Fatigue microdamage in the radial predilection site for osteosarcoma in dogs

Abstract

Objective-To evaluate whether body size and anatomic site influence the quantity of bone microdamage in dogs without osteosarcoma (QS). Sample Population-Pairs of radii were collected from 10 small dogs (< 15 kg) and 10 large dogs (> 25 kg). Procedure-Specimens were stained in basic fuchsin for bone microdamage. Transverse sections were cut from each proximal and distal radial metaphysis at 15 and 85% of bone length. The following variables were determined for each region: mean microcrack length (CrLe, μm), microcrack density (CrDn, microcracks/mm2), microcrack surface density (CrSDn, μ/mm2), and estimated activation frequency (Acf, microcracks/mm2/y). Results-Metaphyseal region did not significantly influence CrDn, CrLe, and CrSDn. The CrDn and CrSDn were influenced by body size, with microdamage being increased in large dogs, compared with small dogs. However, mean CrLe was not significantly influenced by body size. Acf significantly decreased with age and was significantly decreased in large dogs and in the distal radial metaphysis, compared with small dogs and the proximal radial metaphysis, respectively. Conclusions and Clinical Relevance-Our data did not reveal an increase in microdamage or remodeling at the OS predilection site (ie, the distal metaphysis of the radius), suggesting that induction of microdamage and an associated increase in bone remodeling are unlikely to be an important risk factor for induction of OS.