Imaging-guided subacromial therapeutic injections: prospective study comparing abnormalities on conventional radiography with patient outcomes.

Objective: The purpose of this study was to compare abnormalities detected on conventional shoulder radiography with improvement in pain and shoulder function after subacromial injections.
Subjects and Methods: We conducted a prospective outcomes study including 98 consecutive patients after fluoroscopy-guided subacromial injections who returned outcome questionnaires and who underwent routine shoulder radiography. Numeric pain rating scale (NRS) data were collected before and, along with patient global impression of change (PGIC) data, at 1 week and 1 month after injection. Outcome differences were assessed using the Student t test and Mann-Whitney U test. Logistic regression analysis was done, including radiographic variables compared with the outcome improvement. The odds ratios with 95% CIs were identified for the significant predictors.
Results: A significant difference in overall improvement was found depending on the posterior acromial slope. Patients with a slope of more than 36° had significantly lower NRS and PGIC scores at 1 week and 1 month (p < 0.025) compared with those with a slope of 36° or less, with 86.4% of patients with a slope of more than 36° reporting significant improvement at 1 month. This was the only variable linked with improvement in the logistic regression analysis, with an odds ratio of 2.16 (95% CI, 1.11-4.22). Patients with calcific tendinitis had significantly lower NRS scores at both 1 week and 1 month (p = 0.03 and 0.05, respectively) and PGIC scores at 1 week (p = 0.05).
Conclusion: A posterior acromial slope of more than 36° and the presence of calcific tendinitis on conventional shoulder radiography are associated with better outcomes. Patients with a slope of more than 36° showed the best improvement.