10—Two patients with unusual fractures. A, 65-year-old woman who presented to emergency department after ground-level fall at shopping mall. Anteroposterior radiograph shows comminuted subtrochanteric femur fracture. She had been taking alendronic acid (Fosamax, Merck) for 10 years for osteoporosis. Abnormal thickening of proximal lateral femoral cortex (arrow) is partially obscured by trauma board. B, 46-year-old man after ground-level fall. Anteroposterior radiograph shows subtrochantericintertrochanteric proximal femur fracture with separate lesser trochanter fragment and marked angulation. Pathology at time of intramedullary rod placement showed metastatic cancer.
Fig. 11—54-year-old man with left total hip arthroplasty. A and B, Frontal radiograph of pelvis (A) and froglateral view of left hip (B) show oblique fracture (arrow, B) of mid shaft of femur extending to level of femoral stem tip.
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Musculoskeletal Imaging Review
Alice S. Ha1 Jack A. Porrino Felix S. Chew Ha AS, Porrino JA, Chew FS
Radiographic Pitfalls in Lower Extremity Trauma OBJECTIVE. Radiography remains the imaging standard for fracture detection after trauma. However, fractures continue to be the most common type of missed injuries. In this article, we describe common radiographic pitfalls in lower extremity trauma and describe strategies for dealing with them. CONCLUSION. Pitfalls include insufficient views, improperly positioned or technically imperfect radiographs, nondisplaced fractures, commonly missed locations, small avulsions portending large injury, sesamoid injuries, satisfaction of search, incomplete or faulty reasoning, and periprosthetic fractures.
R
Keywords: fracture, lower extremity, pitfalls, radiography DOI:10.2214/AJR.14.12626 Received January 30, 2014; accepted after revision April 23, 2014. 1
All authors: Department of Radiology, University of Washington, Box 354755, 4245 Roosevelt Way NE, Seattle, WA 98105. Address correspondence to A. S. Ha ([email protected]).
AJR 2014; 203:492–500 0361–803X/14/2033–492 © American Roentgen Ray Society
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adiography remains the initial modality to detect or exclude the presence of a fracture. According to the American Academy of Orthopaedic Surgeons [1], 7,310,000 physician visits and 3,148,000 emergency department visits were related to extremity fractures in 2003, leading to 867,000 hospitalizations. Pitfalls for the radiologist that may result in a missed or delayed diagnosis abound in this circumstance. Failure to diagnose is the most common error alleged in medical malpractice suits against radiologists, and extremity fractures are the second most frequently missed diagnosis (after breast cancer) [2]. Although some missed fractures may be related to perceptual errors that appear to be avoidable in retrospect, others are related to anatomic, technical, and physiologic factors that are out of the interpreting radiologist’s control. In a recent study of 3081 confirmed fractures in emergency department patients, 115 fractures were initially missed [3]. Fifty-three percent of missed fractures occurred in the lower extremities, with the foot being the most missed location. Postulated reasons for these errors included subtle fractures (37%) and radiographically occult fractures (33%). Leeper et al. [4] showed that, of missed injuries at a level I trauma center (15%), 70% were fractures. In this article, we identify several common radiographic pitfalls in lower extremity trauma and describe strategies for dealing with them.
