Overview of the Clavicle and Its Importance
The clavicle, commonly called the collarbone, is a long bone that connects the sternum (breastbone) to the scapula (shoulder blade). It plays a critical role in shoulder function, upper limb positioning, and protection of underlying neurovascular structures. Positioned just above the first rib, it forms the anterior connection of the upper limb to the axial skeleton. Because it lies subcutaneous, it is both palpable and prone to injury. Understanding its anatomy, biomechanics, and typical pathologies helps explain symptoms, guide treatment, and set realistic expectations for recovery.
Anatomy and Biomechanics of the Clavicle
Bony Structure and Landmarks
The clavicle has an S-shaped curvature that allows it to serve as a strut between the trunk and the shoulder. It is divided into three main regions: the medial (sternal) third, the lateral (acromial) third, and the intermediate (shaft) third. The medial end articulates with the manubrium of the sternum at the sternoclavicular (SC) joint, which is the only bony connection between the upper limb and the trunk. The lateral end articulates with the acromion of the scapula at the acromioclavicular (AC) joint. The shaft provides attachment sites for multiple muscles and ligaments, including the deltoid, trapezius, pectoralis major, and various shoulder stabilizers.
Function and Movement Roles
The clavicle stabilizes the shoulder girdle and transmits forces from the upper limb to the axial skeleton. During arm elevation, it rotates and elevates at the SC joint, allowing greater overhead reach. It also protects the brachial plexus and subclavian vessels that lie deep to it. Because it is a load-bearing bone, repetitive stress or acute trauma can lead to fractures, ligament sprains, or degenerative changes. Its biomechanics make it susceptible to injury in falls, contact sports, and high-impact activities.
Common Injuries and Conditions
Clavicle Fractures
Clavicle fractures are among the most common shoulder girdle injuries, often occurring from a direct fall onto the shoulder or an outstretched hand. They account for approximately 2–5% of all adult fractures. Most fractures occur in the midshaft region due to the bone’s natural curvature and relative weakness. In younger individuals, high-energy trauma such as motorcycle or skiing accidents can cause comminuted or displaced fractures. In older adults, lower-energy falls may still result in complete fractures, particularly in individuals with reduced bone density.
AC Joint Injuries and Degeneration
- AC joint separations range from mild ligament sprains (Type I) to complete ligament ruptures with joint dislocation (Type VI), often graded by the Rockwood classification.
- Chronic overuse or aging can lead to AC joint arthritis, causing anterior shoulder pain and tenderness at the top of the shoulder.
- Repetitive overhead activities may contribute to distal clavicle osteolysis, especially in weightlifters or manual laborers.
Diagnosis and Clinical Evaluation
Diagnosis typically begins with a focused history and physical examination, noting mechanism of injury, location of tenderness, and range of motion. Imaging is often required to confirm the diagnosis and guide management. Plain radiographs are usually the first step, including an anteroposterior (AP) view, and sometimes Zanca or axillary views to better visualize the AC joint. In select cases, computed tomography (CT) or magnetic resonance imaging (MRI) may be used to assess complex fractures, ligamentous injuries, or occult pathology. Clinical judgment remains essential to avoid overimaging while ensuring important injuries are not missed.
Treatment Approaches and Recovery
Nonoperative Management
Nonoperative treatment is commonly used for nondisplaced or moderately displaced midshaft clavicle fractures. It typically includes immobilization with a sling or figure-of-eight brace for comfort, early gentle range-of-motion exercises, and progressive strengthening as healing advances. Pain control, education, and scheduled follow-up are key components. Most patients achieve satisfactory function without surgery, though some may have persistent deformity or ache. Indications for surgery generally include severe displacement, skin tenting, neurovascular compromise, or associated injuries.