Proximal Humerus Fractures

Proximal humerus fractures make up 4-5% of all fractures and are the third most common fracture in the elderly, after the hip and the distal radius. They are strongly associated with osteoporosis.

Who and how. The distribution is bimodal: young males injured by high energy, and elderly females injured by low energy. Incidence peaks between 60 and 90 years, and the female predominance increases with age.

• Low-energy fall onto the outstretched hand in the elderly - 80%
• High-energy trauma in the young - motor vehicle accidents, sports
• Pathological fracture in metastatic disease

The four parts. Neer's classification divides the proximal humerus into four segments, Codman's parts. The muscles attached to each decide which way it displaces.

• Articular segment (head) - the blood supply concern
• Greater tuberosity - supraspinatus, infraspinatus and teres minor attach; supraspinatus pulls it superiorly
• Lesser tuberosity - subscapularis attaches and internally rotates it
• Shaft - pectoralis major, deltoid and latissimus attach; pectoralis major pulls it medially, and the deltoid may displace it laterally

The classic teaching. The arcuate artery, the intraosseous continuation of the anterolateral ascending branch of the anterior circumflex humeral artery, enters at the intertubercular (bicipital) groove and spirals into the head. The textbook line is that it is the head's main supply. It is a real and important vessel, a terminal one with poor collaterals, and it is torn in about 80% of displaced fractures.

The corrected version. Osteonecrosis after these fractures is uncommon, and that mismatch with the 80% is the clue that the classic teaching is only half right. Quantitative gadolinium MRI in twenty-four cadaver shoulders found that the posterior circumflex humeral artery supplies 64% of the humeral head and the anterior circumflex only 36%, the posterior vessel dominating in three of the four head quadrants (Hettrich, PMID 20360519). The posterior circumflex supplies the greater tuberosity as well.

Why it matters. Two consequences change what you do.

• A head can stay perfused despite an obviously disrupted arcuate artery, so judge its viability by the posteromedial hinge and the calcar, not by assuming the arcuate is the whole story.
• The posterior circumflex runs with the axillary nerve through the quadrangular space, so protect both during posterior dissection and inferior screw placement.

The axillary nerve. It exits the quadrangular space and wraps around the surgical neck 5-7cm below the acromion. It is at risk with anterior dislocation and at surgery.

Neer (1970). The category is the number of parts displaced past the threshold of over 1cm of translation or over 45° of angulation. Count displaced parts, not fracture lines or fragments. A shattered-looking film with nothing past the threshold is a one-part fracture, and a comminuted surgical neck with one displaced greater tuberosity is two-part.

Neer or AO. The AO/OTA system (11-A/B/C) is more comprehensive, but Neer is more commonly used clinically and in the orthopaedic exam. Be familiar with both, and use Neer for treatment decisions.

History. The arm is held adducted, supported by the other hand. Establish the mechanism, pre-injury activity level and hand dominance, and comorbidities: osteoporosis, diabetes and rotator cuff disease.

Examination. Look for swelling, deformity and ecchymosis that tracks to the chest and arm; feel for crepitus and localised tenderness. Movement is severely limited by pain. The neurovascular examination covers the axillary nerve, the brachial plexus and the pulses.

Associated injuries. Rotator cuff and brachial plexus injuries are associated with the fracture. In high-energy trauma, assess for an ipsilateral clavicle fracture (floating shoulder), scapula and rib fractures, and pulmonary injury. After a low-energy fall in the elderly, consider other fragility fractures and the need for bone health assessment.

Radiographs. Three views are essential: the true AP (Grashey), the scapular Y and the axillary. Together they form the trauma series and allow assessment of all four parts and of dislocation. When the axillary view is limited, the Velpeau view, a modified axillary taken with the patient leaning back over the cassette, avoids the need to abduct the arm and is useful in acute trauma with limited mobility.

CT. Recommended for all operative cases. 3D reconstructions help with the fracture pattern, articular involvement and head viability, and are superior for understanding complex patterns and for identifying head viability in valgus-impacted fractures. Always get a CT for:

• 3-part and 4-part fractures
• Head-split patterns
• Fracture-dislocations
• Pre-operative planning

MRI. Rarely indicated acutely. It may help assess the rotator cuff in the subacute phase, or evaluate the blood supply to the head with contrast enhancement.

The decision. Classify the pattern by Neer displacement, then weigh it against the patient's age, demand, comorbidity and bone quality. 85% of fractures are minimally displaced, one-part, and are treated non-operatively with good outcomes.

PROFHER. This landmark UK trial found no difference in functional outcome at 2 years between surgical and non-surgical treatment of displaced fractures, and changed practice significantly toward non-operative management, especially in elderly patients: the majority can be treated non-operatively with outcomes equivalent to surgery. Its population was adults with displaced fractures involving the surgical neck. The Evidence Base sets out what it did not cover, and those patterns are where surgery is still argued for.

Algorithm

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Reverse over hemiarthroplasty. Reverse shoulder arthroplasty (RSA) has largely replaced hemiarthroplasty for fractures. With RSA the deltoid becomes the primary elevator rather than the rotator cuff, so it gives reliable pain relief and function regardless of tuberosity healing and allows earlier active motion; hemiarthroplasty outcomes depend heavily on tuberosity healing.

What the evidence supports. The Cochrane review found only very low-certainty evidence of a minimal functional difference between RTSA and hemiarthroplasty, but a lower complication and reoperation rate with RTSA, and registry data show lower cumulative revision after RTSA (see Evidence Base).

AVN. Risk tracks head ischaemia. Anatomic neck and head-split fractures carry the highest risk; 4-part fractures (15-35%) and 3-part fractures (3-14%) are also at risk. Valgus-impacted patterns have a lower risk because the medial soft-tissue hinge is preserved.

Malunion and stiffness. Malunion is the most common complication, especially of the greater tuberosity, where it causes impingement. Stiffness is common after both non-operative and operative treatment, and early ROM is key to preventing it.

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Prognostic factors. Function at 1-2 years is the best predictor of long-term outcome. The factors that affect it:

• Age - older patients have more stiffness
• Initial displacement, which correlates with soft-tissue injury
• Bone quality
• Patient activity level
• Tuberosity healing, for arthroplasty

Global Epidemiology

Proximal humeral fractures account for roughly 4-5% of all fractures and are the third most common fragility fracture in older adults after the proximal femur and distal radius. In Court-Brown's epidemiology (Injury 2018), their incidence is rising across high-income populations as longevity increases, with a marked female predominance from low-energy falls and a smaller cohort of younger patients sustaining high-energy injuries.

Side-by-Side Guidance and Evidence

Registry Evidence and Practice Variation

Bone Health and Medications