Shoulder

Shoulder Instability

The shoulder is the most mobile joint in the human body — and, as a consequence, the most commonly dislocated. When the stabilizing structures that hold the ball in the socket are torn or stretched, recurrent instability can derail athletic careers and limit everyday function. With accurate diagnosis and the right surgical approach tailored to your anatomy and activity level, shoulder instability is highly treatable, and most patients return to full sport. Maryland Orthopedic Specialists' fellowship-trained shoulder surgeons perform the full spectrum of stabilization procedures — from arthroscopic Bankart repair to the Latarjet procedure — so every patient receives a plan matched to their specific pathology.

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What is shoulder instability?

Anatomy: The glenohumeral joint is a ball-and-socket articulation between the humeral head (ball) and the glenoid (socket). Shoulder instability: A condition in which the ball of the shoulder joint slips partially or fully out of the socket, causing pain, a feeling of looseness, or recurrent dislocations.

Anatomy

The glenohumeral joint is a ball-and-socket articulation between the humeral head (ball) and the glenoid (socket). Because the glenoid is inherently shallow — resembling a golf tee more than a deep cup — stability depends on a combination of static and dynamic restraints:

Labrum: A fibrocartilaginous rim that deepens the glenoid by approximately 50%, increasing articular contact area and providing the attachment point for the glenohumeral ligaments.
Glenohumeral ligaments and capsule: Thickenings of the joint capsule. The inferior glenohumeral ligament (IGHL) — specifically its anterior band — is the primary static stabilizer against anterior translation with the arm in the abducted and externally rotated (ABER) position. Injury to this structure is the defining lesion of traumatic anterior instability.
Rotator cuff: Acts as the primary dynamic stabilizer, compressing the humeral head into the glenoid during active motion.

Types of Instability

Anterior instability (most common) Accounts for roughly 95% of all shoulder dislocations. The humeral head displaces forward relative to the glenoid, most often as the result of forced abduction and external rotation — a common mechanism in contact sports, falls, or throwing. The hallmark injury is the Bankart lesion: avulsion of the anteroinferior labrum and IGHL complex from the glenoid rim. When the labrum tears but remains attached to periosteum (ALPSA lesion), or when bony avulsion of the glenoid occurs (bony Bankart), the anatomy and surgical strategy differ.

Posterior instability Far less common (about 2–5% of cases), posterior instability typically results from a direct blow to the anterior shoulder, a seizure, or repetitive loading in the flexed/adducted/internally rotated position seen in blocking and bench-press activities. The corresponding labral injury is a posterior labral tear (reverse Bankart). A reverse Hill-Sachs lesion (McLaughlin defect) on the anteromedial humeral head may also be present.

Multidirectional instability (MDI) MDI is defined as symptomatic glenohumeral laxity in two or more directions, most commonly inferior plus anterior and/or posterior. It is typically atraumatic in origin and associated with generalized ligamentous laxity, redundant capsular volume, or repetitive overhead loading. Distinguishing MDI from unidirectional instability with coexisting laxity is critical because the initial treatment strategy — and the surgical procedure of choice — differs fundamentally.

Traumatic vs. atraumatic instability Traumatic instability follows a discrete injury event and is characterized by a structural lesion (Bankart tear, bony avulsion). Atraumatic instability develops insidiously, often in hyperlax individuals or overhead athletes; the primary pathology is capsular redundancy rather than labral detachment.

Hill-Sachs Lesion: Engaging vs. Non-Engaging

When the humeral head dislocates anteriorly, it impacts the posterosuperior glenoid rim, creating an impression fracture on the humeral head called a Hill-Sachs lesion. Not all Hill-Sachs lesions are clinically equivalent:

Non-engaging lesion: The defect lies medial to the glenoid rim throughout normal range of motion. Bankart repair alone is typically sufficient.
Engaging lesion: The defect is oriented parallel to the anterior glenoid rim and engages (locks) with it during abduction/external rotation, producing recurrent instability even after soft-tissue repair. Engaging lesions require additional treatment (remplissage or Latarjet).

Glenoid Bone Loss and the "Off-Track" Concept

Recurrent dislocations progressively erode the anterior glenoid rim, reducing the bony arc length of the socket. As bone loss increases, the risk of recurrent instability after soft-tissue–only repair rises sharply.

Critical threshold: A general consensus identifies glenoid bone loss >20–25% of the inferior glenoid diameter as the point at which bony augmentation — typically the Latarjet procedure — is necessary rather than optional.
Off-track concept (glenoid track): Introduced by Yamamoto et al., the glenoid track is the medial-to-lateral width of glenoid contact on the humeral head during ABER. When a Hill-Sachs lesion is wider than the glenoid track, it is classified as "off-track" and is at high risk of engagement regardless of its size in isolation. Off-track lesions require either Latarjet (which widens the glenoid track) or remplissage (which fills the Hill-Sachs defect), or both. This concept integrates glenoid bone loss and Hill-Sachs size into a single unified framework that guides surgical decision-making.

