Experimental study of bone lengthening in dogs by means of backscattered scanning electron microscopy.
OBJECTIVE
To describe the morphology of calcified tissues involved in distraction osteogenesis (DO) by means of backscattered scanning electron microscopy (BS-SEM).


METHODS
Experimental study.


METHODS
Adult female Beagle dogs (n=12).


METHODS
Non-simultaneous and bilateral transverse mid-diaphyseal osteotomies performed in tibiae were stabilized and distracted by a Type Ia external skeletal fixation device. After a latency period of 5 days, distraction was applied at a rate of 0.5 mm every 12 hours for 10 days. Then, the external fixator was maintained in a static mode during the consolidation period until bone healing or euthanasia at 1, 2, 3, 4, 6, 8, 10, 12, 14, and 18 weeks after operations, whichever came first. Distracted regions were isolated and their structure was examined by BS-SEM.


RESULTS
Calcified chondroid tissue was prominent during distraction and calcified cartilaginous tissue during consolidation; both tissues were successively replaced by woven, lamellar, and osteonal bone.


CONCLUSIONS
In osteotomized tibia, chondroid tissue is the main component of the mineralization front during distraction, calcified cartilaginous tissue during consolidation, and then both tissues are replaced by woven, lamellar, and osteonal bone. The ossification mechanism of distraction callus is transchondroidal.


CONCLUSIONS
BS-SEM is an effective technique for studying progression of bone healing during DO. The presence of chondroid tissue during DO explains why callus mineralization occurs more rapidly during distraction than during static stabilization.
Lafuente
Pilar
P
Department of Animal Medicine and Surgery, College of Veterinary Medicine, Autonomous University of Barcelona, Barcelona, Spain. mp_lafuente@yahoo.es
Franch
Jordi
J
Durall
Ignacio
I
Manzanares
Cristina
C
D000818:Animals; D001344:Autopsy; D001858:Bone Nails; D002113:Calcification, Physiologic; D004285:Dogs / Q000601:surgery*; D016267:External Fixators; D005260:Female; D008855:Microscopy, Electron, Scanning / Q000379:methods / Q000662:veterinary; D019857:Osteogenesis, Distraction / Q000379:methods / Q000662:veterinary*; D010027:Osteotomy; D011859:Radiography; D013977:Tibia / Q000000981:diagnostic imaging / Q000601:surgery*