Diagnostic accuracy of the Ottawa Knee Rule in adult acute knee injuries: a systematic review and meta-analysis

The utility of standing knee radiographs for detection of lipohemarthrosis: comparison with supine horizontal beam radiographs

OBJECTIVES

Lipohemarthrosis is a key finding in acute trauma patients and indicates an intra-articular fracture. The horizontal beam lateral radiography with supine position is known to be the best technique to demonstrate knee lipohemarthrosis. Our main purpose was to compare the sensitivity of supine and standing lateral knee radiographs to detect lipohemarthrosis.

METHODS

In our retrospective study, consecutive patients with lipohemarthrosis on computed tomography of the knee between October 2019 and September 2021 were included. Fractured bone, the presence of lipohemarthrosis, and image quality in both standing and supine anteroposterior and lateral knee radiographs were evaluated. Interobserver reliability of the three observers was calculated. Fisher exact chi-square and z-proportion tests were used to compare lateral and anteroposterior knee radiographs. Krippendorff's Alpha and Kappa coefficients were used for inter-observer agreement.

RESULTS

A total of 61 patients (38 men [62.3%], 23 women [37.7%]; mean age, 43 years ± 17 [standard deviation]) were included. The most common type of fracture was isolated tibial fractures (n = 32; 52.5%). The sensitivity of showing lipohemarthrosis of standing lateral knee radiographs (95.5%) was higher than supine lateral radiographs (38.5%) (p < 0.001). While non-optimal image quality did not affect lipohemarthrosis detection on lateral radiographs (p > 0.99), it caused a significant decrease in the diagnosis of lipohemarthrosis on anteroposterior radiographs (p = 0.036). We found a good-excellent interobserver agreement in lipohemarthrosis detection.

CONCLUSIONS

Standing lateral radiographs have higher sensitivity than supine lateral radiographs in detecting lipohemarthrosis and are beneficial for detecting lipohemarthrosis which indicates the presence of occult-evident intraarticular fracture in patients with knee trauma.

CLINICAL RELEVANCE STATEMENT

Standing lateral knee radiographs offer a useful method for reducing the misdiagnosis of the occult intra-articular fractures by showing the fat-fluid leveling more clearly. Its advantages may be more prominent when the advanced imaging modalities are limited.

KEY POINTS

• Fat-fluid level (lipohemarthrosis) is an important radiographic sign to assess patients with acute trauma. It almost always indicates an intra-articular fracture. • Our retrospective study results support that lipohemarthrosis sign could be observed more frequently in standing lateral knee radiographs than in supine lateral radiographs. • Knee trauma patients, when available, should be evaluated with standing lateral radiographs for the diagnosis of lipohemarthrosis.

Construction and validation of a functional diagnostic score in anterior cruciate ligament ruptures of the knee in the immediate post-traumatic period. Preliminary results of a multicenter prospective study

INTRODUCTION

Knee ligament injuries are frequent and their number is constantly increasing with the development of sports activities. Dynamic knee maneuvers usually make it possible to diagnose anterior cruciate ligament (ACL) injuries but they remain difficult to perform in the early post-traumatic phase. This leads to the almost systematic use of MRI scans, many of which turn out to be superfluous. The aim of this study was to construct a screening score based solely on history-taking, in order to help diagnose ACL injuries, and to define thresholds that could help inform recommendations for MRI usage. The hypothesis was that this score could distinguish a population of patients with a ruptured ACL from a population of patients with other knee injuries.

MATERIAL AND METHODS

This prospective multicenter study included 166 patients. Patients were included if they were between 18 and 55 years of age, with knee trauma that had occurred in the last 10 days, and without a bone fracture on standard radiographs. They were excluded if the trauma required immediate surgical management and if they had a history of knee trauma. The screening score was completed by the physician. The score included the following items: assessment of pain, immediate post-traumatic functional impairment, notion of a "pop", feeling of instability and presence of a swelling. An MRI was systematically performed and the patient consulted a referring physician to compare the initial score with the diagnosis.

RESULTS

Eighty-six patients had an injured ACL and 80 had a healthy ACL. Two thresholds could be identified. For a score lower than 4, the risk of an ACL injury was low with a sensitivity of 96% and a negative predictive value of 87%. For a score above 8, the ACL injury was highly probable with a specificity of 88% and a positive predictive value of 83%.

DISCUSSION/CONCLUSION

The score was able to distinguish a population of patients with a ruptured ACL from a population of patients with other knee injuries. These preliminary results confirm that the selected items are relevant and that the score can help improve the diagnostic orientation of patients with recent knee trauma. Increasing the sample size in combination with an analysis of influencing factors will determine whether the performance of this score can be refined.

LEVEL OF EVIDENCE

II prospective multicenter study.

Physical therapy students' application of an imaging decision rule for acute knee pain

BACKGROUND

Evidence supports direct referral for imaging by physical therapists. Accuracy and self-efficacy for imaging decisions have not been investigated in entry-level doctor of physical therapy (DPT) students.

