Subacromial bursitis and shoulder pain: Exploring the predictors for a negative anaesthetic response

Abstract

The aim of this retrospective cross-sectional study was to (1) investigate the association between the presence of subacromial bursal pathology and response to subacromial anaesthetic injection; (2) identify variables that are predictive of a negative anaesthetic response; and (3) calculate diagnostic accuracy of these predictors. A total of 208 people with shoulder pain referred from primary care received an ultrasound guided local anaesthetic injection into the subacromial bursa following standardised clinical examination. Pain was recorded on a visual analogue scale immediately prior to and within 15 min post-anaesthetic injection. No difference in pain reduction post injection was found between those with and without bursal pathology (p < 0.05). Five potential predictors of a negative anaesthetic response were identified, but did not reach statistical significance. Clusters of three of the five predictors (high occupational shoulder demands; high or low sport/recreational shoulder demands; no current history of night pain; loss of passive external rotation range of motion of more than 30° and shoulder pain reproduced on cervical spine testing) may have clinical relevance despite not reaching statistical significance. Use of a cluster of any three predictors results in post-test probability of 93% (pre-test probability 69%). The identified predictors may inform clinical decisions regarding the use of injection therapy in those with bursal pathology observed with ultrasound and therefore potentially reduce unnecessary and costly healthcare utilisation.