Pitfalls Pitfall 1: Insufficient Views Many fractures are visible on only a single view. If that view is not obtained, then the examination will be interpreted as falsely negative. Most radiology departments follow protocols that call for orthogonal views in frontal (anteroposterior or posteroanterior) and lateral projections for the long bones. For the hip, knee, ankle, and foot, various additional views may also be obtained (Table 1). At the knee, fractures of the patella may not be evident unless an axial patellar view is obtained (Fig. 1). The lack of weight-bearing views can lead to false-negative radiographic findings in Lisfranc or Chopart joint injuries [5, 6]. Stress views may be necessary to show injury to the ankle mortise or syndesmotic diastasis. When there is high clinical suspicion for a fracture despite initial negative radiographic findings, obtaining extra radiographic views in an attempt to identify a fracture may not be the most efficient or cost-effective course [7–10]. Instead, when available, CT or MRI may be a better option. MRI is better at identifying soft-tissue injuries that may have clinical importance. Pitfall 2: Improperly Positioned or Technically Imperfect Radiographs When a fracture is present, the best chance of seeing it on radiographs is with multiple views that are properly positioned and technically adequate. With digital radiography,
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Pitfalls in Radiography of Lower Extremity Trauma insufficient tube current (milliamperes) will result in an underexposed radiograph that will have less information than a properly exposed radiograph. However, because the display settings may present the image with the expected gray scale, contrast, and brightness, the radiograph may appear to be properly exposed. We present an example in which fractures were obvious on a properly positioned and exposed radiograph but were not apparent on an improperly positioned and underexposed follow-up radiograph obtained several days later (Fig. 2). Other pitfalls with modern radiography that may impede the diagnosis of fractures include the use of image compression and the use of substandard or handheld displays. Although radiologists using a PACS should not encounter these issues, for clinicians without U.S. Food and Drug Administration–approved display monitors, subtle and even not-so-subtle abnormalities may be overlooked if displays do not have the appropriate luminance, contrast, bit depth, and image enhancement tools. For clinicians working in brightly lit spaces, glare and reflections may further reduce the information available from a radiograph [11]. Pitfall 3: Nondisplaced Fractures Even with properly positioned and technically excellent radiographs, some fractures are undetectable on radiographs because they are nondisplaced. These fractures are symptomatic and have the appropriate clinical findings and mechanism of injury, but they are not evident on radiographs. In essence, the radiograph findings are falsely negative, because the method itself is insufficient to reveal the fracture. The detection of acute fractures on radiographs generally requires that they be displaced to some degree. With a high clinical index of suspicion, further evaluation with additional imaging is typically required, particularly if the results of this imaging will affect clinical management. An example of this is the older or elderly adult with hip pain after a groundlevel fall, coupled with an inability to bear weight. Osteoporosis often further adds to the difficulty of detecting nondisplaced fractures. Radiograph findings may be negative or equivocal because diffuse loss of bone mineral makes nondisplaced fracture lines less conspicuous. Because the management of a proximal femur fracture is usually surgical, when the pretest probability of fracture is high according to the clinical presentation, further evaluation with CT or MRI is
TABLE 1: Standard Trauma Radiographs Performed at the University of Washington Body Part
Standard Views
Hip
Anteroposterior and crosstable or frogleg lateral of affected hip
Femur
Anteroposterior and lateral
Knee
Anteroposterior, lateral, and both obliques
Tibia and fibula
Anteroposterior and lateral
Ankle
Anteroposterior, oblique (ankle mortise), and lateral
Foot
Anteroposterior, oblique, and lateral
Calcaneus
Lateral, Harris-Beath (axial)
typically performed. Although the American College of Radiology [12] recommends MRI (rating 9) in favor of CT (rating 6) or radionuclide bone scan (rating 4) for middle-aged or elderly patients whose radiographs show negative or indeterminate findings, there is mixed opinion in the literature regarding the diagnostic superiority of CT versus MRI to exclude the presence of a radiographically occult hip fracture [13]. CT may provide the best option if MRI is unavailable or the patient has a contraindication to MRI. However, MRI is superior at detecting bone marrow edema (Fig. 3). Bone scans have been applied to the initial diagnosis of radiographically occult fractures [14] but have minimal use in our practice because of the ubiquitous availability of CT. Bedside sonography has recently been studied as a modality for detecting fifth metatarsal fractures, essentially