Treatment options

Non-Operative Management

Physical therapy is the first-line treatment for: - MDI — Structured rotator cuff and periscapular strengthening addresses the dynamic stabilizer deficit responsible for capsular laxity. Burkhead and Rockwood reported good-to-excellent outcomes in >80% of atraumatic instability patients treated with rehabilitation alone. MDI is primarily a non-surgical diagnosis unless 4–6 months of supervised PT fails to provide adequate relief. - First-time dislocators in older, low-demand patients — The recurrence risk after a first dislocation drops significantly in patients over 40, and the risk of rotator cuff tear (present in up to 40% of first-time dislocators over age 40) must be ruled out before initiating PT. - In-season athletes — Bracing and therapy may allow completion of a season before definitive surgical planning. Non-operative management is generally not recommended for young contact/collision athletes after a first traumatic dislocation, given recurrence rates exceeding 80–90% in this demographic without surgical stabilization.

Surgical Procedure

Bankart Repair (Shoulder Instability)

Arthroscopic suture anchor repair of the anterior-inferior glenoid labrum to restore the primary capsuloligamentous restraint against anterior dislocation. Appropriate when glenoid bone loss is below 20–25% — above that, the Latarjet is preferred.

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Remplissage (Hill-Sachs Lesion Treatment)

Arthroscopic filling of an engaging Hill-Sachs humeral head defect by tacking the posterior rotator cuff into the bony lesion, preventing the engaging dislocation mechanism. Combined with Bankart repair when the defect exceeds 20% of the humeral head.

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Latarjet Procedure

Open transfer of the coracoid process with its attached conjoint tendon to the anterior glenoid, creating a bony buttress and a dynamic soft-tissue sling to prevent recurrent dislocation in patients with significant glenoid bone loss.

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Frequently Asked Questions

Will my shoulder keep dislocating if I don't have surgery?

It depends on your age, activity level, and number of prior episodes. In patients under 25 who participate in contact or overhead sports, the risk of recurrent dislocation without surgery exceeds 80–90%. Each subsequent dislocation accumulates additional bone loss from the glenoid and humeral head, progressively worsening the anatomy and narrowing future surgical options. For older, lower-demand patients after a first dislocation, non-operative management with PT is a reasonable initial path. Your MOS surgeon will review your specific risk profile and help you weigh the options.

What is a Bankart repair?

A Bankart repair is an arthroscopic procedure that reattaches the torn anteroinferior labrum and inferior glenohumeral ligament to the glenoid rim using suture anchors. It restores the labral bumper that deepens the socket and the ligamentous tension that prevents the humeral head from slipping forward. The procedure is performed through small portals under general anesthesia and typically takes 45–75 minutes. It is the gold standard for traumatic anterior instability in patients without significant glenoid bone loss or high-risk anatomy.

What is the Latarjet procedure?

The Latarjet procedure transfers a small piece of the coracoid bone — along with its attached conjoint tendon — to the front of the glenoid, restoring the bony arc of the socket and creating a tendon sling that actively prevents re-dislocation. Unlike the Bankart repair, which works only on soft tissue, the Latarjet addresses both bony and soft-tissue deficits simultaneously. It is the preferred procedure for patients with glenoid bone loss greater than 20–25%, off-track Hill-Sachs lesions, or recurrent instability in collision athletes.

Can physical therapy fix my shoulder instability?

For MDI and atraumatic instability, PT is the primary treatment and succeeds in the majority of patients with a committed, supervised program. For traumatic instability — particularly in young athletes with a discrete labral tear — PT can reduce symptoms and improve dynamic stability but does not repair the structural lesion. The torn labrum does not reliably heal on its own, and non-operative management in high-risk patients is associated with very high recurrence rates and progressive bone loss. Your MOS surgeon will help you determine whether PT alone is appropriate or whether surgery should be considered early.

Am I too young for surgery?

Quite the opposite: younger age is actually the strongest risk factor for recurrent dislocation after a first-time event, and early surgical stabilization in adolescent and young adult athletes is increasingly supported by the evidence. The risk of recurrence is highest (>80%) in patients under 20 in contact sports. Delaying surgery to "see what happens" risks repeated dislocations that erode glenoid bone and make surgery more complex. MOS surgeons are experienced in performing labral stabilization in teenage athletes and guide families through the timing decision thoughtfully.

What is glenoid bone loss, and why does it matter?

The glenoid is the shallow socket of the shoulder joint. With each anterior dislocation, the leading edge of the glenoid can fracture or erode, progressively reducing the arc of bone that keeps the humeral head centered. When this deficit exceeds roughly 20–25% of the glenoid's diameter, the socket is too shallow to hold the ball in place with soft-tissue repair alone — the Bankart repair will fail at an unacceptably high rate. In these cases, a Latarjet procedure is needed to restore the bony arc. CT with 3D reconstruction is used to measure the exact percentage of bone loss so the correct operation can be planned.