The distal clavicle, the lateral portion of the collarbone, plays a crucial role in shoulder stability and function. Injuries to this area are common, especially in athletes, manual laborers, and individuals involved in falls or direct trauma to the shoulder. Proper classification of distal clavicle fractures is essential for guiding management and predicting outcomes. Among various classification systems, the Neer classification remains widely used due to its practical approach in describing fracture patterns, displacement, and involvement of the coracoclavicular ligaments. Understanding the Neer classification allows clinicians to make informed decisions about conservative versus surgical management and helps in prognostic evaluation.
Anatomy of the Distal Clavicle
The distal clavicle is the lateral segment of the collarbone, articulating with the acromion to form the acromioclavicular (AC) joint. It is stabilized by several ligaments, including the acromioclavicular ligaments and the coracoclavicular ligaments, which consist of the conoid and trapezoid ligaments. These ligaments play a pivotal role in maintaining vertical and horizontal stability. Fractures in this region can disrupt ligament integrity, resulting in variable displacement patterns that are critical to classify accurately for treatment planning.
Overview of Neer Classification
The Neer classification, introduced by Charles S. Neer in 1963, categorizes distal clavicle fractures based on the location of the fracture relative to the coracoclavicular ligaments and the AC joint. This system is particularly valuable because it correlates fracture pattern with potential instability and the likelihood of nonunion. The classification primarily identifies three main types of fractures and subtypes, focusing on the relationship between the fracture fragments and the coracoclavicular ligament attachments.
Type I Fractures – Minimal Displacement
Type I fractures occur lateral to the coracoclavicular ligaments. The ligaments remain intact, maintaining stability between the proximal and distal fragments. These fractures typically show minimal displacement due to ligamentous support. Radiographs reveal a fracture near the distal end of the clavicle without significant vertical separation. Type I fractures are usually managed conservatively with immobilization using a sling or figure-of-eight bandage, allowing natural healing while maintaining function.
Type II Fractures – Displaced Fractures
Type II fractures are further subdivided into Type IIA and Type IIB, depending on the involvement of the conoid and trapezoid ligaments
- Type IIAThe fracture occurs medial to both the conoid and trapezoid ligaments. Both ligaments remain attached to the distal fragment, but the medial fragment may displace superiorly. These fractures are prone to displacement due to the weight of the arm and muscle forces.
- Type IIBThe fracture occurs between the conoid and trapezoid ligaments. The conoid ligament remains attached to the medial fragment, while the distal fragment remains with the trapezoid ligament. This results in significant displacement and potential instability, increasing the risk of nonunion.
Type II fractures often require surgical intervention, particularly when displacement is substantial or the patient demands early functional recovery, such as athletes or manual laborers. Options include open reduction and internal fixation using plates, screws, or suture-button constructs.
Type III Fractures – Intra-Articular Extension
Type III fractures extend into the acromioclavicular joint, involving the articular surface of the distal clavicle. The coracoclavicular ligaments generally remain intact, maintaining vertical stability, but joint congruity is disrupted. These fractures may be associated with osteoarthritis over time if not properly reduced. Management often depends on the degree of displacement and the patient’s activity level. Non-displaced Type III fractures can be treated conservatively, while displaced cases may require surgical fixation to restore joint alignment and prevent long-term dysfunction.
Type IV and Type V Fractures
Although less commonly discussed, some modern adaptations of the Neer classification include Type IV and Type V fractures
- Type IVPediatric periosteal sleeve fractures of the distal clavicle, often seen in children due to the unique anatomy of the developing clavicle.
- Type VComminuted fractures with severe displacement, sometimes considered unstable variants of Type II fractures, frequently requiring surgical intervention.
Radiological Evaluation
Accurate radiographic assessment is crucial in applying the Neer classification. Standard imaging includes
- Anteroposterior (AP) viewProvides general alignment and fracture location.
- Cephalad tilt or Zanca viewOffers better visualization of distal clavicle fractures and AC joint involvement.
- CT scansUseful in complex or comminuted fractures for precise evaluation and preoperative planning.
Radiographs help identify fracture type, displacement, and ligamentous involvement, allowing clinicians to categorize the fracture accurately according to Neer criteria. Misclassification can result in inappropriate treatment and higher rates of nonunion or malunion.
Clinical Implications
Understanding the Neer classification is critical because it directly influences treatment decisions. Type I fractures, being stable, generally heal well with nonoperative management. Type II fractures, particularly Type IIB, are prone to displacement and nonunion if managed conservatively. Surgical fixation is often recommended to restore anatomical alignment, maintain shoulder function, and prevent long-term complications. Type III fractures require careful assessment of joint involvement, and surgical management may be indicated for displaced intra-articular fractures to prevent post-traumatic arthritis.
Management Strategies Based on Neer Classification
Non-Surgical Management
Non-displaced and stable fractures, primarily Type I and selected Type III fractures, are treated conservatively. Key aspects of conservative management include
- Immobilization using a sling or figure-of-eight bandage for 3-6 weeks.
- Pain control with analgesics or anti-inflammatory medications.
- Gradual mobilization after initial immobilization to restore range of motion and prevent stiffness.
Surgical Management
Indications for surgical treatment include unstable or displaced Type II fractures, displaced Type III fractures, and fractures in active individuals requiring early return to function. Surgical options include
- Open reduction and internal fixation using precontoured distal clavicle plates.
- Intramedullary fixation or tension band wiring for selected cases.
- Coracoclavicular ligament reconstruction in cases of severe displacement or chronic instability.
Prognosis and Outcomes
Prognosis depends on fracture type, displacement, and treatment approach. Stable fractures generally heal well with conservative management, with minimal functional impairment. Unstable fractures that are inadequately managed may result in nonunion, chronic pain, or shoulder dysfunction. Surgical intervention, particularly for Type II fractures, yields high rates of fracture union and restoration of shoulder function. Radiographic follow-up is essential to monitor healing and detect potential complications early.
The Neer classification of distal clavicle fractures provides a practical framework for understanding fracture patterns, ligamentous involvement, and potential instability. Accurate classification is essential for guiding management decisions, whether conservative or surgical, and predicting outcomes. Radiological evaluation, including AP and Zanca views, as well as CT imaging for complex cases, plays a pivotal role in identifying fracture type and planning treatment. Clinicians should recognize the clinical significance of each fracture type to ensure optimal patient outcomes, minimize complications, and restore shoulder function effectively. Understanding the Neer classification is a cornerstone in the management of distal clavicle fractures, offering a standardized approach that enhances communication, treatment planning, and prognostic assessment.