Accuracy of Anterior Shoulder Injections Without Image Guidance: A Prospective Controlled Study.

Abstract

Introduction: This study aims to assess the accuracy of glenohumeral joint injections through an anterosuperior approach using anatomical landmarks as a guide and arthroscopic visualization as the control method and to evaluate whether there is any association between accuracy, the physicians training, and the patient's pathology.

Materials and methods: A sample size of 124 patients was calculated. A prospective cohort study including 164 consecutive patients was conducted. All patients over 18 years of age who underwent shoulder arthroscopy during the study period were included. A needle was placed using an anterosuperior approach before the beginning of the surgery alternating between a shoulder surgeon and a resident. Direct visualization through a posterior arthroscopic view was used to verify correct needle placement. Each case was classified as success or failure based on the arthroscopic intra-articular visualization of the needle. Univariate and multivariate analyses were performed to evaluate the relationship between injection accuracy, operator experience, and patient pathology. A p-value less than 0.05 was considered statistically significant.

Results: Of the 164 needles placed, 131 were intra-articular, giving a total correct placement rate of 80% (95% CI, 73-86%). Experts had an accuracy of 88%, compared to a precision rate of 72% for residents (p<0.001). A logistic regression was performed to evaluate which factors are independently associated with injection accuracy failure. Patients diagnosed with adhesive capsulitis had an OR of 6.15 for injection failure.

Conclusions: This study shows that an anterior-superior approach shoulder injection technique performed by a shoulder specialist without image guidance has a high precision rate. However, in physicians with no experience in shoulder surgery, as well as in some pathologies such as adhesive capsulitis, the accuracy of the procedure decreases significantly and thus, in these cases, the use of some type of image guidance during the procedure may be recommended to achieve greater precision.