Humeral Head Fractures

Humeral head fractures involve the articular surface of the proximal humerus, which sets them apart from extra-articular tuberosity and surgical neck fractures. They are difficult for three reasons: the risk of avascular necrosis (AVN), post-traumatic arthritis, and the technical difficulty of reduction.

Mechanism. In the young the injury is high energy: an axial load, a fall from height or a motor vehicle accident. In the elderly a low-energy fall is enough. Osteoporotic bone collapse and seizures complete the list, and a seizure should make you think of a posterior dislocation with an impression fracture.

Prognosis. Complication rates are high and AVN is the primary concern. Stiffness is common. Arthroplasty is reliable for pain relief, but function after it is variable.

The head. The articular surface is spheroid, retroverted 20-30 degrees and inclined at 130 degrees.

Bone quality. The subchondral bone is dense, but the centre of the head is cancellous and porous and gives poor screw hold, so fixation relies on subchondral purchase. That poor central bone stock is what makes fixation difficult in the elderly.

Head-splitting fractures. A vertical fracture line runs through the articular surface and separates the head into anterior and posterior, or medial and lateral, segments. A true head split has a very poor prognosis for AVN and is difficult to fix reliably.

Impression fractures. The articular surface is compressed, an indent made by impact against the glenoid rim. The Hill-Sachs lesion is posterolateral and follows anterior dislocation; the reverse Hill-Sachs is anteromedial and follows posterior dislocation. Reverse Hill-Sachs impressions affecting more than 40% of the head surface are often caused by missed posterior dislocations.

The fracture pattern dictates whether the head can be reconstructed.

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AVN is the complication that defines this topic, and the account of the head's blood supply has been revised.

The classic teaching. The anterior humeral circumflex artery (AHCA) is the dominant supplier, through its ascending branch, the arcuate artery ("Laing's arcuate"). It runs up the lateral bicipital groove and enters the head at the ligamentous insertion to perfuse most of it. Anatomical-neck fractures sever it as it enters the head, which is why they carry the highest AVN risk and why the classic exam answer to "which artery is most at risk?" remains the AHCA and its arcuate branch. The surgical lesson drawn was to protect the arcuate artery in the groove.

The modern revision. Quantitative perfusion studies, contrast-enhanced MRI and cadaveric injection work, have shown that the posterior humeral circumflex artery (PHCA), classically a minor contributor, supplies the majority of the head, on the order of two-thirds. It enters posteromedially, by way of the posterior cuff. The anterior circumflex remains a real but smaller contribution.

Why the calcar matters. An intact dorsomedial metaphyseal segment, the Hertel "calcar", preserves the posterior circumflex contribution, and preserving the medial hinge protects that supply. This is why a short calcar predicts ischaemia, and why disruption of the medial calcar often compromises perfusion. Medial periosteal disruption is a further risk factor for AVN.

History. The patient has severe pain, global swelling and crepitus with any motion. Severe crepitus suggests intra-articular comminution.

Inspection. Look for extensive ecchymosis over the chest wall and arm, and for deformity.

Neurovascular status. Always assess the axillary nerve, by deltoid tone and patch sensation: its proximity to the surgical neck puts it at risk. Check the distal pulses to ensure the vascular tree is intact.

Do not test range of motion. Aggressive motion can displace the fragments further, so allow gentle pendulum movement only if the fracture is stable. The aim is to protect the soft tissues and the neurovascular structures.

Radiographs. The trauma series is a screening tool only:

• AP (Grashey) - joint space narrowing, fragmentation
• Scapular Y - dislocation check
• Axillary - key for head shape and tuberosity position

Plain films often underestimate articular involvement, and overlapping shadows obscure split lines. They cannot accurately characterise the percentage of articular involvement or the number of head fragments.

CT is mandatory. Order it whenever articular involvement is suspected. The two-dimensional cuts show fracture lines through the cartilage, CT quantifies the impression as a percentage of surface area, and three-dimensional reconstruction with the scapula subtracted is vital for surgical planning.

Angiography and MRI. Angiography is rarely indicated unless pulses are absent, and MRI is not typically used in the acute fracture setting.

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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.

The decision. Whether to fix or replace turns on age and comminution. Whichever is chosen, the goals are the same: an anatomic reduction that restores the articular surface, tuberosities that heal (critical for cuff function), and early motion to prevent stiffness.

Impression fractures by size. The size of the defect sets the treatment, together with its zone of contact: does it engage in function?

• Less than 20% - non-operative; the defect can be ignored
• 20-40% - disimpaction, grafting or transfer
• Greater than 40% - arthroplasty or allograft

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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 here (Sebastia-Forcada), only about 57-65% of tuberosities healed.

Why reverse has overtaken hemiarthroplasty. The functional outcome of a hemiarthroplasty depended on tuberosity healing, whereas a reverse arthroplasty performed well even when the tuberosities failed, because its deltoid-driven mechanics do not rely on the cuff. That contrast is the decisive advantage, and the core reason RTSA has overtaken hemiarthroplasty for the elderly fracture.

When they fail. 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. RTSA tolerates this far better, so 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.

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Avascular necrosis. Ischaemia leads to head collapse, screw cut-out and joint destruction. Displaced head-split fractures are widely regarded as carrying a high AVN risk, and once split the articular surface cannot be preserved, which is why arthroplasty dominates the pattern. No series cited on this page quantifies the rate, so do not quote one.

Post-traumatic arthritis. Even when the fracture heals, the articular damage leads to rapid arthrosis, and conversion to arthroplasty may be needed later.

Tuberosity nonunion. After ORIF or hemiarthroplasty, tuberosities that do not heal leave poor function, with loss of active elevation and rotation. Reverse arthroplasty is the exception described above.

Stiffness and frozen shoulder. Scarring and pain limit motion. Early rehabilitation has to be balanced against the stability of the fixation.

ORIF. Function is good if the reduction is maintained and AVN avoided. Reoperation is roughly twice as likely after operative than after non-operative treatment of proximal humeral fractures (Handoll & Brorson, RR 2.06, 95% CI 1.18-3.60), though that is a surgical-neck cohort, not head splits. Solberg's plate arm still outscored hemiarthroplasty in three-part fractures, despite six osteonecroses and six screw perforations in 38 patients.

Reverse arthroplasty. In the one cited RCT (Sebastia-Forcada, over-70s), RSA gave a mean forward elevation of 120 degrees and a Constant score of 56.1, against 79.8 degrees and 40.0 for hemiarthroplasty. Rotation is the persistent limitation of reverse designs.

Hemiarthroplasty. Pain relief is variable and depends on glenoid wear. It is a good option if the glenoid is pristine, but RTSA is surpassing it for reliability.

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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.

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