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Collar Bone

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What is a Collarbone?

IVSAT 2024

The clavicle, also known as the beauty bone or collarbone, is a long, slender S-shaped bone that serves as a connector between the shoulder blade and the sternum (breastbone). There are two clavicles - one on the left and one on the right. The clavicle is the body's only horizontally oriented long bone. The shoulder girdle is made up of a clavicle and the shoulder blade. It's a touchable bone, and in those with less fat in this area, the placement of the bone is obvious since it causes a bulge in the skin.


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Since the bone rotates along its axis like a key when the shoulder is abducted, it gets its name from the Latin clavicula meaning “small key.” The most frequently fractured bone is the clavicle. Impacts to the shoulder from the power of falling on outstretched arms or a direct contact can easily fracture the collarbone. Due to its prominent location on the body, the clavicle, or collarbone, is often known as the "beauty bone." It is the only long bone in the body that is horizontal. Because of its unusual anterior and posterior curvatures, the clavicle has an elongated 'S' shape.


Structure of Collarbone

The collarbone is a long, thin, double-curved bone that joins the arm to the body's trunk. It works as a strut to keep the scapula in place so that the arm can hang freely. It's situated right above the first rib. It articulates with the manubrium of the sternum (breastbone) at its rounded medial end at the sternoclavicular joint (sternal end). The bone articulates with the acromion, a projection of the scapula (shoulder blade), at its flattened lateral end at the acromioclavicular joint (acromial end).


The rounded medial section of the shaft (sternal region) has a long lateral and anterior curve that runs the length of two-thirds of the shaft. The shaft's flattened lateral section (acromial region) has a greater posterior curvature to articulate with the scapula's acromion. The medial part of the clavicle is the longest, taking up two-thirds of the shaft. The lateral area is the clavicular region that is both the widest and the thinnest. A rough inferior surface bears a ridge, the trapezoid line, and a little rounded projection, the conoid tubercle, on the lateral end (above the coracoid process). These surface structures serve as attachment points for shoulder muscles and ligaments. The collarbone has three parts: a medial end, a lateral end, and a shaft.


Medial End

The sternal end is often referred to as the medial end. The sternoclavicular joint is formed by articulating with the clavicular notch of the manubrium of the sternum. For articulation with the first costal cartilage, the articular surface extends to the inferior aspect.


Lateral End

The lateral end is also known by other names like the acromial end. From the top to the bottom, it is completely flat. The acromioclavicular joint is formed by a facet that articulates with the shoulder bones. The joint capsule is attached to the area surrounding the joint. The anterior border is concave in the forward direction and convex in the backward direction.


Shaft

The medial and lateral parts of the shaft are separated into two sections. The sternal region, also known as the medial region, is the clavicular region with the most length, accounting for around two-thirds of the shaft's length. The lateral region, also known as the acromial region, is the clavicular region that is both the widest and the thinnest.


Functions of the Collar Bone 

The collarbone serves several functions, including:


  • It serves as a rigid support from which the scapula and free limb are hanging; this position keeps the upper limb away from the thorax and allows the arm to move freely. It acts as a flexible crane-like strut that permits the scapula to move freely on the thoracic wall.

  • It protects the upper limb's neurovascular bundle by covering the cervicoaxillary canal.

  • Physical impacts from the upper limb are transmitted to the axial bone.


How is Collarbone Fracture Caused?

Clavicle fractures (sometimes known as broken collarbone) are caused by trauma or injury. When a person falls horizontally on their shoulder or with an outstretched hand, the most common type of fracture occurs. A direct strike to the collarbone might also potentially result in a fracture. The direct strike usually occurs from the lateral side of the bone to the medial side. The weakest part of the bone, the junction between the two curvatures, is the most common site of fracture. As a result, the sternocleidomastoid muscle elevates the medial portion superiorly, potentially causing perforation of the overlying skin.


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Collarbone Fracture Treatment

Pain may be treated with medication. It's uncertain if surgery or conservative treatment is better. If the bone bursts through the skin, antibiotics and tetanus immunisation may be given, but this is uncommon. They are frequently treated without surgery. In extreme cases, surgery may be required.


Non-Operative Treatment

An external immobiliser is frequently used to maintain the joint stable and reduce the risk of additional injury. The figure-of-eight splint, which wraps across the shoulders to keep them pressed back, and a simple broad arm sling are the two most prevalent methods of fixation (which supports the weight of the arm). The major indication is to alleviate discomfort. In terms of healing, the type of sling employed appears to have no effect, however, patient satisfaction is lower with the figure-of-eight bandage. There is no difference in functional outcomes between the two methods of immobilisation.


The current standard of care for small fractures with minor displacement is to provide a sling, and pain treatment while allowing the bone to heal on its own, with X-rays taken every week or a few weeks if necessary. Surgery is used in about 5–10% of instances. However, a meta-analysis of 2 144 midshaft clavicle fractures suggests that totally displaced midshaft clavicular fractures in active adult patients should be treated with primary plate fixation. The risk of nonunion is higher if the fracture is on the lateral end than if it is on the shaft.


Surgical

In children, with clavicle breaks in the middle, surgery resulted in a faster recovery but greater problems. As of 2015, the evidence for various forms of surgery for breaks in the central section of the clavicle was weak.


Surgery may be considered when one or more of the following is present:


  • Separation and comminution (bone is broken into multiple pieces)

  • Skin penetration (open fracture)

  • Trauma to the neurological and vascular systems (brachial plexus or supraclavicular nerves)

  • Nonunion after several months (3–6 months, typically)

  • Displaced distal third fractures (high risk of nonunion)

  • Although shortening (due to overlap of fracture ends) has been cited as a reason for surgery, research indicated that persons who were treated without surgery for midshaft clavicle fractures had no adverse effects.


A clavicular fracture often results in a discontinuity in the bone formation that is apparent through the skin if it is not repaired with surgery. Surgical methods are frequently required for open reduction internal (plate) fixation, which involves screwing an anatomically shaped titanium or steel plate to the superior part of the bone. Due to pain, the plate is sometimes removed after healing to avoid tissue aggravation, osteolysis, or subacromial impingement. This is especially true for a form of fixing plate known as a hook plate. Anatomical plate removal is considered an elective treatment that is rarely required. Elastic TEN intramedullary nailing is an alternative to plate fixation. These implants are inserted into the clavicle's canal to provide internal support for the bone. Infection, neurological problems distal to the incision (often to the extremity), and nonunion of the bone are all common surgical consequences (failure of the bone to properly fuse together).


Did You Know?

Are you aware that the collarbone pain is heart-related? In some cases, the collar bone pain may be a symptom of a serious or life-threatening condition that should be immediately evaluated in an emergency setting. Pain that extends from the chest up to the shoulder, usually on the left side, is a symptom of a heart attack.

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FAQs on Collar Bone

1. What are the two prominent features of clavicle bone?

The ends of the clavicle bone can be used to determine its orientation: a broad, flat acromial end (also known as the lateral third); and a round pyramidal-like sternal end (referred to as the medial two-thirds). Depending on whether the superior or inferior surface of the bone is examined, each end has its own bony markers.

2. How long does it take for a clavicle fracture treatment?

A clavicle fracture, also known as broken collar bone, is a common injury. It is usually caused by a fall or a direct strike to the shoulder. Adults recover in 6 to 8 weeks, whereas children recover in 3 to 6 weeks.


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