Differential Diagnosis for Limited External Shoulder Rotation
The following differential diagnosis is organized into categories to help guide the thought process.
Single most likely diagnosis
- Adhesive capsulitis (frozen shoulder): This condition is the most common cause of limited external shoulder rotation, especially in the absence of significant limitation in abduction. The inflammation and scarring of the shoulder joint capsule lead to restricted movement.
Other Likely diagnoses
- Subscapularis tendonitis or tear: Inflammation or damage to the subscapularis tendon can limit external rotation due to its role in this movement. However, abduction may remain relatively preserved.
- Glenohumeral joint osteoarthritis: Early stages of osteoarthritis can cause pain and stiffness, leading to limited external rotation, but may not significantly impact abduction initially.
- Labral tears: Tears in the labrum, the cartilage surrounding the socket of the shoulder joint, can cause mechanical symptoms and limit external rotation.
Do Not Miss diagnoses
- Septic arthritis: Although less common, septic arthritis is a medical emergency that can present with limited movement due to pain and swelling. Missing this diagnosis can lead to severe consequences, including joint destruction.
- Brachial plexus injury: Certain types of brachial plexus injuries can affect the nerves controlling shoulder movement, potentially limiting external rotation. This condition requires prompt recognition and treatment to avoid long-term disability.
Rare diagnoses
- Rheumatoid arthritis: While more commonly associated with symmetric joint involvement, rheumatoid arthritis can occasionally present with asymmetric shoulder symptoms, including limited external rotation.
- Synovial chondromatosis: A rare condition characterized by the growth of cartilage in the synovial membrane of the joint, which can cause mechanical symptoms and limited movement.
- Osteonecrosis of the humeral head: A condition where the blood supply to the bone tissue is interrupted, leading to bone death. This can cause pain and limited movement, including external rotation, especially if the necrosis affects the articular surface.