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Can Elbow Extension be Used as a Test of Clinically Significant Injury?

A. Docherty, MD, A. Schwab, MD, O. MA, MD

South Med J 95(5):539-541, 2002. © 2002 Southern Medical Association

Abstract and Introduction

Abstract

Introduction

In the current climate of managed care and rationing of health care

resources, several studies have been undertaken in an attempt to reduce the

number of radiologic tests used to evaluate bone injuries of various

anatomic sites.[1,2] Rules for making clinical decisions, such as the Ottawa

ankle and knee rules, have been validated in clinical practice and have led

to a decrease in unnecessary radiographs.[3,4] To date, only 1 published

report has studied a patient's ability to extend the injured elbow as an

indicator of the presence or absence of significant injury.[5] Since most of

the patients in that study were less than 20 years old, the applicability of

the elbow-extension test to the adult population remains unclear. The

objective of this study was to analyze whether the elbow-extension test

could be used as a sensitive screening test in determining bone/joint injury

at the elbow joint.

Materials and Methods

This prospective study was conducted from December 1, 1996, to November 30,

1997, in an urban emergency department (ED) with an annual census of 48,000

patients. The department supports a fully accredited emergency medicine

residency program, and the hospital serves as the primary teaching hospital

for the medical school. The study site's institutional review board approved

the study.

All patients over the age of 14 years presenting to the ED with an acute

(less than 24 hours old) elbow injury were included in the study. Patients

with altered mental status due to concomitant central nervous system injury

or drug intoxication were excluded from the study. During the clinical

evaluation, the examining physician completed a brief study data sheet and

assessed the seated patient's ability to actively extend and lock the

injured elbow with the arm in a supine position. The inability to actively

extend the elbow fully was defined as a positive test. A comparison test on

the unaffected elbow was done in patients with a positive test. Information

collected on the data sheet included the mechanism of injury and the

perceived need for radiographs, in addition to the results of the

elbow-extension test. The data sheet was completed before obtaining

radiographs; the need for radiographs was left to the discretion of the

examining physician.

The examining physician interpreted the radiographs. The official radiology

reading was done by an attending radiologist blinded to all clinical

information, including the results of the elbow-extension test; this

official reading was used to determine the presence or absence of bone/joint

injury. Bone/joint injury was defined as a fracture, dislocation, or joint

effusion; joint effusions were included because they have been associated

with occult bone injuries.[6,7]

Information from the data sheets was compared with the official radiology

reading. Sensitivity, specificity, and positive and negative predictive

values, along with their 95% confidence intervals (CI), were calculated for

the elbow-extension test.[8]

Results

During the study period, 114 patients with acute elbow injuries were

enrolled in the study. Review of ED logs did not identify any patients with

a primary complaint of elbow injury who were not enrolled. No victims of

multiple trauma were enrolled. There were 53 males and 61 females, with a

mean age of 37 years (range, 16 to 76 years). All 114 patients had study

data forms completed; 110 patients had elbow radiographs done. The patients

in the study population presented between 30 minutes and 22.5 hours after

the injury occurred (median, 3.75 hours after injury). The 4 patients who

did not have radiographs done were excluded from analysis; however, all 4

were able to fully extend the injured elbow, and chart review failed to

identify subsequent ED or clinic visits for elbow pain.

Bone/joint injury was identified in 38 patients (Table 1). Mechanisms of

injury for these patients included direct blow (30 patients), hyperextension

(7 patients), and crush injury (1 patient). There were no discrepancies

between the preliminary ED reading and the final radiology reading.

The clinical performance of the elbow-extension test is shown in Table 2.

The single false-negative test (patient with a bone injury who could fully

extend the elbow) occurred in a patient with a nondisplaced radial-head

fracture.

Discussion

This study was designed to evaluate whether radiographically significant

elbow injuries could be predicted based on the patient's ability to fully

extend the affected elbow. The test was easy to perform in the ED and proved

to be sensitive, though not specific in predicting bone injury. In this

study's adult population, our sensitivity of 97.3% and specificity of 69.4%

were similar to the findings of Hawksworth and Freeland,[5] who reported a

sensitivity of 90.7% and a specificity of 69.5%.

The most clinically useful findings of this study were the high sensitivity

and negative predictive values. Given a 35% prevalence of bone injury, it

appears that plain radiographs of the elbow can be safely deferred in

patients who are able to fully extend the injured elbow. Since one of our

patients with a nondisplaced radial-head fracture was able to fully extend,

it may be prudent to carefully examine the radial head and consider

radiographs in patients with an appropriate mechanism for this injury, even

if they can fully extend the elbow.

