Tibial segmental bone defect treated with bone plate and cage filled with either xenogeneic composite or autologous cortical bone graft

Abstract

Tibia segmental defect healing in sheep were clinically, radiographically and histologically evaluated. Twelve young sheep aged four to five months were divided into two groups, G1 and G2. A 3.5 cm long segmental defect was created in the right tibial diaphysis with maintenance of the periosteum. The bone defects in both groups were stabilized with a bone plate combined with a titanium cage. In G1 the cage was filled with pieces of autologous cortical bone graft. In G2 it was filled with a composite biomaterial which consisted of inorganic bovine bone, demineralized bovine bone, a pool of bovine bone morphogenetic proteins bound to absorbable ultra-thin powdered hydroxyapatiteand bone-derived denaturized collagen. Except for one G1 animal, all of them showed normal limb function 60 days after surgery. Radiographic examination showed initial formation of periosteal callus in both groups at osteo-tomy sites, over the plate or cage 15 days postoperatively. At 60 and 90 days callus remodeling occurred. Histological and morphometric analysis at 90 days after surgery showed that the quantity of implanted materials in G1 and G2 were similar, and the quantity of new bone formation was less (p = 0.0048) and more immature in G1 than G2, occupying 51 +/- 3.46% and 62 +/- 6.26% of the cage space, respectively. These results suggest that the composite biomaterial tested was a good alternative to autologous cortical bone graft in this experimental ovine tibial defect. However, additional evaluation is warranted prior to its clinical usage.

Replacement, refinement, and reduction: Necessity of standardization and computational models for long bone fracture repair in animals

“…Besides artificial fracture models and osteotomies with and without defined gap sizes for examination of common fracture healing, studies could also be found where critical size defects in the sheep model are examined . The defect size varied between 10 mm and 50 mm and the tibia was used in all cases but one.…”

“…134,135 Besides artificial fracture models and osteotomies with and without defined gap sizes for examination of common fracture healing, studies could also be found where critical size defects in the sheep model are examined. [136][137][138][139][140][141] The defect size varied between 10 mm and 50 mm and the tibia was used in all cases but one. In general, plating is the predominant fixation method for these critical size defects, although different plating systems are described.…”

Radiographic measurement of tibial joint angles in sheep

“…Several orthopaedic studies have used sheep as an experimental model to test materials or surgical procedures for use on human beings, such as replacement or reconstruction of the cranial cruciate ligament (10)(11)(12) and the treatment of fractures and segmental bone defects using bone plates (13)(14)(15)(16) and external fixators (17,18). However, the influence of the bone axial alignment and joint orientation on the support of bodyweight loads during locomotion is possibly a predisposing factor for osteoarthritis development or implant failure, and have not been evaluated in sheep.…”

Preclinical Animal Models for Segmental Bone Defect Research and Tissue Engineering

“…At 60 and 90 days callus remodelling occurred. Histological and morphometric analysis 90 days post surgery showed that the quantity of implanted materials still present were similar for both groups while the quantity of newly formed bone was less (p = 0.0048) in the cortical bone graft group occupying 51 ± 3.46% and 62 ± 6.26% of the cage space, respectively (Teixeira et al 2007 ) .…”