Schulterinfo.ch - Acromioclavicular AC Joint - Osteroarthritis / Arthrose
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Abstract
Acromioclavicular osteoarthritis is a painful pathology with typical sonographic and radiographic findings.
Asymptomatic osteoarthritis of the AC-joint is very common, which may conceal possible differential diagnoses.
Patients present with pain during active and passive motion in the superior or anterior aspect of the shoulder. Pain accentuates with overhead or cross-body activities. Often there is local tenderness.
In order to diagnose acromioclavicular osteoarthritis, ultrasound or x-ray images are needed in which typical radiographic findings of osteoarthritis can be seen.
To lessen ailment, physical therapy and pain killers may be of help. Acutely exacerebrated OA may be in need of an intraarticular ultrasound guided steroid injection. If all fails, surgical intervention with resection of the distal part of the clacivula might be necessary.
Acromioclavicular osteoarthritis is a painful condition with typical sonographic and radiographic signs of advanced joint degeneration.
As is the case with every other joint in the body, osteoarthritis of the acromioclavicular joint is a result of worn-down cartilage. Like the menisci, the degeneration of the intraarticular fibrocartilage or disk is a process of fraying and tearing, which in the end leads to substantial damage of the cartilage tissue underneath. Underlying causes may be [1]:
- Idiopathic
- Age-related degeneration
- Posttraumatic (AC-dislocations according to Rockwood or Tossy Classifications)
- Osteolysis of the distal clavicle
- Inflammatory diseases
- Septic arthritis
- Joint instability
As asymptomatic osteoarthritis of the AC-joint is very common, numbers regarding the prevalence are vague. It can be said however, that osteoarthritis is the most widespread condition of the AC joint and therefore should never be overlooked, if patients present with shoulder pain [1].
The commonest symptom is pain during active and passive motion in the superior or anterior shoulder, which accentuates with overhead or cross-body activities. Pain can also be referred to the anterolateral neck and deltoid or even to the trapezius muscle. There is often local tenderness to pressure. Other symptoms range from reduced mobility and functionality to grinding within the joint [1, 2].
The physician should inquire all dimensions of pain as well as any clinical history with the different aetiologies in mind. Also, there are characteristic professions and sports such as weightlifting, basketball and swimming with a lot of overhead work which can be included in the anamnesis.
As with any shoulder pathology, the whole shoulder girdle is to be inspected as well as the cervical spine in order to rule out cervical lesions which can imitate the exact same pain locations. On visual examination, AC osteoarthritis may present itself as a swelling (if activated) and tenderness above the joint space. Paraarticular palpable or visible ganglia often develop when the joint and stabilizing ligaments are degenerated.
To complement visual examination, specific tests can be performed on the patient. These include (videos at the end of the page):
- Cross-body adduction test (most sensitive)
- The examiner places the shoulder in 90° forward flexion and maximal adduction. Pain during this motion is regarded as a positive test. [1]
- O’Brien test (most specific)
- With the patient in either sitting or standing position, the examiner brings the shoulder in 90° flexion and 10-15° adduction. The patient is instructed to fully internally rotate the shoulder and pronate in the elbow. The examiner subsequently applies downward force on the patient’s forearm as he/she presses against it. This is recreated, although this time the patient fully externally rotates the shoulder and supinates in the elbow. The test is positive if pain can be felt, especially if pain is alleviated in supination. Since O’Brien’s test was originally created to diagnose SLAP-lesions, the positive findings can further be distinguished. If pain ‘sits deep in the shoulder’ it usually indicates a SLAP-lesion. If pain however is situated above or in the AC-joint and the pain is not fully alleviated by supination one should lean towards pathologies of the AC-joint [1].
To diagnose osteoarthritis, imaging is needed. More specifically high resolution ultrasound and x-ray imaging in Zanca view, which allows the joint to be visualized the best [2]. Findings may be:
- Joint space narrowing
- Subchondral cysts
- Osteophytes
- Subchondral sclerosis
It should be brought to attention that radiographic findings of this nature are very common in asymptomatic patients [2]. That is why adjacent structures should be thoroughly assessed and additional imaging such as Ultrasound, CT or MRI to rule out other underlying causes of shoulder pain.
- Cervical spine disorders
- Injuries to the rotator cuff
- Subacromial impingement
- Symptomatic ‘Os acromiale’
- Myofascial problems
- Enthesopathy of the deltoid muscle
- Clavicle pathology
First line of therapy consists of nonoperative treatment, where patients try to increase range of motion with physical therapy and are instructed to reduce overhead work or other motions that might be responsible for pain. In addition to that, NSAID’s (if not contraindicated) can be taken and/or other local therapies such as warming of the joint might be worth an attempt. In some cases, immobilisation with a sling might also lessen inflammation. If these options do not have a positive effect or OA is acutely exacerbated, intraarticular injection of steroids should be considered [1].
Indications for invasive procedures are worsening of shoulder pain or function despite several attempts of conservative treatment [3]. Both open surgery and arthroscopic interventions are common, where parts of the distal clavicula are excised. Depending on the concomitant injuries the surgeon must carefully plan the procedure in order to achieve the best result for each individual patient.
Prognosis and progressive course of disease
Osteoarthritis is by nature a progressive disease and occasionally requiring surgical intervention in later stages. Both procedures have favourable outcomes, with reports of good and very good outcomes in up to 91% of arthroscopic interventions and 79% of open surgeries [3]. The advantage of arthroscopic distal clavicle resections lies in the preservation of the superior AC ligaments, thereby reducing the risk of secondary instability.
- Mall, Nathan A., Emily Foley, Peter N. Chalmers, Brian J. Cole, Anthony A. Romeo, and Bernard R. Bach. 2013. "Degenerative Joint Disease Of The Acromioclavicular Joint". The American Journal Of Sports Medicine 41 (11): 2684-2692. doi:10.1177/0363546513485359.
- Precerutti, Matteo, Manuela Formica, Mara Bonardi, Caterina Peroni, and Francesco Calciati. 2020. "Acromioclavicular Osteoarthritis And Shoulder Pain: A Review Of The Role Of Ultrasonography". Journal Of Ultrasound 23 (3): 317-325. doi:10.1007/s40477-020-00498-z.
- Lenz, R., P.C. Kreuz, and T. Tischer. 2014. "Arthroskopische Resektion Des Akromioklavikulargelenks". Operative Orthopädie Und Traumatologie 26 (3): 245-253. doi:10.1007/s00064-013-0279-7.
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