Clinical Assessment of Anatomical Landmarks of the Shoulder for Safe Intramuscular Injections. A Cross-Sectional Study among Adult Patients
Sex-Based Differences in Shoulder Landmarks for Safe Deltoid Injections
DOI:
https://doi.org/10.69750/dmls.02.04.0115Keywords:
Deltoid Muscle, Intramuscular Injection, Anatomical Landmarks, Shoulder Anthropometry, Ultrasound Measurement, PakistanAbstract
Background: Standard deltoid intramuscular injection landmarks may not account for sex-specific anatomical variations, increasing the risk of subcutaneous injection, periosteal contact, or neurovascular injury.
Objectives: To quantify deltoid region anthropometry and tissue-depth biomarkers in Pakistani adults and assess sex differences to improve injection safety.
Methods: This cross-sectional study (June 2023–November 2024) enrolled 100 outpatients (50 men, 50 women; aged 18–65 years) at Nawaz Sharif Medical College and Aziz Bhatti Shaheed DHQ Hospital, Gujrat, following ethical approval and informed consent. Acromion–tuberosity distance and upper arm circumference were measured with a flexible tape; triceps skinfold thickness with Harpenden calipers; and deltoid muscle thickness using a 7.5 MHz ultrasound probe. Data were analysed with independent-samples t-tests and Pearson correlation in SPSS v26 (p < 0.05).
Results: Mean acromion–tuberosity distance was 53.2 ± 4.8 mm, higher in men (55.6 ± 4.2 mm) than women (50.8 ± 4.1 mm; p < 0.001). Upper arm circumference averaged 28.5 ± 2.9 cm (men: 30.2 ± 2.7 cm; women: 26.8 ± 2.3 cm; p < 0.001). Triceps skinfold thickness was greater in women (13.4 ± 4.0 mm) than men (11.8 ± 3.5 mm; p = 0.014), while deltoid muscle thickness was higher in men (19.2 ± 3.1 mm) than women (17.6 ± 3.0 mm; p = 0.022). Triceps skinfold showed strong correlation with BMI (r = 0.65; p < 0.001), and deltoid muscle thickness showed moderate correlation (r = 0.42; p = 0.005).
Conclusion: Although the 50 mm landmark generally identifies deltoid muscle, significant sex differences in muscle and fat warrant individualised needle selection using anthropometric or ultrasound guidance to minimise injection-related complications.
Downloads
References
Nakajima Y, Fujii T, Mukai K, Ishida A, Kato M, Takahashi M, et al. Anatomically safe sites for intramuscular injections: a cross-sectional study on young adults and cadavers with a focus on the thigh. Hum Vaccin Immunother. 2020;16(1):189-96.doi: 10.1080/21645515.2019.1646576
Nakajima Y, Fujii T, Mukai K, Ishida A, Kato M, Takahashi M, et al. Anatomically safe sites for intramuscular injections: a cross-sectional study on young adults and cadavers with a focus on the thigh. Human Vaccines & Immunotherapeutics. 2019;16.doi: 10.1080/21645515.2019.1646576
Charmode SH, Mishra AK, Mehra S. ‘The Recommended Deltoid Intramuscular Injection Sites in the Adult Population: A Cadaveric study with an Orthopedic Perspective’. medRxiv. 2024:2024.06.14.24308929.doi: 10.1101/2024.06.14.24308929
Susai S, Chandrupatla M, Kusneniwar G. Determination of safe sites of intramuscular arm injections and its relevance to the community. Journal of Family Medicine and Primary Care. 2023;11:6101-6.doi: 10.4103/jfmpc_792_22
Charmode S, Mehra S, Mishra AK. The Recommended Deltoid Intramuscular Injection Sites in the Adult Population: A Cadaveric Pilot Study With an Orthopedic Perspective. Cureus. 2024;16(8):e66391.doi: 10.7759/cureus.66391
Asma Zulfiqar SAMFKPASSSUA. Anatomical Variations and Clinical Significance of the Frozen Shoulder Variant: A Cross-Sectional Study in the Pakistani Population. Pakistan Journal of Medical & Health Sciences. 2023;17(01):886.doi: 10.53350/pjmhs2023171886
Kassam F, Lim B, Afroz S, Boissonnault È, Reebye R, Finlayson H, et al. Canadian Physicians’ Use of Intramuscular Botulinum Toxin Injections for Shoulder Spasticity: A National Cross-Sectional Survey. Toxins [Internet]. 2023; 15(1).doi: 10.3390/toxins15010058
