# Clavicle Fractures: When to Operate

## Anatomy and Biomechanics

### Bony Anatomy

The clavicle is an S-shaped bone that serves as the only bony connection between the upper extremity and the trunk, linking the axial and appendicular skeleton. The medial two-thirds is tubular and convex anteriorly, while the lateral one-third is flat and concave anteriorly. The middle third represents the narrowest cross-section and the transition zone between these two morphologies, making it the most common fracture location at approximately 80% of all clavicle fractures.

### Ligamentous Attachments

The coracoclavicular ligaments (conoid and trapezoid) maintain vertical stability of the lateral clavicle. The acromioclavicular ligaments provide horizontal stability of the AC joint. The sternoclavicular ligaments anchor the medial clavicle, and the costoclavicular ligament serves as an additional medial stabilizer.

### Neurovascular Relationships

The subclavian artery and vein lie posterior and inferior to the mid-clavicle, and the brachial plexus runs posterior to the clavicle. The supraclavicular nerves cross superficially and are at risk during surgical approach. The lung apex sits in proximity, creating a pneumothorax risk with posterior cortex penetration during drilling.

### Muscular Attachments

The sternocleidomastoid attaches to the medial fragment and displaces it superiorly and posteriorly, while the trapezius attaches laterally. The deltoid and pectoralis major act on the distal fragment, displacing it inferiorly and medially. These deforming forces create the classic displaced midshaft fracture pattern.

## Classification

### Allman Classification

The Allman classification divides clavicle fractures by location: **Group I** involves the middle third (80%), **Group II** the lateral third (15%), and **Group III** the medial third (5%).

### Neer Classification (Lateral Third)

The Neer classification addresses lateral third fractures specifically. **Type I** fractures occur lateral to the coracoclavicular ligaments and are stable, managed nonoperatively. **Type II** fractures occur medial to the coracoclavicular ligaments and are unstable with a high nonunion rate; subtype IIA has both the conoid and trapezoid intact on the distal fragment, while subtype IIB has the conoid torn with the trapezoid attached to the distal fragment. **Type III** fractures are intra-articular AC joint fractures that are usually treated nonoperatively. **Type V** is the pediatric periosteal sleeve fracture variant, also typically managed nonoperatively.

### Edinburgh Classification (Robinson)

The Edinburgh classification subclassifies midshaft fractures by displacement and comminution. Type 2B1 (displaced simple) and 2B2 (displaced comminuted) are the most relevant categories for surgical decision-making.

## Epidemiology and Mechanism

Clavicle fractures are the most common fracture in children and young adults, representing 2.5-5% of all fractures. The typical mechanism is a fall onto the shoulder (direct) or a fall on an outstretched hand (indirect). There is a male predominance, especially in sports and high-energy mechanisms, and a bimodal age distribution affecting young athletes and elderly patients who fall.

## Nonoperative Management

### Indications

Nonoperative management is indicated for non-displaced or minimally displaced midshaft fractures, most lateral third fractures (Neer Type I and III), most medial third fractures, and low-demand patients with displaced fractures.

### Treatment

A simple sling for comfort over 2-4 weeks is the standard. The figure-of-eight bandage is no longer recommended as it offers no benefit over a sling and is less comfortable. Early range of motion is encouraged as pain allows, including pendulum exercises and gentle shoulder motion. Return to full activity takes 6-12 weeks for non-displaced fractures and 8-16 weeks for displaced fractures. The nonunion rate for non-displaced midshaft fractures is less than 1-2%.

### Outcomes of Nonoperative Treatment for Displaced Fractures

The COTS trial (Canadian Orthopaedic Trauma Society, 2007) demonstrated that plate fixation was superior to nonoperative treatment for displaced midshaft fractures, showing a lower nonunion rate (3% vs. 14%) and better shoulder scores with surgery. Subsequent meta-analyses have shown nonunion rates of 5-20% with nonoperative treatment for displaced fractures. Symptomatic malunion with shortening can cause shoulder dysfunction and cosmetic deformity, though many patients do well nonoperatively despite radiographic malunion.

## Operative Management

### Indications for Surgery (Midshaft)

Established indications include open fractures, associated vascular or neurologic injury (subclavian vessel injury, brachial plexus compromise), tenting skin with impending open fracture, floating shoulder (ipsilateral clavicle plus scapular neck fracture), and polytrauma requiring earlier mobilization. Relative indications where controversy exists include shortening greater than 1.5-2 cm, displacement greater than 100% (no cortical contact), comminution with shortening, patient preference or high-demand athletes, and bilateral clavicle fractures.

### Plate Fixation

**Superior plating** places the plate on the superior surface of the clavicle. It is biomechanically strong as tension-side plating but carries hardware prominence that is symptomatic in up to 30% of patients and may require removal; the supraclavicular nerve is also at risk. **Anteroinferior plating** places the plate on the anterior or anteroinferior surface, offering less hardware prominence, better cosmesis, and lower implant removal rates, though it is potentially less biomechanically ideal; clinical outcomes are equivalent to superior plating in most studies. Anatomic precontoured locking plates (3.5 mm) are used, with lag screw fixation for simple oblique patterns and bridge plating for comminution. Overall complication rates are 5-15%, including hardware irritation, infection, nonunion, and refracture after plate removal.

### Intramedullary Fixation

Intramedullary fixation uses titanium elastic nails (TEN) or other IM devices. Advantages include smaller incisions, lower infection rates, less hardware prominence, and better cosmesis. Disadvantages include less rotational control, potential hardware migration toward the great vessels or chest (rare but potentially serious), and limited reduction capability for comminuted fractures. This technique is best for simple transverse or short oblique fractures but has a higher reoperation rate than plating in some studies.

