Surface anatomy and levator scapulae muscle injection: A cadaveric investigation

Abstract

Accurate detection of the levator scapulae muscle is critical for effective diagnostic and therapeutic interventions. The commonly used surface anatomy approach has not been validated and is less accurate than ultrasound-guided techniques. Therefore, we determined the needle insertion point for the levator scapulae using a new technique based on the anatomy of the scapula. This investigation used 15 fresh-frozen cadavers to explore the relationship between the acromial angle and medial tip of the scapular spine (O) of the scapular spine. Based on the x-axis (the distance [L] from Point O to point acromial angle) and the y-axis perpendicular to the x-axis passing through Point O, the barycentric coordinates were determined through the intersections of each axis and the superior angle of the scapula with the levator scapulae. Various ratios involving the established distance L) were ascertained, we compared the measurements and ratios between the male and female groups, and the accuracy of the new technique was compared with the conventional technique. The optimal site of the new technique was within 6 to 7% of distance L on the x-axis and 42 to 44% of distance L on the y-axis. This technique was significantly more accurate than the conventional technique (P = .006). Although ultrasound allows for accurate injections via real-time visualization, its unavailability in some cases highlights the importance of understanding surface anatomy landmarks. Our new technique, based on the anatomy of the scapula and relative measurements, is more accurate than the conventional technique. This should enable more precise detection of the levator scapulae for accurate and efficient diagnostic and therapeutic procedures.