Pediatrics/Original Research
Validation of the Ottawa Knee Rule in children: A multicenter study☆,☆☆

Presented as a platform presentation at the Pediatric Academic Society annual meeting, Seattle, WA, May 2003.
https://doi.org/10.1067/mem.2003.196Get rights and content

Abstract

Study objective: The main objective of this study was to determine the sensitivity and specificity of the Ottawa Knee Rules when they were applied to children. The secondary objective was to determine post hoc whether use of the rules would reduce the number of knee radiographs ordered. Methods: This prospective, multicenter validation study included children aged 2 to 16 years who presented to the emergency department with a knee injury sustained in the preceding 7 days. Children were assessed for the variables comprising the Ottawa Knee Rules, and physicians ordered radiographs at their discretion. A positive outcome was defined as any fracture. A negative outcome was defined as children who did not have a fracture on radiograph or, if no radiograph was obtained, were asymptomatic after 14 days. Results: A total of 750 children were enrolled. The mean age was 11.8±3.1 years, and 443 (58.7%) were male patients. Seventy children had fractures. Radiography was performed for 670 children, whereas 80 children had only a structured telephone interview. The Ottawa Knee Rules were 100% sensitive (95% confidence interval [CI] 94.9% to 100%), with a specificity of 42.8% (95% CI 39.1% to 46.5%). Only 460 children would have required a radiograph if radiographs had been performed according to the Ottawa Knee Rules, which would have resulted in an absolute reduction of 209 (31.2%) radiographs. Conclusion: The Ottawa Knee Rules are valid in children and have the potential to decrease the use of radiography in children with knee injuries. [Ann Emerg Med. 2003;42:48-55.]

Introduction

Of all children presenting to the emergency department (ED), between 10% and 20% have a chief complaint involving an extremity injury.1, 2 More than 90% of children presenting with extremity injuries undergo radiographic studies.1, 2, 3, 4 Approximately 8% of these injuries involve the knee.2 Clinical decision rules have been developed for adults and have been shown to be sensitive in the detection of fractures. The implementation of these rules has reduced the number of radiographs ordered and may decrease health care costs and waiting times in the ED.5, 6, 7, 8, 9

Studies by Stiell et al8, 9 in the adult population have found that the Ottawa Knee Rules are 100% sensitive for detecting clinically significant fractures in adults with knee injuries. The Ottawa Knee Rules state that knee roentgenography is required only for patients who have acute knee injury and at least 1 of the following findings related to age, tenderness, or function (Figure): (1) aged 55 years or older, (2) tenderness at head of fibula, (3) isolated tenderness of patella (no bone tenderness of knee other than patella), (4) inability to flex to 90 degrees, and (5) inability to bear weight immediately and in the ED (defined as an inability to transfer weight twice onto each lower limb, regardless of limping).8Clinically significant fractures were defined as any bone fragment at least 5 mm in breadth or any avulsion fracture regardless of size, if associated with complete disruption of tendons or ligaments. Applying these rules resulted in a 28% reduction in the number of radiographs ordered.10

As pointed out by Plint et al,7 extremity injuries in children have several complicating factors. Children have open epiphyseal plates (growth plates) and may sustain Salter-Harris fractures. Assessment of pain and weight bearing may also be difficult in a young or frightened child. However, the authors were able to apply the Ottawa Ankle Rules in children in a prospective study and found them to be 100% sensitive.7

Only 1 small previous study has been published that prospectively applied the Ottawa Knee Rules to children with knee injuries.11 However, this study enrolled only 234 patients and identified only 13 fractures, which resulted in wide confidence intervals (CIs).

The main objective of this study was to determine the sensitivity and specificity of the Ottawa Knee Rules when they were applied to children aged 2 to 16 years. The rule was modified to include bone fragments of any size as being a significant fracture because there is no evidence in the literature to suggest otherwise in this population. A secondary objective was to determine post hoc whether use of the rules would reduce the number of knee radiographs ordered for children presenting with knee injuries to the ED.