as an extension of the physical examination, and shows some promise when compared with radiographs [15]. However, sonography performed less well than radiography in a polytrauma screening situation [16]. Pitfall 4: Common Locations of Errors Prior analyses have stratified common locations for missed fractures [1, 3, 17]. A study of overlooked fractures in the emergency department found that 51.4% of missed fractures involved the ankle or foot [18]. In a study by Wei et al. [3], missed fractures of the lower extremity involved, in descending order, the foot, the knee, the hip, and the ankle. In our experience, site-specific anatomic issues may be troublesome. For example, an anteroposterior view of the pelvis is taken with the leg in approximately 15° of internal rotation in an effort to obtain the most optimal view of the proximal femur. However, because nonresponsive patients with highenergy trauma often present with the femur in external rotation, a Judet view with 40° of
angulation of the pelvis is often performed to offset this conundrum [12]. Rotated, and therefore foreshortened, views of the proximal femurs should be considered equivocal or indeterminate if no actual fracture is seen. At the knee, avulsion fractures may occur at the various surfaces of the femur, tibia, fibula, and patella, where soft-tissue structures attach; these are often obscured by overlying bones. Tibial plateau fractures, when nondepressed, may be difficult to see unless the x-ray beam happens to be directed along the plane of the fracture. The presence of a lipohemarthrosis would indicate the presence of an intraarticular fracture and, if no fracture is seen, should trigger consideration for CT or MRI. At the ankle, one must be alert to the possibility of proximal fibular fractures, beyond the FOV (Fig. 4), and of foot fractures. For example, Maisonneuve fracture is a pronation-external rotation injury with concomitant distal tibiofibular syndesmotic disruption and proximal fibular fracture [19]. Understanding the fracture pattern with the associated pattern of injury mechanism is crucial, especially in the ankle [20]. The foot itself has some of the most complex bony anatomy in the body, with multiple oddly shaped bones that overlap with one another. The subtle nature of some foot fractures and the complex anatomy may result in an increased propensity to missed fractures of the foot. Small osteochondral fractures of the talar dome or small avulsion fractures around the hindfoot and midfoot may be difficult to find [21]. The anatomy of the hindfoot and midfoot makes it challenging to identify fractures, particularly of the talus [22] (Fig. 5), cuboid (Fig. 6), cuneiforms [23–25], anterior process of the calcaneus [26], and Lisfranc joint [27]. Lisfranc and Chopart joint injuries can be subtle or occult on non-weight-bearing radiographs. Delayed diagnosis of fractures can lead to nonunion,
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Ha et al. secondary osteoarthritis, avascular necrosis, pseudoarthrosis, and even neuropathic joints [5, 6, 28]. Calcaneal fractures may be associated with lumbar spine fractures. The radiologist should be aware of locations in which fractures are commonly missed and pay special attention to these regions. We typically use CT or MRI for problem-solving in regions of complex anatomy.
[31]. Accessory ossicles can be confusing without a thorough understanding of where they typically occur. The ankle is a proverbial hot spot for accessory bones, as are the metatarsal phalangeal joints. Although these ossicles should not be confused with displaced fracture, these small bones should not be taken for granted, because they too can be fractured [32, 33].
Pitfall 5: Little Avulsion Fractures, Big Trauma Small avulsion fractures may be easy to overlook. Sometimes they portend major injuries. For example, posterior malleolar avulsion fractures of the ankle usually occur when the distal fibula is laterally displaced away from the tibia by forceful abnormal movement of the talus, rupturing the syndesmosis and the anterior tibiofibular ligament [17] (Fig. 7A). The strong posterior tibiofibular ligament remains intact but avulses off the posterior tibia where it attaches. If the fracture is reduced before radiographs are obtained, the injury may be overlooked [21]. Another classic example would be the Segond fracture (Figs. 7B and 7C). This fracture occurs along the lateral tibia and appears to be the result of avulsion of the lateral knee joint capsule. There have been numerous studies showing a high association of the Segond fracture with major soft-tissue injury, including the anterior cruciate ligament and the menisci [29, 30]. Other frequent sites of avulsion fractures include the medial and lateral femoral condyles, the median eminence of the tibia, the fibular head, the medial and lateral malleoli of the ankle, the anterolateral margin of the distal tibia, the dorsal neck of the talus, the anterior process of the calcaneus, and the bases of the second and fifth metatarsals. When a small avulsed fracture fragment is present, the radiologist should consider the underlying soft-tissue ramifications by determining which soft-tissue structure attaches to the bone fragment.
