The optimal size range of particulate demineralized bone matrix for osteoinduction

Abstract

There have been several investigations to determine the optimal particle size range of demineralized bone matrix (DBM) for osteoinduction. Results from these investigations have not been in agreement. Particulate bone matrix preparations can be combined with biodegradable delivery systems to treat ablative bony wounds. Therefore, an optimization of the particle size range is important. The purpose of this study was to determine the optimal size range of particulate DBM for osteoinduction at both a heterotopic and an orthotopic site. DBM was prepared according to the method of Reddi-Huggins and sieved to 13 different size ranges. In the first phase of the experiment DBM (20 mg) was placed in gelatin capsules, sealed in nylon mesh baskets, and implanted in the pectoralis muscle of 210 Long-Evans male and female rats (27 to 35 days old). In the second phase DBM (20 mg) was implanted in an 8 mm critical sized calvarial defect in an additional 210 Long-Evans male and female rats. There were 15 animals per treatment group in each phase of the study. Specimens were retrieved at 28 days post surgery, and embedded, undecalcified in plastic, sectioned, and stained using von Kossa stain. Bone formation was quantitated by radiomorphometry and histomorphometry using a Quantimet 520 Image Analysis System. Moreover, alkaline phosphatase and calcium were quantitated by atomic absorption spectrophotometry in the heterotopic site. All implants demonstrated a high degree of biocompatibility and no significant inflammatory cell infiltrates were observed in any of the specimens. Results indicate that the 590-710 um range particles produced significantly more new bone than all other size ranges (p {dollar}<{dollar} 0.05). These results further narrow those obtained by Reddi and Huggins, who found the optimum size range for particles to be 420-850 um.