An audit of accuracy and efficacy of injections for subacromial impingement comparing consultant, registrar and physiotherapist

Methods: 49 patients presenting to the outpatient clinic with subacromial impingement agreed to take part in the study. They were allocated according to date of referral to either the consultant, the physiotherapist or registrar grade for injection via an anterior approach into the subacromial bursa. The therapeutic injection contained a specified volume of radiocontrast as well as depomedrone and lignocaine.

Antero-posterior and scapula-Y radiographs were performed immediately after injection. The Constant shoulder score was evaluated before and at six weeks after injection and all radiographs were reviewed by an independent, blinded radiologist recording the position of contrast.

Results: Accuracy rates of 67% through an anterior approach were obtained by both the consultant and the physiotherapist. At registrar level 48% accuracy was achieved. Improvement in shoulder score was obtained in 70% of patients with accurate injections, but additionally in 59% of patients with inaccurate injections.

Only 7% of cases had contrast confined to the subacromial space; in the remainder, contrast tracked medially around the rotator cuff muscle bellies in 59%, gleno-humeral joint in 20% and within the cuff tendon in 16%.

Conclusions: In our practice, the specialist physiotherapist already has an established role in administering therapeutic subacromial injections. Our audit demonstrates acceptable and equal accuracy to the consultant which we feel justifies this particular part of their role. However, at registrar grade the level of accuracy is reduced and most likely reflects inexperience, as over time accuracy improved.