EFFECT OF HOMOLOGOUS FIBRIN ADHESIVE ON CALLUS FORMATION AND EXTRACORTICAL BONE BRIDGING AROUND A POROUS-COATED SEGMENTAL ENDOPROSTHESIS INDOGS

Modular, porous-coated, titanium segmental endoprostheses were implant ed bilaterally in the femoral diaphysis of 7 adult mixed-breed dogs. A utogenous bone graft in particle form was placed around the implant an d bone. In 1 limb, homologous fibrin adhesive was mixed with the graft in situ before soft tissue closure. The contralateral limb was grafte d in identical manner, but without fibrin adhesive, and served as a co ntrol. Radiography was performed immediately after surgery and 1, 2, 3 , 4, 6, 8, 10, and 12 weeks later to assess callus area and bone remod eling. At 12 weeks, dogs were euthanatized and bone/implant fixation s trength was tested under torsion and compared with values for 6 in vit ro controls. Histomorphometric and microradiographic analyses of trans verse sections of the distal portion of the implanted femurs were perf ormed. Radiographic callus area was significantly (P < 0.05) smaller i n the femurs grafted with fibrin adhesive, compared with the contralat eral control. New bone formation (21.4 +/- 1.8% vs 19.2 +/- 2.4%), unl abeled bone (64.8 +/- 3.0% vs 67.9 +/- 4.2%), porosity (13.9 +/- 0.7% vs 12.9 +/- 0.8%), and bone ingrowth into the porous coating (10.3 +/- 0.9% vs 10.0 +/- 1.2%) were not significantly different between fibri n- and nonfibrin-grafted implants, respectively. There were no signifi cant differences in torsional strength of implant fixation between the fibrin- and nonfibrin-grafted femurs or between the in vivo implanted femurs and the in vitro controls. These data indicate that fibrin adh esive may have been advantageous in maintaining apposition of bone gra ft adjacent to the endoprosthesis, but it probably did not have an enh ancing effect on extracortical bone bridging or ingrowth over a porous -coated segmental bone replacement endoprosthesis.