Published online March 3, 2008
PEDIATRICS
(doi:10.1542/peds.2007-1899)
Utility of Total Lower Extremity Radiography Investigation of Nonweight Bearing in the Young Child
Christopher M. Baron, MDa,
Jayne Seekins, DOa,
Marta Hernanz-Schulman, MDa,
Chang Yu, PhDb and
J. Herman Kan, MDa
a Department of Radiology and Radiological Sciences, Vanderbilt Children's Hospital
b Department of Biostatistics, Vanderbilt University, Nashville, Tennessee
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ABSTRACT
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OBJECTIVES. The purpose of this work was to determine the utility of total lower extremity radiographs versus dedicated tibia radiographs in the evaluation of the young child presenting with nonweight bearing without localizing signs.
METHODS. This was an institutional review board-approved retrospective review of 263 consecutive patients between the ages of 9 months and 4 years who were referred for total lower extremity radiography between September 29, 2001, and November 7, 2006. Among these, a total of 133 study subjects met inclusion criteria of presentation with nonweight bearing without localizing signs or history of previous trauma. The control population was selected from 1089 consecutive patients between the ages of 9 months and 4 years evaluated from January 5, 1999 and December 8, 2006, who had only tibia radiographs at presentation. From this group, a final control population of 128 patients was selected with similar presentation of nonweight bearing without localizing signs or history of previous trauma. Causes of nonweight bearing were recorded for both groups based on radiograph findings and additional studies performed during workup.
RESULTS. At initial presentation, fractures were present in 13 study patients (9.8%) and in 23 control patients (17.9%). Total fractures (when including follow-up) were present in 14 study patients (10.5%) and in 26 control patients (20.3%). Fractures were located in the tibia alone in 100% of patients in the study group. Extratibial fracture (metatarsal) was present in 1 patient in the control group (0.7%). Among the study group, additional diagnoses included rickets (n = 1), cerebellar ataxia (n = 1), and discitis with epidural abscess (n = 1).
CONCLUSIONS. Our study findings indicate that the diagnostic value of total lower extremity radiography is similar to dedicated tibia radiography in the workup of the nonweight-bearing young child without trauma history or localizing signs. Radiation and cost savings can be realized by reserving additional radiographs for patients with high clinical suspicion and normal findings on dedicated tibia radiography.
Key Words: fractures • radiation reduction in children • leg radiography • tibia fractures • gait
Abbreviations: ACR—American College of Radiology
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INTRODUCTION
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Tibial fractures are one of the most common causes of nonweight bearing in the preschool-aged child without localizing physical examination findings or history of infection or specific traumatic event.1,2 In some centers, these patients are nevertheless referred for total lower extremity radiography to assess for fractures involving other extremity bones or alternative causes for nonweight bearing, such as developmental dysplasia of the hip or early Legg-Calves-Perthes disease. The problem with this approach is that total lower extremity radiography, which may include the pelvis, knee, femur, foot, and ankle, adds additional radiation exposure and cost, whereas the clinical impact is uncertain compared with limiting the initial workup to radiographs of the tibia. The purpose of this study was to determine the utility of total lower extremity radiography versus dedicated tibia radiography in the initial evaluation of nonweight bearing in the young child without localizing signs or specific trauma history.
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METHODS
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Total lower extremity radiographs are defined as dedicated anteroposterior and lateral views of the tibia and dedicated anteroposterior and lateral views of the femur. The majority of patients will also have additional anteroposterior and froleg lateral views of the pelvis if requested.
Patient Selection
This study was approved under our institutional review board with waiver of patient consent. We conducted a retrospective cohort study in which we examined 2 groups of patients at a major tertiary care children's hospital. One cohort, the study group, represents those patients who underwent total lower extremity radiography. The second cohort, the control group, represents those patients who underwent initial dedicated tibia radiographs. For both groups, the clinical history, gathered through our electronic clinical database, included nonweight bearing with no history of trauma and a nonlocalizing clinical examination. Patients were excluded if there was known metabolic bone disease, malignancy, known mechanism of injury, or a localizing clinical examination (eg, focal bony tenderness, ecchymosis, or limited range of motion at 1 joint). Similar exclusion and inclusion criteria were used in the control group, which was otherwise defined as patients in whom only radiographs of the tibia were requested.
Our study population was generated by retrospectively reviewing 263 consecutive patients aged 9 months to 4 years who were referred to our institution for total lower extremity radiography between September 29, 2001 and November 7, 2006. A total of 133 (mean age: 2.1 years; male/female ratio: 1.4:1.0) patients met our inclusion and exclusion criteria as outlined above, and this constituted our study population.
Our control population was generated by retrospective review of a total of 1089 consecutive patients between the ages of 9 months and 4 years referred to our institution for tibia radiographs between January 5, 1999 and December 8, 2006. A total of 128 patients (mean age: 1.9 years; male/female ratio: 1.6:1.0) met our inclusion and exclusion criteria as outlined above, and this constituted our control population.
