ALPSA Lesions
"In Situ Repair" Because the ALPSA lesion heals, it can look like a normal (but small) labrum. If you just put anchors in and stitch it, you validate the malposition. You have NOT restored the bumper. Recurrence is guaranteed.
"Mobilize and Elevate" You must incise the healed tissue. Elevate the labrum off the glenoid neck. Bring it up to the articular margin (the 'face'). Only then do you fix it.
- Bankart Lesion
- Torn (Detached)
- ALPSA Lesion
- Intact (Stripped)
- Bankart Lesion
- Floating
- ALPSA Lesion
- Medialized on Neck
- Bankart Lesion
- Does not heal (Gap)
- ALPSA Lesion
- Heals in bad position
- Bankart Lesion
- Standard risk
- ALPSA Lesion
- Higher risk (if not mobilized)
GAPVariants of Instability
Hook:Mind the GAP in the labrum.
Overview
An ALPSA lesion (Anterior Labroligamentous Periosteal Sleeve Avulsion) involves the avulsion of the anterior labrum and IGHL from the glenoid rim. Critically, the anterior scapular periosteum remains intact but stripped, allowing the labrum to displace medially and heal inferiorly on the glenoid neck.
This "medialization" effectively shortens the anterior restraints and eliminates the glenoid depth, predisposing the joint to recurrent anterior instability even with minor trauma.
This contrasts with a Bankart lesion, where the periosteum tears, creating a distinct separation. The "sleeve" nature of the ALPSA allows the tissue to essentially slide down the neck and scar in a non-functional position.
Pathophysiology and Mechanisms
The Labroligamentous Complex
- Labrum: Fibrocartilaginous bumper. Increases glenoid depth by 50%.
- IGHL: Inferior Glenohumeral Ligament. Main static restraint.
- Periosteum: Thick anterior scapular periosteum.
In ALPSA, the forceful anterior dislocation strips the periosteum without rupturing it.
This creates a "sleeve" that slides medially.
MINTPathology
Hook:The labrum is stuck in a MINT condition (not really).
Classification Systems
Neviaser Classification
- Acute (Type I): Less than 3 months. Tissue is mobile. Can be reduced easily.
- Chronic (Type II): Greater than 3 months. Tissue is scarred and fixed. Requires sharp dissection/release.
This distinction is crucial for surgical planning.
Chronic lesions often require a capsular release (anterior and inferior) to gain excursion.
Clinical Presentation
Presentation
- Recurrent Instability: Often reports "loose" shoulder.
- Clicking/Catching: Can occur.
- Mechanism: Often a history of multiple dislocations.
- Age: Common in young patients (under 25).
- Symptom Duration: Chronic symptoms suggest ALPSA vs acute Bankart.
- Provoking Positions: Abduction and external rotation (ABER position).
The history is identical to Bankart instability.
Red Flags
- First-time dislocation over age 40 (rotator cuff tear risk).
- Neurological symptoms (axillary nerve injury).
- Unable to reduce (locked posterior dislocation).
These red flags warrant urgent imaging and specialist referral.
Examination
Physical Exam
- Apprehension: Positive.
- Relocation: Positive.
- Load and Shift: Increased translation (Grade 2-3).
- Sulcus Sign: May be present (multidirectional component).
- Jobe Relocation Test: Relief with posterior force.
- Gagey Hyperabduction Test: Assesses inferior capsular laxity.
You cannot clinically distinguish ALPSA from Bankart.
Imaging is the only differentiator.
Imaging
Axial T2 / PD Fat Sat. Look for the labrum ("black triangle"). Normal: Sitting on the rim. ALPSA: Rounded, scarred bundle sitting medial to the rim on the glenoid neck. The periosteum may be visualized as a low signal line connecting the labrum to the scapula (the sleeve).
MRI Signs
- Medialization: The key sign.
- Synovial Stripping: Contrast tracking under the sleeve.