Pitfall 7: Satisfaction of Search When radiologists interpret radiographs with multiple abnormalities and find some but not all of the abnormalities, satisfaction of search may be invoked as the cause. Satisfaction of search occurs when the detection of one abnormality somehow interferes with the recognition of others; in other words, abnormalities are missed because other abnormalities are found. This phenomenon was initially studied in chest radiographs in which simulated lung nodules were added to an experimental set of cases as distractors but were omitted in the control set [34]. Berbaum et al. [34] found that radiologists performed more poorly with respect to finding the nonsimulated abnormalities in the experimental set than in the control set, confirming a substantial satisfaction-of-search effect. In various ways, this finding has been replicated in extremity radiographs. In a series of experiments, Bernbaum et al. [35, 36] created multiimage musculoskeletal cases in which they were able to test whether an abnormality detected in the first image interfered with detection of abnormalities on the subsequent images with ROC analysis; they found that the initial finding of nondisplaced fractures evoked satisfaction-of-search errors but that the initial finding of a severe fracture with high morbidity did not. Ashman et al. [37] simply studied radiologists’ performance on skeletal radiographs with two or more abnormalities and considered that a satisfaction-of-search error had occurred whenever there was a failure to find all of the abnormalities (Fig. 9). Fleck et al. [38] found that satisfaction of search is affected by the relative frequency of types of abnormalities, time pressure, and expectations about the frequency of abnormalities. Their work suggests that, when observers look for a particular abnormality and find it, they become less likely to find a perceptually different abnormality that is less common. In their study of gaze dwell times, Berbaum et al. [39] suggested that satisfaction-of-search effects were not the result of faulty visual
Pitfall 6: Bipartite Sesamoid Versus Fracture Sesamoid bones and accessory ossicles pose a unique challenge for the radiologist. Sesamoid bones are often multipartite; therefore, distinguishing fracture from normal anatomic variations can be difficult (Fig. 8). The radiologist must rely on the clinical picture and knowledge of the more predictable appearance of the normal multipartite sesamoid bone. Special attention should be paid to possible sesamoid injury (stress reaction or fracture) in runners with forefoot pain
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scanning of the remaining images after the first abnormality was found. Whether Rogers’ [40] suggested strategy of paying better attention can systematically reduce satisfaction-of-search errors is unknown, but in our opinions, it is well worth trying. Pitfall 8: Faulty Reasoning Once fractures have been identified, the radiologist should characterize them so that further management can be planned. However, there may be more information that the radiologist can provide beyond the scope of a simple fracture description. Fractures of particular anatomic sites are often more frequent at particular ages and typically occur as a result of a specific mechanism. Identification of a fracture that is atypical for site, age, and mechanism should lead to further investigation. For example, fractures of the proximal femoral shaft (subtrochanteric or intertrochanteric-subtrochanteric) typically occur in healthy adults as a result of a major traumatic event, such as a motor vehicle crash or a fall from a height. Proximal femoral shaft fractures may occur as a result of a ground-level fall in very elderly populations with skeletal fragility or in those with some underlying condition that predisposes the bone to fracture. Therefore, the finding of a proximal femoral shaft fracture in a young or middle-aged