Evaluation of the safety of a novel intramuscular injection point by insertion of gel and determination of the optimal depth of insertion in cadavers.

Abstract

In our previous study, we identified a novel intramuscular injection point at the intersection of the horizontal line from the anterior superior iliac spine and the perpendicular line from the middle portion of the trochanter major with the extended hip joint, and clarified that this point is as safe as the point of Clark for intramuscular injection. In the present study, we used 29 right buttocks of cadavers aged 59-100. We injected 1 mL gel into both the point of Clark and our novel intramuscular injection point to examine the relationship of the two points with nerves and blood vessels by investigating whether they were present in the gel. Ultrasound tomography was used to measure the thickness of the subcutaneous tissue and the gluteal muscle at both points. The incidence of accidental insertion to nerves or blood vessels at the two sites was almost the same as we experienced in our previous study. This indicates that our novel intramuscular injection point provides an appropriate site for intramuscular injection to the gluteal muscle. The injected gel made a mass between the gluteus medius and minimus muscles, suggesting the possibility that hematomas could be formed with negative effects on nerves and blood vessels. Since the thickness of subcutaneous tissue ranged from 1.2 to 2.6 cm at both points, we consider that a depth of 3 cm at a right angle to the skin is appropriate for both the point of Clark and our novel intramuscular injection point. However, assessment of the thickness of fatty tissue with confirmation of the position of blood vessels by ultrasound tomography is recommended for safe intramuscular injection.