Osteoarthritis and instability of the AC joint

…do they lead to the same symptoms?

  • AC pathology can be classified into different themes.
  • Osteoarthritis or instability lead to partially specific problems
  • New measurement instruments required for obtaining a comprehensive image

Patients with osteoarthritis (OA) of the acromioclavicular (AC) joint experience partially different symptoms and problems than patients with AC joint instability. This emerged from interviews with sixteen patients and four orthopaedic surgeons. Existing measuring instruments do not cover all occurring problems and differences and are therefore insufficient for evaluating the effect of treatment, according to Canadian researchers.


The Canadian researchers compared these results with existing measurements for AC complaints and concluded that many items – particularly those that differed between patients with OA and instability – are missing in the current measurement instruments and tests. For instance, neither the Specific AC Score (SACS) nor the Nottingham Clavicular Score (NCS) mention the AC joint as a specific pain location, and they don’t differentiate between burning or dull pain. They also do not determine whether the pain is linked to specific positions or movements, such as keeping it above your head or turning the arm on the back. Therefore, the researchers advocate new or additional measuring instruments to assess complaints of patients with AC joint disorders as comprehensively as possible. A general measurement for AC complaints is not specific enough to evaluate complaints: subsections might be needed that depend on the underlying pathology. Only then the rehabilitation can be matched optimally to individual complaints and goals of patients with OA or instability of the AC joint.


The Canadian researchers interviewed ten patients who were on average 44 years old with instability, six patients with OA who were on average 55 years of age and four orthopaedic surgeons with on average 14 years of experience. The five focus group discussions with patients took on average less than an hour, those with surgeons half an hour. The researchers asked how the disorders of the AC joins influenced the daily activities, work, sport, free time, and quality of life of the patients. They also inquired what patients and specialists thought of as important outcomes of conservative or operative treatment.

> From: Aldhuhoori, Disabil Rehabil (2020) (Epub ahead of print). All rights reserved to Informa UK Ltd. Click here for the online summary. Translation by Casper Martens

Expert opinion by John Bos, MSc.

This explorative qualitative study contains clinically useful information about the diagnostic orientation in patients with shoulder (-pain) symptoms that are related to the acromioclavicular joint – this information makes possible a more refined orientation on these symptoms. This study provides insight into the consultation room reality, from the perspective of the experts (orthopaedic surgeons) and the patients. As the authors noted themselves, the number of participants in this study deserves a critical note. Nevertheless, the results of this study show that there are specific outlines in the clinical presentation of the investigated patient group. From these outlines even patterns of clinical manifestations can be deduced which make differential diagnosis in patients with AC related (pain) symptoms possible by using pattern recognition. On top of that, the article provides a comparative oversight (Table 4 in the paper) of the diagnostic outcome measures used by the experts and the symptoms of the patient group. It is noteworthy that  the expert reality shows a lot of discrepancy with the patient reality!

The implications for the daily physiotherapy practice are:

  • In patients with shoulder (pain) complaints, distinguish between (painful) involvement of the glenohumeral joint and the acromioclavicular joint. 
  • Diagnostically orientate on clinical manifestations (symptoms and dysfunctions)
    • Study the similarities in clinical presentations which refer to (painful) involvement of the AC joint – with this, the interpretation of the AC involvement gains significance:
      • Pain around the AC joint / painful horizontal adduction / pain when lying on the painful shoulder.
    • Study the differences in clinical presentations which refer to the clinical manifestation of instability or OA of the AC joint – by using pattern recognitions the differential diagnosis gains significance:
      • Burning pain with OA,  combined with movement-dependent pain/ providing force with the arm – inflammatory nociceptive pain.
      • Dull pain with instability, combined with position or posture dependent pain and discomfort – non-inflammatory nociceptive pain.
  • A targeted diagnostic orientation brings the perspective of the expert closer to that of the patients – this benefits the orientation of the clinical process. 

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