The Apley Scratch Test is a common, non-invasive orthopedic technique used to quickly screen the functional mobility of the shoulder joint complex. This simple assessment requires no special equipment and is frequently performed by clinicians to gain immediate insight into a patient’s shoulder health and potential limitations. By observing the patient’s ability to complete a specific pair of movements, the test provides a rapid evaluation of both the presence of pain and the available range of motion. It simulates the complex movements the shoulder performs during activities of daily living, serving as a foundational step in a physical examination to determine if a more detailed diagnostic workup is warranted.
Assessing Overall Shoulder Mobility
The test evaluates the full, active range of motion of the shoulder through two distinct paths. The first motion, the superior scratch, involves the patient reaching the tested arm up and over the shoulder to touch the upper portion of the opposite shoulder blade. This movement requires a combination of shoulder abduction (lifting the arm away from the body) and external rotation to position the hand behind the neck.
The second motion, the inferior scratch, requires the patient to reach the tested arm behind the back and up the spine toward the opposite shoulder blade. This movement challenges the shoulder’s ability to perform adduction (drawing the arm toward the body) and internal rotation. Successfully completing both the superior and inferior movements demonstrates the full range of motion needed for common tasks such as getting dressed, fastening a bra, or reaching into a back pocket.
Identifying Specific Rotator Cuff Involvement
The dual nature of the Apley Scratch Test provides specific clues about the function of the rotator cuff muscles. The superior scratch demands significant abduction and external rotation, directly involving the muscles responsible for these motions. Limitations here often suggest issues with the supraspinatus (which initiates abduction) and the infraspinatus and teres minor (the primary external rotators). Pain or an inability to reach the opposite shoulder blade may indicate tendinopathy or a tear in one of these posterior or superior rotator cuff components.
Conversely, the inferior scratch is a powerful screen for the subscapularis muscle. This reaching motion is highly dependent on internal rotation and adduction. A restriction during the inferior scratch suggests a functional deficit in internal rotation, which is the main action of the subscapularis. A difference in reach between the two scratch directions helps the clinician localize the area of potential muscle or tendon involvement within the rotator cuff system.
The test isolates the two main rotational capacities of the glenohumeral joint, linking functional movement to specific anatomical structures. While overall restriction reflects the flexibility of the joint capsule and other large muscles like the latissimus dorsi and pectoralis major, distinct patterns of limitation in the superior versus inferior reach suggest specific rotator cuff tendon compromise.
Clinical Significance of Limited Range of Motion
A result from the Apley Scratch Test showing a significant reduction in reach or causing pain carries immediate clinical meaning. A restricted range of motion suggests an underlying shoulder pathology that is impeding the smooth movement of the joint. This finding can indicate common conditions, including shoulder impingement syndrome (where tendons are compressed) or a partial or full-thickness rotator cuff tear.
A limited scratch distance in all directions may also be a sign of adhesive capsulitis, commonly known as frozen shoulder, which involves stiffness and inflammation of the joint capsule. The test is also used to assess the functional impact of glenohumeral joint arthritis, which causes degenerative changes and loss of cartilage. A positive result signals the need for objective follow-up testing, such as detailed imaging or specialized orthopedic tests, to confirm a diagnosis.