Data Analysis
Data points recorded for both groups include the presence of fracture and location, evidence of callus formation, other pathologies that could explain their symptoms, percentage with clinical follow-up (this includes clinical only or clinical with radiographs), additional extremity radiographs that were obtained during the initial clinical visit, and subsequent pathologies found at follow-up. The total cost (technical and professional fees) of tibia and fibula views and the additional costs of pelvis and femur views were also obtained from our institution. In addition, cost difference between beginning the radiographic workup of nonweight bearing with tibia and fibula radiographs versus total lower extremity radiography was calculated.
Statistical Analysis
Proportions of patients with the study end points are summarized in Tables 1 and 2. A Pearson 
2 test or Fisher's exact test was used to assess the difference on these categorical end points between the 2 groups. P values <.05 are considered statistically significant. All of the tests were 2 tailed. Statistical analyses were performed with the statistical package SAS 9 for Windows (SAS Institute, Inc, Cary, NC).
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RESULTS
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For the study and control population, tibia fractures were by far the most common pathologic finding (Tables 1 and 2). There were no extratibial fractures in the study population, and there was a single extratibial fracture (metatarsal) in the control population. At initial presentation, callus formation was evident in none of the patients in the study group and 4 of the patients in the control group. Buckle-type fractures were present in 1 patient in the study group and 8 patients in the control group. The remainder of the fractures was either transverse or oblique fractures. None of the fractures were displaced at presentation.
Follow-up occurred at our institution in 33.8% of study subjects and 43% of control subjects (Table 1). There were 4 subjects with tibia fractures found only at follow-up (1 study, 3 control subjects) who were initially radiographically negative and were treated presumptively for a tibia toddler's fracture with either a short leg walking cast or hard-soled boot.
No patients in the study and control populations were found to have developmental dysplasia of the hip or Legg-Calves-Perthes disease. No femur or pelvis fractures were found. One study patient was ultimately diagnosed with discitis and epidural abscess, initially presented with nonweight bearing with no history of trauma. After negative total lower extremity radiography, he was discharged. When the symptoms persisted, the patient returned with more localizing pain, was afebrile, and had an erythrocyte sedimentation rate that measured 53 mm per hour. Plain radiographs of the lumbar spine were obtained suggesting discitis, which was confirmed by MRI.
One study patient was diagnosed with acute cerebellar ataxia, initially presented with a nonlocalizing examination, low grade fever, and limp with negative total lower extremity radiography. This child had a worsening ataxic gait, discoordination, and frequent falls, and subsequent workup led to the clinical diagnosis of acute cerebellar ataxia, which resolved spontaneously.
The total cost (technical and professional fees) of beginning the workup of nonweight bearing with tibia and fibula radiographs alone is $294. The total cost of initially requesting total lower extremity radiography is $830, which is $536 more than beginning the radiographic workup with tibia and fibula radiographs alone. The additional cost of including the pelvis and femur radiographs is $242 and $296, respectively.
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DISCUSSION
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There are several options in the management of nonweight bearing in the young child with a nonlocalizing clinical examination without witnessed or recalled trauma. The patient may be treated conservatively and observed to see if symptoms resolve spontaneously. Should the patient proceed to imaging, the choice of what to image, when to image, and which modality to choose is very problematic when history and clinical examination are nonspecific.
Imaging workup recommendations of the nonweight bearing young child vary among various published studies, mainly because the study populations are heterogeneous. Blatt et al3 evaluated outpatient children 1 to 5 years of age, 51% of whom had a history of recent trauma, who presented with a gait disturbance without localizing physical examination findings, and none of the 84 patients had fractures or osseous abnormality to explain their symptoms. Their conclusion was that radiographs were unlikely to contribute to the diagnosis of the gait disturbance. On the other hand, Oudjhane et al4 showed that 20% of all preschool children with an unexplained limp had fractures. The distribution of these fractures included 56% tibia, 30% femur, and 2% pelvic fractures, but the limitation of this study is that the preceding clinical examination findings for these patients is not described in detail.4 This study would suggest that physicians should routinely obtain total lower extremity radiography, given that 32% of fractures occurred above the knee in preschool children with an acute limp. Bone scintigraphy has been proposed as an alternative option in the workup of the preschool-aged child with acute nonweight bearing and a nonlocalizing clinical examination in the workup of the toddler's tibia fractures.5 Englaro et al6 observed a high incidence of tarsal bone injuries (53%) in preschool children when performing bone scintigraphy in patients with a history of limp or lower extremity pain.
The potential benefit of total lower extremity radiography in the initial workup of nonweight bearing is that it may provide assurance that no extratibial fracture or radiographically visible osseous abnormality is present to explain symptoms. Surprisingly, in addition to not finding any extratibial fractures in our study population, we also did not find any cases of developmental dysplasia of the hip or Legg-Calves-Perthes disease. When total lower extremity radiography is unrevealing, the additional workup of causes of nonweight bearing without localizing signs remains unchanged. Therefore, imaging evaluation of the thoracolumbar spine, the workup and exclusion of toxic synovitis, and the laboratory and imaging workup of septic arthritis and osteomyelitis will still need to be performed.
