# Proximal Humerus Fractures: Nonoperative vs. Operative Management

## Anatomy

### Bony Anatomy

The proximal humerus is understood through Codman's four-part anatomy, comprising the articular segment (head), greater tuberosity, lesser tuberosity, and shaft. The anatomical neck lies at the articular margin, while the surgical neck sits below the tuberosities and represents the most common fracture location. The normal head-shaft angle is approximately 130-135 degrees, with the head retroverted approximately 20-30 degrees relative to the transepicondylar axis.

### Vascular Supply

The primary blood supply to the humeral head comes from the **anterior humeral circumflex artery**, which gives rise to the arcuate artery. The **posterior humeral circumflex artery** supplies the posteroinferior head and greater tuberosity. Both vessels arise from the third part of the axillary artery. This vascular supply is vulnerable in displaced fractures, creating the risk of avascular necrosis. The ascending branch (arcuate artery) enters the bone in the bicipital groove and is disrupted in 4-part fractures.

### Muscular Deforming Forces

The supraspinatus pulls the greater tuberosity superiorly and posteriorly, while the subscapularis pulls the lesser tuberosity medially. The pectoralis major displaces the shaft medially and anteriorly, and the deltoid abducts the shaft. Understanding these deforming forces guides fracture pattern recognition and reduction strategies.

### Neurovascular Structures at Risk

The axillary nerve wraps around the surgical neck and is at risk with surgical neck fractures and the deltopectoral approach; its function is tested by assessing sensation over the lateral deltoid (regimental badge area). The axillary artery is at risk in severely displaced fractures and fracture-dislocations, and the brachial plexus may be injured in high-energy fracture-dislocations.

## Classification

### Neer Classification

The Neer classification is based on displacement of Codman's four parts, where a "part" is considered displaced if there is greater than 1 cm of translation or greater than 45 degrees of angulation. A **non-displaced (1-part)** fracture has all parts minimally displaced regardless of the number of fracture lines, and approximately 85% of proximal humerus fractures fall into this category. A **2-part** fracture has one part displaced with the other three non-displaced; the surgical neck pattern is the most common 2-part configuration, greater tuberosity fractures are important for rotator cuff function, and lesser tuberosity fractures are associated with posterior dislocation. **3-part** fractures have two parts displaced from the remaining two. **4-part** fractures have all four parts displaced and carry the highest risk of AVN. Additional patterns include head-splitting fractures involving the articular surface and fracture-dislocations combining any fracture pattern with glenohumeral dislocation.

### Limitations

The Neer classification has poor interobserver reliability (kappa 0.3-0.5) even with CT imaging. It oversimplifies the spectrum of fracture patterns. CT with 3D reconstruction improves pattern recognition but does not fully resolve reliability issues.

## Imaging

### Trauma Series

The standard trauma series includes a true AP (Grashey) view taken with 30-40 degrees of body rotation to profile the glenohumeral joint, a scapular Y (lateral) view to identify anterior or posterior dislocation, and an axillary lateral view that is essential to rule out dislocation and must always be obtained. If the axillary view is not possible, a Velpeau axillary taken through the sling is an acceptable alternative.

### CT with 3D Reconstruction

CT with 3D reconstruction is the standard for surgical planning. It assesses articular involvement, head-splitting, tuberosity displacement, and medial calcar comminution. 3D reconstructions with humeral head subtraction improve understanding of glenoid and tuberosity morphology.

## Nonoperative Management

### Indications

Nonoperative management is appropriate for non-displaced or minimally displaced fractures (85% of proximal humerus fractures), low-demand elderly patients with displaced fractures, patients with significant medical comorbidities precluding surgery, and those who will not comply with postoperative restrictions.

### Evidence for Nonoperative Treatment

The **PROFHER trial** (2015) found no significant difference between surgical and nonoperative treatment for displaced proximal humerus fractures at 2 years, including 2-part, 3-part, and 4-part fractures treated with plates, nails, or hemiarthroplasty. This trial has been criticized for its heterogeneous surgical techniques and variable surgeon experience. The **DelPhi trial** (2020) compared reverse shoulder arthroplasty versus nonoperative treatment for 3- and 4-part fractures in elderly patients, demonstrating better functional outcomes with RSA at 2 years, thus challenging the PROFHER findings for the most severe patterns. The current interpretation is that many displaced fractures do well nonoperatively, but selected patients with severe patterns (3-part, 4-part) may benefit from surgery.

