Characterization of a Pre-Clinical Mini-Pig Model of Scaphoid Non-Union

Dominique Behrends,Nadia Zayed,Paul Martineau,Janet Henderson,Leticia Khendek,Chan Gao

doi:10.3390/jfb6020407

Abstract

A fractured scaphoid is a common disabling injury that is frequently complicated by non-union. The treatment of non-union remains challenging because of the scaphoid’s small size and delicate blood supply. Large animal models are the most reliable method to evaluate the efficacy of new treatment modalities before their translation into clinical practice. The goal of this study was to model a human scaphoid fracture complicated by non-union in Yucatan mini-pigs. Imaging and perfusion studies were used to confirm that the anatomy and blood supply of the radiocarpal bone in mini-pigs were similar to the human scaphoid. A 3 mm osteotomy of the radiocarpal bone was generated and treated with immediate fixation or filled with a dense collagen gel followed by delayed fixation. Bone healing was assessed using quantitative micro computed tomography and histology. With immediate fixation, the osteotomy site was filled with new bone across its whole length resulting in complete bridging. The dense collagen gel, previously shown to impede neo-vascularization, followed by delayed fixation resulted in impaired bridging with less bone of lower quality. This model is an appropriate, easily reproducible model for the evaluation of novel approaches for the repair of human scaphoid fractures.

Highlights

The scaphoid bone at the base of the thumb and the distal radius are the two most commonly fractured bones in the upper extremity [1]
The diagnosis of scaphoid fracture remains challenging as its clinical presentation is indistinguishable from a wrist sprain and is not always apparent on plain radiographs [3]
The problems associated with clinical presentation of scaphoid fractures can delay treatment, significantly increasing the risk of non-union, which occurs in 10% of cases

Summary

Introduction

The scaphoid bone at the base of the thumb and the distal radius are the two most commonly fractured bones in the upper extremity [1]. The diagnosis of scaphoid fracture remains challenging as its clinical presentation is indistinguishable from a wrist sprain and is not always apparent on plain radiographs [3]. The problems associated with clinical presentation of scaphoid fractures can delay treatment, significantly increasing the risk of non-union, which occurs in 10% of cases. Another factor contributing to the high incidence of scaphoid non-union, the proximal pole, is the relatively tenuous blood supply [4]. Whereas the distal scaphoid has direct arterial inflow, the proximal pole is supplied solely by intra-osseous retrograde flow, which is susceptible to interruption in the case of a fracture. Development of a relevant and reliable pre-clinical model to examine therapeutic interventions to promote scaphoid repair in the setting of delayed treatment is of critical importance to reduce disability in young, physically active individuals

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