Our control and study populations are unique compared with previously published studies, because we restricted our study to patients without witnessed or recalled history of trauma and in whom the clinical examination was nonlocalizing. Controlling these clinical variables showed that no additional information is provided by total lower extremity radiography compared with tibia radiographs alone in the initial workup of nonweight bearing. No additional extratibial fractures were found in patients with total lower extremity radiography, and only 1 was found in the control group, in an area beyond the scope of the total lower extremity imaging. Our results additionally confirm that clinically occult tibia fractures are the most frequent cause of acute nonweight bearing in the infant and young child with no localizing signs; therefore, this should be excluded before pursuing additional radiographic workup, in the interest of optimizing management and reducing radiation and financial exposure. We speculate that clinically significant causes for nonweight bearing other than tibia fractures in the young child will present with localizing physical examination findings or history; hence, these patients were not evaluated in our study.
The 2000 American College of Radiology (ACR) appropriateness criteria for the limping child from 0 to 5 years by Royal et al7 have proposed 2 variations of the workup of the limping child: variant 1, the nonfocal clinical examination, and variant 2, the focal clinical examination. For the workup of the limping child with a nonfocal clinical examination, the 2000 ACR appropriateness criteria states that anteroposterior pelvis, femur, leg, and foot radiographs are all equally moderately appropriate (rated a 6 on a scale of 1–9, where 1 is least appropriate and 9 is most appropriate). Based on our results, we would recommend that the tibia radiographs have a much higher appropriateness rating compared with radiography elsewhere of the lower extremity.
In the nonweight-bearing child without localizing examinations and negative radiographs, we do not advocate screening hip sonography or routine MRI investigation; these studies should be reserved when there are focal clinical examination findings. Furthermore, MRI should be performed when there is a high clinical concern for alternative diagnosis other than occult fracture, such as infection, and the potential need for sedation has been considered. Bone scintigraphy can play a valuable role in the initial screening of the nonweight-bearing child; however, it is a time-consuming examination (2.5–3.0 hours) and is not routinely available at all hours of the day.
The limitations of our study include its retrospective nature and that the choice of imaging examination workup was at the discretion of the referring physician. Second, the referring clinicians' orthopedic expertise was variable, because study and control patients were referred from emergency department physicians, pediatricians, and orthopedists. This could have introduced imaging referral bias; however, the referral pattern for both the study patient and control groups was the same. Third, some patients had follow-up with their pediatricians, and their electronic medical charts were not available in our system; therefore, the actual number of pathologic conditions may potentially be higher than our study suggests for both the study and control population. However, major medical conditions for nonweight bearing that would require advanced imaging with sedation or advanced treatment expertise probably were not missed, because our institution is the only regional tertiary children's hospital. In addition, unless patients present to an outside emergency department, it is also unlikely that relatively minor medical conditions, such as a toddler's delayed tibia fracture, would be missed in the patients without electronic follow-up, because the vast majority of regional pediatric imaging is performed at our institution. Fourth, the ages of our study population (1.9 years) and of our control population (2.1 years) were not identical, and the impact of this on our results is not known. Nevertheless, our findings that tibia fractures were the most common injury regardless of radiographic workup strategy remain valid.
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CONCLUSIONS
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Total lower extremity radiography for the initial workup of nonweight bearing with nonlocalizing signs in the young child does not provide additional information that is not already provided from dedicated tibia radiographs. Tibia toddler fractures were the most common explanation for nonweight bearing. Therefore, if initial tibia radiographs are normal, follow-up feet radiographs can be done, and femoral and pelvic radiographs can be reserved for patients with a high clinical suspicion for fracture. Based on these findings, we believe that the 2000 ACR appropriateness criteria in the imaging workup of nonweight bearing in the young child with nonlocalizing sign should reflect a higher appropriateness score for tibia radiographs compared with radiographs elsewhere of the lower extremity.
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FOOTNOTES
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Accepted Aug 31, 2007.
Address correspondence to J. Herman Kan, MD, Department of Radiology and Radiological Sciences, Vanderbilt Children's Hospital, Vanderbilt University, 2200 Children's Way, Nashville, TN 37232. E-mail: herman.kan{at}vanderbilt.edu
The authors have indicated they have no financial relationships relevant to this article to disclose.
| What's Known on This Subject
The current 2000 American College of Radiology appropriateness criteria for the limping child 0 to 5 years of age without localizing signs states that radiographs of the pelvis, femur, leg, and foot are equally moderately appropriate.
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| What This STudy Adds
The diagnostic value of total lower extremity radiography is similar to dedicated tibia radiography in the workup of the limping child without localizing signs. Radiation and cost savings can be realized by reserving additional radiographs for patients with high clinical suspicion and normal findings on dedicated tibia radiography.
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PEDIATRICS (ISSN 1098-4275). ©2008 by the American Academy of Pediatrics
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ABSTRACT
INTRODUCTION