OBJECTIVE

The purpose of this study was to understand the relationship between entry-level DPT instruction and accuracy and self-efficacy for imaging referral due to acute knee trauma. A second purpose was to identify relationships between accuracy and self-efficacy.

METHODS

An online survey was sent via e-mail to program directors in accredited DPT programs in the United States with an invitation to forward the survey to DPT students. The survey captured demographic information and included five questions that assessed the respondent's ability to apply the Ottawa Knee Rules (OKR). Self-efficacy was assessed using the Physiotherapist Student Self-Efficacy (PSE) questionnaire, a self-rated 5-point Likert scaled tool.

RESULTS

Of 240 surveys, DPT students who completed imaging coursework had greater accuracy and higher self-efficacy (68.0% correct (95% CI, 63.6-72.5), PSE = 3.67, P < .001) compared to students who had not (45.8% correct (95% CI, 40.8-50.7), PSE = 2.67, P < .001). Conclusion: Accuracy by DPT students who completed imaging coursework was significantly improved and comparable to values from autonomous providers.

Differences in emergency nurse triage between a simulated setting and the real world, post hoc analysis of a cluster randomised trial

OBJECTIVES

In the TRIAGE trial, a cluster randomised trial about diverting emergency department (ED) patients to a general practice cooperative (GPC) using a new extension to the Manchester Triage System, the difference in the proportion of patients assigned to the GPC was striking: 13.3% in the intervention group (patients were encouraged to comply to an ED or GPC assignment, real-world setting) and 24.7% in the control group (the assignment was not communicated, all remained at the ED, simulated setting). In this secondary analysis, we assess the differences in the use of the triage tool between intervention and control group and differences in costs and hospitalisations for patients assigned to the GPC.

SETTING

ED of a general hospital and the adjacent GPC.

PARTICIPANTS

8038 patients (6294 intervention and 1744 control).Primary and secondary outcome measures proportion of patients with triage parameters (reason for encounter, discriminator and urgency category) leading to an assignment to the ED, proportion of patients for which the computer-generated GPC assignment was overruled, motivations for choosing certain parameters, costs (invoices) and hospitalisations.

RESULTS

An additional 3.1% (p<0.01) of the patients in the intervention group were classified as urgent. Discriminators leading to the ED were registered for an additional 16.2% (p<0.01), mainly because of a perceived need for imaging. Nurses equally chose flow charts leading to the ED (p=0.41) and equally overruled the protocol (p=0.91). In the intervention group, the mean cost for patients assigned to the GPC was €23 (p<0.01) lower and less patients with an assignment to the GPC were hospitalised (1.0% vs 1.6%, p<0.01).

CONCLUSION

Nurses used a triage tool more risk averse when it was used to divert patients to primary care as compared with a theoretical assignment to primary care. Outcomes from a simulated setting should not be extrapolated to real patients.

TRIAL REGISTRATION NUMBER

NCT03793972.

Imaging Review of Snowboard Injuries

Snowboarding and skiing remain the two most popular winter sports worldwide. Musculoskeletal (MSK) injuries are common in snowboarding, and the number has increased significantly since the advent of snow parks. The number of injuries is the highest for novice snowboarders; more experienced boarders generally sustain more severe injuries. Snowboarders can experience a wide array of MSK injuries, but some injury types are more frequently encountered because of the specific injury mechanism unique to snowboarding. This article reviews the most common snowboarding injuries with a focus on the current understanding of the injury mechanism and provides an approach to imaging.

Validation of the Ottawa knee rule in adults: A single centre study

INTRODUCTION

This clinical audit aimed to evaluate performance of the Ottawa Knee Rule (OKR) and degree of compliance by emergency referrers for acute knee injuries in adults.

METHODS

Knee radiography requests were analysed retrospectively for eligibility. Data were extracted from eligible requests under headings describing the OKR criteria, patient history, diagnosis and referrer profession. Sensitivity, specificity, negative likelihood ratio and positive likelihood ratio were calculated with 95% CI for the entire sample and each profession (consultant doctors, resident medical officers [RMO], physiotherapists and triage nurses) individually. The frequency of each OKR criterion and correlation with fracture, referrer compliance to the rule and the relative reduction in radiography were also calculated.

RESULTS

Of 713 patients identified, 149 were enrolled by the eligibility criteria. The overall sensitivity, specificity, negative likelihood ratio and positive likelihood ratio of the OKR for knee fracture were 71% (95%CI, 49-87%), 46% (95%CI, 37-55%), 0.64 (95%CI, 0.33-1.22) and 1.3 (95%CI, 0.96-1.76), respectively. Physiotherapists and triage nurses demonstrated better rule performance than consultant doctors and RMOs, with a sensitivity of 100% and negative likelihood ratio of 0.0. Physiotherapists were most compliant at 73% (19/26). Only 85 requests were OKR positive and, when abiding by the rule, this would have reduced radiography by 43% (64/149).

CONCLUSIONS

In this first Australian study, moderate OKR performance and variable compliance by emergency referrers were observed. This led to unnecessary irradiation of patients without a fracture. The findings suggest emergency referrers could benefit from education on applying and documenting the OKR on radiography requests.