A histomorphometric study of bone reactions to titanium implants in irradiated bone and the effect of hyperbaric oxygen treatment

The present study was undertaken to histomorphometrically analyze early per i-implant bone tissue reactions that occur after radiotherapy and to determ ine whether hyperbaric oxygen therapy (HBO) affects bone tissue at the micr oscopic level by altering bone morphology. Twelve rabbits received a single dose (15 Gy) of cobalt(60) radiation to one hind leg and the other hind le g served as a control. Titanium screws were placed into the femur and tibia directly after irradiation. Six animals received HBO during the first 4 po stoperative weeks. After 8 weeks of follow-up, bone specimens containing th e screws were prepared for histomorphometry. Bone-metal contact and the amo unt of bone in the thread areas and in the mirror areas were measured in a blinded manner. Periosteal bone formation and bone remodeling decreased aft er irradiation; also after HBO treatment. Hyperbaric oxygen therapy improve d bone formation in nonirradiated bone and to some extent also in the irrad iated bone. Bone maturation was improved in the HBO animals after irradiati on. It was concluded that irradiation reduces the capacity for osseointegra tion of titanium implants. Hyperbaric oxygen treatment may improve bone for mation and especially has positive effects on bone maturation after irradia tion.