Neer Classification — Overview
A segment qualifies as a Neer "part" when displaced >1 cm or angulated >45°. Four anatomic segments are defined: humeral head, greater tuberosity (GT), lesser tuberosity (LT), and humeral shaft.
The majority of proximal humerus fractures (80–85%) are 1-part (minimally displaced) and are managed conservatively.
Neer Classification Table
| Type | Parts Involved | Key Feature | Management Pearl |
|---|---|---|---|
| 1-Part | Any segment; none displaced >1 cm or >45° | Most common (80–85%) | Sling immobilization; early physical therapy |
| 2-Part Surgical Neck | Shaft + head-GT-LT unit | Most common 2-part pattern; shaft displaced anteriorly and medially by pectoralis major pull | Usually closed reduction + percutaneous pinning or ORIF |
| 2-Part GT | GT displaced from head | >5 mm displacement = rotator cuff equivalent injury; >3–5 mm in young active patients is surgical | Surgical fixation if displaced — risk of impingement and cuff dysfunction |
| 2-Part LT | LT displaced (subscapularis avulsion) | Associated with posterior glenohumeral dislocation; posterior Hill-Sachs and reverse Bankart | ORIF; assess for associated dislocation |
| 3-Part | GT or LT + surgical neck | Rotator cuff imbalance; head rotated by intact cuff attachment on remaining tuberosity | ORIF in younger patients; hemiarthroplasty in older or osteoporotic patients |
| 4-Part | All 4 segments | AVN risk 13–34%; anterior circumflex blood supply stripped | THA or hemiarthroplasty; ORIF in young patients with good bone quality |
| 4-Part Valgus-Impacted | All 4 segments; head impacted into shaft in valgus | Better prognosis despite appearance; medial periosteum preserved → lower AVN risk (10–20%) | ORIF preferred; more predictable outcome than classic 4-part |
| Head-Splitting | Articular surface fracture | Coronal split of humeral head, often with comminuted articular surface | Usually requires arthroplasty; ORIF rarely feasible |
Key Reporting Thresholds
- Neer part definition: displacement >1 cm OR angulation >45°
- Greater tuberosity: >5 mm displaced = surgical in young/active patients; >3 mm if posteriorly displaced (supraspinatus/infraspinatus dysfunction). Superior GT displacement = supraspinatus; posterior displacement = infraspinatus/teres minor.
- Surgical neck: >50% shaft width translation or >100% bayonet apposition = displaced
- AVN risk: highest in classic 4-part (13–34%); lower in valgus-impacted 4-part (10–20%) due to preserved medial periosteal hinge
Associated Injuries
- Hill-Sachs defect — posterolateral humeral head; associated with anterior dislocation
- Reverse Hill-Sachs / trough lesion — anteromedial humeral head; associated with posterior dislocation
- Osseous Bankart — anterior glenoid rim fracture
- Reverse Bankart — posterior glenoid rim fracture; associated with LT fracture and posterior dislocation
- HAGL — humeral avulsion of the glenohumeral ligament; requires MR arthrogram for diagnosis
- AVN: highest risk in classic 4-part (13–34%); lower in valgus-impacted 4-part (10–20%) due to preserved medial periosteal hinge
Reporting Checklist — Proximal Humerus Fracture
- Displacement: measure in mm or cm — threshold ≥1 cm per Neer
- Angulation: measure in degrees — threshold ≥45° (note: some surgeons use ≥30° for varus/valgus)
- Articular split: present or absent; simple vs comminuted; fragments detached from both tuberosities or dislocated into joint?
- Anatomic neck fracture: high AVN risk; if anatomic neck fractured, measure medial metaphyseal segment — length <8 mm and displacement >2 mm = higher AVN risk
- Segmental surgical neck fracture: shaft segment isolated between two fracture lines
- Greater tuberosity: displacement direction (superior = supraspinatus; posterior = infraspinatus/teres minor); >5 mm → surgical in young/active patients
- Lesser tuberosity: displacement → subscapularis avulsion; associated posterior dislocation?
- Glenohumeral dislocation: direction (anterior/posterior); location of articular fragments; Hill-Sachs / reverse Hill-Sachs; glenoid rim fracture
- Neer classification: 1-part / 2-part (specify segment) / 3-part / 4-part / 4-part valgus-impacted / head-splitting
- Acromion, coracoid, AC joint: integrity
Reference: Sandstrom CK et al. Acute Shoulder Trauma. RadioGraphics. 2015;35(2):475–92.