Section snippets

Materials and methods

This prospective, multicenter validation study was conducted between January 1999 and May 2002 at 5 urban academic pediatric EDs with a combined census of approximately 195,000 patient visits yearly. All children who were between 2 and 16 years of age and presented with acute injuries to the knee were eligible for the study. The lower age limit of 2 years was based on the article validating the Ottawa Ankle Rule,7 in which 2 years was chosen as a cutoff age that maximized enrollment but

Results

During the study period from January 1, 1999, to May 31, 2002, a total of 1,139 children were eligible for enrollment. Of these, 92 met exclusion criteria and 297 were missed, leaving a total of 750 (66%) children that were enrolled at the 5 centers (Table 1).The overall mean age in the study group was 11.8±3.1 years, and 443 (58.7%) were male patients, which was similar to those who were not enrolled, in which the average age was 12.0±2.9 years and male patients accounted for 52.9% (n=206).

The

Discussion

To our knowledge, no other study has prospectively examined such a large number of children with knee injuries to determine the sensitivity and specificity of a clinical decision rule. To avoid changing physician management, children did not need to have a radiograph to be enrolled in the study. It was thought that all children who were asymptomatic on follow-up at 14 days postinjury did not experience a fracture. As with adults, the Ottawa Knee Rules are 100% sensitive in identifying fractures

Acknowledgements

We thank Mary Cheang, PhD, for her statistical consultation.

References (24)

  • KM McConnochie et al.

    Prediction rules for selective radiographic assessment of extremity injuries in children and adolescents

    Pediatrics

    (1990)
  • IG Stiell et al.

    Decision rules for the use of radiography in acute ankle injuries, refinement and prospective validation

    JAMA

    (1993)

    • Cited by (60)

    • MSK Trauma

      2023, Problem Solving in Pediatric Imaging

    • Growing bones

      2021, A Comprehensive Guide to Sports Physiology and Injury Management: An Interdisciplinary Approach

    • The preferences of physiotherapy clinical educators on a learning package for teaching musculoskeletal clinical prediction rules – A qualitative study

      2019, Musculoskeletal Science and Practice
      Citation Excerpt :

      There was some disagreement as to whether this should be an exhaustive list of ‘all the CPRs you might use’ (as expressed by Ellen), or just those most commonly used, or perhaps those which have been validated and shown to have a positive impact on health outcomes and healthcare resources. Nonetheless, there was considerable support for the various Ottawa rules, which have been well-validated in multiple studies (Bachman et al., 2004; Bulloch et al., 2003; Emparanza et al., 2001; Gravel et al., 2009; Libetta et al., 1999; Moore et al., 2005; Plint et al., 1999; Richman et al., 1997; Stiell et al., 1993; Stiell et al., 1996; Vijayasankar et al., 2009) and are the best known CPRs amongst physiotherapy clinical educators and students (Knox et al., 2015; Knox et al., 2017). The inclusion of background information on CPRs was considered valuable, and there was support for copies of, or at least links to, study papers that describe the development of some specific CPRs.

    • Reduction of Radiography with Point-of-Care Elbow Ultrasonography for Elbow Trauma in Children

      2018, Journal of Pediatrics
      Citation Excerpt :

      According to our data, point-of-care elbow US, in combination with history and physical examination, can reduce the use of radiography by 23%. This difference is comparable with the reduction in radiography that occurs with application of other adult and pediatric musculoskeletal imaging guidelines, such as the National Emergency X-Radiography Utilization Study criteria for cervical spine injuries (13% reduction),3 the Ottawa Knee Rule (31% reduction),12 and the Ottawa Ankle Rule (16%-29% reduction).13 Similar to previous studies,7,8 we have demonstrated a higher sensitivity and negative predictive value than a specificity or positive predictive value for identification of elbow fracture by US.

    • Evaluation and management of traumatic knee injuries in the emergency department

      2015, Emergency Medicine Clinics of North America
      Citation Excerpt :

      In the original study, application of the rule was 100% sensitive in ruling out a fracture, and resulted in a relative reduction in plain film use by 28%. The Ottawa Knee Rule has since been validated prospectively and can also be applied to children.8 The Pittsburgh Decision Rule was described by Seaberg and Jackson9 in 1994 (Box 2).

    • Acute Sports-Related Lower Extremity Injuries

      2013, Clinical Pediatric Emergency Medicine
    View all citing articles on Scopus
    ☆

    This study was funded by a grant from the Children's Hospital Foundation of Manitoba, Inc.

    ☆☆

    Reprints not available from the authors.

    View full text
    Copyright © 2003 American College of Emergency Physicians. Published by Mosby, Inc. All rights reserved.