Nakajima Y, Fujii T, Mukai K, Ishida A, Kato M, Takahashi M, et al. Anatomically safe sites for intramuscular injections: a cross-sectional study on young adults and cadavers with a focus on the thigh. Human vaccines & immunotherapeutics. 2020;16(1):189-96.doi: 10.1080/21645515.2019.1646576
Rached RDVA, Iuamoto LR, Kim AHJ, Sikusawa GY, Souza FM, Hsing WT. Anatomical landmarks and procedure technique of Levator Scapulae Plane Block (LeSP block): Case report: Ultrasound-guided block of the superficial, deep and distal planes of the levator scapulae muscle for treatment of shoulder girdle myofascial pain. Radiology Case Reports. 2024;19(12):6502-8.doi: https://doi.org/10.1016/j.radcr.2024.09.050
Desmeules F, Roy J-S, Lafrance S, Charron M, Dubé M-O, Dupuis F, et al. Rotator Cuff Tendinopathy Diagnosis, Nonsurgical Medical Care, and Rehabilitation: A Clinical Practice Guideline. Journal of Orthopaedic & Sports Physical Therapy. 2025;55(4):235-74.doi: 10.2519/jospt.2025.13182
Benzon HT, Elmofty D, Shankar H, Rana M, Chadwick AL, Shah S, et al. Use of corticosteroids for adult chronic pain interventions: sympathetic and peripheral nerve blocks, trigger point injections - guidelines from the American Society of Regional Anesthesia and Pain Medicine, the American Academy of Pain Medicine, the American Society of Interventional Pain Physicians, and the International Pain and Spine Intervention Society. Regional Anesthesia & Pain Medicine. 2024:rapm-2024-105593.doi: 10.1136/rapm-2024-105593
Kianian S, Bansal J, Lee C, Zhang K, Bergese SD. Perioperative multimodal analgesia: a review of efficacy and safety of the treatment options. Anesthesiology and Perioperative Science. 2024;2(1):9.doi: 10.1007/s44254-023-00043-1
Yi K-H, Choi Y-J, Lee J-H, Hu H, Gil Y-C, Hu K-S, et al. Anatomical Considerations for the Injection of Botulinum Neurotoxin in Shoulder and Arm Contouring. Aesthetic Surgery Journal. 2024;44(3):319-26.doi: 10.1093/asj/sjad250
Benzon HT, Provenzano DA, Nagpal A, Souza D, Eckmann MS, Nelson AM, et al. Use and safety of corticosteroid injections in joints and musculoskeletal soft tissue: guidelines from the American Society of Regional Anesthesia and Pain Medicine, the American Academy of Pain Medicine, the American Society of Interventional Pain Physicians, and the International Pain and Spine Intervention Society. Regional Anesthesia & Pain Medicine. 2025:rapm-2024-105656.doi: 10.1136/rapm-2024-105656
Selected Abstracts from the joint Meeting of 16th Congress of the European Association of Clinical Anatomy (EACA) and the XII Meeting of the International Symposium of Clinical and Applied Anatomy (ISCAA) Padova, Italy, held remotely via zoom platform, Date 14th to 16th September 2021. Surgical and Radiologic Anatomy. 2023;45(10):1331-98.doi: 10.1007/s00276-023-03224-6
Mackenzie LJ, Bousie JA, Newman P, Waghorn J, Cunningham JE, Bushell M-JA. Healthcare Practitioners Knowledge of Shoulder Injury Related to Vaccine Administration (SIRVA). Vaccines [Internet]. 2022; 10(12).doi: 10.3390/vaccines10121991
Naredo E, Rodriguez-Garcia SC, Terslev L, Martinoli C, Klauser A, Hartung W, et al. The EFSUMB Guidelines and Recommendations for Musculoskeletal Ultrasound – Part II: Joint Pathologies, Pediatric Applications, and Guided Procedures. Ultraschall Med. 2021;43(03):252-73.doi: 10.1055/a-1640-9183
Downloads
PlumX Metrics
Published
Issue
Section
License
This work is licensed under a Creative Commons Attribution 4.0 International License.
© The Author(s) 2025. Open Access. This article is licensed under a Creative Commons Attribution 4.0 International License , which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ . The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/ ) applies to the data made available in this article, unless otherwise stated in a credit line to the data.
