Subacromial bursitis is a common ultrasound finding. It is often assumed to be the cause of a patient’s symptoms and used as justification for a subacromial corticosteroid injection. While in some cases this can be a useful treatment, in many cases this is of no value. One of the reasons for this is the extremely high incidence of both ‘rotator cuff tears’ and ‘bursitis’ in asymptomatic shoulders. Studies have shown that these features can be present in about 80% of ‘normal’ shoulders.
Clinicians should look for other causes of pain before deciding on a diagnosis of “bursitis” and attempting a corticosteroid injection. For example, acromioclavicular joint pain and adhesive capsulitis are also quite common causes of pain. The other consideration is that a thickened subacromial bursa is only one possible contributor to impingement symptoms. A patient’s posture, the presence of a subacromial spur or hooked acromion and rotator cuff pathology all contribute to this condition. Treating the bursa (with a steroid injection) in isolation is therefore almost always doomed to fail when these contributors.
A final consideration is the potential negative effect that a steroid injection might have on the rotator cuff. A history of more than two steroid injections has been shown to be associated with a poorer outcome in patients who go on to have rotator cuff surgery. As a result, steroid injections should be used with some caution.