The collarbone (clavicle) helps connect the upper limb to the trunk. The inner end of the clavicle, close to the center of the chest, rests on the sternum through the sternoclavicular (SC) joint. What an interesting joint! It needs to have stout, strong ligaments to serve as a stable connection between the limb and the trunk. And at the same time, the clavicle moves a lot in reference to the sternum with active use of the limb: it tilts and rotates in multiple directions. Accidents may result in ligament tears (or even fractures through growth cartilage or bone) that will leave the inner portion of the clavicle dislocated in the front or the back. Surgery for these injuries can actually be dangerous, you know why? Because the inner end of the clavicle is very close to vital structures, in particular blood vessels that if torn by accident at the time of surgery can lead to some serious bleeding. Safety is first with any surgery, but particularly with procedures around the SC joint…
My SC joint looks swollen and deformed, why?
If you had an accident, and the inner portion of your collarbone looks very different on one side, chances are you injured your SC joint. During human development, bones grow in length through cartilage. In most individuals, the growth cartilage on the inner end of the collarbone does not completely fuse until the age of 25. Thus, in teenagers SC joint injuries may occur through cartilage, which complicates the diagnosis because cartilage does not show on radiographs. In adults, SC injuries typically result in ligament tearing and dislocation of the SC joint.
Depending on the nature of the injury, the inner end of the collarbone may end out of place in the front or the back; in Medicine, front is called anterior, and back is called posterior. The implications of these two injuries are very different. Anterior SCJ dislocations are very visible (cosmetically unappealing) and may lead to residual pain and poor function, but posterior ACJ dislocations may additionally lead to compression of vital structures in the chest, especially blood vessels and vital structures located at the throat area.
Some individuals will develop an SCJ dislocation without a major injury because their soft tissues are excessively elastic. This is due to abnormalities in the fine threads that form the matrix of the soft-tissues: the collagen molecules. Ehlers-Danlos syndrome and other generalized hypermobility syndromes are examples of these conditions. Not uncommonly, these patients can demonstrate both collarbones moving in and out of place with movement of the limb in different directions.
However, not every SC joint that looks swollen or deformed has sustained a dislocation or fracture. Swelling may also occur when arthritis develops (osteoarthritis, rheumatoid, and others). The SC joint may also become infected with bacteria. Very rarely, swelling is created by the development of a tumor.
Good assessment of the SC joint really needs advanced imaging…
Radiographs are the most useful test for the majority of problems assessed by shoulder specialists. However, the inner end of the collarbone is particularly difficult to evaluate on radiographs due to the overlap of ribs, sternum, the lungs and other structures within the chest. Computed tomography (CT) provides a series of multiple small radiographic images in three planes, which allows better assessment of the SC joints. In addition, software packages can render a three-dimensional reconstruction of the sternum and collarbones that may be rotated in space. When injuries to the blood vessels behind the collarbone may have occurred, a liquid contrast may be injected in a vein in the forearm (same site used for blood tests or to donate blood) just before obtaining the CT; the shapes of the vessels may then be visualized behind the bones as contrast flows through them. This test is called CT angiogram, and is recommended in the majority of posterior SC joint dislocations. When an injury through the growth cartilage is suspected in a child or teenager, magnetic resonance (MR) may be better than CT, since MR is best to visualize cartilage.
Pain, deformity, what else?
In some individuals with anterior dislocation of one SC joint, the only complaint is cosmetic: the dislocated joint is unsightly, but there is no major pain, especially in individuals with disorders of the collagen molecules and spontaneous instability. However, many individuals with a dislocated SC joint do complain of pain, to the point that some activities may become impossible to perform. Occasionally, most of the pain is around the shoulder blade: loss of the support provided by the clavicle will lead to overcompensation by the muscles around the shoulder blade (shoulder specialists call this phenomenon “secondary scapular dyskinesis” (scapula = shoulder blade; dys-kynesis = poor-motion). Some individuals may complain of additional problems, especially when there is a posterior dislocation, a fracture dislocation, or substantial arthritic enlargement of the inner end of the clavicle: difficulty with swallowing or breathing, a hoarse voice, or even occasional fainting.
What are the treatment options?
Well, that depends… Posterior dislocations are considered dangerous if left alone, whereas anterior dislocations may provoke little pain or dysfunction. As a general rule, replacing the collarbone in place (closed reduction) is recommended for posterior dislocations, and it is best performed under anesthesia. Movement of the arm under anesthesia in specific directions may suffice, but not uncommonly it is necessary to grasp the dislocated medial clavicle with a metal clip through the skin in order to relocate it forward. Interestingly, most of the times the clavicle stays in good position once reduced. If the clavicle dislocates again to the back, surgery is required to reposition the collarbone in place and repair the torn ligaments (or fix the cartilage or bone if fractured).
Many shoulder specialists also recommend closed reduction for anterior dislocations: under anesthesia, the arm is pulled forward while pressure is placed on the medial end of the clavicle to pop it back into place. However, in many individuals the clavicle will not want to stay located and will pop forward again; in these circumstances, since anterior dislocations may be well tolerated, surgery is oftentimes not performed with the hopes that discomfort will be minimal after a few weeks; injuries through cartilage would be an exception, since they seem to heal very reliably with surgery.
What if the injury was missed or becomes a problem later?
Chronic conditions of the SC joint may benefit from surgery. This may include individuals that suffered a dislocation that was never relocated, as well as patients with arthritis or rarely infection (in which case antibiotics would be required as well). As mentioned before, evaluation prior to surgery will likely include a computed tomography with three-dimensional reconstruction, supplemented with angiography when the proximity of the blood vessels needs to be assessed (common in posterior injuries).
If your dislocated SCJ continues to bother you, surgery would entail reconstruction of the joint ligaments, since in the chronic setting ligament repair does not seem to heal strong enough. A tendon (typically from a tissue donor, sometimes from your own body) is connected to the sternum and clavicle to create new ligaments (tendon graft reconstruction). In patients with arthritis or infection, the diseased inner end of the clavicle is removed, and removal of a small amount of clavicle typically is needed in chronic dislocations as well. There are multiple ways to reconstruct the SC joint. A procedure commonly quoted is the “Figure of 8” procedure. We have developed and prefer the “sternal docking technique”.
In the sternal docking technique, tunnels are created in the clavicle and sternum. A tendon graft from a donor is then weaved through these tunnels in a very specific fashion and secured to itself.
What to expect afterwards…
After surgery, patients are recommended to use a shoulder immobilizer for 6 weeks. So-called isometric strengthening exercises for the shoulder blade may commence right away. Formal shoulder therapy starts at week 6 and continues for 3-4 months. Remember that the collarbone is right under the skin; even if surgery is successful in restoring joint stability, the area around the joint may look swollen for a long time, and of course the scar after surgery is in a very visible place. For these reasons, it is important to think twice before considering surgery just for cosmetic reasons.