### Protocol

Treatment involves sling immobilization for 1-2 weeks with early pendulum exercises within the first week. Progressive range of motion begins at 2-4 weeks (passive then active-assisted), followed by active ROM and strengthening at 6 weeks, with full activity by 3-4 months. Some residual stiffness is acceptable, as functional outcomes are often good despite imperfect radiographic reduction.

## Operative Management

| Option | Indications | Key Advantages | Key Disadvantages |
|--------|------------|----------------|-------------------|
| ORIF (Locking Plate) | Displaced 2-part, 3-part in active patients | Anatomic reduction; preserves native head | Screw perforation (12-20%); AVN risk; varus collapse |
| IM Nailing | 2-part surgical neck | Minimally invasive; load-sharing | Cuff damage at entry; limited to simple patterns |
| Hemiarthroplasty | 4-part fractures in younger patients | Addresses head viability | Unpredictable outcomes; tuberosity healing critical |
| Reverse TSA (RSA) | 3/4-part fractures in elderly (>65-70) | Deltoid-powered; independent of tuberosity healing | Instability; scapular notching; infection |
| Percutaneous Pinning | 2-part / select 3-part in good bone | Minimally invasive; preserves blood supply | Pin migration; loss of reduction; close follow-up |

### ORIF with Locking Plates

Open reduction and internal fixation with locking plates is indicated for displaced 2-part and 3-part fractures in active patients with adequate bone quality. The deltopectoral approach provides an internervous plane between the deltoid and pectoralis major. Anatomic proximal humerus locking plates (PHILOS, Proximal Humerus Internal Locking System) are used. Key technical points include restoring medial calcar support with an inferomedial oblique locking screw to reduce the risk of varus collapse, suture fixation of tuberosities through plate holes, avoiding superior plate placement that causes impingement, and ensuring screws support subchondral bone without penetrating the articular surface. Complications include screw perforation (12-20%), AVN (4-10%), varus malunion, and subacromial impingement.

### Intramedullary Nailing

Intramedullary nailing is indicated for 2-part surgical neck fractures. The antegrade entry passes through the rotator cuff (supraspinatus), raising concerns about cuff damage and shoulder pain from the superior entry. Some studies demonstrate lower complication rates than plating for simple patterns, but nailing is not suitable for fractures with tuberosity involvement or significant displacement.

### Hemiarthroplasty

Hemiarthroplasty is indicated for 4-part fractures, head-splitting fractures, and fracture-dislocations in younger active patients. Tuberosity healing is critical for function, requiring meticulous repair of tuberosities to the prosthesis and shaft. Tuberosity malunion or nonunion is the leading cause of poor outcomes, and long-term results are unpredictable with significant rates of tuberosity failure, erosion, and poor function.

### Reverse Total Shoulder Arthroplasty (RSA)

Reverse total shoulder arthroplasty is indicated for displaced 3-part and 4-part fractures in elderly patients (over 65-70 years). Unlike hemiarthroplasty, RSA does not depend on tuberosity healing for function because it is deltoid-powered and compensates for rotator cuff deficiency. The DelPhi trial supports RSA over nonoperative treatment for 3- and 4-part fractures in elderly patients, demonstrating better early functional outcomes and fewer secondary procedures than hemiarthroplasty. Complications include instability, scapular notching, infection, and acromion fracture. The growing consensus is that RSA has replaced hemiarthroplasty as the arthroplasty of choice for most elderly patients with complex proximal humerus fractures.

### Percutaneous Pinning

Percutaneous pinning is a minimally invasive technique using K-wires for 2-part and selected 3-part fractures in good bone. It preserves blood supply but requires close follow-up due to risks of pin migration and loss of reduction. This technique is less commonly performed now with the availability of locking plates.

## Specific Fracture Patterns

### Greater Tuberosity Fractures

Greater tuberosity fractures with displacement greater than 5 mm warrant operative fixation, especially in active patients, because malunion causes subacromial impingement and rotator cuff dysfunction. Even 3-5 mm of superior displacement can be symptomatic. Fixation options include suture anchors, screws, or plate fixation through a superior or lateral deltoid-splitting approach. These fractures are associated with anterior shoulder dislocations, and post-reduction films must be obtained to confirm tuberosity position.

### Lesser Tuberosity Fractures

Lesser tuberosity fractures are often associated with posterior shoulder dislocation. Displaced fractures require ORIF with screws or suture fixation. A missed posterior dislocation with lesser tuberosity fracture is a classic diagnostic pitfall.

