title: Long-term BMP-2-induced bone formation in rat island and free flaps.
abstract: Ectopic osteoinduction by exogenous bone morphogenetic proteins (BMPs) is rapid but heretofore characterized as transient. A rat model of carrier-free recombinant human BMP-2 intramuscular implantation was used, followed by creation of either an island flap or transplantation of a free flap. BMP-2 injection into an unaltered gastrocnemius, thigh adductor, or cutaneous trunci (thoracic wall) muscle site led to bone resorption at 4 weeks. In contrast, creation of an island or free flap of the muscle/injection site caused the newly formed ossicle to maintain its bony composition with active osteoblastic presence, from 3-8 weeks. Muscle denervation or sectioning of the Achilles tendon (for gastrocnemius injections) did not prevent bone resorption at 4 weeks. There was little osteoclastic activity within de novo bone sites of island- and free flap-injected muscles at 4 and 8 weeks. These data demonstrate that simple injection of BMP-2 into a surgically isolated flap site results in the prolonged presence of de novo bone. These findings suggest that BMP-injected island or free muscle flaps may be used to generate new bone for reconstruction of a bony defect.
authors.affiliation: Department of Orthopaedic Surgery, Medical College of Wisconsin, 8701 Watetrtown Plank Road, Milwaukee, WI 53226, USA. bcooley@mcw.edu
authors.forename: Brian C
authors.initials: BC
authors.lastname: Cooley
authors.forename: Roger A
authors.initials: RA
authors.lastname: Daley
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Toth
mesh_terms: D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology*; D008866:Microsurgery; D023421:Models, Animal; D016348:Osseointegration / Q000187:drug effects*; D051381:Rats; D013524:Surgical Flaps
chemical_list: D019485:Bone Morphogenetic Proteins