A SLAP lesion is a rupture or tear of the glenoid labrum in the glenoid cavity. The glenohumeral joint consists of the joint head, which is part of the humeral head, and the socket, which is located between the shoulder blade and the collarbone.
The glenoid cavity is smaller than the articular head and therefore does not provide the necessary stability to keep the upper arm securely in the socket.
For this reason, the joint is stabilized by muscles that run around the upper arm and shoulder joint and also by the so-called labrum.
The labrum is an articular lip that extends around the socket and thus gives the socket the necessary enlargement.
The advantage is that the labrum does not have a fixed structure such as a bone so that the upper arm has sufficient room to move in the socket.
A muscle-tendon is attached to the upper part of the joint lip, which is counted as a biceps muscle. Both structures are anatomically, also called labrum-biceps complex.
Injuries and damage to this complex are called slap lesions.
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Causes of the SLAP lesion
The reason why a SLAP lesion is triggered can be acute or chronic.
One of the chronic causes is the overstrain of the shoulder joint.
If excessive loads are carried or balanced or lifted over a long period, the entire shoulder joint, including the labrum-biceps complex, maybe under such heavy strain that at some point a tear or tearing results.
In addition to chronic overloading, chronic incorrect loading can also lead to parts of the labrum-biceps complex being subjected to greater stress than other parts. This can also lead to cracks or tears.
Some sports are also often mentioned as risk factors for slap lesions. Usually, these are bat-swinging sports, such as baseball, tennis, or table tennis, which place a particularly heavy load on the shoulder area due to the repeated arm movements continuously.
If acutely very heavy loads are carried (e.g., weight lifting for untrained persons), immediate tearing or tearing can also occur.
The same can also happen in accidents. In this case, so-called high-speed traumas, such as those that occur in car accidents or sports accidents, can be the main triggers for an acute slap lesion. If the shoulder is squeezed or twisted without breaking, these acute slap lesions can occur.
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If the slap lesion is chronic, the patient may not notice anything at first.
If the lesion is progressing and has not been treated, the patient will usually report pain when the strain is severe, whereas an acute slap lesion or lesions that have progressed far will report immediate pain.
The character of the pain is described as biting or burning; it is localized in the area of the shoulder but can also spread by pulling over the entire shoulder, up to the upper back.
The pain often causes patients to assume relieving postures to reduce the intensity of the pain. However, these relieving postures often result in the shoulder joint being incorrectly loaded, which in turn can lead to hardening of the muscles, bone wear, and further pain.
In addition to the pain that already occurs at rest when the slap lesion has progressed, movement can also be impaired, especially in severe cases. These are caused on the one hand by the fact that the patient no longer performs the movements entirely due to the pain.
A further and perhaps more important reason is the instability that develops in the shoulder joint, which is caused by the fact that the shoulder joint stabilizing effect is no longer or only insufficiently given by the tear or rupture of the labrum-biceps complex.
Sometimes this instability can be so severe that the patient can only lift the arm to an angle of 90 degrees and then stops moving.
The fear of a dislocation of the joint also means that the patient is very careful in the arm movements and is accordingly restricted in his everyday life.
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Diagnosis of a SLAP lesion
The diagnosis of a slap lesion is not always easy. In any case, it is essential to conduct a detailed patient survey to determine whether the patient is at risk for a slap lesion (incorrect loading, overloading, racket, or ball sports).
Then it should be asked exactly which complaints occur and especially during which movement. After the questioning, a detailed physical examination should be carried out, which should first explore an active movement in the shoulder joint (what can the patient do himself?), then a passive movement by the examiner (the patient lets the arm hang, the movements are carried out by the examiner).
If the suspicion of a slap lesion is thereby hardened, e.g., due to an identified instability, it should be considered which imaging method should be used.
Both ultrasound and classic x-rays can be used to visualize the shoulder joint, but are very limited in their ability to show the soft tissues in the joint. Both methods of examination cannot or can hardly show a slap lesion.
Often the SLAP lesion can only be visualized by MRI of the shoulder (magnetic resonance imaging/shoulder), which can provide a more transparent, if not 100% view.
However, even MRI of the shoulder is often unable to detect it without a contrast medium that has to be injected directly into the joint. Since the injured biceps tendon anchor is tiny, it is often not possible to reliably classify the SLAP lesion in the MRI of the shoulder even with contrast medium.
Today, the safest method to prove a slap lesion is arthroscopy. It is usually only carried out when previous examinations have not shown any indication of a slap lesion, but the symptoms are typical of a slap lesion.
During the examination, also known as arthroscopy, two small skin incisions are made on the disinfected shoulder joint, and a camera and examination equipment are inserted into the joint.
The camera delivers live images and sends them to a monitor. With the help of the second instrument, smoothing devices, scissors and forceps can be inserted into the joint.
In the case of a visible slap lesion, the surgical treatment method is often the only therapeutically sensible procedure.
Sometimes the above-mentioned diagnostic arthroscopy is already used for treatment. Torn off parts, which are seen during the examination, are rejoined by sutures.
Torn free tissue, which is located in the joint space and potentially disturbs movement in the joint, is usually grasped with small forceps and removed from the joint.
Depending on the severity of the slap lesion, the procedure takes a few minutes to 1-2 hours.
Today, arthroscopic treatment is only rarely started, and open shoulder surgery is only continued. This can happen if the examiner cannot gain a proper view of the anatomical conditions of the shoulder joint during endoscopy or cannot treat the corresponding lesion due to lack of space.
After the treatment of a slap lesion, the arm can usually be fully loaded immediately. However, care must be taken to ensure that movements that have led to this injury should not be performed at first. Physiotherapeutic treatment can also be useful. Pain treatment is usually no longer necessary after the operation. If it is, cooling measures or anti-inflammatory painkillers should be given.
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