Humeral Head Fractures

Humeral head fractures involve the articular surface of the proximal humerus. They are distinct from extra-articular tuberosity or surgical neck fractures. These injuries pose significant challenges due to the risk of avascular necrosis (AVN), post-traumatic arthritis, and technical difficulty in reduction.

Anatomical Considerations

Blood SupplyStructural AnatomyFracture Patterns

Arcuate Artery

• Branch of Anterior Humeral Circumflex artery.
• Ascends in bicipital groove.
• Enters head at ligamentous insertion.
• Main supplier to humeral head.

Posterior Circumflex

• Current evidence suggests this provides significant supply via posterior cuff.
• Medial hinge preservation protects this supply.

Disruption of the medial calcar often compromises perfusion.

Articular Surface

• Spheroid shape.
• Retroverted 20-30 degrees.
• Inclined 130 degrees.

Bone Quality

• Subchondral bone is dense.
• Central head is cancellous/porous (poor screw hold).
• Fixation relies on subchondral purchase.

Poor central bone stock makes fixation difficult in elderly.

Head Split:

• Vertical fracture line through articular surface.
• separates head into anterior/posterior or medial/lateral.

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Impression:

• Compression of articular surface.
• "Indent" fracture from glenoid rim impact.
• E.g., Hill-Sachs (Posterior-lateral) or Reverse Hill-Sachs (Anteromedial).

Fracture pattern dictates re-constructability.

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Because AVN is the complication that defines this topic, the blood supply deserves to be developed in full - including the modern revision that the anatomy tab hints at ("current evidence suggests the posterior circumflex provides significant supply") but never explains.

The classic teaching is that the anterior humeral circumflex artery (AHCA) is the dominant supplier, via its ascending branch (the arcuate artery / "Laing's arcuate"), which runs up the lateral bicipital groove and enters the bone to perfuse most of the head. This is why the classic exam answer to "which artery is most at risk?" remains the AHCA/arcuate, and why anatomical-neck fractures (which sever it as it enters the head) carry the highest AVN risk.

The modern revision. Quantitative perfusion studies (contrast-enhanced MRI and cadaveric injection work) have shown that the posterior humeral circumflex artery (PHCA) actually supplies the majority of the humeral head - on the order of two-thirds - entering posteromedially. This reframes the medial calcar / medial hinge as critical: an intact dorsomedial metaphyseal segment (the Hertel "calcar") preserves the PHCA contribution, which is exactly why a calcar under ~8 mm predicts ischaemia.

This is why the two facts in this topic fit together: the arcuate artery is the classic "named" vessel disrupted in anatomical-neck splits, but it is the length of attached medial calcar (preserving the posterior circumflex) that most strongly predicts whether the head will actually stay perfused.

Classification

History and Physical Examination

Imaging Studies

A head-splitting or impression fracture must be distinguished from the more common proximal humeral injuries and from non-fracture causes of acute shoulder pain, because management diverges sharply.

Algorithm

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Treatment Decision Making

Operative fixation

The topic repeatedly states that "tuberosity healing improves rotation" and a viva explicitly asks "how do you secure the tuberosities?" - yet the technique and its importance are never developed. This is the step that most determines the functional result of arthroplasty done for a head fracture.

Why it matters. When the head is replaced for a comminuted fracture, the greater and lesser tuberosities (carrying the rotator cuff) are free fragments that must be reattached and must heal as bone for the cuff to work. In the randomised data cited in this topic, only about 57-65% of tuberosities healed, and crucially the functional outcome of a hemiarthroplasty depended on tuberosity healing, whereas a reverse arthroplasty performed well even when the tuberosities failed (its deltoid-driven mechanics do not rely on the cuff). That single contrast is the core reason RTSA has overtaken hemiarthroplasty for the elderly fracture.

Consequence of failure. Tuberosity nonunion or resorption gives a poor result: loss of active external rotation and elevation, and - in a hemiarthroplasty - anterosuperior escape of the prosthetic head. Because RTSA tolerates this far better, it is the safer choice when the tuberosities are badly comminuted or osteoporotic. (Generic RTSA technique and complications such as notching are covered in reverse-total-shoulder-arthroplasty.)

Potential Complications

Rehabilitation Protocol

Prognosis

• ORIF: High reoperation rate (20-30%) due to hardware removal or AVN conversion. Good function if reduction maintained and AVN avoided.
• RTSA: Reliable pain relief (90%). Active elevation greater than 130 degrees. Rotation depends on tuberosity healing.
• Hemiarthroplasty: variable pain relief (depends on glenoid wear). Good option if glenoid is pristine, but RTSA is surpassing it for reliability.

Head-splitting and impression fractures are rare, so almost no dedicated guideline addresses them directly; recommendations are extrapolated from the broader proximal humeral fracture literature, which is dominated by surgical-neck patterns.

Global epidemiology

• Proximal humeral fractures are the third most common fragility fracture after hip and distal radius, with a strongly bimodal distribution (young high-energy, elderly low-energy osteoporotic).
• True head-splitting fractures represent a small minority of proximal humeral injuries; isolated impression fractures are usually a feature of locked dislocations (anterior dislocation produces a Hill-Sachs lesion; posterior dislocation produces a reverse Hill-Sachs).

Registry evidence

• Multiple national arthroplasty registries (AOANJRR, NJR, the Nordic registries) document a marked shift from hemiarthroplasty to reverse total shoulder arthroplasty for fracture indications in patients over 65, with better implant survivorship and lower revision rates for RSA than fracture hemiarthroplasty.
• Registry data consistently show that fracture is a higher-risk arthroplasty indication than elective osteoarthritis, reinforcing careful patient selection.

High- vs limited-resource practice variation

• High-resource settings: routine CT with 3D reconstruction, ready access to headless compression screws, osteoarticular allograft, and modular reverse arthroplasty systems.
• Limited-resource settings: reliance on plain radiographs, greater use of non-operative management or hemiarthroplasty where reverse systems or allograft are unavailable, and selective referral of young reconstructable head splits to tertiary centres.
• Long-term surveillance for AVN and post-traumatic arthritis (clinical and radiographic, typically to 2 years) is recommended wherever feasible.

Self-Assessment Questions