Synonyms in a broader sense
Acromioclavicular dislocation, acromioclavicular dislocation, acromioclavicular dislocation, clavicle dislocation, Tossy injury, Rockwood injury, clavicle, clavicle, acromion, acromioclavicular dislocation, ACG osteoarthritis
Definition
Acromioclavicular dislocation is a dislocation of the lateral end of the clavicle towards the acromion with injury to the stabilizing capsule-ligament apparatus of the acromioclavicular joint.
Causes
The most common cause of a dislocation of the acromioclavicular joint/shoulder joint is a fall on the shoulder with direct force application to the acromioclavicular joint. Indirect injuries caused by a fall on the outstretched arm are rarer. This often results in a collarbone fracture. A frequent cause of accidents are falls from a bicycle, horse or while skiing.
- Acromion
- Clavicle
- Difference = raised collarbone
Symptoms
A acromioclavicular joint dislocation manifests itself mainly in three symptoms: Typically, an acromioclavicular joint dislocation manifests itself with immediate, shooting pain. The affected person often adopts a relieving posture, since any kind of movement of the shoulder or arm increases the discomfort, such as: For example, turning the arm inwards prevents pain and movement. As a rule, the protective posture involves the arm being bent, held in front of the body and supported by the healthy arm.
The relieving posture immobilizes the acromioclavicular joint (which is also what one would like to achieve, for example, during therapy with a backpack bandage), which leads to a significant reduction in pain. As an immediate measure, the arm can be stabilized with a bandage or sling in front of the abdomen. The consequence of a acromioclavicular dislocation is often a rupture of the capsule in the shoulder area.
It is therefore recommended to also deal with the following topic: Capsule rupture in the shoulder
- Pain directly above the shoulder joint
- Swelling of the shoulder area and
- Gentle posture
- Overhead movements
- Lateral lifting of the arm or
- Arm lift against resistance.
If the acromioclavicular joint dislocation occurs during sport, the pain usually forces the person affected to stop the sporting activity. Exerting pressure on the shoulder region also causes additional pain, so lying on the injured shoulder can be extremely uncomfortable. In the case of an acromioclavicular joint dislocation, the arm can be moved relatively well passively, which means that another person (e.g. the examining doctor) can perform movements with the injured arm and shoulder without the active assistance of the affected person.
This good passive mobility in a acromioclavicular dislocation is an important distinction from a dislocation of the shoulder (dislocation), and passive mobility would also be limited. Active mobility and the movement possibilities of the affected shoulder or arm are usually considerably restricted and can only be performed with great pain. Under certain circumstances, a partial or complete instability of the shoulder can be determined by the acromioclavicular dislocation.
Shortly after the injury, there is usually a swelling that extends to parts of the shoulder and upper arm. Sometimes a bruise (haematoma) is also formed. Cooling with ice can prevent a more severe tissue swelling and thus even greater pain.
Depending on the severity of the injury, not only the symptoms of pain, swelling and relieving posture may occur. In some cases, the collarbone (clavicle) can shift in position due to the acromioclavicular joint dislocation, which can be explained by a tear in the affected ligaments of the acromioclavicular joint. This can be explained by a tear in the affected ligaments of the acromioclavicular joint.
The outer end of the clavicle may protrude upwards and form a bulge under the skin. However, it is only apparently a raised position of the clavicle; actually, a low position of the arm or shoulder joint due to the weight of the arm and gravity is the reason for the protrusion of the clavicle. If all ligament structures are completely torn apart, the full picture of a shoulder joint dislocation exists.
On physical examination, the “piano key phenomenon” is evidence (pathognomonic) for the presence of a complete acromioclavicular dislocation, since the displaced clavicle can be pressed down with the finger like a piano key, but when the pressure is released, it immediately springs back up again. Sometimes it can be heard that the bones rub against each other (crepitation).This usually painful symptom can be masked by shoulder swelling if the elevation of the collarbone is slightly pronounced. The extent of the piano key phenomenon is an indirect indication of the severity of the ligament injury in the case of a shoulder corner joint dislocation.
Due to the very typical symptoms, the diagnosis of a acromioclavicular joint dislocation can often already be suspected. The swelling in the shoulder area, relieving posture and a localized pressure pain over the shoulder joint indicate a rupture of the acromioclavicular joint. As a rule, movements between the upper arm and the shoulder blade cause no pain when the shoulder blade is stabilized.
To confirm the diagnosis, an x-ray examination of the shoulder joint is necessary in addition to the typical symptoms. When the acromioclavicular joint is disrupted, the various ligament structures around the joint and the collarbone often tear as a result of a fall on the shoulder. Depending on how many ligaments are injured and what type of injury is involved, the pain can also vary in intensity.
Especially in the area of the acromioclavicular joint at the outer end of the collarbone, strong pain occurs, which can then also radiate into the arm. Often the pain is already so severe that the patient is no longer able to move the shoulder or arm. Often, even the mere hanging of the arm hurts a lot, which is why patients usually support the shoulder in the other hand.
In addition, swelling can also occur around the shoulder area and the shoulder is very sensitive to pressure. A further typical symptom of a complete shoulder corner joint dislocation grade III according to Tossy is the so-called piano key phenomenon. Due to the rupture of the ligaments, the collarbone protrudes so far down that it can be pressed down like a piano key and rises again.
To relieve the pain, the patient can take medication such as ibuprofen or paracetamol. After taking the patient’s medical history and physical examination, an x-ray is taken regularly in the case of acromioclavicular joint dislocation. In the event of a fall on the shoulder, the shoulder is x-rayed in two planes (from the front (a. p.) and laterally) and additionally, if there is a corresponding suspicion of an injury, a target image of the acromioclavicular joint is taken.
In order to further intensify the piano touch phenomenon, the X-ray target image can be taken under stress and in lateral comparison. For this purpose, a weight (10 kg) is wrapped around each patient’s wrist, pulling the acromion further towards the foot and revealing a possibly unrecognized piano key phenomenon. Sonography (ultrasound) can also be used to diagnose an acromioclavicular dislocation.
In the case of ligament injuries, bleeding in the joint area can be detected (low-echo area) and the 3-4 mm joint space can be enlarged in the frontal plane. An advantage of sonography is also that the shoulder tendons (rotator cuff) can be examined simultaneously for an injury. Older patients in particular are more frequently affected by an injury to the rotator cuff.
–> Continue to the topic Classification of acromioclavicular joint dislocationThe classification according to Tossy is a degree classification of acromioclavicular joint dislocation. It contains different degrees according to which the severity of the injury is assessed. In addition, this classification is also used to make an assessment of the indication for surgery.
It depends on the number of injured structures. In Tossy I, a strain or partial rupture of the capsule and ligament is located in the acromiclavicular part of the shoulder. The other ligaments of the clavicle are not injured and the clavicle is not higher.
There is a widening of the joint space of the acromioclavicular joint. Tossy II is a complete rupture of the capsule and the ligament between acromion and clavicle. In addition, the ligaments of the clavicle are torn.
This shows a slight elevation of the collarbone in the outer area. Finally, in Tossy III, all the ligaments at the acromioclavicular joint and the clavicle are torn, resulting in a visible elevation of the clavicle according to the piano key phenomenon. In the x-ray image a clear widening of the joint space becomes visible.
