Evaluation of Key's hypothesis in the feline tibia: an experimental model for augmented bone healing studies
Toombs, J.P.; Wallace, L.J.; Bjorling, D.E.; Rowland, G.N.
American Journal of Veterinary Research 46(2): 513-518
1985
ISSN/ISBN: 0002-9645 PMID: 3994120 Document Number: 242647
Key's hypothesis states that a segmental long bone defect 1.5 times the diaphyseal diameter exceeds the regenerative capacity of bone in skeletally mature dogs and results in nonunion. This hypothesis was evaluated in 5 adult cats with rigidly fixed segmental tibial ostectomies ranging from 1.25 to 1.52 times the diaphyseal diameter. Clinical, radiographic, and histological data were obtained over a 12-week period. Healing was classified as mature bony union, clinical union, delayed union, or nonunion. Absence of a consolidating callus and instability after removal of fixation devices was found for all cats at 12 weeks. Scant formation of new bone within the gap was histologically evident for only one cat. In the remaining 4 cats, fibrous tissue and striated muscle predominated within the gap, and independent healing of the proximal and distal cut ends of the bone were observed. The occurrence of 4 nonunions and 1 equivocally delayed union indicated that Key's hypothesis overestimates the regenerative capacity of bone in the cat.