Recurrent Shoulder Instability — Why Does the Shoulder Keep Giving Way?

If the shoulder repeatedly dislocates, partially slips out, or gives a clear sensation of “giving way”, recurrent glenohumeral instability may be the cause. Not every click or snap represents instability. Diagnosis depends on the pattern of episodes, stability testing and appropriately selected imaging.

What does it mean when the shoulder “comes out”?

In a complete dislocation, the humeral head loses contact with the glenoid and usually requires reduction. A subluxation is a partial, often brief loss of joint congruity; the shoulder may return to position spontaneously. Patients may describe sudden slipping, apprehension in a particular arm position, or the need to stop the movement immediately.

Painless clicking, scapular crepitus or tendon snapping do not necessarily indicate instability. More important are true loss of control, visible deformity, numbness, weakness or repeated episodes after a previous dislocation.

Why does instability recur?

A traumatic anterior dislocation may damage the anterior labrum and capsuloligamentous structures, classically producing a Bankart lesion. Recurrent episodes can increase bone loss from the glenoid or humeral head. Recurrence risk is higher in younger patients, particularly those involved in contact and overhead sports.

A different mechanism is seen in generalized ligamentous laxity or multidirectional instability. In these patients the shoulder may be excessively mobile without a single major traumatic event. Rehabilitation and indications for surgery differ from those used after a typical traumatic anterior dislocation.

How does an orthopaedic surgeon assess shoulder instability?

The history is essential: the arm position during the first and subsequent episodes, whether reduction was required, the number of recurrences, the patient’s activity or sport, and any associated numbness or weakness. Examination includes range of motion, rotator cuff strength, scapular control, the direction of instability and generalized ligamentous laxity.

X-ray, MRI, CT and ultrasound

• X-ray assesses joint position, fractures and some osseous changes related to previous dislocations.
• MRI or MR arthrography can assess the labrum, capsule, ligaments, cartilage and associated tendon injury.
• CT is particularly useful when glenoid or humeral head bone loss must be quantified before surgery.
• Ultrasound can add dynamic information and assess selected labral, tendon and nerve structures, but it does not replace MRI or CT when comprehensive surgical planning is required.

Is surgery always necessary?

No. In some forms of instability, the first-line approach is structured rehabilitation: improving scapular and humeral head control, strengthening the rotator cuff, gradually restoring confidence in movement, and modifying activities that provoke instability. Progress is assessed over months rather than after a few sessions.

Surgery is considered particularly after recurrent dislocations, persistent giving-way despite appropriate rehabilitation, a high predicted recurrence risk, or clinically relevant labral and bone injury. The procedure depends on the direction of instability, tissue quality and the amount of bone loss. A “loose shoulder” alone does not determine one operation.

Return to sport

Return to sport should not be based only on the number of weeks since injury or surgery. Relevant criteria include pain-free range of motion, strength and endurance, shoulder control in sport-specific positions, absence of instability or apprehension, and tolerance of progressively increasing training loads.

When is urgent assessment needed?

A new visible deformity, inability to move the arm, severe pain, increasing numbness or weakness, or a pale or cold hand require urgent assessment. A suspected dislocation should not be reduced without appropriate training and assessment. Even when the shoulder appears to relocate spontaneously, neurovascular examination and usually an X-ray are still advisable.

References

1. Poboży T, et al. Clock-Face Sonography of the Glenoid Labrum: A Pictorial Technical Protocol for Patients Ineligible for MRI/MR Arthrography. Diagnostics. 2025;15(23):3031. DOI: 10.3390/diagnostics15233031.
2. American Academy of Orthopaedic Surgeons. Chronic Shoulder Instability.
3. Van Gastel ML, et al. Clinical practice on treatment of primary traumatic anterior shoulder dislocation: a multidisciplinary guideline. Acta Orthopaedica. 2026;97:531–537. DOI: 10.2340/17453674.2026.46434.

For Patients · Polish version

Content prepared by: Tomasz Poboży - orthopaedic surgeon.