- Bone Loss: Assess for concomitant Bony Bankart (often remodelled in chronic cases).
- Hill-Sachs: Usually present due to recurrence.
Look for the "Cul-de-sac" deep to the capsule.
The lesion is defined on imaging, so know why MR arthrography (MRA) beats plain MRI here:
- Direct (intra-articular gadolinium) MRA is substantially more sensitive and specific for labroligamentous lesions than conventional non-contrast MRI, because the contrast distends the joint and tracks into the lesion and under the stripped periosteal sleeve, outlining the medialised labrum.
- The healed/scarred chronic ALPSA and the re-apposed Perthes can look near-normal on non-contrast MRI and even on neutral-position MRA — they are easily missed.
- The ABER (ABduction-External Rotation) view is the key manoeuvre: it tensions the anteroinferior IGHL-labral complex and pulls contrast into the lesion, "unmasking" non-displaced or healed anteroinferior labral lesions that the neutral view misses.
- So a suspected instability lesion warrants MR arthrography, ideally including ABER images (CT arthrography is the alternative when bone loss must be quantified precisely or MRI is contraindicated).
Differential Diagnosis
Differential Diagnosis
- Bankart Lesion: True labral detachment, floating labrum.
- Perthes Lesion: Non-displaced periosteal sleeve avulsion.
- GLAD Lesion: Glenolabral articular disruption (cartilage focus).
- HAGL Lesion: Humeral avulsion of glenohumeral ligament.
- Bony Bankart: Labrum with attached bone fragment.
- Multidirectional Instability: Global capsular laxity, atraumatic.
Key Distinguishing Features
- Periosteum
- Torn
- Labrum Position
- Floating/Detached
- Stability
- Unstable
- Periosteum
- Intact
- Labrum Position
- Medialized
- Stability
- Unstable
- Periosteum
- Stripped
- Labrum Position
- In situ
- Stability
- Unstable
- Periosteum
- Intact
- Labrum Position
- Intact
- Stability
- Stable
Everything above is anterior; examiners may ask for the posterior analogue. The POLPSA (Posterior Labrocapsular Periosteal Sleeve Avulsion) is the direct mirror of the ALPSA — in posterior instability the posterior labrum and capsule are stripped with an intact periosteal sleeve and displace/medialise on the posterior glenoid neck, and the same principle applies (mobilise the medialised tissue before fixation). Related posterior lesions:
- Reverse Bankart — a discrete postero-inferior labral detachment, the posterior equivalent of the Bankart.
- Kim lesion — an incomplete, "concealed" avulsion of the postero-inferior labrum (a marginal crack with an intact superficial surface) that must be completed and then repaired.
- Reverse Hill-Sachs (McLaughlin) lesion — the anteromedial humeral-head impaction of a posterior dislocation, classically after a seizure or electrocution.
Posterior instability is more often atraumatic or from repetitive loading (e.g. linemen, bench-pressing) than a single dislocation, but the labroligamentous-sleeve concept is identical.
Management Algorithm
Decision Making
- Non-Operative: High failure rate in young patients. (Not recommended for athletes).
- Operative: Indicated for recurrent instability.
- Approach: Arthroscopic Repair is Gold Standard. Open repair rarely needed unless massive bone loss.
The key is the technical execution of the repair.
Surgical Considerations
Arthroscopic Repair Steps
- Diagnostic Scope: Confirm diagnosis (Probe the labrum - it may feel "healed" but lacks bumper function).
- Mobilization (CRITICAL):
- Use an elevator or shaver to detach the scarred labrum from the glenoid neck.
- Release anteriorly and inferiorly (around the corner).
- "Float the Labrum": It must rise to the rim effortlessly.
- Preparation: Decorticate the glenoid rim (create bleeding bed).
- Fixation: Suture anchors on the face (articular margin).
- Shift: Tension the tissue superiorly and laterally to restore the bumper.