Use of the elbow-extension test to exclude the need for radiographs in our

study population would have reduced radiographic evaluation by nearly 50%.

If our findings can be validated in other settings, the potential savings

would be substantial.

Limitations of this study included a relatively small sample size and the

failure to obtain radiographs on every patient. The 4 patients who did not

have imaging presented less than 4 hours after injury. It is possible that

hemarthrosis could have developed later in these and other early presenters;

whether the development of delayed hemarthrosis would convert some negative

tests to positive cannot be determined by this study. This study did not

determine whether the inability to fully extend was due to highly developed

arm-flexor musculature, as might be seen in trained athletes, nor did the

study address the issue of patient expectations regarding the performance of

radiographs.

The presumption that a joint effusion in the setting of acute injury

indicates chondral or osteochondral injury is widely accepted but not

invariably correct.[9] It is possible that patients with underlying diseases

causing elbow effusions (such as rheumatoid arthritis) were included in the

study population. These patients might bias the results.

Future studies should apply the elbow-extension test prospectively and

follow the clinical course of patients who did not undergo radiographs to

determine whether significant injuries are missed. Patient satisfaction

assessments to determine acceptability of this approach would be useful.

Conclusions

The elbow-extension test can be used as a sensitive clinical screening test

for patients with acute elbow injuries. The elbow-extension test may allow

clinicians to forego ordering plain radiographs in adult patients with acute

elbow injuries. Patients who can fully extend the affected elbow may be

safely treated without the aid of plain radiographs.

Tables

Table 1. Types of Elbow Injury

Injury No. of

Patients

Olecranon fracture 6

Coronoid fracture 5

Radial-head fracture 17

Capitellum fracture 3

Epicondyle fracture 1

Posterior dislocation 2

Joint effusion 4

Total 38

Table 2. Clinical Performance of the Elbow-Extension Test

Bone Injury No Bone Injury

Unable to Extend (positive test) 37 22

Able to Extend (negative test) 1 50

Sensitivity = 97.3%

(95% CI = 84.6-99.9) Specificity = 69.4%

(95% CI = 57.3-79.5)

PPV = 62.7%

(95% CI = 49.1-74.7) NPV = 98.0%

(95% CI = 88.2-99.9)

CI = Confidence interval, PPV = positive predictive value, NPV = negative

predictive value.

References

Gleadhill DNS, Thomson JY, Simms P: Can more efficient use be made of x-ray

examinations in the accident and emergency department? BMJ 1987; 294:943-947

McConnochie KM, Roghmann KJ, Pasternack J, et al: Prediction rules for

selective radiographic assessment of extremity injuries in children and

adolescents. Pediatrics 1990; 86:45-57

Stiell IG, McKnight RD, Greenberg GH, et al: Implementation of the Ottawa

ankle rules. JAMA 1994; 271:827-832

Stiell IG, Wells GA, Hoag RH, et al: Implementation of the Ottawa knee rule

for the use of radiography in acute knee injuries. JAMA 1997; 278:2075-2079

Hawksworth CRE, Freeland P: Inability to fully extend the injured elbow: an

indicator of significant injury. Arch Emerg Med 1991; 8:253-256

Manns RA, Lee JR: Critical evaluation of the radial-head capitellum view in

acute elbow with an effusion. Clin Radiol 1990; 42:433-436

JE, Holder JC: Fat pad signs in the diagnosis of subtle fractures.

Am Fam Physician 1988; 37:93-102

Fenn Buderer NM: Statistical methodology: incorporating the prevalence of

disease into the sample size calculation for sensitivity and specificity.

Acad Emerg Med 1996; 3:895-899

WA, Siegel MJ: Elbow fat pads with new signs extended differential

diagnosis. Radiology 1977; 124:659-665

Sidebar: Key Points

Patients who can fully extend and lock an acutely injured elbow with the arm

in supination are unlikely to have radiographic evidence of elbow injury.

The elbow-extension test may be less reliable in patients with radial-head

fractures.

This study did not assess the reliability for the test in patients with

multiple injuries.

Reprint Address

Reprint requests to A. Schwab, MD, Truman Medical Center, Department

of Emergency Medicine, 2301 Holmes St, Kansas City, MO 64108.

A. Docherty, MD, A. Schwab, MD, and O. MA, MD, Department

of Emergency Medicine, University of Missouri-Kansas City School of

Medicine, Truman Medical Center, Kansas City, Mo.

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