The Recommended Deltoid Intramuscular Injection Sites in the Adult Population: A Cadaveric study with an Orthopedic Perspective

BackgroundThe deltoid is a common site for intramuscular injections, but guidelines for administration lack standardization. Global researchers propose various techniques, and recent study reports indicate a 1.5-15% incidence of nerve palsies due to injections. Our cadaveric study is aimed to standardize the deltoid intramuscular injection sites in the Southeast-Asian population. MethodsA cadaveric study of a 2-year duration was conducted in the Department of Anatomy in which twelve upper extremity specimens were dissected by the end of the pilot phase. Anthropometric measurements of deltoid muscle along with the distance of underlying neuro-vascular structures like the Axillary nerve and Posterior Circumflex Humeral Artery were measured from neighboring bony landmarks. ResultsIn adults, in anatomical position, the mean distances of the Axillary nerve, and Posterior Circumflex Humeral Artery from the mid-acromial point are 8.19 {+/-} 0.616 cm; and 8.66 {+/-} 0.968 cm respectively. The deltoid thickness at 3, 5, and 7 cm from mid-acromial point was observed to be 1.079 {+/-} 0.13 cm (0.5 cm to 1.78 cm), 1.599 {+/-} 0.12 cm (1 cm to 2.96 cm), 1.815 {+/-} 1.0 cm (1.2 cm to 2.5 cm) respectively. The acquired qualitative and quantitative data were tabulated, graphically represented, and statistically analyzed. ConclusionsThe deltoid IMI must be given at or below the level of the midpoint of the deltoid muscle, but never in the upper half. We recommend a site, 4 fingerbreadths / 9cm below the mid-acromion point as the safest site to avoid injury to any underlying neurovascular structures.