Failure to mobilize turns this into a non-anatomical plication.
TRIPSurgical Steps
Hook:Take a TRIP to the glenoid rim.
Complications
- Recurrence: The most common complication. Often due to failure to mobilize the lesion fully.
- Stiffness: Excessive tightening (Overtensioning).
- Hardware Issues: Loose anchors, chondrolysis (if placed on face too proud).
- Nerve Injury: Axillary nerve (during inferior dissection).
- Infection: Rare.
Chondrolysis Risk Placing anchors on the articular face is necessary for ALPSA repair, BUT they must not be prominent. Prominent metal or hard PEEK anchors can destroy the humeral head cartilage (Chondrolysis). Use soft anchors or ensure knotless anchors are countersunk.
Rehabilitation
-
Phase 1 (0-6 weeks):
- Sling immobilization.
- Protect ER (usually restricted to 0 or 30 degrees).
- Pendulums.
-
Phase 2 (6-12 weeks):
- Regain ROM.
- Active assistive to Active.
- Scapular control.
-
Phase 3 (3-6 months):
- Strengthening.
- Proprioception.
- Return to sport at 6 months (contact sports).
Protocol is identical to Bankart Repair.
Return to Sport Criteria
- Full, pain-free Range of Motion.
- Symmetrical strength (ER/IR/Abduction).
- Psychological readiness (ACL-RSI or similar scale).
- Completion of sport-specific training drills.
- No apprehension in apprehension position.
Sling Removal Criteria
- No pain at rest.
- Control of scapula.
- Ability to perform ADLs waist level.
Contact Progression
- 4 months: Non-contact drills (passing, catching).
- 5 months: Controlled contact (pad work).
- 6 months: Unrestricted contact (tackling).
Prognosis
- Recurrence Rate: With proper mobilization, results equal Bankart repair (5-10% recurrence).
- Without Mobilization: Recurrence rates are significantly higher.
- Return to Sport: High (greater than 85%).
- Arthritis: Long term risk exists due to initial cartilage damage (GLAD component often co-exists).
Prognostic Factors
- Age: Younger patients have higher recurrence risk.
- Bone Loss: Significant glenoid bone loss (greater than 20%) requires Latarjet.
- Hyperlaxity: Beighton score greater than 5 increases failure risk.
- Sport: Collision athletes have higher recurrence.
Guidelines, Registries & Global Practice
- No ALPSA-specific society guideline exists — it is a lesion subtype rather than a stand-alone diagnosis, so management follows the broader anterior shoulder instability literature (ISAKOS, AAOS, BOA-BESS and shoulder-society instability working groups) on labral repair and bone-loss thresholds.
- Epidemiology: ALPSA is over-represented in chronic, recurrent instability and in collision/contact athletes worldwide (rugby, American football, AFL, wrestling, ice hockey), reflecting the repeated dislocations that drive the medialised, scarred lesion.
- Standard of care: Recognition of the medialised lesion and mobilisation (takedown and float to the rim) before fixation is a universally expected technical standard; an "in-situ" repair that fixes the labrum on the neck is regarded internationally as a technical error and a cause of revision.
- Bone-loss integration: Across guidelines the decision is increasingly driven by quantified glenoid bone loss and the glenoid track (subcritical/critical thresholds, off-track Hill-Sachs), so a chronic ALPSA with significant bone loss may need a bony procedure (Latarjet) rather than soft-tissue repair alone.
- Practice variation reflects access to MR arthrography/CT arthrography for diagnosis and to bony-augmentation options, not disagreement on the mobilisation principle.
MCQ Practice Points
Q: What structure remains intact in an ALPSA lesion that is torn in a Bankart? A: The anterior scapular periosteum.
Q: What does ALPSA stand for? A: Anterior Labroligamentous Periosteal Sleeve Avulsion.
Q: What is the most critical step in ALPSA repair? A: Mobilization (Takedown) of the labrum.
