Evaluation of an osteoconductive resorbable calcium phosphate cement and polymethylmethacrylate for augmentation of orthopedic screws in the pelvis of canine cadavers.
OBJECTIVE
To evaluate the effect of an osteoconductive resorbable calcium phosphate cement (CPC) on the holding power of bone screws in canine pelvises and to compare the effect with that for polymethylmethacrylate (PMMA).


METHODS
35 pelvises obtained from canine cadavers.


METHODS
Each pelvis was sectioned longitudinally. Within each pair of hemipelvises, one 4.0-mm cancellous screw was placed in the sacroiliac (SI) region and another in the iliac body. Similar regions on the contralateral-matched hemipelvis were assigned 1 of 3 augmentation techniques (CPC-augmented 4.0-mm cancellous screws, PMMA-augmented 4.0-mm cancellous screws, and CPC-augmented 3.5-mm cortical screws). Pullout force was compared between matched screws and between treatment groups prior to examination of cross sections for evaluation of cement filling and noncortical bone-to-cortical bone ratio.


RESULTS
CPC and PMMA augmentation significantly increased pullout force of 4.0-mm screws inserted in the SI region by 19.5% and 33.2%, respectively, and CPC augmentation significantly increased pullout force of 4.0-mm cancellous screws inserted in the iliac body by 21.2%. There was no difference in the mean percentage augmentation between treatment groups at either location. Cement filling was superior in noncortical bone, compared with filling for cortical bone. Noncortical bone-to-cortical bone ratio was significantly greater in the sacrum (6.1:1) than the ilium (1.3:1).


CONCLUSIONS
CPC and PMMA improve the ex vivo holding strength of 4.0-mm cancellous screws in the SI and iliac body regions and SI region, respectively. Cement augmentation may be more effective in areas with greater noncortical bone-to-cortical bone ratios.
Hutchinson
Geoffrey S
GS
Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana 61802, USA.
Griffon
Dominique J
DJ
Siegel
Arthur M
AM
Pijanowski
Gerald J
GJ
Kurath
Peter
P
Eurell
Jo Ann C
JA
Johnson
Ann L
AL
D015502:Absorptiometry, Photon / Q000662:veterinary; D000818:Animals; D001843:Bone Cements; D015519:Bone Density; D001863:Bone Screws / Q000662:veterinary*; D002130:Calcium Phosphates; D004285:Dogs / Q000601:surgery*; D005260:Female; D005593:Fracture Fixation, Internal / Q000379:methods / Q000662:veterinary*; D008297:Male; D010388:Pelvis / Q000601:surgery*; D019904:Polymethyl Methacrylate; D011897:Random Allocation; D012446:Sacroiliac Joint / Q000601:surgery; D013718:Tensile Strength
D001843:Bone Cements; D002130:Calcium Phosphates; D019904:Polymethyl Methacrylate; C020243:calcium phosphate