Anterior shoulder instability is the loss of stability at the glenohumeral joint following a dislocation in which the humeral head is displaced forward and below the glenoid. Anterior dislocation accounts for more than 90 percent of all shoulder dislocations. Each subsequent dislocation causes progressive damage to the stabilizing structures of the shoulder, which is why timely evaluation and treatment matter.
What Is Anterior Shoulder Instability?
The shoulder is stabilized by bone, soft tissue, and dynamic muscle control. The humeral head sits against the glenoid like a golf ball on a tee, relying on the labrum (the soft-tissue rim around the glenoid), the capsule and glenohumeral ligaments, and the rotator cuff to stay centered. When the shoulder dislocates anteriorly, the forces tear the labrum and attached capsule off the front of the glenoid, an injury called a Bankart lesion. In some dislocations a portion of the glenoid bone also fractures, producing a bony Bankart lesion. The humeral head can indent against the glenoid rim on exit, creating an impression defect called a Hill-Sachs lesion.
Once these structures are damaged, the shoulder loses its full complement of stabilizers and instability persists. Recurrent dislocations become easier and can occur with progressively lower-energy movements such as reaching overhead or rolling over in bed.
Causes and Risk Factors
Anterior dislocations typically result from a fall on an outstretched arm, a direct blow with the arm abducted and externally rotated, or a contact sport collision. Risk factors for recurrence include:
- Young age at first dislocation (under 25 carries the highest re-dislocation rate)
- Contact and overhead sport participation
- Glenoid bone loss greater than 13 to 15 percent
- Hill-Sachs lesion that engages the glenoid rim during motion
- Generalized ligamentous laxity
Symptoms
- Sudden, severe shoulder pain at the moment of dislocation
- Visible deformity with the humeral head displaced forward
- Inability to move the arm or bear weight on it until reduction
- After reduction, apprehension and instability with the arm abducted and externally rotated
- Recurrent episodes of partial dislocation (subluxation) in specific arm positions
Diagnosis
Dr. Chudik’s evaluation covers the dislocation history, the mechanism of each event, and a physical examination that reproduces the sense of instability in specific arm positions. The apprehension and relocation tests help confirm anterior instability. X-rays evaluate for associated fractures, glenoid bone loss, and humeral head impression defects. MRI characterizes the labrum, capsule, and cartilage. CT is added when quantifying bone loss matters for surgical planning. The Westmont office has on-site high-field MRI and X-ray.
Treatment
Non-surgical treatment is appropriate for first-time dislocators over 40, for lower-demand patients, and in cases where the labrum appears to have healed adequately. It involves a period of immobilization followed by physical therapy focused on the dynamic stabilizers and scapular control.
For younger active patients, the re-dislocation rate without surgery is very high, and arthroscopic stabilization is recommended after the first dislocation. Dr. Chudik performs arthroscopic Bankart repair, reattaching the labrum and capsule to the glenoid with suture anchors. When the injury involves significant glenoid bone loss, Dr. Chudik performs Arthroscopic Bony Bankart Repair and Glenoid Reconstruction, a technique he developed to address bone loss arthroscopically where conventional treatment requires open surgery. Patients over 40 are also evaluated for rotator cuff injury, which is more common in this age group and may need simultaneous repair.
Recovery and Outcomes
Recovery after arthroscopic stabilization typically includes four to six weeks of sling protection, progressive range of motion over two to three months, and strengthening over three to four months. Return to contact sport is typically five to six months. Outcomes depend on the extent of bone loss, the number of prior dislocations, and adherence to rehabilitation. Repairing after a first dislocation produces better outcomes than waiting through multiple episodes, because the labral tissue is healthier and bone loss is typically less.
When to See Dr. Chudik
Schedule an evaluation after any shoulder dislocation, even if the shoulder reduces on its own, or if the shoulder feels unstable with specific movements. Call 630-324-0402 or request an appointment online.