Accelerated fracture healing in the geriatric, osteoporotic rat with recombinant human platelet‐derived growth factor‐bb and an injectable beta‐tricalcium phosphate/collagen matrix

Aging and osteoporosis contribute to decreased bone mass and bone mineral density as well as compromised fracture healing rates and bone repair quality. Consequently, the purpose of this study was to determine if recombinant human platelet‐derived growth factor‐BB (rhPDGF‐BB) delivered in an injectable beta‐tricalcium phosphate/collagen matrix would enhance tibial fracture healing in geriatric (>2 years of age), osteoporotic rats. A total of 80 rats were divided equally among four groups: Fracture alone; Fracture plus matrix; Fracture plus matrix and either 0.3 mg/mL or 1.0 mg/mL rhPDGF‐BB. At 3 and 5 weeks, rats were euthanized and treatment outcome was assessed histologically, radiographically, biomechanically, and by micro‐CT. Results indicated rhPDGF‐BB‐treated fractures in osteoporotic, geriatric rats caused a statistically significant time‐dependent increase in torsional strength 5 weeks after treatment. The healed fractures were equivalent in torsional strength to the contralateral, unoperated tibiae. Data from the study are the first, to our knowledge, to underscore rhPDGF‐BB efficacy in an injectable beta‐tricalcium phosphate/collagen matrix accelerated fracture repair in a geriatric, osteoporotic rat model. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J. Orthop Res 26:83–90, 2008