adult as a result of a ground-level fall should trigger immediate suspicion of an underlying predisposing condition. There are often clues to the underlying pathophysiology on the initial trauma radiographs. Thickening of the lateral femoral cortex, especially if there is a triangular peaked appearance, has been recognized as characteristic for a bisphosphonate-associated insufficiency fracture [41] (Fig. 10). The presence of bone destruction, either permeated or geographic, may indicate the presence of a tumor or of osteomyelitis. The proximal femur is the most common site of bone metastasis [42]. In particular, the presence of a lesser trochanteric femur fracture in an adult should elicit strong clinical concern for pathologic fracture due to metastatic disease [43, 44]. This information is valuable to the clinician in tailoring treatment. Pitfall 9: Fractures After Hardware Placement Fracture evaluation can be challenging in patients after hardware placement, such as that seen with fracture fixation or joint replacement, for various reasons [45, 46]. Dense overlapping metallic densities can limit visualization of hardware fractures or periprosthetic bone frac-
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Pitfalls in Radiography of Lower Extremity Trauma tures. Oblique views are often helpful. Crosssectional imaging, such as CT or MRI, can be limited by metal artifacts and should be performed with modified metal artifact reduction protocols when available. Hardware implants alter the stresses on the host bone, resulting in chronic bone loss where stress-shielding occurs and bony hypertrophy where stresses are concentrated. When subjected to trauma, forces tend to concentrate where there is an abrupt interface between implant and bone. Fractures often begin at those interfaces and then propagate away from the point of concentration. For example, femoral fractures in patients with hip implants usually pass through the tip of the femoral stem (Fig. 11). Fractures through bones with internal fixation tend to pass through the cortex at the end of the plate. Conclusion Most fractures that are missed on radiographs are the result of errors in perception. Many of these misses occur in predictable locations where the radiographic anatomy is complex. Specific attention to these anatomic sites may increase fracture detection. Double reading of radiographs may avoid some of these errors but may not be practical or cost effective [47]. The precise correlation of physical examination findings—site of maximal pain and tenderness—with radiographs may be helpful, even if it requires that the radiologist examine the patient. With PACS and teleradiology, the radiologist may be at some distance from the patient, and communication with the provider who has examined the patient may be the best that the radiologist can do. Further imaging may be necessary when the results are likely to change management. Although splinting and obtaining follow-up radiographs are sensible options for the upper extremity, because the lower extremities are weight-bearing, the associated morbidity for a patient with an undiagnosed fracture or dislocation is often greater. CT is an excellent immediate option; however, MRI often provides a more comprehensive evaluation for soft-tissue injuries and may allow the identification of a nondisplaced radiographically and CT-occult fracture. Some researchers have reported that sonography may have a role in fracture diagnosis as well, but perhaps more for screening at the point of care [48] rather than problem solving for radiographically occult fractures. References 1. Weisel BB, Saunders, RA, Weisel SW. Chapter 23: physical impairment ratings for fractures. In:
