Effect of low intensity pulsed ultrasound on healing of an ulna defect filled with a bone graft substitute.
A 1.5 cm unilateral rabbit ulna defect model was performed in 18 adult NZ white rabbits. The defects were filled with a beta-tricalcium phosphate bone graft substitute (JAX TCP). The surgical site in half the animals was treated daily with 20 min of low intensity pulsed ultrasound (LIPUS). Animals were sacrificed at 4 weeks (n = 3 per group) or 12 weeks (n = 6 per group) following surgery for radiographic and histologic endpoints. Radiography revealed some resorption of the JAX TCP by 12 weeks in the control and LIPUS treated groups. LIPUS treatment did not accelerate this resorption. Some new bone formation was noted in the control groups at the defect margins while little bone formed in the center of the defect at 4 and 12 weeks. In contrast, radiographs revealed more new bone at 4 and 12 weeks in the LIPUS treated animals throughout the section. Bone mineral density (DEXA) revealed a statistically significant difference at 4 weeks with LIPUS while no differences were found at 12 weeks. Histology of the LIPUS treated sections demonstrated new woven bone formation on and between the JAX TCP bone graft substitute particles across the defect. VEGF expression was increased with LIPUS treatment at 4 weeks and remained elevated at 12 weeks compared with controls. CBFA-1 expression levels were elevated with LIPUS treatment at both time points. LIPUS treatment increased bone formation in ulna defect healing with a beta-tricalcium phosphate bone graft substitute.
Walsh
William R
WR
Surgical and Orthopaedic Research Laboratories, University of New South Wales, Division of Surgery, Prince of Wales Hospital, Randwick, New South Wales, Australia. w.walsh@unsw.edu.au
Langdown
Andrew J
AJ
Auld
Jason W
JW
Stephens
Paul
P
Yu
Yan
Y
Vizesi
Frank
F
Bruce
Warwick J M
WJ
Pounder
Neill
N
D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D015519:Bone Density; D016723:Bone Remodeling; D001862:Bone Resorption; D018786:Bone Substitutes / Q000737:chemistry*; D016025:Bone Transplantation / Q000379:methods*; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000473:pathology*; D002130:Calcium Phosphates / Q000494:pharmacology; D007150:Immunohistochemistry / Q000379:methods; D015233:Models, Statistical; D011817:Rabbits; D014457:Ulna / Q000473:pathology*; D014465:Ultrasonics; D014463:Ultrasonography
D001672:Biocompatible Materials; D018786:Bone Substitutes; D002130:Calcium Phosphates; C485817:beta-tricalcium phosphate