Ossification defects detected in CT scans represent early osteochondrosis in the distal femur of piglets

Abstract

ABSTRACT:The purpose of the current study was to validate the use of CT for selection against osteochondrosis in pigs by calculating positive predictive value and comparing it to the positive predictive value of macroscopic evaluation, using histological examination as the reference standard. Eighteen male, hereditarily osteochondrosis-predisposed piglets underwent terminal examination at biweekly intervals from the ages of 82-180 days old, including CT scanning, macroscopic, and histological evaluation of the left distal femur. Areas of ischemic chondronecrosis (osteochondrosis) were confirmed in histological sections from 44/56 macroscopically suspected lesions, resulting in a positive predictive value of 79% (95% CI: 67-84%). Suspected lesions, that is; focal, radiolucent defects in the ossification front in CT scans corresponded to areas of ischemic chondronecrosis in 36/36 histologically examined lesions, resulting in a positive predictive value of 100% (95% CI: 90-100%). CT was superior to macroscopic evaluation for diagnosis of early stages of osteochondrosis in the distal femur of piglets. The current histologically validated observations can potentially be extrapolated to diagnostic monitoring of juvenile osteochondritis dissecans in children, or to animal models of human juvenile articular cartilage injury and repair. ß

An Update on the Pathogenesis of Osteochondrosis

“…11). Plain computed tomography (CT) scan, reprinted with permission from Olstad et al 82 Figure 11. Landrace pig, 174 days old: there is a lesion consisting Figure 11.…”

“…Sagittal, barium-perfused, and Spalteholz-cleared slab, reprinted with permission from Ytrehus et al 132 other than osteochondrosis (1 growth plate fracture and 3 mixed radiopacity defects at the origin of the long digital extensor tendon). 82 Focal, uniformly radiolucent defects in the ossification front of growing pigs were therefore highly specific for ischemic chondronecrosis and may be used in CT screening for osteochondrosis. 82 Thirty of the 36 lesions of osteochondrosis (83%) contained multiple, closely adjacent radiolucent defects or ''lobes'' (Fig.…”

“…Thus, in addition to the fact that focal, uniformly radiolucent defects in the ossification front were highly specific for osteochondrosis, multilobulated defects may be pathognomonic for primary disease of the cartilage canals (see ''Causes of Vascular Failure,'' below) and resultant ischemic chondronecrosis. 82 It should be noted that because they do not alter attenuation, the intracartilaginous areas of ischemic chondronecrosis (osteochondrosis latens) that were detectable in the equine arterial contrast-enhanced CT scans 77,79 were not detectable in the plain porcine CT scans. 82 However, all lesions detected in pigs that were 159 days old included at least 1 area of ischemic chondronecrosis that was surrounded by the ossification front (osteochondrosis manifesta) and therefore detectable in CT scans.…”

“…82 It should be noted that because they do not alter attenuation, the intracartilaginous areas of ischemic chondronecrosis (osteochondrosis latens) that were detectable in the equine arterial contrast-enhanced CT scans 77,79 were not detectable in the plain porcine CT scans. 82 However, all lesions detected in pigs that were 159 days old included at least 1 area of ischemic chondronecrosis that was surrounded by the ossification front (osteochondrosis manifesta) and therefore detectable in CT scans. 82 In vivo longitudinal monitoring of spontaneous lesions in pigs by serial CT examination.…”

Genetic trends of conformation traits and genetic correlations to osteochondrosis in boars

“…In a study described by Olstad (2014), a cohort of piglets was serially scanned from two to eight times at biweekly intervals with conventional CT, Aasmundstad, Gjerlaug-Enger, Grindflek and Vangen and then, following the last scan for each piglet, a postmortem sectioning of distal femur into slabs were performed. The lesions seen with CT were attempted validated by histology, and a high correlation was found.…”