Definition

Weightlifter’s shoulder is a relatively rare overuse injury of the acromioclavicular joint, which primarily affects powerlifters and weightlifters. The intervertebral disc in the joint wears down, followed later by the cartilage. This is followed by mechanically induced inflammation of the bones rubbing against one another and, ultimately, osteolysis or bone necrosis. The ACG is considered to be relatively unstable due to the incongruent joint surfaces and the three-dimensional movement, which is cushioned by a disc. Its stability is primarily provided by the capsule and the ligaments. The triggering movements are transverse adduction, lateral adduction, internal rotation and frontal abduction are cited as triggering movements; specifically, bench presses and overhead presses, but also volleyball, basketball, tennis and swimming are considered potential triggers. A distinction is made between two forms:

1. post-traumatic: trauma-induced subchondral fractures lead to osteolysis weeks or even years later
2. non-traumatic: repetitive microtraumas caused by repeated intensive training can lead to fatigue fractures

In both cases, various aetiological factors are postulated, such as mild chronic instabilities or inadequate surgical treatment, post-traumatic synovitis or autonomic dysfunction. Metaplastic bone formations are observed, along with increased osteoclast and osteoblast activity. The condition progresses at varying rates, ranging from subchondral changes and cysts to overt osteolysis, and is considered to be self-limiting. It primarily affects young people, although the condition can, in principle, occur at any age. With changing sporting habits, an increasing number of women are now affected compared to earlier times, when this condition almost exclusively affected young male athletes. It is not uncommon for the medical history to reveal periods of suspended sporting activity which have led to an improvement in symptoms. On MRI, the condition is only visible 4 weeks after the trauma. The symptoms of the condition are generally moderate; the pain is not particularly severe, on palpation crepitus can be felt, and mobility in the ACG is reduced. There is usually tenderness over the ACG, and occasionally a pain-related limitation in the use of strength. There need not necessarily be any apparent restrictions in movement. Moderate postures and movements of the arm are often pain-free, particularly if extensive endorotation and extensive lateral abduction as well as frontal abduction are avoided.

Causes

1. Overuse during movements that put strain on the ACG
2. traumatic

Predisposing

1. high-intensity weight training
2. Weightlifting
3. Volleyball, basketball, tennis, swimming

Diagnosis

1. In the early stages, X-rays show no abnormalities, whereas an MRI scan detects the condition much earlier. If the condition has been present for some time, a strip of the clavicle approximately 0.5 to 3 cm wide is affected.
2. Tests and signs: Hawkins’ test, Scarf’s test
3. MRI, ultrasound
4. Intra-articular corticosteroid injections administered on a trial basis should alleviate the pain

Symptoms

1. Tenderness of the ACG
2. Pain on loading of the ACG, particularly when the joint is positioned far from anatomical zero
3. restrictions on movement, which may be painless but are usually painful

Therapy

1. typically conservative; in one study, conservative treatment was successful in 93% of cases
2. from load reduction to immobilisation
3. NSAIDs, if necessary
4. Improving the range of motion of the shoulder joint and strength of the rotator cuff in cases of additional shoulder conditions
5. Technical adjustments such as maintaining a minimum distance of 4–6 cm above the chest and limiting the hand spacing to 1.5 times the acromion distance during the bench press
6. Botulinum toxin injections as a treatment for pain
7. Open or arthroscopic surgery, where appropriate. Surgical procedures may enable a quicker return to sport
8. The activity responsible may need to be discontinued permanently

Complications