Muscle Weakness in the Empty and Full Can Tests Cannot Differentiate Rotator Cuff Tear from Cervical Spondylotic Amyotrophy: Pain Provocation is a Useful Finding.

Eiichiro Iwata,Kazuya Inoue,Takuya Egawa,Yoshihiro Sakamoto,Yasuhito Tanaka,Hideki Shigematsu

doi:10.2174/1874325001711011081

Eiichiro Iwata, Kazuya Inoue + Show 4 more

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https://doi.org/10.2174/1874325001711011081

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Abstract

Purpose:Rotator cuff tears and cervical spondylotic amyotrophy (CSA) are often confused as the main symptom in those with difficulty in shoulder elevation. Empty and full can tests are frequently used for the clinical diagnosis of rotator cuff tears. The aim of the present study was to investigate whether the empty and full can test results can help differentiate rotator cuff tears from CSA.Methods:Twenty-seven consecutive patients with rotator cuff tears and 25 with CSA were enrolled. We prospectively performed empty and full can tests in patients with rotator cuff tears and CSA. The following signs were considered positive: (a) muscle weakness during the empty can test, (b) muscle weakness during the full can test, (c) pain provocation during the empty can test, and (d) pain provocation during the full can test. We calculated the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of rotator cuff tears for each positive finding.Results:The sensitivity and specificity of each index were as follows (sensitivity, specificity, PPV, NPV): (a) 77.8%, 0%, 45.7%, 0%; (b) 66.7%, 4.0%, 42.9%, 10.0%; (c) 88.9%, 96.0%, 96.0%, 88.9%; and (d) 74.1%, 96.0%, 95.2%, 77.4%. There were significant differences for each index.Conclusion:Muscle weakness during the empty and full can tests was not useful in differentiating rotator cuff tears from CSA because of low specificity and PPV. However, pain provocation was useful in differentiating these two conditions because of high specificity and PPV.

Highlights

The causes of difficulty in shoulder elevation are often difficult to identify, as this complaint might originate from various shoulder and cervical spine disorders
Rotator cuff tears were diagnosed by an orthopedic surgeon specializing in shoulder surgeries, and the diagnosis was based on the following criteria: (1) Magnetic resonance imaging (MRI) revealed a tear, and (2) the surgeon who operated recognized the tear intraoperatively
Proximal-type cervical spondylotic amyotrophy (CSA) was diagnosed by an orthopedic surgeon specializing in spine surgeries and the diagnosis was based on the following criteria: (1) the chief complaint was difficulty in shoulder elevation, no or insignificant sensory deficit, and no lower extremity symptoms; (2) MRI or computed tomography (CT) myelography revealing C5 or C6 nerve or anterior horn compression; and (3) electromyography performed by a neurologist excluded other diseases, such as amyotrophic lateral sclerosis or motor neuron disease

Summary

Introduction

The causes of difficulty in shoulder elevation are often difficult to identify, as this complaint might originate from various shoulder and cervical spine disorders. Rotator cuff tears and cervical spondylotic amyotrophy (CSA) are often confused, as one of the main symptoms in both is difficulty in shoulder elevation. The clinical characteristics of the proximal type of CSA include muscle atrophy in the upper extremities, the absence of or insignificant sensory deficits and lower-extremity symptoms, and weakness of the deltoid and biceps muscles, which often causes dropped shoulder syndrome [3 - 7]. The empty and full can tests are frequently used for the clinical diagnosis of rotator cuff tears, which elicit weakness or pain secondary to a torn supraspinatus tendon [10, 11]. Some authors reported the clinical usefulness of the empty and full can tests for determining the presence of a torn supraspinatus tendon [12 - 14]

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