The clavicle is an elongated, S-shaped bone that rests horizontally at the sternum across the upper part of the ribcage, and the acromial end of the scapula. This bone is an important part of the skeletal system since it plays an essential role in everyday functional movement, serving as the connection between the axial skeleton and the pectoral girdle.
The clavicle (collarbone) extends between the manubrium of the sternum and the acromion of the scapula. It is classed as a long bone and can be palpated along its length. In thin individuals, it is visible under the skin. The clavicle attaches the upper limb to the trunk as part of the ‘shoulder girdle, Protects the underlying neurovascular structures supplying the upper limb, Transmits force from the upper limb to the axial skeleton.
The clavicle acts to transmit forces from the upper limb to the axial skeleton. Given its relative size, this leaves it particularly susceptible to fracture. The most common mechanism of injury is a fall onto the shoulder or onto an outstretched hand.
Although classified as a long bone, the clavicle (in most cases) does not have a medullary cavity like its long bone counterparts. Previous studies have shown periosteal arterial blood supply to the bony structure but no central nutrient artery. The suprascapular artery, thoraco-acromial artery and the internal thoracic artery have all been found to provide arterial supply to the clavicle.
Controversy surrounds the primary sensory innervation of the clavicle. Anesthetizing studies following clavicular fracture have suggested there may be involvement individually or in a combination of the supraclavicular nerve, subclavian nerve and long thoracic/suprascapular nerve. A common anatomical variation is a perforating branch of the supraclavicular nerve that passes in the superior surface of the clavicle. Post-mortem studies have revealed insertion of the nerve in bony tunnels or grooves that would prove susceptible to injury and may explain entrapment neuropathy following clavicular fracture.
Clavicle fracture is a common fracture at all age groups. It usually results from a fall on the shoulder or sometimes on an outstretched hand. The junction of the middle and outer-third of the clavicle is the commonest site, the other common site being the outer-third of the clavicle. This fracture is usually displaced. The outer fragment displaces medially and downwards because of the gravity and pulls by the pectoralis major muscle attached to it. The inner fragment displaces upwards because of the pull by the sternocleidomastoid muscle attached to it.
Diagnosis is simple in most cases. There is a history of trauma followed by pain, swelling, crepitus at the site of fracture; one must look for any evidence of neurovascular deficit in the distal limb. The diagnosis can be confirmed on an X-ray.
Fractures of the clavicle unite readily even if displaced; hence reduction of the fragment is not essential. A trimgalar sling is sufficient in cases with minimum displacement. Active shoulder exercises should be started as soon as the initial severe pain subsides, usually 10-14 days after the injury. A figure of bandage may be applied to a young adult with a displaced fracture. It serves the purpose of immobilization, and gives pain relief. Open reduction and internal fixation is required, either when the fracture is associated with neurovascular deficit, or in some severely displaced fractures, where it may be more of a cosmetic concern. In such cases, the fracture is fixed internally with a plate or a nail.
Early complications: The fractured fragment may injure the subclavian vessels or brachial plexus.Late complications: Shoulder stiffness is a common complication, especially in elderly patients. It can be prevented by shoulder mobilization as soon as the patient becomes pain free. Malunion and non-union (the latter being very rare) often cause no functional disability and need no treatment. Rarely, for a painful non-union of the clavicle, open reduction and internal fixation with bone grafting may be necessary.