Morphology and anatomical relations of iliac and femoral bony landmarks, gluteal muscles and the sciatic nerve: Sex differences and clinical implication

The objective of this study was to determine sex differences in the anatomical relations between clinically relevant and palpable bony landmarks (anterior superior iliac spine, or ASIS), posterior superior iliac spine (PSIS), iliac tubercle and greater trochanter, and with the gluteal muscles and sciatic nerve. After dissection, distances along the iliac crest, angles and distances between bony landmarks, muscle thicknesses of gluteus maximus and gluteus medius, the fibre angles of gluteus maximus, and anatomical relations between the sciatic nerve and bony landmarks, were measured. In 23 cadavers (11 males; 12 females), iliac crest total length, distances between the greater trochanter, ASIS and iliac tubercle, and between the sciatic nerve and iliac crest, but only the angle at the PSIS between the iliac tubercle and greater trochanter, were significantly larger in males. Distances and angles reflecting horizontal measures, iliac crest proportions, and gluteus maximus fibres angles were not different between sexes. Gluteus maximus muscle fibre angles differed significantly along the sagittal plane and from medial to lateral. In conclusion, while males have a larger ilium and taller pelvis, there was no sex difference in pelvic width. Therefore, the female pelvis is shorter and relatively wider with respect to pelvic height, but is not absolutely wider than the male pelvis. This puts females at a greater risk of sciatic nerve injury with a dorsogluteal site injection. The angles of the gluteus maximus muscle fibres varied along their length and were not consistently 45o as commonly described

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Effects of thickness of muscle and subcutaneous fat on efficacy of gluteal intramuscular injection sites.

Intramuscular injections given at the dorsogluteal and ventrogluteal sites are intended for the gluteus maximus and gluteus medius muscles, respectively. However, little research has confirmed the reliability of these sites for the presence and thickness of the target and other muscles, and subcutaneous fat. This study characterised and compared these at the V-method and G-method ventrogluteal sites and dorsogluteal site (n=60). Gluteus maximus, medius and minimus were identified at each site, plus tensor fascia latae at ventrogluteal sites. Gluteus maximus and subcutaneous fat were significantly thicker and gluteus minimus significantly thinner at the dorsogluteal site than both ventrogluteal sites. Gluteus medius was the thickest muscle at each injection site, and thicker at the G-method than the V-method ventrogluteal site. Therefore, the dorsogluteal site reliably targets gluteus maximus, and the G-method ventrogluteal site was more reliable than the V-method ventrogluteal site to target gluteus medius in terms of presence and thickness.

Comparison of the G and V methods for ventrogluteal site identification: Muscle and subcutaneous fat thicknesses and considerations for successful intramuscular injection.

The ventrogluteal site is increasingly recommended for long-acting antipsychotic intramuscular injections; however, it remains infrequently utilized due to nurses' lack of confidence in site identification. The more recent G (geometric) method of ventrogluteal site identification is less subjective and likely more reliable than the V method for successful intramuscular injection outcomes. Knowledge of muscle and subcutaneous fat thicknesses, and the influence of sex and anthropometry on theoretical injection outcome, is necessary to support evidence-based use of the ventrogluteal site. In the presents study, we compared the V and G methods for injection site subcutaneous fat, muscle, and total tissue thicknesses, and theoretical injection outcome (bone injury, intramuscular or subcutaneous), and determined anthropometric predictors of injection outcome. Subcutaneous fat and muscle thicknesses were measured via ultrasound, bilaterally at V and G method sites (28 males, 32 females). Muscle and total tissue were significantly thicker, and successful intramuscular injection significantly more likely, using the G versus V method (75% versus 57%). Females had significantly thicker subcutaneous fat than males at both sites. Even using the G method, 92% of males but only 59% of females, would have a successful intramuscular injection, with remaining females at risk of bone injury (16%) or subcutaneous injection (25%). The G method site is more reliable for successful intramuscular injection, with less risk of bone injury than the V method site. Appropriate needle-length selection is essential for females with a body mass index (BMI) <23 kg m-2 and weight <60 kg (to avoid bone injury), and BMI >30 kg m-2 and hip >90 cm (to avoid subcutaneous injection).

Influence of gender, BMI and body shape on theoretical injection outcome at the ventrogluteal and dorsogluteal sites.

