Resorbable calcium phosphate particles as a carrier material for bone marrow in an ovine segmental defect

Resorbable calcium phosphate ceramics are only osteoconductive; therefore, their combination with osteogenic substances may lead to stimulation of bon e healing. In the present study this combination, using autologous bone mar row, was investigated. In 31 sheep, a 3-cm tibial segmental defect was crea ted and stabilized with an intramedullary nail. The animals were divided in to four groups: empty defects (group 1, n = 7), and defects filled with 10- mL dense resorbable calcium phosphate particles (group 2, n = 8), with 10-m L particles soaked in bone marrow (group 3, n = 8), or with 10-mL autologou s bone (group 4, n = 8). On evaluation after 12 weeks, significantly higher values were seen in group 3 than in group 2 for callus volume (p = .016), bone mineral density ratio (p = .03), bone mineral content ratio (p = .04), torsional strength (p = .005), and torsional stiffness (p = .01). For all end points, the outcome of group 3 was lower than that of group 4. In the h istology, there was direct contact between newly formed bone and remnants o f the particles. There were no signs of inflammatory reactions. Although a stimulatory effect of bone marrow was seen, the combination of resorbable c alcium phosphate particles with bone marrow does not provide an alternative for autologous bone grafting. (C) 2000 John Wiley & Sons, Inc.