Browner BD, Jupiter JB, Levine AM, Trafton PG, Krettek C, eds. Skeletal trauma: basic science, management, and reconstruction, 4th ed. Philadelphia, PA: Elsevier, 2009 2. Whang JS, Baker SR, Patel R, Luk L, Castro A 3rd. The causes of medical malpractice suits against radiologists in the United States. Radiology 2013; 266:548–554 3. Wei CJ, Tsai WC, Tiu CM, Wu HT, Chiou HJ, Chang CY. Systematic analysis of missed extremity fractures in emergency radiology. Acta Radiol 2006; 47:710–717 4. Leeper WR, Leeper TJ, Vogt KN, Charyk-Stewart T, Gray DK, Parry NG. The role of trauma team leaders in missed injuries: does specialty matter? J Trauma Acute Care Surg 2013; 75:387–390 5. van Rijn J, Dorleijn DM, Boetes B, Wiersma-Tuinstra S, Moonen S. Missing the Lisfranc fracture: a case report and review of the literature. J Foot Ankle Surg 2012; 51:270–274 6. van Dorp KB, de Vries MR, van der Elst M, Schepers T. Chopart joint injury: a study of outcome and morbidity. J Foot Ankle Surg 2010; 49:541–545 7. Dorsay TA, Major NM, Helms CA. Cost-effectiveness of immediate MR imaging versus traditional follow-up for revealing radiographically occult scaphoid fractures. AJR 2001; 177:1257–1263 8. Brooks S, Cicuttini FM, Lim S, Taylor D, Stuckey SL, Wluka AE. Cost effectiveness of adding magnetic resonance imaging to the usual management of suspected scaphoid fractures. Br J Sports Med 2005; 39:75–79 9. Blackmore CC, Mann FA, Wilson AJ., Helical CT in the primary trauma evaluation of the cervical spine: an evidence-based approach. Skeletal Radiol 2000; 29:632–639 10. Theocharopoulos N, Chatzakis G, Damilakis J. Is radiography justified for the evaluation of patients presenting with cervical spine trauma? Med Phys 2009; 36:4461–4470 11. Krupinski EA, Williams MB, Andriole K, et al; ACR; AAPM; Society for Imaging Informatics in Medicine. Digital radiography image quality: image processing and display. J Am Coll Radiol 2007; 4:389–400 12. American College of Radiology. ACR appropriateness criteria: acute hip pain—suspected fracture. American College of Radiology website. www.acr.org/~/media/ACR/Documents/AppCriteria/Diagnostic/AcuteHipPainSuspectedFracture. pdf. Published 2013. Accessed May 15, 2014 13. Gill SK, Smith J, Fox R, Chesser TJ. Investigation of occult hip fractures: the use of CT and MRI. ScientificWorldJournal 2013; 2013:830319 14. Lewis SL, Rees JI, Thomas GV, Williams LA. Pitfalls of bone scintigraphy in suspected hip fractures. Br J Radiol 1991; 64:403–408 15. Yesilaras M, Aksay E, Atilla OD, Sever
M, Kalenderer O. The accuracy of bedside ultrasonography as a diagnostic tool for the fifth metatarsal fractures. Am J Emerg Med 2014; 32:171–174 16. Bolandparvaz S, Moharamzadeh P, Jamali K, et al. Comparing diagnostic accuracy of bedside ultrasound and radiography for bone fracture screening in multiple trauma patients at the ED. Am J Emerg Med 2013; 31:1583–1585 17. Jibri Z, Mukherjee K, Kamath S, Mansour R. Frequently missed findings in acute ankle injury. Semin Musculoskelet Radiol 2013; 17:416–428 18. Er E, Kara PH, Oyar O, Ünlüer EE. Overlooked extremity fractures in the emergency department. Ulus Travma Acil Cerrahi Derg 2013; 19:25–28 19. Levy BA, Vogt KJ, Herrera DA, Cole PA. Maisonneuve fracture equivalent with proximal tibiofibular dislocation: a case report and literature review. J Bone Joint Surg Am 2006; 88:1111–1116 20. Okanobo H, Khurana B, Sheehan S, Duran-Mendicuti A, Arianjam A, Ledbetter S. Simplified diagnostic algorithm for Lauge-Hansen classification of ankle injuries. RadioGraphics 2012; 32:E71–E84 21. Prokuski LJ, Saltzman CL. Challenging fractures of the foot and ankle. Radiol Clin North Am 1997; 35:655–670 22. Dale JD, Ha AS, Chew FS. Update on talar fracture patterns: a large level I trauma center study. AJR 2013; 201:1087–1092 23. Eraslan A, Ozyurek S, Erol B, Ercan E. Isolated medial cuneiform fracture: a commonly missed fracture. BMJ Case Rep 2013; 2013:bcr2013010093 24. Olson RC, Mendicino SS, Rockett MS. Isolated medial cuneiform fracture: review of the literature and report of two cases. Foot Ankle Int 2000; 21:150–153 25. Kou JX, Fortin PT. Commonly missed peritalar injuries. J Am Acad Orthop Surg 2009; 