Differential Diagnosis for Empty Can Positive Right Shoulder
- Single most likely diagnosis
- Rotator cuff tendinitis or tear, specifically supraspinatus tendon: The empty can test is highly specific for supraspinatus tendon pathology. A positive test indicates weakness or pain in the supraspinatus muscle, which is a common cause of shoulder pain and dysfunction.
- Other Likely diagnoses
- Subacromial bursitis: Inflammation of the subacromial bursa can cause pain and weakness in the shoulder, particularly with movements that involve abduction and internal rotation, such as the empty can test.
- Shoulder impingement syndrome: This condition, where the rotator cuff tendons are compressed against the acromion, can cause pain and weakness, especially with movements that involve lifting the arm.
- Adhesive capsulitis (frozen shoulder): Although it may not directly cause a positive empty can test, the pain and stiffness associated with adhesive capsulitis can lead to weakness and a positive test.
- Do Not Miss diagnoses
- Axillary nerve injury or neuropathy: The axillary nerve supplies the deltoid and teres minor muscles. Damage to this nerve can cause significant weakness and could potentially result in a positive empty can test if the supraspinatus is compensating.
- Fracture (e.g., greater tuberosity fracture): A fracture in the shoulder region could cause pain and weakness, leading to a positive empty can test. Missing a fracture could lead to improper healing and long-term dysfunction.
- Brachial plexus injury: Although less common, a brachial plexus injury could affect the nerves supplying the shoulder muscles, potentially causing a positive empty can test.
- Rare diagnoses
- Polymyalgia rheumatica: This inflammatory condition can cause widespread muscle pain and stiffness, including in the shoulder, potentially leading to a positive empty can test.
- Rheumatoid arthritis or other autoimmune disorders: These conditions can cause inflammation and damage to the joints, including the shoulder, potentially resulting in a positive empty can test.
- Tumor or cyst (e.g., ganglion cyst) compressing the supraspinatus tendon or nerve supply: Although rare, a tumor or cyst in the shoulder region could compress the supraspinatus tendon or its nerve supply, causing pain and weakness.