Clavicle—introduction
Introduction
Incidence
Fractures of the clavicle are common and occur most frequently in the middle third of the bone (76–82%) and less often in the lateral (12–21%) or medial (3–6%) thirds. The most common causes of injury are sports activities and motor vehicle accidents.
Current methods of treatment
Most clavicular fractures heal with conservative treatment which usually consists of an arm sling or figure-of-eight strapping for 4–6 weeks. Some degree of malunion may result but these are often minor and are well tolerated with little compromise to overall function.
Accepted indications for primary stabilization of clavicular fractures are:
Open fractures
Associated neurovascular injury
Tenting of the skin with impending penetration by a sharp bone spike
Associated with ipsilateral fractures of the scapular neck or proximal humerus resulting in instability
Widely separated fractures
There are many implants available for fixation of clavicular fractures, including:
Different types of intramedullary pins
Dynamic compression plate (DCP) or limited contact dynamic compression plate (LC-DCP) 3.5
Reconstruction plate 3.5
Locking compression plate (LCP) 3.5
LCP reconstruction plate 3.5
The reconstruction plate 3.5 is particularly suitable for use in clavicular fractures because it allows for accurate contouring—an important requirement in the clavicle due to its peculiar curved anatomy. It can be applied to either its superior or anterior surface. Anterior placement of the plate allows the use of longer screws but carries a higher risk of injury to the brachial plexus, although the risk of vascular injury is significantly reduced.
The LCP reconstruction plate 3.5 has all the advantages of the reconstruction plate 3.5 plus the possibility of the locking head screw (LHS) which imparts angular stability, thus making it more suitable for use in osteoporotic bone. Unlike the application of the LCP in other locations, when used in the clavicle accurate contouring of the plate is recommended to reduce the prominence of the implant subcutaneously. Another measure to reduce plate prominence is to use standard cortex screws to press the plate close to the bone before applying the LHS. However, in tall or heavy patients, using an LCP 3.5 or an anatomical clavicle LCP is stronger and tolerates more stress, preventing deformation of the plate before healing is completed.
Indications and contraindications for MIPO
While there are no definite indications for MIPO of clavicular fractures, suitable cases for MIPO technique include acute injury, and fractures displaced more than 2.5 cm that could not be reduced by closed methods. Comminuted fractures of the middle third with severe displacement are also suitable cases for MIPO. The clavicle is subcutaneous bone with thin soft-tissue coverage so MIPO technique is the recommended technique for fixation.
MIPO should not be attempted in case of severe wound contamination, infection, neurovascular injuries, or non-unions.
A direct approach to the fracture usually causes disruption of the soft tissue attached to the fracture fragment resulting in complications, such as disturbed healing, implant failure, and damage to the cutaneous nerve.
Surgical anatomy
The clavicle lies directly under the skin throughout its length. It is an S-shaped bone, concave anteriorly at its lateral end, and convex anteriorly at its medial end. The cross-sectional anatomy along its lateral to medial course changes from flat to tubular to prismatic. The junction from the flat region to the tubular region is a stress riser and this explains the high incidence of midshaft fractures ( Fig 11.1-1 ).
Plates can be applied over the superior or anterior surface of the clavicle after appropriate plate contouring.
The sternocleidomastoid muscle, which inserts on the medial third of the clavicle, acts as a deforming force and following a fracture it pulls the medial fragment superiorly ( Fig 11.1-2 ). Pushing the shoulder upward helps to reduce the lateral fragment to the medial fragment.
The neurovascular structures, namely the subclavian artery and vein and the brachial plexus, pass from a posterosuperior to posteroinferior direction, between the first rib and the clavicle at the junction of its medial and middle thirds. They are therefore vulnerable in this region during surgery and instrumentation ( Fig 11.1-3 ).
In the middle third or tubular portion, the subclavius muscle and fascia protect the neurovascular structures from the fracture. However, to avoid injury to the neurovascular structures care should be exercised when using sharp instruments in this area.
Preoperative assessment
The general condition of the patient should be assessed preoperatively. The condition of the skin and soft tissue as well as the neurovascular status of the upper limb should be evaluated. Associated injuries and fractures elsewhere in the body should be examined.
Radiological assessment includes AP, caudocranial (45° upward projection or tangential), and craniocaudal (45° downward projection) views of the clavicle, which are useful for assessing the displacement and configuration of the fracture ( Fig 11.1-4 ). A scapular Y-view is taken to determine the relationship between the acromion/coracoid and the scapula. A chest x-ray should also be included.
Operating room setup
Anesthesia
Due to the proximity of the vessels to the middle third of the clavicle there is a risk of subclavian vein penetration during surgery that can create an air embolism, so general anesthesia with positive pressure ventilation is recommended.
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