### Lateral Third Fractures (Neer Type II)

Neer Type II lateral clavicle fractures have a high nonunion rate with nonoperative treatment (up to 30-40%). Fixation options include hook plates (effective but frequently cause subacromial impingement and require routine removal at 3-4 months after union to prevent acromial erosion), coracoclavicular fixation with suture button or screw fixation to the coracoid, locking plates with supplemental coracoclavicular stabilization, and anatomic lateral clavicle locking plates.

## The Pendulum of Evidence

### Early Evidence (COTS Trial, 2007)

The COTS trial favored surgery with lower nonunion rates and better function, leading to a significant increase in operative fixation rates.

### Subsequent Studies

Multiple RCTs have shown mixed results. Some demonstrate equivalent functional outcomes between operative and nonoperative treatment, while surgery consistently shows lower nonunion rates. However, operative complications (hardware irritation, infection, refracture after removal) balance the benefits. The current consensus supports shared decision-making: surgery is appropriate for specific indications but not mandatory for all displaced fractures.

### Patient Factors in Decision-Making

Young athletes may prefer surgery for faster return to sport. Manual laborers may benefit from more predictable union and alignment. Cosmetic concerns involve weighing visible malunion against a surgical scar. Patients should understand the nonunion risk (10-15% nonoperative) versus operative complications (5-15%).

## Complications

### Nonunion

Nonunion occurs in 5-20% of displaced fractures treated nonoperatively and 1-5% treated operatively. Risk factors include smoking, female sex, comminution, shortening greater than 2 cm, and advanced age. Treatment involves plate fixation with iliac crest bone grafting.

### Hardware-Related

Plate prominence is symptomatic in 15-30% of patients and is the most common reason for hardware removal. Implant removal rates range from 10-40% depending on plate position and study. Refracture after plate removal occurs in 2-5% of cases, and patients should be counseled about this risk.

### Infection

Superficial wound infection occurs in 2-5% and deep infection in 1-3% of cases. Risk factors include smoking, diabetes, and open fracture.

### Neurovascular

Supraclavicular nerve injury causes numbness over the anterior chest wall and is common but often resolves. Pneumothorax is rare but reported with drilling through the posterior cortex. Subclavian vessel injury is rare and associated with high-energy fractures or hardware prominence.

<image>An anatomical illustration of the clavicle showing the S-shaped contour with the medial two-thirds (tubular, convex anteriorly) and lateral one-third (flat, concave anteriorly). Label the sternoclavicular joint, acromioclavicular joint, coracoclavicular ligaments (conoid and trapezoid), and the muscular attachments (sternocleidomastoid superiorly on the medial fragment, deltoid and pectoralis major on the distal fragment). Show arrows indicating the deforming forces that create the classic displaced midshaft fracture pattern with the medial fragment displaced superiorly and the distal fragment displaced inferiorly.</image>

<image>A comparison diagram of plate fixation options for midshaft clavicle fractures. Left panel: superior plating with a precontoured locking plate on the superior surface of the clavicle — show the plate prominence beneath the skin. Right panel: anteroinferior plating with the plate applied to the anterior-inferior surface — show the lower profile and reduced prominence. Include cross-sectional views at the midshaft showing the plate position relative to the clavicular cortex and subclavicular neurovascular bundle.</image>

<image>A diagram of the Neer classification of lateral clavicle fractures. Show four views of the distal clavicle and coracoclavicular ligaments: Type I (fracture lateral to intact CC ligaments — stable), Type IIA (fracture medial to CC ligaments — both ligaments on distal fragment — unstable medial fragment), Type IIB (conoid torn, trapezoid on distal fragment — unstable), and Type III (intra-articular AC joint fracture). Label the conoid and trapezoid ligaments, acromioclavicular joint, and fracture lines for each type.</image>

## Clinical Pearls

Eighty percent of clavicle fractures occur in the middle third at the narrowest, most vulnerable point. The figure-of-eight bandage offers no benefit over a simple sling and should not be recommended. The COTS trial showed superior outcomes with plating for displaced midshaft fractures, but the evidence pendulum has moderated and not all displaced fractures require surgery. Shortening greater than 2 cm is associated with shoulder dysfunction and higher nonunion rates and should prompt consideration of surgery. Neer Type II lateral clavicle fractures have high nonunion rates with nonoperative treatment and fixation should be strongly considered. Hardware removal rates after clavicle plating are high (10-40%), and patients should be counseled preoperatively about the potential need for a second surgery. Anteroinferior plating is gaining popularity over superior plating due to less hardware prominence and comparable biomechanical performance. A chest radiograph should always be obtained after clavicle fixation to rule out pneumothorax from posterior cortex screw penetration.

## References

- Canadian Orthopaedic Trauma Society. Nonoperative treatment compared with plate fixation of displaced midshaft clavicular fractures. *J Bone Joint Surg Am*. 2007;89(1):1-10.
- Robinson CM. Fractures of the clavicle in the adult: epidemiology and classification. *J Bone Joint Surg Br*. 1998;80(3):476-484.
- McKee MD, et al. Deficits following nonoperative treatment of displaced midshaft clavicular fractures. *J Bone Joint Surg Am*. 2006;88(1):35-40.
- Neer CS 2nd. Fractures of the distal third of the clavicle. *Clin Orthop Relat Res*. 1968;58:43-50.
- Woltz S, et al. Plate fixation compared with nonoperative treatment for displaced midshaft clavicular fractures: a meta-analysis. *J Bone Joint Surg Am*. 2017;99(12):1051-1057.