Surgical Approaches for Peripheral Nerve Injury Models in Yucatan Pigs

Peripheral nerve injury (PNI) is a common component of combat extremity trauma, frequently associated with residual disability. Large animal models are critical for the study of PNI because of their anatomical and physiological similarities to human nerves. This study describes reproducible surgical techniques for creating PNI models in Yucatan pigs using the median and sciatic nerves.

For median and ulnar nerve exposure, pigs were positioned in the right lateral recumbent with the left forelimb retracted off the field. A transverse incision was made at the axillary crease, exposing the superficial pectoral muscle and its distal fascia insertion. This was subsequently incised, exposing the median and ulnar nerves. The nerves were isolated from surrounding tissues, extending from the brachial plexus to the elbow. For sciatic nerve exposure, pigs were positioned in the left lateral recumbent, and an incision was made connecting the lateral femoral epicondyle and the greater trochanter. The fascia lata and biceps femoris were incised and bluntly dissected off the femur posteriorly, exposing the sciatic nerve. All nerve injuries were created using a #10 scalpel with the intent of minimizing pressure during transection and creating perpendicular cut faces for appropriate neurorrhaphy. Both the median and sciatic nerves were used for single-cut injuries, although the median nerve was used to create segmental defects between 2-5cm which were reconstructed using an ipsilateral ulnar nerve autograft.

These techniques were applied successfully to 36 experimental animals without modifications to the landmarks or intervals. All nerve injuries created were amenable to immediate re-approximation with primary neurorrhaphy, or autograft reconstruction in the case of segmental defects. There were no instances of infection or wound dehiscence, and all animals were able to ambulate. Multiple study surgeons were trained using these approaches and injury methods, including surgeons without prior nerve surgery experience. Mean operative time from skin incision to nerve repair was under one hour for single-cut defects (mean 49.75 ± 16.38 minutes) and under 90 minutes for segmental defects (mean 76.26 ± 21.17 minutes).

This work expands existing porcine PNI literature by describing reproducible surgical techniques for forelimb nerve injury and supplementing prior work focused predominantly on hindlimb models using the sciatic and common peroneal nerves. These techniques provide a structured framework for large-animal PNI experimentation and may reduce technical variability during early model development.