Acute Knee Injuries


Chapter 9
Acute Knee Injuries


Jesse M. Pines1,2 and Fernanda Bellolio3


1 US Acute Care Solutions, Canton, OH, USA


2 Department of Emergency Medicine, Drexel University, Philadelphia, PA, USA


3 Department of Emergency Medicine, Mayo Clinic, Rochester, MN, USA


Background


Acute knee pain is a common complaint in the emergency department (ED). It is the most commonly injured joint in athletes with an estimated 2.5 million sports‐related injuries presenting to EDs annually, and an overall rate of 2.29 knee injuries per 1000 population. In one study, including more than 6 million ED visits secondary to knee injuries from 1999 through 2008, patients aged 15 to 24 years had the highest injury rate (3.83 per 1000). Injuries were associated with sports and recreation in one‐half of the cases. Older patients are more likely to sustain injuries after a fall.1 Prior to the advent of clinical decision rules, plain radiographs of the knee were typically obtained to rule out a fracture after blunt knee trauma where there was any clinical suspicion of fracture. However, similar to ankle injuries, knee fractures are identified in only a small proportion (4–7%) of knee injuries. Two clinical decision rules have been created to identify patients in whom knee radiography may be deferred in the setting of an acute knee injury: the Ottawa knee rule and the Pittsburgh knee rule. The Ottawa knee rule and the Pittsburgh knee rule are described in Table 9.1.


Table 9.1 Clinical decision rules to defer radiography in patients with blunt knee trauma































The Ottawa knee rule
The Ottawa knee rule recommends radiography if any of the following is present in the context of an acute knee injury:


  1. Age > 55 years


  1. Tenderness at the head of fibula


  1. Isolated tenderness at the patella


  1. Inability to flex knee to 90 degrees


  1. Inability to transfer weight for four steps, both immediately after the injury and in the ED
Exclusion criteria for the Ottawa knee rule include age < 18 years, superficial skin injuries, injuries more than 7 days old, reevaluation of recent injuries, altered levels of consciousness, paraplegia, or multiple injuries
The Pittsburgh knee rule
The Pittsburgh knee rule recommends radiography if:
The mechanism of injury is either blunt trauma or a fall AND either


  1. Age is < 12 years or > 50 OR


  1. There is an inability to walk four weight‐bearing steps in the ED
Exclusion criteria for the Pittsburgh knee rule are knee injuries > 6 days prior to presentation, only superficial lacerations and abrasions, a history of previous surgeries or fractures on the injured knee, and patients being reassessed for the same injury

Clinical question


How well does the Ottawa knee rule identify patients requiring knee radiography?


A systematic review of studies on the Ottawa knee rule directly addressed this question.2 The authors included articles that reported patient‐level information to determine sensitivity and specificity. Two reviewers independently tallied data on study samples, the details about how the Ottawa knee rule was used, and methodological characteristics. Of the 11 studies identified, data were collected from six, resulting in a set of 4249 adult patients who were considered appropriate for pooled analysis. The aggregate negative likelihood ratio was 0.05 (95% confidence interval [CI

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May 14, 2023 | Posted by in Uncategorized | Comments Off on Acute Knee Injuries

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