Essential neural anatomy for creating a clinically translatable osseointegrated neural interface for prosthetic control in sheep

Abstract

Aim: Ovine models for osseointegrated prosthetics research are well established, but do not consider neural control of advanced prostheses. The validity of interfacing technologies, such as the Osseointegrated Neural Interface (ONI), in their ability to provide communication between native nerves and advanced prosthetics is required, necessitating a stable, longitudinal large animal model for testing. The objective of this study is to provide a detailed anatomic description of the major nerves distal to the carpal and tarsal joints, informing the creation of a chronic ONI for prosthetic control in sheep. Methods: Six pelvic and six thoracic cadaveric limbs from mature female, non-lactating sheep were utilized. Radiographs were obtained to determine average bone length, medullary canal diameter, and cortical bone thickness. Microsurgical dissection was performed to discern topographical neuroanatomy and average circumferences of the major nerves of the pelvic and thoracic limbs. Histologic analysis was performed. A surgical approach for the creation of ONI was designed. Results: Average metacarpal and metatarsal length was 15.0 cm (± 0.0) and 19.7 cm (± 1.0), respectively. Average intramedullary canal diameter was 12.91 mm (± 3.69) for forelimbs and 12.60 mm (± 3.69) for hindlimbs. The thoracic limb nerves consisted of one dorsal and three ventral nerves, with an average circumference of 5.14 mm (± 2.00) and 5.05 mm (± 1.06), respectively. Pelvic limb nerves consisted of two dorsal and one ventral nerve with an average circumference of 6.27 mm (± 1.79) and 5.40 mm (± 0.53), respectively. Conclusions: These anatomic data inform the surgical approach and manufacture of a sensory ONI for chronic testing in awake, freely ambulating animals for future clinical translation.