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Children's Hospital Medical Center Cincinnati, OH 45229-3039
I read with interest the article by Major and Crawford [1] concerning posttraumatic elbow effusions with no radiographic evidence of fracture compared with findings on MR imaging. By using a more sensitive test (MR imaging) as the gold standard for detecting fracture, the authors have brought further understanding to the question of whether a joint effusion without fracture may be considered synonymous with occult fracuture. I applaud the authors' diligence in identifying such patients in the emergency setting and arranging for these patients to undergo MR imaging on a research basis. In the discussion section of their article, the authors state that the purpose of the study was "to investigate whether an abnormality exists when an elbow joint effusion is present in the setting of trauma and to refute the idea by Donnelly et al." [2]. The authors conclude that on the basis of findings on MR imaging, "an occult fracture usually is present in the setting of effusion without radiographically visualized fracture" [1]. I take issue with the authors' implications toward my previous article [2] and with their conclusions as they pertain to pediatric patients.
There has been much debate concerning the significance of a traumatic elbow joint effusion with no radiographically identifiable fracture in children. It has been a common teaching in radiology that a traumatic elbow joint effusion with no identifiable fracture should be considered synonymous with an occult fracture. Early publications supported this assertion [3,4,5] by showing that a nearly 100% development of periosteal reaction on follow-up radiography indicated occult fracture in such patients. Several years ago, we noted that this did not seem to be our experience when interpreting follow-up trauma radiographs in our orthopedic clinics. In a review of 54 children who had follow-up radiography for traumatic elbow effusion with no initial evidence of fracture, only 17% showed sclerosis or periosteal reaction to suggest healing occult fracture [2]. One of our conclusions was that "joint effusion in the absence of visualized fracture is not associated with a high incidence of occult fracture. Therefore, the two scenarios should not be considered synonymous" [2]. There have been other reports of similar low incidence of occult fractures in this setting, as defined by evidence of healing on follow-up radiographs [6].
Major and Crawford made the next step and evaluated such patients with a more sensitive test, MR imaging, to determine the incidence of fractures not shown by initial radiography. As Major and Crawford point out, their study population included both adults (n = 6) and children (n = 7) [1]. However, it is important to evaluate the pediatric patients as a separate group because conclusions concerning adult patients often, if not usually, do not apply to children and can lead to misconceptions concerning pediatric imaging. Despite the high sensitivity of MR imaging, only 54% of the seven children they studied had evidence of a fracture. As one might expect, all had some degree of traumatic marrow edema. I would argue that these findings further support the conclusions from our previous publication: traumatic joint effusions should not be considered synonymous with occult fracture [2]. In almost half of cases, a fracture was not revealed, even by MR imaging.
Major and Crawford [1] state in the introduction to their article that because of the debate over the incidence of occult fracture in this setting, "the usefulness of the posterior fat pad sign has come into question." I do not think that this has ever been the issue: certainly, we did not previously suggest it. A joint effusion is a sign of a significant traumatic injury and should be treated accordingly, and it should raise suspicion that a subtle fracture may be present—even if the incidence of occult fracture is markedly lower than initially thought. As we previously stated, "In virtually all children, an elbow injury associated with hemarthrosis is considered significant and subsequently reevaluated clinically, whether a fracture is present or not" [2].
This brings up the other major point that we tried to make: the identification of a subtle fracture does not alter the management of pediatric patients with traumatic elbow hemarthrosis [2]. This is an academic rather than a clinically significant debate in regard to children. Children with elbow hemarthrosis should be treated with posterior splinting and clinical reevaluation, regardless of whether a subtle fracture is identified. In Major and Crawford's series [1] as well as another series using MR imaging to evaluate pediatric elbow trauma [7], findings on MR imaging did not change the treatment of the affected children.
In conclusion, I believe Major and Crawford's findings [1] that only approximately half of children with traumatic elbow effusion have fractures depicted on MR imaging support the notion that traumatic elbow hemarthrosis without fracture shown on radiography should not be considered synonymous with occult fracture in children. To suggest that such elbow effusions are synonymous with occult fracture in children may result in unnecessary pediatric radiologic examinations. Obtaining multiple radiographs at different obliquities to identify a fracture—or obtaining follow-up radiographs only on the basis of the belief that an occult fracture must be present—does not alter pediatric patients' management, and the practice results in unnecessary radiation exposure. The conclusions stated in Major and Crawford's article concerning the high incidence of radiographically occult fracture and their statement that the detection of those fractures by MR imaging altered patients' management [1] pertain to the adult rather than the pediatric patients studied.
References
Duke University Medical Center Durham, NC 27710
Mallinckrodt Institute of Radiology St. Louis, MO 63108
Dr. Donnelly's letter is insightful and thorough. The premise of our article [1] developed after reading the article by Donnelly et al. [2]. I was surprised to learn from their work that only a small percentage of conventional radiographs showed periosteal reaction on follow-up examination, suggesting that perhaps not all effusions were a result of fractures. Because we had MR imaging available to evaluate elbow effusions in the setting of trauma, we investigated the cause of the effusion. Although our patient population was small, our findings indicated that fractures did occur, but not in 100% of these patients. Even the pediatric population had fractures more than half the time, as Donnelly points out.
As Donnelly mentions, management of the patients in our study did not change on the basis of the findings of a fracture. Patients were treated with a posterior splint as they would have been had they not been examined using MR imaging. We did not anticipate that findings on MR imaging would alter patient management; instead, we hoped that the findings would educate us about the possible abnormalities that might explain the presence of a joint effusion. Despite our small patient population, we did note both radial head fractures and supracondylar fractures in the pediatric population. We thank Donnelly for his comments and thank him for his article that led to our study.
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