A biomechanical evaluation and assessment of the accuracy of reduction of two methods of acetabular osteotomy fixation in dogs.
OBJECTIVE
To compare the accuracy of reduction, biomechanical characteristics, and mode of failure of two methods of acetabular osteotomy repair.


METHODS
Acetabular osteotomies were created in 16 paired hemipelves and stabilized with a screw/wire/polymethylmethacrylate composite fixation technique (SWP) or a 2-mm veterinary acetabular plate (VAP). Eight intact hemipelves were used as controls.


METHODS
Twelve canine cadavers.


METHODS
Accuracy of osteotomy reduction was evaluated grossly and by measurement of articular incongruencies formed in polyvinylsiloxane impression casts. Acetabula were loaded in modified bending until failure using a universal testing machine. Data from load-deformation curves were used to determine the biomechanical characteristics of the repaired and intact acetabula. Mode of failure was evaluated grossly and radiographically.


RESULTS
Osteotomy reduction was superior in acetabula stabilized with SWP. Mean values +/- standard deviation for load at failure and stiffness of the intact acetabula were 2,796 +/- 152.9 N and 267.5 +/- 61.9 N/mm. Corresponding values for SWP and VAP were 1,192 +/- 202.7 N and 136.3 +/- 76.5 N/mm, and 1.100.5 +/- 331.6 N and 110.0 +/- 51.3 N/mm, respectively. The mean load at failure and stiffness of intact acetabula was significantly greater than acetabula stabilized with SWP or VAP. There was no significant difference between SWP and VAP for load at failure or stiffness. Failure of acetabula stabilized with SWP occurred by fracture of the polymethylmethacrylate and ventrolateral bending of the wires. Acetabula stabilized with VAP failed by ventrolateral twisting of the plate and bending of the caudal screws.


CONCLUSIONS
SWP and VAP provide comparable rigidity, however, the SWP facilitates more accurate osteotomy reduction.


CONCLUSIONS
These findings support the use of the SWP technique as an alternative method of acetabular fracture repair.
Stubbs
W P
WP
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, USA.
Lewis
D D
DD
Miller
G J
GJ
Quarterman
C
C
Hosgood
G
G
D000077:Acetabulum / Q000293:injuries / Q000601:surgery*; D000818:Animals; D001696:Biomechanical Phenomena; D001843:Bone Cements / Q000592:standards; D001860:Bone Plates / Q000592:standards / Q000662:veterinary; D001863:Bone Screws / Q000592:standards / Q000662:veterinary; D001864:Bone Wires / Q000592:standards / Q000662:veterinary; D002102:Cadaver; D004285:Dogs / Q000293:injuries / Q000601:surgery*; D005593:Fracture Fixation, Internal / Q000379:methods / Q000592:standards / Q000662:veterinary*; D050723:Fractures, Bone / Q000601:surgery / Q000662:veterinary*; D010027:Osteotomy / Q000379:methods / Q000662:veterinary*; D019904:Polymethyl Methacrylate / Q000592:standards; D011897:Random Allocation
D001843:Bone Cements; D019904:Polymethyl Methacrylate