Shoulder

Shoulder Instability

Shoulder instability means the ball of the shoulder slips partly or completely out of the socket. It may follow a traumatic dislocation or develop from ligamentous laxity and repetitive activity. Treatment depends on the direction of instability, labral injury, bone loss, age, sport, and goals—not on a single MRI measurement or threshold.

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What is shoulder instability?

Shoulder instability occurs when the humeral head slips partly or completely out of the socket because the labrum, ligaments, capsule, or bone no longer provide reliable restraint. It may follow a traumatic dislocation or develop gradually, and treatment is individualized to the instability pattern, anatomy, activity, and goals.

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.

Bone-loss spectrum: Historically, glenoid bone loss around 20–25% was considered a critical threshold for soft-tissue repair. Current planning also recognizes clinically important “subcritical” loss below that level and considers the glenoid track, Hill-Sachs lesion, sport, age, prior instability, and previous surgery together.
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.

Symptoms — do you recognize these?

Shoulder instability exists on a spectrum from subtle apprehension to frank, repeated dislocations. Common presentations include:

Sensation of the shoulder slipping, popping, or "coming out" with specific movements — particularly with the arm elevated and rotated outward
Frank dislocation requiring reduction — either self-reduced, reduced in the field, or requiring urgent medical evaluation and manipulation
Apprehension and guarding — an involuntary resistance to externally rotating the arm when abducted to 90°, reflecting the patient's fear of re-dislocation (apprehension sign)
Pain with overhead or throwing activities — especially at the late-cocking phase of the throwing cycle when the shoulder is maximally abducted and externally rotated
Recurrent subluxations — partial, self-reducing episodes of the humeral head slipping forward or backward, sometimes described as a "dead arm" sensation followed by rapid recovery
Inferior laxity or a sulcus sign in MDI — a visible or palpable dimple below the acromion when downward traction is applied to the arm
Voluntary dislocators — a distinct subgroup, typically younger patients with hypermobility who can produce dislocation voluntarily; this group requires careful psychological and functional assessment before any surgical consideration, as operative intervention alone is rarely successful without addressing the voluntary component

If any of these symptoms are affecting your daily life or athletic performance, call Maryland Orthopedic Specialists at (301) 515-0900 to schedule an evaluation with one of our shoulder specialists.

How we diagnose it

History and Physical Examination

A detailed history — mechanism of initial dislocation, number of subsequent events, activity level, dominant arm, and sport — guides the entire diagnostic pathway. Physical examination includes:

Anterior apprehension test: With the patient supine, the arm is abducted to 90° and passively externally rotated. A positive test produces apprehension (not merely pain) and strongly correlates with anterior labral pathology.
Relocation test (Fowler sign): Posterior pressure applied to the anterior humeral head during the apprehension maneuver relieves symptoms; release of this pressure reproduces them (release test). Together with the apprehension test, these maneuvers carry high sensitivity and specificity for anterior instability.
Posterior apprehension (jerk test): The arm is loaded axially in the flexed, adducted, internally rotated position and moved from flexion to extension; a palpable or audible clunk with reproduction of symptoms indicates posterior labral pathology.
Load-and-shift test: Manual anterior and posterior translation of the humeral head is graded (I–III) to quantify the degree of laxity.
Sulcus sign: Inferior traction applied with the arm at the side; a sulcus that persists with the arm in 30° external rotation indicates inferior capsular redundancy and supports a diagnosis of MDI.

Imaging

X-ray (weight-bearing series)

AP view in internal and external rotation — evaluates glenoid morphology and identifies a Hill-Sachs defect on the posterosuperior humeral head
True AP (Grashey) view — best for glenohumeral joint space and bony Bankart fragments
Axillary lateral view — essential for detecting anterior glenoid rim fractures, a bony Bankart lesion, or the "bare spot" landmark used in bone-loss estimation
Stryker notch view — tangential view that maximizes visualization of the Hill-Sachs lesion on the posterosuperior humeral head

CT scan with 3D reconstruction The gold standard for quantifying glenoid bone loss. Surface-area or best-fit-circle methods allow precise measurement of the glenoid defect. When bone loss exceeds the critical threshold of 20–25%, or when off-track assessment is being performed, CT is indispensable. We routinely obtain bilateral CT in young athletes to correct for normal glenoid size variability using the contralateral side as a reference.

MRI arthrogram (MRA) Intra-articular gadolinium distends the joint capsule, dramatically improving sensitivity for labral tears, IGHL avulsions, capsular stripping, and SLAP lesions compared to standard MRI. MRA is our preferred study for:

Confirming Bankart, ALPSA, or posterior labral tears
Identifying capsular redundancy in MDI
Detecting partial articular-surface rotator cuff tears that frequently co-exist with instability in overhead athletes

After your appointment, you will leave with a clear diagnosis, imaging review, a summary of your pathology, and a personalized treatment plan explained in plain language.

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. For young contact or collision athletes after a first traumatic dislocation, recurrence risk may be high. Rehabilitation and early stabilization are discussed through shared decision-making that considers age, sport, season, imaging, bone loss, and the consequences of another instability event.

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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Recovery & rehabilitation

Recovery timelines vary by procedure, patient age, sport, and individual healing. Below are evidence-based benchmarks our team uses for planning.

Arthroscopic Bankart Repair

Sling immobilization — 4–6 weeks
Pendulum and passive range of motion — Weeks 2–4
Active-assisted range of motion — Weeks 4–8
Strengthening phase (rotator cuff, periscapular) — Weeks 8–16
Sport-specific functional training — Months 4–5
Return to non-contact sport — ~5 months
Return to contact/collision sport — 6–9 months
Recurrence rate — ~10–15% overall; higher in young collision athletes

Latarjet Procedure

Sling immobilization — 4–6 weeks
Progressive range of motion — Weeks 4–8
Strengthening phase — Weeks 8–16
Return to non-contact sport — ~5–6 months
Return to contact/collision sport — 6–9 months
Recurrence rate — ~2–3% at 2–5 years

Return to contact sport after either procedure in collision athletes (rugby, football, wrestling) is expected between 6 and 9 months, with clearance based on achieving symmetric strength (>90% limb symmetry index on rotator cuff testing), full pain-free range of motion, and successful sport-specific functional milestones.

Recurrence rates in perspective: The Latarjet procedure has consistently demonstrated substantially lower recurrence rates (approximately 2–4%) compared to arthroscopic Bankart repair (approximately 10–15%) in high-risk patients, particularly those with glenoid bone loss or in contact/collision sports. In appropriately selected low-risk patients, however, arthroscopic Bankart repair achieves excellent outcomes with lower procedural morbidity.

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.