17:775–786 26. Renfrew DL, el-Khoury GY. Anterior process fractures of the calcaneus. Skeletal Radiol 1985; 14:121–125 27. Gupta RT, Wadhwa RP, Learch TJ, Herwick SM. Lisfranc injury: imaging findings for this important but often-missed diagnosis. Curr Probl Diagn Radiol 2008; 37:115–126 28. Sherief TI, Mucci B, Greiss M. Lisfranc injury: how frequently does it get missed? And how can we improve? Injury 2007; 38:856–860 29. Hess T, Rupp S, Hopf T, Gleitz M, Liebler J. Lateral tibial avulsion fractures and disruptions to the anterior cruciate ligament: a clinical study of their incidence and correlation. Clin Orthop Relat Res 1994; 303:193–197 30. Gottsegen CJ, Eyer BA, White EA, Learch TJ, Forrester D. Avulsion fractures of the knee: imaging findings and clinical significance. RadioGraphics 2008; 28:1755–1770 31. Kindred J, Truby C, Simons SM. Foot injuries in
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Ha et al. runners. Curr Sports Med Rep 2011; 10:249–254 32. Smith JT, Johnson AH, Heckman JD. Nonoperative treatment of an os peroneum fracture in a high-level athlete: a case report. Clin Orthop Relat Res 2011; 469:1498–1501 33. Tang JY, Mulcahy H, Chew FS. High energy fracture of the fabella. Radiol Case Rep 2010; 5:454 34. Berbaum KS, Franken EA Jr, Dorfman DD, et al. Satisfaction of search in diagnostic radiology. Invest Radiol 1990; 25:133–140 35. Berbaum KS. Satisfaction of search in osteoradiology. AJR 2001; 177:252–253 36. Berbaum KS, El-Khoury GY, Ohashi K, et al. Satisfaction of search in multitrauma patients: severity of detected fractures. Acad Radiol 2007; 14:711–722 37. Ashman CJ, Yu JS, Wolfman D. Satisfaction of search in osteoradiology. AJR 2000; 175:541–544 38. Fleck MS, Samei E, Mitroff SR. Generalized “satisfaction of search”: adverse influences on dual-target search accuracy. J Exp Psychol Appl
2010; 16:60–71 39. Berbaum KS, Brandser EA, Franken EA, Dorfman DD, Caldwell RT, Krupinski EA. Gaze dwell times on acute trauma injuries missed because of satisfaction of search. Acad Radiol 2001; 8:304–314 40. Rogers LF. Keep looking: satisfaction of search. AJR 2000; 175:287 41. Porrino JA Jr, Kohl CA, Taljanovic M, Rogers LF. Diagnosis of proximal femoral insufficiency fractures in patients receiving bisphosphonate therapy. AJR 2010; 194:1061–1064 42. Jacofsky DJ, Haidukewych GJ. Management of pathologic fractures of the proximal femur: state of the art. J Orthop Trauma 2004; 18:459–469 43. Rouvillain JL, Jawahdou R, Labrada Blanco O, Benchikh-El-Fegoun A, Enkaoua E, Uzel M. Isolated lesser trochanter fracture in adults: an early indicator of tumor infiltration. Orthop Traumatol Surg Res 2011; 97:217–220 44. Phillips CD, Pope TL Jr, Jones JE, Keats TE, MacMillan RH 3rd. Nontraumatic avulsion of the
lesser trochanter: a pathognomonic sign of metastatic disease? Skeletal Radiol 1988; 17:106–110 45. Schwarzkopf R, Oni JK, Marwin SE. Total hip arthroplasty periprosthetic femoral fractures: a review of classification and current treatment. Bull Hosp Jt Dis 2013; 71:68–78 46. Haidukewych GJ, Langford J, Liporace FA. Revision for periprosthetic fractures of the hip and knee. J Bone Joint Surg Am 2013; 95:368–376 47. Kung JW, Melenevsky Y, Hochman MG, et al. On-call musculoskeletal radiographs: discrepancy rates between radiology residents and musculoskeletal radiologists. AJR 2013; 200:856–859 48. Safran O, Goldman V, Applbaum Y, et al. Posttraumatic painful hip: sonography as a screening test for occult hip fractures. J Ultrasound Med 2009; 28:1447–1452 49. Mulcahy H, Chew FS. Foot (case 9–27): location 1636. In: Chew FS, Maldjian C, eds. Broken bones: the x-ray atlas of fractures. Seattle, WA: BareBonesBooks, 2009
Fig. 1—20-year-old man who sustained transient lateral patellar dislocation that spontaneously reduced on field of injury. Fractures were not visible on lateral and anteroposterior radiographs. Sunrise view shows multiple avulsion fragments (arrow) along medial margin of patella.
