Glenoid Fractures

Glenoid fractures range from acute rim fragments to fossa fractures extending into the scapular neck or body. Rim fractures are often discussed in the instability literature, but an acute bony fragment is not biologically equivalent to chronic attritional glenoid loss, which is a different mechanical problem as well.

Rim fractures. A bony Bankart is an avulsion of the anteroinferior glenoid rim with the labrum and capsule attached; with the posterior rim fracture it makes up the rim group, where the key issue is instability. Assess humeral-head centring, fragment displacement and viability, labral attachment and instability.

Fossa fractures. Body fractures (Ideberg II-V) are articular fractures, where joint congruity and stability both matter and treatment turns on displacement and the joint surface. Assess articular congruity, comminution and extension into the scapular neck or body.

Mechanism. Rim fractures most often follow an anterior dislocation. The other mechanisms are:

• Direct trauma - high-energy impact to the shoulder
• FOOSH - a fall with axial loading through the shoulder
• Sports injury - contact sports, rugby, American football

The glenoid. A shallow articular surface, approximately 25mm wide inferiorly and 35mm from superior to inferior, retroverted 5-7° relative to the scapular body. Its inferior tilt varies but affects stability.

What holds the head. Bony congruity with the glenoid provides 50% of stability, and the labrum deepens the socket by 50%. The capsule and ligaments are the static restraints; the rotator cuff provides the dynamic stabilisers.

The acute fragment. An acute rim fragment may retain viable bone and its attached labrum, and it may remodel when the humeral head is centred. Centring and stability are assessed before deciding on repair.

The fossa. A step, gap or comminution in the fossa alters articular congruity and load distribution. The plan comes from the CT morphology and the reduction that can be achieved.

Chronic loss. With attritional loss and a Hill-Sachs lesion, the risk of bipolar instability increases continuously. The percentage thresholds from these shoulders cannot be imported uncritically into acute fracture care, and even here the glenoid track and the patient's context guide treatment rather than one percentage alone.

Ideberg's classification (1984) describes glenoid fossa fractures; Type VI was added later. The AO/OTA scheme separates rim, simple fossa and multifragmentary articular patterns. Both describe morphology rather than prescribing treatment.

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History. Establish the mechanism (dislocation, direct trauma, sport), then ask about:

• Number of prior dislocations
• Hand dominance and sport level
• Prior shoulder surgery
• Occupation and functional demands

Examination. Inspect the contour, swelling and bruising, and palpate the bony landmarks; a bony defect is sometimes palpable. Range of motion is usually limited acutely.

Instability tests. The apprehension test is positive with anterior instability, and the load-and-shift test may demonstrate increased translation. Look for associated rotator cuff weakness, especially over the age of 40.

Associated injuries. Assess the direction of dislocation, a Hill-Sachs lesion, cuff and labral injury, a scapular-neck or body fracture, chest injury, and axillary or suprascapular nerve function.

Radiographs. The initial films identify the injury. Each view has its target:

• AP in internal rotation - Hill-Sachs
• Axillary - glenoid rim, anterior bone loss
• West Point - anteroinferior glenoid
• Stryker notch - Hill-Sachs

CT. CT is valuable for complex or operative patterns, while radiographs may suffice for clearly minor stable injuries. Multiplanar and three-dimensional CT define fragment orientation, step, gap, comminution and scapular extension when plain films are insufficient or surgery is considered.

• 3D reconstruction - the gold standard for bone loss
• En-face glenoid view - bone loss quantification
• Humeral subtraction - removes overlap
• Axial cuts - fracture pattern and displacement

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MRI. MRI shows the labral pathology of a Bankart lesion, rotator cuff tears (especially in older patients) and capsular damage such as HAGL and ALPSA lesions. Bone marrow oedema confirms the injury location.

The aim. Treatment aims for a centred, stable humeral head and acceptable articular congruity. Fragment size is one variable among morphology, displacement, the patient and associated injury.

Rim Fractures (Bony Bankart)Body Fractures (Ideberg II-V)Bone Augmentation Options

Management follows the acute fracture and the instability phenotype, in three steps.

Define the fragment. Assess its size, displacement, comminution, labral attachment and viability, and whether the humeral head is concentrically reduced.

Test stability. Consider first episode versus recurrence, sport, laxity, neurological status and any associated Hill-Sachs or cuff injury.

Select the strategy. This is a shared decision. A centred stable shoulder may be observed, a displaced viable fragment may be fixed arthroscopically or open, and chronic attritional loss may require a separate bone-augmentation strategy.

Do Not Treat the Percentage Alone

Latarjet, free bone graft, fragment fixation, Bankart repair and remplissage solve different problems. Choose among them from fragment biology, centring, track interaction, prior surgery and patient demand.

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Open reduction and internal fixation restores articular congruity. Approaches and fixation are under Surgical Technique.