Q: A chronic, fixed ALPSA lesion is classified as: A: Neviaser Type II.
Q: What MRI finding differentiates ALPSA from Bankart lesion? A: Medially displaced labrum with intact periosteal sleeve (labrum lies against glenoid neck rather than at rim).
Q: Why do ALPSA lesions have higher recurrence rates if not properly mobilized? A: The medialized labrum heals in a non-anatomic position, failing to restore the labral bumper effect and capsular tension.
Viva Scenarios
Practise clinical reasoning and management decisions out loud
“You are shown an MRI of a 19-year-old rugby player. There is a dark lump of tissue sitting on the anterior glenoid neck, medial to the rim. What is this and how does it differ from a Bankart?”
“You are scoping a 'Bankart'. You enter the joint and the labrum looks 'healed' but the shoulder is loose (Drive-through sign positive). Probe shows it is firmly attached but medial. What do you do?”
“A patient had a stabilisation elsewhere and re-dislocated. MRI shows the anchors are in the glenoid neck, not the face. The labrum is still medial. Why did it fail?”
“You are shown a CT arthrography of a 26-year-old footballer with chronic anterior instability. Contrast tracks medially along the glenoid neck with the labrum. What is the diagnosis and how does this affect your surgical planning?”
Diagnosis
- History: Recurrent Instability
- MRI: Medialized Labrum
- MRI: Intact Periosteal Sleeve
- Sign: Drive-through positive
Management
- Arthroscopic Repair is Gold Standard
- CRITICAL: Mobilize/Takedown lesion
- Fix to Glenoid Face (Not neck)
- Restore Bumper Effect
Key Differentiators
- Bankart: Torn Periosteum, Floating
- ALPSA: Intact Periosteum, Medialized
- GLAD: Cartilage defect
- Perthes: Undisplaced sleeve
Evidence Base
Every citation below has been checked against its source record in PubMed (and several were corrected during review). Neviaser's 1993 paper is the original description; Ozbaydar's 2008 comparative series is the key outcome data — and it shows ALPSA has a HIGHER recurrence than a discrete Bankart after repair, not an equivalent one. Bigliani's glenoid-rim-lesion classification and Burkhart & De Beer's bone-loss paper frame the associated bony pathology that worsens instability outcomes.
The anterior labroligamentous periosteal sleeve avulsion lesion (original description)
- Original description of the ALPSA lesion, found in 4 of 8 acute primary anterior dislocations
- Unlike a Bankart, the anterior scapular periosteum does NOT rupture, allowing the labroligamentous structures to displace medially and rotate inferiorly on the scapular neck
- The lesions heal in this medialised position and cause recurrent dislocation through subsequent incompetence of the anterior inferior glenohumeral ligament; the described arthroscopic technique converts the ALPSA back into a Bankart before repair
Results of arthroscopic capsulolabral repair: Bankart lesion versus ALPSA lesion
- 93 shoulders undergoing arthroscopic suture-anchor repair: 67 (72%) discrete Bankart, 26 (28%) ALPSA
- Recurrence at a mean 47 months was HIGHER in the ALPSA group (5/26, 19.2%) than the Bankart group (5/67, 7.4%) (P = .05)
- ALPSA patients had significantly more pre-operative dislocations/subluxations (mean 12.3 vs 4.9)
Glenoid rim lesions associated with recurrent anterior dislocation of the shoulder
- Classified anterior glenoid rim lesions in 25 unstable shoulders into Type I (displaced avulsion fracture with capsule), Type II (a medially displaced fragment malunited to the rim — analogous to the medialised ALPSA concept), and Type III (rim erosion, IIIA under 25% / IIIB over 25%)
- Detected on plain radiographs and CT-arthrograms; treatment reattached the fragment and/or capsule to the rim and addressed capsular laxity
- 88% (22/25) had satisfactory results without recurrence; 12% redislocated