### Valgus-Impacted 4-Part Fractures

In valgus-impacted 4-part fractures, the humeral head is laterally displaced and impacted into the shaft. The periosteal hinge (medial calcar) may be preserved, resulting in a lower AVN risk than classic 4-part fractures. These fractures are amenable to ORIF with plate fixation if the head fragment is viable and carry a better prognosis than true 4-part fractures with complete displacement.

## Complications

### Avascular Necrosis (AVN)

The risk of AVN increases with displacement and number of parts. In 4-part fractures, AVN occurs in 10-30% with ORIF and approaches 100% with fracture-dislocations. Medial calcar comminution predicts AVN as it disrupts the ascending branch of the anterior circumflex artery. AVN may take 6-24 months to become radiographically apparent.

### Stiffness

Stiffness is common after both operative and nonoperative treatment, resulting from adhesive capsulitis and subacromial fibrosis. Prevention focuses on early range of motion as fracture stability permits. Refractory cases may require manipulation under anesthesia or arthroscopic capsular release.

### Malunion

Varus malunion is the most common malunion after plating, resulting from loss of medial calcar support. Greater tuberosity malposition causes impingement and cuff dysfunction. Symptomatic malunion may require corrective osteotomy or arthroplasty.

<image>An anteroposterior diagram of the proximal humerus showing Codman's four-part anatomy: the articular segment (humeral head), greater tuberosity (with supraspinatus, infraspinatus, and teres minor attachments), lesser tuberosity (with subscapularis attachment), and the shaft (with pectoralis major and deltoid insertions). Show arrows indicating the deforming forces of each muscle on its respective fragment. Label the anatomical neck, surgical neck, and bicipital groove.</image>

<image>A vascular anatomy diagram of the proximal humerus showing the anterior and posterior humeral circumflex arteries arising from the third part of the axillary artery. Highlight the ascending branch (arcuate artery) entering the bone in the bicipital groove as the primary blood supply to the humeral head. Show how a 4-part fracture disrupts this blood supply by displacing all four fragments, with the arcuate artery torn at its entry point.</image>

<image>A comparative illustration showing three surgical options for displaced proximal humerus fractures. Left panel: ORIF with a proximal humerus locking plate (PHILOS) showing the plate on the lateral proximal humerus with locking screws into the head and shaft, sutures through the plate holes repairing tuberosities, and an inferomedial calcar screw. Middle panel: hemiarthroplasty with the prosthetic head replacing the humeral head and tuberosities sutured to the prosthesis and shaft. Right panel: reverse total shoulder arthroplasty with the glenosphere on the glenoid and the humeral socket component — deltoid-powered design independent of rotator cuff function.</image>

## Clinical Pearls

Eighty-five percent of proximal humerus fractures are minimally displaced and can be treated nonoperatively with excellent results. The PROFHER trial found no benefit to surgery for most displaced proximal humerus fractures, but the DelPhi trial suggests RSA may benefit elderly patients with 3- and 4-part fractures. The axillary view is mandatory and must never be omitted from the trauma series, as posterior dislocations are commonly missed without it. Medial calcar comminution predicts AVN and varus collapse, making the inferomedial calcar screw critical when plating. RSA has largely replaced hemiarthroplasty for elderly patients with complex fractures because it does not depend on tuberosity healing. Greater tuberosity displacement greater than 5 mm warrants fixation because even small amounts of superior displacement cause impingement. When the vascularity of the humeral head is uncertain in 4-part fractures, arthroplasty should be considered over ORIF to avoid the morbidity of AVN. The axillary nerve should always be checked before and after surgery by testing sensation at the regimental badge area.

## References

- Rangan A, et al. (PROFHER Trial). Surgical vs nonsurgical treatment of adults with displaced fractures of the proximal humerus: the PROFHER randomized clinical trial. *JAMA*. 2015;313(10):1037-1047.
- Beks RB, et al. (DelPhi Trial). Reverse shoulder arthroplasty vs nonoperative treatment for 3- or 4-part proximal humeral fractures. *JAMA Surg*. 2020;155(11):1037-1045.
- Neer CS 2nd. Displaced proximal humeral fractures. I. Classification and evaluation. *J Bone Joint Surg Am*. 1970;52(6):1077-1089.
- Hertel R, et al. Predictors of humeral head ischemia after intracapsular fracture of the proximal humerus. *J Shoulder Elbow Surg*. 2004;13(4):427-433.
- Launonen AP, et al. Treatment of proximal humerus fractures in the elderly. *J Bone Joint Surg Am*. 2015;97(15):1264-1273.