1052 - Accuracy of Landmark-Guided SI Joint Injection Between Medical Trainees and Advanced Practitioner

Objectives: To evaluate the accuracy of landmark-guided sacroiliac (SI) joint injections performed by medical students compared to an experienced practitioner, using cadaveric dissection as the validation method. The goal was to assess the feasibility, safety, and instructional value of teaching this technique to novice trainees.

 

Design: Nineteen formalin-embalmed cadavers were used. One experienced practitioner and two medical students each performed bilateral landmark-guided SIJ injections on every cadaver, totaling 38 injections per participant. Each injection used 2cc of color-coded acrylic paint delivered via a 20-gauge, 3.5-inch needle. Paint location was assessed through dissection. Injections were labeled as “hits” if ≥50% of the dye stained intraarticular or periarticular SIJ structures.
 

Results: Accuracy rates were 84% for the provider, 76% for student A, and 58% for student B. Combined student accuracy was significantly lower than the provider’s (p = 0.037). Student A's accuracy was not significantly different from the provider (p = 0.41), while student B’s was (p = 0.007). Missed injections sometimes stained the sacral foramen, piriformis, or facet joints—raising anatomical safety concerns.

 

Conclusions: SIJ injection accuracy appears to improve with provider experience. While the posterior approach is generally safe, misplaced injections may risk injury to neural or vascular structures if directed too deep or medially. These findings underscore the importance of proper training and anatomical awareness. Individual variability among learners suggests some may achieve competency faster than others. Although landmark-guided injections are widely used, future studies should assess whether differences in anatomical accuracy translate into differences in clinical outcomes—especially given prior evidence that even inaccurately placed SIJ injections may still provide symptom relief.