Fig. 2—19-year-old man after sports injury. A, Initial oblique radiograph shows incomplete second and third metatarsal shaft fractures. Reprinted with permission from [49]. B, Follow-up radiograph obtained 1 week later at outpatient office without radiologic technologists does not show metatarsal fractures because of underpenetration and improper tube angulation. Note lack of trabecular bone detail and poor visualization of tarsometatarsal and naviculocuneiform joints.
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Fig. 3—65-year-old man after ground-level fall with nondisplaced fracture not seen on radiographs. A, Anteroposterior radiograph appears normal. Lateral view was also normal. Patient complained of right hip pain and was unable to bear weight or walk. B, Coronal T1-weighted MRI shows nondisplaced femoral neck fracture. C, Fracture was internally fixed with three compression screws.
A
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Fig. 4—28-year-old woman after ground-level fall. A, Oblique view of ankle shows syndesmotic widening and subtle medial malleolar avulsion fracture. B, Lateral view of proximal leg shows oblique proximal fibular shaft fracture, constituting Maisonneuve fracture.
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Ha et al. Fig. 5—53-year-old man with talus fracture. A and B, Anteroposterior (A) and lateral (B) radiographs show comminuted medial talar body fracture. C and D, Subsequent sagittal (C) and axial (D) CT images more comprehensively show additional oblique fracture (arrows) through talar body extending into subtalar joint.
Fig. 6—35-year-old woman with foot pain after fall. A, On radiographs, including lateral view, fracture is difficult to see even in retrospect. B, Intraarticular fracture of cuboid at fourth tarsometatarsal joint (arrow) is seen on this sagittal CT reformation.
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Fig. 7—Two patients with avulsion fracture signaling underlying injury. A, 32-year-old man with ankle injury sustained in fall. Lateral radiograph shows minimally displaced posterior malleolar fracture (arrow), indicative of rupture of ankle syndesmosis. B and C, 30-year-old man after car-versus-pedestrian crash. Coronal (B) and sagittal (C) STIR MR images show acute Segond fracture at lateral tibial plateau (arrow, B) and full-thickness anterior cruciate ligament tear.
A Fig. 8—32-year-old woman who experienced foot injury while playing soccer. Anteroposterior radiograph shows bipartite medial sesamoid with separation extending diagonally across bone. At proximal aspect, there is transverse avulsion fracture (arrow), and sesamoid has retracted distally. Medial soft tissues are swollen. Diagnosis of turf toe was made.
B
Fig. 9—61-year-old woman who sustained polytrauma in motor vehicle crash. Multiple fractures and dislocations led to satisfaction of search. A and B, Initial evaluation of anteroposterior oblique (A) and lateral (B) radiographs of foot focused on multiple metatarsal and toe fractures and multiple metatarsophalangeal joint dislocations. Calcaneal fractures were initially overlooked.
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Ha et al. Fig. 10—Two patients with unusual fractures. A, 65-year-old woman who presented to emergency department after ground-level fall at shopping mall. Anteroposterior radiograph shows comminuted subtrochanteric femur fracture. She had been taking alendronic acid (Fosamax, Merck) for 10 years for osteoporosis. Abnormal thickening of proximal lateral femoral cortex (arrow) is partially obscured by trauma board. B, 46-year-old man after ground-level fall. Anteroposterior radiograph shows subtrochantericintertrochanteric proximal femur fracture with separate lesser trochanter fragment and marked angulation. Pathology at time of intramedullary rod placement showed metastatic cancer.
Fig. 11—54-year-old man with left total hip arthroplasty. A and B, Frontal radiograph of pelvis (A) and froglateral view of left hip (B) show oblique fracture (arrow, B) of mid shaft of femur extending to level of femoral stem tip.
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