Abstract
BackgroundDespite numerous methodological flaws in previous study designs and the lack of validation in primary care populations, clinical tests for identifying acromioclavicular joint (ACJ) pain are widely utilised without concern for such issues. The aim of this study was to estimate the diagnostic accuracy of traditional ACJ tests and to compare their accuracy with other clinical examination features for identifying a predominant ACJ pain source in a primary care cohort.MethodsConsecutive patients with shoulder pain were recruited prospectively from primary health care clinics. Following a standardised clinical examination and diagnostic injection into the subacromial bursa, all participants received a fluoroscopically guided diagnostic block of 1% lidocaine hydrochloride (XylocaineTM) into the ACJ. Diagnostic accuracy statistics including sensitivity, specificity, predictive values, positive and negative likelihood ratios (LR+ and LR-) were calculated for traditional ACJ tests (Active Compression/O’Brien’s test, cross-body adduction, localised ACJ tenderness and Hawkins-Kennedy test), and for individual and combinations of clinical examination variables that were associated with a positive anaesthetic response (PAR) (P≤0.05) defined as 80% or more reduction in post-injection pain intensity during provocative clinical tests.ResultsTwenty two of 153 participants (14%) reported an 80% PAR. None of the traditional ACJ tests were associated with an 80% PAR (P<0.05) and combinations of traditional tests were not able to discriminate between a PAR and a negative anaesthetic response (AUC 0.507; 95% CI: 0.366, 0.647; P>0.05). Five clinical examination variables (repetitive mechanism of pain onset, no referred pain below the elbow, thickened or swollen ACJ, no symptom provocation during passive glenohumeral abduction and external rotation) were associated with an 80% PAR (P<0.05) and demonstrated an ability to accurately discriminate between an PAR and NAR (AUC 0.791; 95% CI 0.702, 0.880; P<0.001). Less than two positive clinical features resulted in 96% sensitivity (95% CI 0.78, 0.99) and a LR- 0.09 (95% CI 0.02, 0.41) and four positive clinical features resulted in 95% specificity (95% CI 0.90, 0.98) and a LR+ of 4.98 (95% CI 1.69, 13.84).ConclusionsIn this cohort of primary care patients with predominantly subacute or chronic ACJ pain of non-traumatic onset, traditional ACJ tests were of limited diagnostic value. Combinations of other history and physical examination findings were able to more accurately identify injection-confirmed ACJ pain in this cohort.
Highlights
Despite numerous methodological flaws in previous study designs and the lack of validation in primary care populations, clinical tests for identifying acromioclavicular joint (ACJ) pain are widely utilised without concern for such issues
While debate surrounds the accuracy of clinical tests for the diagnosis for shoulder conditions such as subacromial impingement [10,11] and glenoid labrum tears [12], the clinical diagnosis of ACJ pain is considered to be less contentious with localised ACJ tenderness [13], the O’Brien’s/Active Compression test [13,14,15], the cross-body adduction test [14,16] and the HawkinsKennedy [13,14] frequently reported in diagnostic studies as index tests for identifying injection-confirmed ACJ pain (Table 1)
Differences in prevalence and disease severity are known to affect the performance of diagnostic tests across populations in which these characteristics differ [17] and the direct application of diagnostic accuracy probabilities obtained for ACJ tests in surgical care settings to primary health care settings may lead the clinician to an incorrect diagnostic conclusion potentially resulting in inappropriate management pathways
Summary
Despite numerous methodological flaws in previous study designs and the lack of validation in primary care populations, clinical tests for identifying acromioclavicular joint (ACJ) pain are widely utilised without concern for such issues. Disorders of the acromioclavicular joint (ACJ) are a common cause of shoulder pain in primary care, affecting patients of all ages and levels of activity [1]. The mechanism of injury as well as the prevalence of painful ACJ conditions and the severity of ACJ disease in these settings are likely to differ considerably from patients presenting with shoulder pain in primary health care. Differences in prevalence (pre-test probability) and disease severity (spectrum bias) are known to affect the performance of diagnostic tests across populations in which these characteristics differ [17] and the direct application of diagnostic accuracy probabilities obtained for ACJ tests in surgical care settings to primary health care settings may lead the clinician to an incorrect diagnostic conclusion potentially resulting in inappropriate management pathways
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