The clavicle, or collarbone, is a bone that is a part of the shoulder girdle. It serves as a solid support to the arm. It is essential for full range movement of the arm because it holds the arm away from the chest. The clavicle also forms the upper part of the canal (“thoracic outlet”) between the neck and the arm through which several important blood vessels and nerves run. Finally, it transmits the force of an impact on the arm to the body. The latter partly explains why it is such a commonly fractured bone – a fall onto the outstretched arm could lead to a fracture of the clavicle. The clavicle is connected to the shoulder blade and the breast bone with strong ligaments.
The clavicle is prone to fracture because of its very superficial localisation. A fall onto the arm, a lateral blow or a direct impact over the clavicle can cause a fracture. It is a very common injury and accounts for approximately 5% to 10% of all fractures in adults. The middle third of the clavicle is the weakest point where it is most commonly fractured, while the lateral third of the clavicle is fractured in about 15% of all clavicle fracture cases. These lateral clavicle fractures are often associated with a rupture of the ligaments between the clavicle and the shoulder blade.
Clavicle fractures are most commonly treated non-operatively – the arm needs to be kept in a sling for 4 to 6 weeks. Of historic importance was the use of “figure of 8” bandages to try and reduce and immobilise the clavicle but they are not used any longer due to the extreme discomfort caused by those bandages and their relative ineffectiveness. Any associated pain needs to be managed during the healing process. It takes 6 to 8 weeks before solid healing is obtained. Initially the fracture zone will be filled with a cartilaginous callus (clot). Later on this callus will be replaced by a bony callus, which will then remodel to the native form of the clavicle.
The callus is often visible and palpable because of the superficial position of the clavicle. Once the callus is strong enough, one will be advised to start with a home based exercise programme. Initially passive mobilisation will be allowed. In the next weeks an increase of the intensity of the exercises and active exercises can be done.
It is important to realise that the displacement of the fracture fragments will not improve after healing has taken place, therefore it is important to make a decision about surgery within the first few days after the injury.
Once healing has taken place heavy activities and sport, where falls and other blows could be expected, the clavicle could still refracture at the previous point of fracture and one should wait for about 2- 3 months before such activities are embarked upon.
On the other hand, surgical treatment is an option. It allows for an earlier start of activities. Fracture pain is also diminished by fixing the fracture. Indications for surgery are:
- A significant shortening of the clavicle (1,5 cm and more)
- Severe angulation,
- Skin penetration,
- Associated nerve or vascular trauma,
- Non-union of the fracture: if no healing of occurs after several months
Different methods of fixation of these fractures exist but plate and screw fixation is most commonly used. This method has stood the test of time and allows for early mobilisation of the shoulder and has a high success rate. A skin incision of several centimetres needs to be made over the collar bone but an expert surgeon can place the incision in a position where it would cause the best looking scar.
The plate can remain on the clavicle permanently but removal could be considered for two reasons:
- In some (especially thin individuals) the plate may be prominent and cause irritiation of the skin
- In sports where falls on to the shoulder can be expected (e.g. mountain biking and motorcycle racing) a repeat fall could fracture the clavicle again. The problem is that the repeat fracture usually does not occur through the previous site but medial (on the side of the breast bone) to the plate, which is a dangerous area close to the large blood vessels and nerves. In such cases the plates are most often removed after 6 to 9 months.
The most common are non-union (the fracture does not heal) and infection. These complications do not occur frequently but have to be regarded due to the fact that the clavicle is a bone which is very superficial under the skin
These are “intra-medullary” methods where small rods are placed inside the shaft of the clavicle. The advantages of these are that the skin incision and resulting scar are much smaller than for the plates. The two most commonly used devices are:
- Haggie pins
- Sonoma rods
The union rate of these fractures is very high. However, there is always the risk for non-union (the fracture not healing). In the clavicle non-union rates are from 0,1% up to 15%. Predisposing factors for non-union are skin perforation by the bone, the association of other lesions, mobilisation being too early and aggressively and smoking. Smoking increases the risk for non-union because of its known negative influence on fracture healing.
If a non-union is present, whether there was previous conservative or operative treatment, the best management is surgery: stabilisation with plate and screws and inserting bone stimulating substances (BMP), either commercially available or by harvesting bone from the hip bone (iliac crest). The rehabilitation is the same as for initial surgery.