Efficacy of a small cell-binding peptide coated hydroxyapatite substitute on bone formation and implant fixation in sheep

Abstract

Cylindrical critical size defects were created at the distal femoral condyles bilaterally of eight female adult sheep. Titanium implants with 2-mm concentric gaps were inserted and the gaps were filled with one of the four materials: allograft; a synthetic 15-amino acid cell-binding peptide coated hydroxyapatite (ABM/P-15); hydroxyapatite + βtricalciumphosphate+ Poly-Lactic-Acid (HA/βTCP-PDLLA); or ABM/P-15+HA/βTCP-PDLLA. After nine weeks, bone-implant blocks were harvested and sectioned for micro-CT scanning, push-out test, and histomorphometry. Significant bone formation and implant fixation could be observed in all four groups. Interestingly, the microarchitecture of the ABM/P-15 group was significantly different from the control group. Tissue volume fraction and thickness were significantly greater in the ABM/P-15 group than in the allograft group. Bone formation and bone ingrowth to porous titanium implant were not significantly different among the four groups. The ABM/P-15 group had similar shear mechanical properties on implant fixation as the allograft group. Adding HA/βTCP-PDLLA to ABM/P-15 did not significantly change these parameters. This study revealed that ABM/P-15 had significantly bone formation in concentric gap, and its enhancements on bone formation and implant fixation were at least as good as allograft. It is suggested that ABM/P-15 might be a good alternative biomaterial for bone implant fixation in this well-validated critical-size defect gap model in sheep. Nevertheless, future clinical researches should focus on prospective, randomized, controlled trials in order to fully elucidate whether ABM/P-15 could be a feasible candidate for bone substitute material in orthopedic practices.

Establishment and effects of allograft and synthetic bone graft substitute treatment of a critical size metaphyseal bone defect model in the sheep femur

“…Also, due to their size, surgical techniques similar or even identical to human surgery can be employed. Many ovine animal models exist to evaluate various aspects of bone healing, ranging from bone chamber implants , confined defects in cancellous bone to segmental defects . In order to replicate the clinical scenario of a metaphyseal bone resection, the largest possible standardized bone voids amenable to this bone region were created with a diameter of 25 mm and a depth of 20 mm.…”

3D perfusion bioreactor‐activated porous granules on implant fixation and early bone formation in sheep

“…The fixation strength between titanium implant and new bone in the gap in large animals was evaluated by push‐out test . A push‐out test of the bone specimens prepared in this study enabled analyses of the fixation of titanium alloy implant surface to the implanted graft materials and host bone.…”

“…Morselized allograft (∅ ∼200–600 µm) was prepared from the distal femurs and proximal tibias from one skeletally mature healthy female sheep at least 6 months before surgery. Sterile vials of 1 mL allograft were kept at −80°C until the day of surgery …”

“…The sampling probe and size were defined in order to sample 100 “hits” for bone per implant site as previously described by others . The bone ingrowth was estimated by line interception technique and was defined as bone in direct contact with implant or porous coating surface …”

“…A bilateral implant defect model previously described was used. 18,19 A concentric defect was created laterally and medially in the distal femurs of sheep. This allowed bilateral FIGURE 1.…”