AC Joint Pain | Cluster of Signs & Symptoms | AC Joint Diagnosis

When evaluating a patient with shoulder pain, the AC joint may be a source of potential nociception. Previous studies evaluating the use of clinical tests to examine a symptomatic non-traumatic AC joint have either contained methodological flaws or have reported only weak accuracy for stand-alone tests or the combination in test clusters.

A study by Cadogan et al. in the year 2013 has not only looked at clinical tests but at signs & symptoms predictive of AC joint pathology as well.

They found a sensitivity of 96% and a negative likelihood ratio of 0.09 for less than 2 positive variables out of 5 and a specificity of 95% and a positive likelihood ratio of 4.98 for four or more positive clinical features. Although this cluster has good diagnostic accuracy, confidence intervals were wide. For this reason, we give this cluster a moderate clinical value in practice.

The cluster contains the following items: 1) Repetitive mechanism of pain onset. This was also the item with the highest specificity of 90% in the study. Be careful with the interpretation thought as other shoulder pathologies may also result or become aggravated by repetitive activity.

2) Absence of referred pain below the elbow. This item has the highest sensitivity in the study with a sensitivity of 100%, meaning that the AC joint can basically be ruled out in case there is pain referral distal to the elbow.

3) A thickened or swollen AC joint, which in isolation was the most accurate item in the study.

4) Absence of typical pain provocation during passive glenohumeral abduction

5) Absence of typical pain during external rotation performed at 90 degrees of abduction

The last two items might be a differentiating factor compared to other shoulder injuries as these movements are associated with glenohumeral capsuloligamentous or intra-articular pathology.

All traditional physical tests for the AC joint were found to be of weak diagnostic accuracy in this study. In a summary, the authors recommend the following decision algorithm to identify pain arising from the acromioclavicular joint:

21 OF THE MOST USEFUL ORTHOPAEDIC TESTS IN CLINICAL PRACTICE

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Other common orthopedic tests to assess for AC Joint Pathology are:

• Cross Body Adduction Test
• Active Compression Test of O’Brien
• AC Joint Line Tenderness
• Paxino’s Sign
• AC Resisted Extension Test
• AC Shear Test
• AC Joint Provocation Cluster by Krill
• AC Joint Provocation Cluster by Chronopoulos

References

Cadogan A, McNair P, Laslett M, Hing W. Shoulder pain in primary care: diagnostic accuracy of clinical examination tests for non-traumatic acromioclavicular joint pain. BMC Musculoskeletal Disorders. 2013 Dec;14(1):1-1.