The rotator interval is a triangular space in the front and upper shoulder joint. This region plays an important role in shoulder function. Understanding this area clarifies how the shoulder moves and maintains stability. It acts as a bridge between tendons and ligaments surrounding the shoulder.
Understanding Rotator Interval Anatomy
This triangular area is in the anterosuperior shoulder, bounded by landmarks. Its upper border is the anterior supraspinatus tendon, and its lower border is the superior subscapularis tendon. The triangle’s base points towards the coracoid process, a bony projection from the shoulder blade.
The rotator interval contains several structures. The rotator interval capsule, an extension of the shoulder joint capsule, forms its roof. Two ligaments reinforce this capsule: the superior glenohumeral ligament (SGHL) and the coracohumeral ligament (CHL). The long head of the biceps tendon also passes through this interval. The coracohumeral ligament originates from the coracoid process and inserts onto the upper arm bone.
The Rotator Interval’s Role in Shoulder Stability
The structures within the rotator interval provide stability to the glenohumeral joint, the shoulder’s main ball-and-socket joint. This region prevents the upper arm bone from shifting downwards or backwards. The superior glenohumeral and coracohumeral ligaments, with capsular fibers, restrain excessive movement.
These structures limit external rotation and adduction of the arm. The coracohumeral ligament restricts external rotation and downward movement of the humeral head. The rotator interval ensures the humeral head remains centered within the glenoid, the shallow socket of the shoulder blade. Ligaments and capsule help the shoulder maintain its position during movement.
Conditions Affecting the Rotator Interval
Medical conditions and injuries can impact the rotator interval. One common condition is adhesive capsulitis, or frozen shoulder, where the rotator interval capsule thickens and becomes fibrotic. This thickening contributes to stiffness and restricted range of motion in frozen shoulder.
Tears can occur within the rotator interval capsule, sometimes mimicking rotator cuff tears. These tears may involve a complete break in the capsule. Such injuries compromise the interval’s integrity and affect shoulder mechanics. The rotator interval can also be implicated in shoulder instability, particularly anterior instability. When structures are compromised, the shoulder may be prone to dislocation or excessive movement.
Diagnosing and Managing Rotator Interval Issues
Identifying rotator interval problems involves physical examination and imaging. During examination, a professional assesses range of motion limitations or pain patterns suggesting an issue. Imaging studies, like MRI and ultrasound, visualize the rotator interval. MRI shows ligaments and capsule, detecting thickening, tears, or inflammation.
Management for rotator interval issues ranges from conservative approaches to surgical interventions, depending on the condition and severity. Conservative treatments include physical therapy to restore range of motion and strengthen muscles, along with medications for pain and inflammation. If conservative measures are insufficient, surgical interventions may be considered. These include arthroscopic procedures, such as release of the rotator interval capsule for stiffness, or repair of damaged structures for stability. The goal is to alleviate symptoms and restore shoulder function.