AIMS AND OBJECTIVES: This study aimed to determine the influences of gender, BMI and observed body shape on subcutaneous fat and muscle thicknesses, and theoretical injection outcome, at the ventrogluteal and dorsogluteal intramuscular injection sites. BACKGROUND: Debate continues as to whether the dorsogluteal or ventrogluteal injection site is more reliable for a successful intramuscular injection outcome. Subcutaneous fat and muscle thicknesses at the injection site are direct determinants of intramuscular injection outcome. BMI and observed body shape influence gluteal subcutaneous fat and muscle thicknesses, and therefore injection outcome, with potentially distinct effects at the ventrogluteal and dorsogluteal sites. DESIGN: This was a cross-sectional study. METHODS: Demographic data were collected, and subcutaneous fat and muscle thicknesses were quantified bilaterally at the dorsogluteal and ventrogluteal injection sites using ultrasound, for 145 participants (57% female). RESULTS: Subcutaneous fat and muscle were significantly thicker at the dorsogluteal than the ventrogluteal site, and 75% and 86% of participants would receive a successful intramuscular injection at these sites, respectively. There were significant effects of gender, BMI and observed body shape on subcutaneous fat thickness and theoretical injection outcome at both sites. Females, obese individuals and endomorph individuals had thicker subcutaneous fat and were more likely to have a subcutaneous injection outcome. CONCLUSIONS: Gender, BMI and observed body shape could be used to guide site and needle length selection when administering gluteal intramuscular injections to increase the likelihood of a successful intramuscular injection outcome. RELEVANCE TO CLINICAL PRACTICE: Both gluteal injection sites should be avoided in obese individuals and endomorph individuals. An intramuscular injection will be successful: using a 32-mm needle at the ventrogluteal site for all males and normal-weight females and using a 38-mm needle for all females at the ventrogluteal site, and for all males and at least 98% of females at the dorsogluteal site.

Ventrogluteal versus dorsogluteal site selection: A cross-sectional study of muscle and subcutaneous fat thicknesses and an algorithm incorporating demographic and anthropometric data to predict injection outcome.

BACKGROUND: The dorsogluteal and ventrogluteal intramuscular injection sites both have their use in clinical practice; however, it has not been established in whom one or the other should be preferentially targeted or avoided. There is a need for an evidence-based approach towards site selection for a successful intramuscular injection outcome and to avoid unwanted injection outcomes of inadvertent subcutaneous injection or bone contact. Injection outcome is dependent on injection site subcutaneous fat thickness and muscle thickness; these are likely influenced by gender and anthropometry. OBJECTIVES: To determine whether subcutaneous fat, muscle, and total tissue thicknesses differ between the dorsogluteal and ventrogluteal sites, and whether theoretical injection outcome (intramuscular, subcutaneous, or bone contact) can be predicted by demographic and anthropometric data and described by an algorithm. DESIGN: Cross-sectional study design. SETTINGS: University in Australia. PARTICIPANTS: 145 volunteers (57% female) of at least 18 years of age recruited through the university community. METHODS: Anthropometric data was collected and subcutaneous fat and muscle thicknesses were quantified by ultrasonography. Anthropometric differences between theoretical injection outcome groups (bone contact versus intramuscular versus subcutaneous at the ventrogluteal and dorsogluteal sites) was determined for each gender (ANOVA). Multiple regression analysis was conducted to determine the influence of demographic and anthropometric data on theoretical intramuscular injection outcome. An algorithm to guide site selection was developed for each gender, based on the anthropometric measures that best discriminated between injection outcomes. RESULTS: Subcutaneous fat, muscle and total tissue were significantly thicker at the dorsogluteal site than the ventrogluteal site, and subcutaneous fat was significantly thicker in females than males at both sites (all p<0.001); there was no gender difference for muscle or total tissue thickness at either site. Female gender, and waist and hip circumference were significant predictors of subcutaneous fat thickness at both sites; male gender was a significant predictor of dorsogluteal site muscle thickness (all p<0.05). In the algorithm developed for site selection based on theoretical injection outcome, the best discriminators were: weight, BMI and waist circumference for females, and weight and distance between the iliac tubercle and anterior superior iliac spine for males. CONCLUSIONS: The algorithm describes when each of the ventrogluteal and dorsogluteal sites is appropriate or should be avoided, based on easily obtained anthropometric data. This has direct relevance in clinical practice in evidence-based site selection for gluteal intramuscular injections for optimal medication and health outcomes.