Localizing the Course of the Radial Nerve Based on Anatomical Landmarks - PowerPoint Presentation

1. Localizing the Course of the Radial Nerve Based on Anatomical LandmarksJake Powell, OMSIII1; Kalan Barnes, MS, OMSII1;Cameron Beck, MS, OMSIV1; Matthew Skinner, MD3; William F Pientka II, MD3; Cara L. Fisher, PhD2Texas College of Osteopathic Medicine1, UNTHSC Department of Physiology and Anatomy2, JPS Health Orthopaedic Surgery3

2. BackgroundLocalization of the posterior course of the radial nerve is important to prevent iatrogenic radial nerve injury during the posterior approach to the humerusIncidence of iatrogenic radial nerve injury ranges from 4.20% (Wang et al.) to 11.53% (Yan et al.)Gerwin et al. study (1996) is the standard for localizing the posterior course of radial nerve

3. BackgroundFigure 1. – Measurement method used by all Gerwin et al. to localize the posterior radial nerve.Red – Distance from point the Radial Nerve is Medial and turns to traverse the Posterior humeral shaft, to the Medial Epicondyle (MRN ME)Yellow – Distance from point the Radial Nerve is Posterior and turns to traverse the Lateral humeral shaft, to the Lateral Epicondyle (LRN  LE)

4. BackgroundDistance in CMStudyRadial Nerve Distances from Epicondyles by Study

5. PurposeThe purpose of this study is to define the course and variability of the radial nerve along the posterior humerus in relationship to the medial and lateral epicondyles utilizing a greater sample size and more accurate measurement than previous works.Figure 2. Measurement of radial nerve using Polhemus deviceFigure 3. Polhemus device and study construct

6. Methods40 fresh cadaveric arms 20 left arms and 20 right arms14 female, 26 male Lateral recumbent position with the shoulder and elbow flexed to 90o to mimic surgical approach (Figure 4.)Medial and Lateral epicondyles dissected to bone surfaceMedial longitudinal incision made over posterior humerus to expose triceps brachii muscleDissection through triceps brachii and radial nerve identified along with profunda brachii vessels Figure 4. Alignment of upper extremity during measurement

7. Methods6 anatomical landmarks used for measurement (Figure 5.) utilizing a Polhemus Electromagnetic Digitizer.Proximal and Distal edges of nerve were averaged to provide accurate measurement from center of radial nerveFigure 5. Anatomic landmarks used in measurement

8. All SpecimensRight ArmLeft ArmMaleFemaleMRN  ME17.26cm + 0.49cm17.26cm17.25cm17.71cm16.40cmLRN  LE12.61cm + 0.38cm12.74cm12.48cm12.88cm12.11cmResults TableFemale 16.40cm vs Male 17.71cm (p<0.01)Female 12.11cm vs Male 12.88cm (p<0.01)

9. DiscussionNumerous recent studies describe novel techniques to identify the course of the radial nerve Theeuwes et al. used wire attached to the radial nerve to identify the course of the radial nerve as it courses posterior to lateral, and lateral to anterior on lateral and ap radiographs Dimerkale et al. showed a correlation between the length of wrist crease to the tip of the 5th digit and the length from the tip from the olecranon to the midpoint of the spiral groove (r=0.623, p<0.001) Seigerman et al. proposed identifying the distal posterior radial nerve course by measuring a distance of 39 +2.1 mm, 2 finger breadths, from the aponeurosis of the lateral and long heads of the triceps to the radial nerve

10. DiscussionGerwin et al. findings still widely used as reference for localizing radial nerveOur ResultsBuilds on Gerwin et al. and Jain et al. with larger sample size and most accurate method of measurement with anatomical precisionResults show greater similarity to Jain et al.Radial nerve location difference between sex identified

11. DiscussionDistance in CM

12. ReferencesGerwin M, Hotchkiss RN, Weiland AJ. . Alternative Operative Exposures of the Posterior Aspect of the Humeral Diaphysis. The Journal of Bone and Joint Surgery-American Volume. 1996;78(11):1690–1695.Wang JP, Shen WJ, Chen WM, et al. Iatrogenic radial nerve palsy after operative management of humeral shaft fractures. J Trauma. 2009;66: 800–803.Yin P, Zhang L, Mao Z, Zhao Y, Zhang Q, Tao S, Liang X, Zhang H, Lv H, Li T, Tang P. Comparison of lateral and posterior surgical approach in management of extra-articular distal humeral shaft fractures. Injury. 2014 Jul;45(7):1121-5. doi: 10.1016/j.injury.2014.02.034. Epub 2014 Mar 12. PMID: 24685053.Kosiyatrakul A, Phongthipakorn P, Chanpoo M, Luenam S. COURSE OF THE RADIAL NERVE IN THE VULNERABLE AREA ALONG THE SHAFT OF THE HUMERUS: A CADAVERIC STUDY. J Southeast Asian Med [Internet]. 2019Jun.11 [cited 2021Apr.14];3(1):8-17. Jain RK, Champawat VS, Mandlecha P. Danger zone of radial nerve in Indian population - A cadaveric study. J Clin Orthop Trauma. 2019 May-Jun;10(3):531-534. doi: 10.1016/j.jcot.2018.02.006. Epub 2018 Feb 21. PMID: 31061584; PMCID: PMC6492309.Theeuwes HP, van der Ende B, Potters JW, Kerver AJ, Bessems JHJM, Kleinrensink GJ. The course of the radial nerve in the distal humerus: A novel, anatomy based, radiographic assessment. PLoS One. 2017 Oct 26;12(10):e0186890. doi: 10.1371/journal.pone.0186890. PMID: 29073240; PMCID: PMC5658097.Demirkale İ, İmamoğlu H, Şık S, Öztürk Ö. Localisation of the radial nerve at the spiral groove: A new technique. J Orthop Translat. 2018 Jul 27;16:85-90. doi: 10.1016/j.jot.2018.07.002. PMID: 30723685; PMCID: PMC6350025.Seigerman DA, Choung EW, Yoon RS, Lu M, Frank MA, Gaines LC, Liporace FA. Identification of the radial nerve during the posterior approach to the humerus: a cadaveric study. J Orthop Trauma. 2012 Apr;26(4):226-8. doi: 10.1097/BOT.0b013e31821d0200. PMID: 21918485.

13. AcknowledgementsWe thank the Willed Body Program at the University of North Texas Health Science Center at Fort Worth and our donors for their invaluable contributions to this project.

14. Questions?