Non-operative care is indicated for:

• Minimal displacement (under 2mm step)
• A stable pattern
• A low-demand patient

Operative indications:

• Displacement over 2-5mm
• Articular step or gap
• Instability
• Associated scapula fractures

The threshold. Read 2-5mm as a range: there is no universal millimetre threshold. The glenoid fracture series in the Evidence Base (Anavian) used a gap or step-off of 4mm or more as its inclusion criterion, so it shows that these fractures do well when operated but cannot locate the displacement at which the balance tips.

Latarjet. The coracoid is transferred with the conjoint tendon to the anterior glenoid and fixed with two screws. It provides 10mm of bone augmentation and a sling effect from the conjoint tendon.

Eden-Hybinette. Iliac crest autograft or allograft, contoured to the glenoid defect and fixed with screws; useful when the coracoid is unsuitable.

Distal tibia allograft. It matches the glenoid curvature well, is available as a larger graft and carries no donor site morbidity.

Arthroscopic options. Arthroscopic Latarjet is technically demanding; with arthroscopic bone block techniques it has a growing evidence base.

The choice depends on surgeon experience and patient factors. The Latarjet's bone-loss indication, over 20-25% (listed under Surgical Technique), is one of the published percentage bands from chronic-instability cohorts; do not convert it into a mandatory Latarjet for an acute bony Bankart.

A traction neurapraxia of the suprascapular nerve is the classic avoidable complication of glenoid fossa ORIF through the posterior approach.

Course. The nerve arises from the upper trunk of the brachial plexus (C5-C6), passes deep to trapezius and omohyoid, and enters the supraspinatus fossa through the suprascapular notch, beneath the superior transverse scapular ligament. It then curves around the base of the scapular spine through the spinoglenoid (great scapular) notch to reach the infraspinatus fossa, giving motor branches to supraspinatus and infraspinatus and sensory branches to the posterior capsule.

The danger points. At the spinoglenoid notch the nerve lies only approximately 2 cm medial to the posterior glenoid rim, the point most at risk during exposure of the posterior glenoid neck and infraspinatus retraction. At the suprascapular notch it lies approximately 2.5 to 3 cm medial to the superior glenoid rim, at risk with superior dissection and medial retraction toward the base of the coracoid.

Protecting it. The nerve is tethered at both notches, so over-medial retraction, not laceration, is the usual mechanism of injury.

• Keep subperiosteal dissection on the posterior scapular neck within roughly 1.5 to 2 cm of the glenoid rim
• Develop the infraspinatus-teres minor interval carefully and avoid forceful medial traction on the infraspinatus and on the medial (body) fragment
• Watch plate and screw position along the lateral scapular pillar: an over-medially directed screw or a medially placed retractor at the spinoglenoid notch endangers the nerve
• Document deltoid and infraspinatus/external-rotation function before and after surgery

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After ORIF. Weight-bearing is restricted until union, and range of motion is set by the stability of the fixation, with earlier motion when fixation is stable.

Ideberg Type VI, comminution of the glenoid fossa, is the highest-energy and hardest-to-fix pattern, and the one most likely to appear in a senior viva.

The injury. Multifragmentary comminution of the articular fossa, almost always from the highest-energy injuries (motor vehicle trauma, falls from height), frequently extending into the scapular neck and body with associated chest-wall, rib or clavicle injury. Rigid anatomic fixation of every articular fragment is often impossible, so the surgical decision is different from the reconstructable II-V patterns.

What decides. Concentricity and reducibility, not fragment count. The key question is whether the humeral head remains concentric and stable beneath a reconstructable articular surface; a centred head under a congruent, even if imperfect, reconstruction predicts a good outcome. CT with 3D reconstruction shows the size and reducibility of the major peripheral fragments, and these, not the small central pieces, dictate whether fixation is feasible.

Management. Three situations:

• Reconstructable major fragments, concentric head - ORIF aimed at restoring the articular arc and rim stability: small-fragment or reconstruction plates buttressing the lateral scapular pillar, with peripheral rim screws or suture anchors capturing the key articular fragments. The goal is a congruent, stable surface, not the reduction of every tiny fragment.
• Unreconstructable fossa, concentric head, low-demand patient - nonoperative treatment with early protected motion can give an acceptable result when the head stays centred
• Unsalvageable articular surface, incongruent or unstable head - delayed reconstruction or, rarely, arthroplasty may be required, as a salvage rather than a primary decision

Even complex, displaced fossa fractures with scapular involvement unite reliably and function well when the reconstructable surface is restored, which supports an attempt at fixation of the major fragments where feasible.

Global epidemiology:

• Anterior shoulder dislocation incidence is highest in young males (peak in the second to third decades) and in contact/collision athletes (rugby, American football, ice hockey).
• A bony Bankart (anteroinferior rim fracture) is present in a substantial minority of first-time dislocations; some degree of glenoid bone loss accumulates with recurrent dislocations.
• Isolated glenoid body (Ideberg II-VI) fractures are uncommon, usually high-energy, and frequently associated with scapular and chest-wall injury.

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