Abstract
Aims
To assess the accuracy of posterior and anterolateral methods of injection into the subacromial space (SAS) of the shoulder.
Patients and methods
Ethical approval was obtained and 50 patients (23 women and 27 men) with mean age of 64.5 years (42-87 years) and clinical diagnosis of subacromial impingement were recruited. Patients with old or recent shoulder fracture, bleeding disorders, and allergy to iodine were excluded. All injections were given by the consultant or an experienced registrar after obtaining informed consent. Patients were randomised into posterior and anterolateral groups and the method of injection was revealed by opening sealed envelopes just before the injection. A combination of 3mls 0.5% bupivacaine and 2mls of radiographic dye (Niopam) was injected in the subacromial space (SAS) using either anterolateral (n-22) and posterior approaches (28).
AP and lateral radiographs of shoulder were taken after injection and were reported by a Consultant Radiologist blinded to the method of injection. Visual analogue scale (VAS) and Constant-Murley shoulder score was used to assess pain and function respectively. Both scores were determined before and 30 minutes after the injection.
Results
22 injections (78.5%) were accurately placed in SAS with the posterior approach and in 14 patients (63.6%) with anterolateral approach. This difference was statistically significant (P< 0.05). Only patients who received injection accurately in SAS with either method had a reduction in pain of an average of 4 points on VAS, and improvement in the Constant score of average 14 points.
Conclusions
The posterior approach of SAS injection is more accurate than anterolateral approach. Injections that are correctly placed in the SAS lead to better reduction of pain and improvement in the Constant score.
