Kd. Johnson et al., POROUS CERAMICS AS BONE-GRAFT SUBSTITUTES IN LONG-BONE DEFECTS - A BIOMECHANICAL, HISTOLOGICAL, AND RADIOGRAPHIC ANALYSIS, Journal of orthopaedic research, 14(3), 1996, pp. 351-369
Three porous ceramic bone graft materials were compared with regard to
their ability to heal a 2.5 cm defect created surgically in a bilater
al canine radius model. The ceramic materials were analyzed at 12 and
24 weeks after surgery and included tricalcium phosphate, hydroxyapati
te, and collagen hydroxyapatite, which contained a mixture of 35% tric
alcium phosphate and 65% hydroxyapatite with added collagen. Each mate
rial was evaluated alone and with added bone marrow aspirate. All the
implants were compared with a graft of autogenous cancellous bone in t
he contralateral radius. Biomechanical testing and radiographic evauat
ion revealed that the addition of bone marrow aspirate was essential f
or tricalcium phosphate and hydroxyapatite to achieve results comparab
le with those of cancellous bone. Collagen hydroxyapatite performed we
ll without the addition of bone marrow although the addition of marrow
did have a positive effect. Further qualitative radiographic and hist
ological analysis demonstrated that tricalcium phosphate was the only
ceramic that showed any sign of degradation at 24 weeks. This observed
degradation proved to be an important factor in evaluating radiograph
s because the radiodensity of collagen hydroxyapatite and hydroxyapati
te interfered with the determination of radiographic union. At 24 week
s, tricalcium phosphate with bone marrow was the material that perform
ed most like cancellous bone. In this study, the biomechanical and rad
iographic parameters of tricalcium phosphate with bone marrow were rou
ghly comparable with those of cancellous bone at 12 and 24 weeks. Tric
alcium phosphate was the only implant that showed significant evidence
of degradation at 24 weeks by both histological and radiographic eval
uations, and this degradation took place only after a degree of mechan
ical competence necessary for weight-bearing was achieved.