Original contributionsPerformance of a decision rule for radiographs of pediatric knee injuries
Introduction
Acute knee injuries are common complaints in children presenting to the emergency department (ED). Despite the large number of children seeking acute medical attention for these injuries, knee fractures are relatively uncommon. In previous studies, fracture rates in adults have ranged from 5–12% and approximately 4–5% in children (1, 2, 3, 4, 5, 6, 7, 8). Although knee radiographs are routinely obtained in many acute care settings, the low incidence of fractures suggests that much of the associated cost and expense of these evaluations can be avoided (9).
Clinical decision rules have been developed for adults with knee injuries (1, 2, 3, 4, 5, 6). The most widely recognized rule is the Ottawa Knee Rule (OKR) (1, 2, 3). This decision rule was developed as a screening tool for adults with knee injuries. The OKR recommends knee radiographs in patients with one or more of the following criteria: age greater than 55 years, inability to bear weight immediately after the injury and in the ED, inability to flex the knee to 90°, and isolated bony tenderness at the head of the fibula or patella (3). Patients under 18 years of age were explicitly excluded during the development of the OKR, and its authors have not suggested that it be routinely applied to pediatric injuries (3, 10).
Cohen et al. applied an adapted version of the OKR retrospectively to children under age 18 with acute knee injuries (7). They combined the inability to bear weight and the inability to flex to 90°, resulting in a theoretical reduction in the number of knee radiographs by 73% and no missed fractures. In their study, point tenderness was not a good predictor of knee fracture in children and did not add to the sensitivity of the rule. Recently, Khine et al. prospectively sought to validate a version of the OKR in children (8). In their study, this version of the OKR did not identify all children with a knee fracture. The purpose of our study was to assess the performance of this adaptation of the OKR in our pediatric ED population.
Section snippets
Methods
Prospective cohorts were identified in three pediatric acute care settings between October 2000 and March 2002. The study was approved by the Colorado Multiple Institutional Review Board and the Institutional Review Boards at the participating facilities. Our standard of care was to obtain radiographs of an injured knee, and this study did not require any deviation from the standard of care. Written, informed consent and applicable assent was obtained from the parent and patient before
Results
A total of 146 patients met inclusion criteria and were enrolled. One patient’s caregiver was approached but declined to participate for unspecified reasons. The demographic and clinical characteristics of the study population are listed in Table 1. These characteristics mirrored those of other patients seen in our settings for extremity injuries: the majority of the patients were male, and many of the injuries were sports related.
All patients had radiographs performed and all had clinical
Discussion
Stiell et al. assessed 23 standardized clinical findings to derive a clinical decision rule for adults with acute knee injuries (2). They then prospectively validated the rule, known as the Ottawa Knee Rule, in 1047 adult patients (3). The rule was 100% sensitive for detecting clinically significant fractures by requiring radiographs in patients with one or more of the following criteria: 1) inability to bear weight either immediately after the injury or in the ED, 2) inability to flex the knee
Conclusions
Decision rules for radiography of acute knee injuries have been shown to be useful and cost-effective in adult patients. However, widespread agreement on the applicability of similar decision rules to pediatric knee injuries does not exist. Our data suggest that a simplified decision rule incorporating only the ability to bear weight has a high negative predictive value for knee fractures in children and may reduce the number of unnecessary, negative radiographs.
Acknowledgments
We thank Carol Turner, md for study development and Shayne Bland, msc for statistical analysis. We also thank Mark Roback, md, for manuscript review.
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Cited by (10)
My knee won’t stop swelling! Osteosarcoma
2021, Pediatric Imaging for the Emergency ProviderACR Appropriateness Criteria® Acute Trauma to the Knee
2020, Journal of the American College of RadiologyCitation Excerpt :In the setting of significant acute trauma to the knee, radiographs should be the first imaging study. It is general agreement that radiographs should be obtained and the clinical decision rule should not be applied for patients with gross deformity [3], a palpable mass [10], a penetrating injury, prosthetic hardware, an unreliable clinical history or physical examination secondary to multiple injuries [3,10], altered mental status (eg, head injury, drug or alcohol use, dementia) [3,10], neuropathy (eg, paraplegia, diabetes) [3,10], or a history suggesting increased risk of fracture. Additionally, in any case scenario, the physician’s judgment and common sense should supersede clinical guidelines [3].
The preferences of physiotherapy clinical educators on a learning package for teaching musculoskeletal clinical prediction rules – A qualitative study
2019, Musculoskeletal Science and PracticeACR Appropriateness Criteria Acute Trauma to the Knee
2015, Journal of the American College of RadiologyCitation Excerpt :Reasons cited include: (1) patient expectations, (2) demands of orthopedic consult, (3) lack of confidence in physical examination, and (4) fear of being sued [8]. Clinical decision rules for the acutely injured knee suggest that radiographic examination of the knee after acute injury can be eliminated in many instances by applying specific clinical guidelines [6-10]. Two of the most common clinical decision rules are the Ottawa Knee Rule and the Pittsburgh Decision Rule.
Evaluation and Treatment of Childhood Musculoskeletal Injury in the Office
2014, Pediatric Clinics of North AmericaCitation Excerpt :These injuries should be triaged based on severity. If patients can bear weight, radiographs are not necessary.2 If patients can bear weight, or if they cannot bear weight but radiographs are negative, a period of watchful observation is appropriate.
Imaging of traumatic injuries of the knee
2007, Journal de Radiologie
Original Contributions is coordinated by John Marx, md, of Carolinas Medical Center, Charlotte, North Carolina
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Current Affiliation: Mayo Clinic, Rochester, Minnesota