Joshua is a Sports Medicine and Athletic Training Instructor and has a Master's degree in Kinesiology.
An Uncommon Shoulder Injury
John, a football player, takes a direct hit to the front of his right shoulder by a defender's helmet during a recent game. He falls to the ground and immediately feels pain at the upper portion of his chest and the top of his right shoulder. After getting himself up to his feet, he notices that he can't move his right arm very well above his elbow.
The team's medical staff evaluates John's chest and shoulder area and notices that there is an obvious deformity in the area of his right sternoclavicular joint that appears to be the clavicle raised up higher than normal. The pain is very intense and John has lost a great deal of movement in his upper arm. John is placed in an arm sling to stabilize his arm and allow the area to begin the healing process. X-rays were taken to confirm that John has an anterior sternoclavicular joint dislocation.
A joint is the articulation, or connection point, between two or more bones that are held together by a single ligament or group of ligaments. A dislocation is a disruption of the joint whereby one or more of the bones loses its connection point with the other bone, usually resulting from the ligament structures being completely torn and creating an unstable structure. In this lesson, we will discuss one particular joint that is designed to ensure stability and movement for the shoulder and chest area, the sternoclavicular joint, or SC joint for short, and look at what a dislocation to this joint involves.
The SC joint is named for the two bones that come together to create this joint, the sternum and the clavicle. The sternum is a flat bone located in the upper center of the chest. The clavicle is a long bone that is curved like an s-shape and connects to the sternum on one end and a prominent projection located at the top of your shoulder at the other end known as the acromion.
The SC joint is known as a plane type synovial joint, sometimes referred to as a saddle type joint. This plane joint allows for forward and backward movements and a small amount of movement towards and away from the body. The stability of this joint is crucial to the trunk as it is the only connection point of the upper limb to the front torso area.
Symptoms & Diagnosis
Symptoms of a dislocation will usually involve moderate to severe pain and edema, the medical term for swelling. In this case, a visible deformity and associated loss of movement of the upper arm is also common. The diagnosis of this injury usually involves taking a brief history of the patient's actions up to the point of injury to try and determine the mechanism or how it happened.
A visible observation determines if there is an obvious deformity as most SC joint dislocations will result in an apparent abnormality. The next step can involve palpation, or touching the area to determine which structure might cause pain and to feel for deformities. In many cases, if a dislocation is suspected, diagnostic testing can be completed in the form of a radiograph, commonly known as an x-ray, or an MRI (magnetic resonance imaging); this will determine the certainty and severity of the injury. A dislocation of the SC joint can either occur to the front, known as anterior, or to the back, known as posterior.
With an anterior sternoclavicular dislocation, the clavicle loses its connection point, sticking out from the body. If the joint suffers a direct hit then a posterior sternoclavicular dislocation may result as the clavicle will be displaced towards the body. In some cases, a visible deformity may be harder to diagnosis with a posterior dislocation compared with an anterior dislocation due to the nature of the clavicle sitting further back behind the skin.
Unlike a dislocation which is rare, the most common injury to the SC joint is known as a sprain, which means there is stretching or tearing to the ligaments that connect the bones together in the joint. Usually a sprain or even a fracture to the clavicle or sternum is more likely to occur before this joint is dislocated.
The most common way this injury happens is by direct blunt force to the area, and in some less common instances from indirect compression on the joint through the humerus, or upper arm bone. A sternoclavicular dislocation will mirror similar symptoms to a severe grade 3 sprain which would result in severe pain, edema, and loss of function. The rupture of the ligaments involved that also hold the joint in place is what causes the instability that leads to a joint dislocation.
In some cases, this injury would require surgery in order to reconstruct the ligament structures that were torn; sometimes it involves taking other tendon structures from another area of the body to replace and secure the original structure. However, in many cases, the clavicle can be re-set to its original position, and the ligament structures will create scar tissue to repair itself. Scar tissue is the body's way of replacing damaged tissue with new connective tissue.
In this lesson, we discussed the sternoclavicular joint and the dislocation injury associated with it. Symptoms for this injury can include pain, edema, deformity, and dysfunction. A dislocation diagnosis can be completed through patient medical history, observation, palpation and diagnostic testing.
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