# Gross Anatomy and Approach to the Humerus and Femur in the White‐Eared Opossum ( Didelphis albiventris )

## TL;DR

This paper describes the anatomy of the humerus and femur in the white-eared opossum to guide surgical approaches for treating fractures.

## Contribution

The study provides detailed anatomical insights and recommends surgical approaches for orthopedic procedures in the white-eared opossum.

## Key findings

- The medial approach is recommended for accessing the humeral diaphysis in the white-eared opossum.
- The craniolateral approach is most appropriate for accessing the femoral diaphysis for surgical interventions.

## Abstract

The white‐eared opossum (
Didelphis albiventris
) is a Neotropical marsupial that readily adapts to urban environments. Due to its presence in anthropogenic habitats, this species is frequently exposed to vehicle collisions and dog attacks. Such trauma often results in long bone fractures, with humeral and femoral fractures being common in roadkill specimens. Long bone fractures can be stabilised using external or internal skeletal fixation devices. Therefore, detailed knowledge of the anatomical features of the humerus and femur, as well as the associated muscular and neurovascular structures in the thoracic and pelvic limbs, is essential to guide surgical access to the humeral and femoral shafts in orthopaedic interventions. In this study, eight white‐eared opossums were examined. Based on anatomical dissections and radiographic imaging, the morphology of the humerus and femur, as well as the muscular and nervous anatomy of the thoracic and pelvic limbs, was documented. The observed anatomical structures were largely consistent with those reported for domestic mammals, such as dogs, and wild species, including paca and capybara. Based on these findings, the medial approach is recommended as the most suitable for surgical access to the humeral diaphysis, while the craniolateral approach is most appropriate for access to the femoral diaphysis for the placement of compression plates in the white‐eared opossum.