Nonunion using a canine model

Abstract

The investigation involved a search for a model of atrophic nonunion. Fifty-two mature, adult, mongrel dogs were used to study the repair after creating a 0.5-cm bone defect in the mid-diaphysis of the radius. In addition, a 2-cm wide strip of periosteum was circumferentially resected from each osteotomy extremity. No immobilization was used thereafter. The reparative process was assessed by X-rays, histology, vascular injection, and scintigraphy. The dogs we distributed into three groups according to the time of follow-up (1, 3, and 6 months). Two kinds of repair were recognized after 3 months and were well-established after 6 months: disturbed healing with much callus (54%) and disturbed healing with absent or scanty callus (46%). In the first instance, the periosteum had regenerated and produced the external callus. The bone ends were capped with fibrocartilage; the vascularization around the defect was increased and displayed a well-defined vascular picture. In the healing pattern with absent external callus (atrophic nonunion), the bone defect was enlarged and filled with fibrous tissue, but there was no deficient vascularization in and around the osteotomy. Radioactivity counting showed an increased uptake around the osteotomy site in both types of repair, which persisted over time but was higher in the 1-month group. It was concluded that the present model yields a consistent pattern of a disturbed reparative process that mimics human cases of atrophic or hypertrophic nonunion. The differences between the two kinds of repair seemed to be related to the periosteal capacity of regeneration.

The use of 18F-fluoride and 18F-FDG PET scans to assess fracture healing in a rat femur model

“…A more stringent preclinical model that could reproducibly distinguish between the formation of bony unions and hypertrophic nonunions, which may also reveal increased signal uptake, would be useful in future studies evaluating the role of PET scans in the assessment of delayed fracture healing. However, to our knowledge, only two published studies have reported the formation of a hypertrophic nonunion from micromotion at the fracture site in an animal model (canine), and none of these nonunions can be reproduced in a consistent manner [71,72].…”

Mechanical induction of critically delayed bone healing in sheep: Radiological and biomechanical results

“…There are only few studies that verify the cessation of the healing in non-unions by analyzing a long-term group (Hietaniemi et al, 1995;Volpon, 1994). However, this seems inevitable especially for hypertrophic non-union models, because a decrease of the movement below the critical amount, e.g.…”

Characterization of pseudarthrosis with ultrasound backscattered signals in rats

“…Several animal species have been used to create a pseudarthrosis 14,[17][18][19][20] , but the authors usually converge their attention to the relevance of vascularization or to the extension of the bone segment injured.…”

“…The success in obtaining pseudarthrosis in dog's models is variable reaching nearby 86 to 95% of the experiments described and it takes three to seven months after surgery to be observed 19 . In the current research with rats it was verified 100% of positive results in the production of this kind of injury within four months after the surgical procedure.…”