Unorthodox Ulnar Nerve Arborization at the Distal Metadiaphyseal Humerus: An Insight into the Neuroanatomical Oddity and its Surgical Implication

/in /by

Journal of Clinical Orthopaedics | Vol 10 | Issue 1 | January-June 2025 | page: 65-68 | Meet Ajay Mehta, Avik Kumar Naskar, Himanshu Pradeep Ganwir, Vikas Anandrao Atram

DOI: https://doi.org/10.13107/jcorth.2025.v10i01.724

Open Access License: CC BY-NC 4.0

Copyright Statement: Copyright © 2025; The Author(s).

Submitted Date: 25 March 2025, Review Date: 29 April 2025, Accepted Date: May 2025 & Published Date: 30 June 2025

Author: Meet Ajay Mehta [1], Avik Kumar Naskar [1], Himanshu Pradeep Ganwir [1], Vikas Anandrao Atram [1]

[1] Department of Orthopaedics, Indira Gandhi Government Medical College and Hospital, Nagpur, Maharashtra, India

Address of Correspondence

Dr Avik Kumar Naskar
Old Resident Hostel, IGGMC and Mayo Hospital, Nagpur – 440018, Maharashtra, India.
E-mail: avik7933@gmail.com

Abstract

Background: Anatomical variations of the ulnar nerve, particularly involving its course and branching pattern near the distal humerus, are exceedingly rare. Such anomalies may pose significant risks during surgical procedures around the elbow due to their potential for entrapment, mechanical stretch, or iatrogenic injury.
Case report: We report a case involving a 59-year-old male with a distal humerus fracture, managed surgically through a posterior paratricipital approach. Pre-operatively, there was no neurological deficit. Intraoperatively, a rare anatomical variant of the ulnar nerve was observed: It exhibited two bifurcations approximately 40 mm and 20 mm proximal to the medial epicondyle. Notably, both aberrant branches pierced the medial intermuscular septum to enter the anterior compartment. In addition, the main trunk of the ulnar nerve was tethered by a dense fascial band extending between the medial intermuscular septum and the medial epicondyle. The fracture was stabilized using bicolumnar plating.
Results: Despite meticulous dissection, the patient developed a post-operative ulnar nerve deficit, likely due to traction or compression injury to the aberrant branches. This unusual branching pattern increased the risk of intraoperative nerve compromise.
Conclusion: This case underscores the importance of considering rare ulnar nerve anatomical variations during surgical planning for distal humerus fractures. Pre-operative vigilance and careful intraoperative dissection are essential to prevent nerve injury.
Keywords: Ulnar nerve, Distal humerus fractures, Peripheral nerves, Nerve compression.

References

1. Spinner RJ, Carmichael SW, Spinner M. Ulnar nerve anomalies: Clinical relevance in entrapment syndromes. J Neurosurg 1996;84:725-32.
2. Sunderland S. Nerves and Nerve Injuries. 2nd ed. Edinburgh: Churchill Livingstone; 1978.
3. Dellon AL. Review of treatment results for ulnar nerve entrapment at the elbow. J Hand Surg Am 1986;11:688-700.
4. Capek L, Kunc V. Anatomical variations of the ulnar nerve in the elbow region. Acta Chir Plast 1984;26:209-16.
5. Wright TW, Glowczewskie F Jr., Cowin D, Wheeler DL. Ulnar nerve excursion and strain at the elbow and wrist associated with upper extremity motion. J Hand Surg Am 2001;26:655-62.
6. Karatas A, Basarir K, Ercin E. Anatomic variations of the ulnar nerve at the elbow. Clin Anat 2012;25:498-503.
7. Chow JC, Papachristos AA, Ojeda A. An aberrant anatomic variation along the course of the ulnar nerve above the elbow with coexistent cubital tunnel syndrome. Clin Anat 2006;19:661-4.
8. Ferre-Martinez A, Miguel-Pérez M, Möller I, Ortiz-Miguel S, Pérez-Bellmunt A, Ruiz N, Sanjuan X, Agullo J, Ortiz-Sagristà J, Martinoli C. Possible Points of Ulnar Nerve Entrapment in the Arm and Forearm: An Ultrasound, Anatomical, and Histological Study. Diagnostics. 2023; 13(7):1332.
9. Roy TS, Sharma M, Sharma A. Martin-Gruber anastomosis in human cadavers and its clinical implications. Clin Anat 2004;17:63-6.
10. Paul S, Das S, Chaudhary S, Mishra P, Nayak BS. Marinacci communication: A rare anomaly of the forearm. Singapore Med J 2007;48:e231-3.
11. Roy TS, Gupta V. Berrettini anastomosis in the human hand. Clin Anat 1997;10:165-8.
12. Posner MA. Compressive neuropathies of the ulnar nerve at the elbow and wrist. Instr Course Lect 2000;49:305-17.

How to Cite this article: Mehta MA, Naskar AK, Ganwir HP, Atram VA. Unorthodox Ulnar Nerve Arborization at the Distal Metadiaphyseal Humerus: An Insight into the Neuroanatomical Oddity and its Surgical Implication. Journal of Clinical Orthopaedics. January-June 2025;10(1):65-68.

 (Article Text HTML)       (Download PDF)