Remodeling of injectable, low‐viscosity polymer/ceramic bone grafts in a sheep femoral defect model

Abstract

Ceramic/polymer composite bone grafts offer the potential advantage of combining the osteoconductivity of ceramic component with the ductility of polymeric component, resulting in a graft that meets many of the desired properties for bone void fillers (BVF). However, the relative contributions of the polymer and ceramic components to bone healing are not well understood. In this study, we compared remodeling of low-viscosity (LV) ceramic/poly(ester urethane) composites to a ceramic BVF control in a sheep femoral condyle plug defect model. LV composites incorporating either ceramic (LV/CM) or allograft bone (LV/A) particles were evaluated. We hypothesized that LV/CM composites which have the advantageous handling properties of injectability, flowability, and settability would heal comparably to the CM control, which was evaluated for up to 2 years to study its long-term degradation properties. Remodeling of LV/CM was comparable to that observed for the CM control, as evidenced by new bone formation on the surface of the ceramic particles. At early time points (4 months), LV/CM composites healed similar to the ceramic clinical control, while LV/A components showed more variable healing due to osteoclast-mediated resorption of the allograft particles. At longer time points (12-15 months), healing of LV/CM composites was more variable due to the nonhomogeneous distribution and lower concentration of the ceramic particles compared to the ceramic clinical control. Resorption of the ceramic particles was almost complete at 2 years. This study highlights the importance of optimizing the loading and distribution of ceramic particles in polymer/ceramic composites to maximize bone healing. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2333-2343, 2017.

Oxidatively degradable poly(thioketal urethane)/ceramic composite bone cements with bone-like strength

“…SEM images of the composites showed minimal porosity was achieved using a low-toxicity, iron-based gelling catalyst (25:1 gel:blow, Figure 2F–G) compared to previously investigated amine-based catalysts with high blowing power (1:20 gel:blow). 10, 13, 23, 34 …”

“…To enhance the osteoconductivity of the PTKUR, it was combined with two different types of ceramics: (1) 85% β-tricalcium phosphate (β-TCP)/15% hydroxyapatite (HA) ceramic mini-granules (MASTERGRAFT ® , MG), or (2) nanocrystalline hydroxyapatite (nHA) particles. 22, 23 The reactivity, rheological properties, mechanical properties, degradation rate, and cell proliferation response of the cements were assessed in vitro . The biocompatibility and remodeling of PTKUR/ceramic composite cements were investigated in a rabbit femoral condyle plug defect model to assess material resorption and integration with the host bone.…”

Settable polymer/ceramic composite bone grafts stabilize weight-bearing tibial plateau slot defects and integrate with host bone in an ovine model

“…For histomorphometric analysis, the defects were divided into rectangular areas of interest (AOI) with 1 mm height and widths one-half of the total depths of the defects as we have described previously (Figure 3). [37, 41] Each AOI was numbered from the center of the defects based on its distance from the mid-section. As shown in Figure 3, the outer AOIs 4 and -4, which lie 3 – 4 mm away from the center line, include both cement and host bone due to the irregular boundaries of the defect.…”

“…As shown in Figure 3, the outer AOIs 4 and -4, which lie 3 – 4 mm away from the center line, include both cement and host bone due to the irregular boundaries of the defect. Considering previous studies reporting densification of host bone surrounding the cement [37, 41], the reaction of the bone to the implanted cement was assessed in the interfacial AOIs 4 and −4. Area-% new bone, CG, and nHA-PEUR were measured for each region at early and late time points using Metamorph ® software.…”

Injectable, compression‐resistant polymer/ceramic composite bone grafts promote lateral ridge augmentation without protective mesh in a canine model

“…The CR composites tested in the lateral ridge defects contained 45 wt% CM particles (MasterGraft, Medtronic Spine & Biologics). This FDA‐approved ceramic was chosen based on its compression‐resistant and osteoconductive properties observed when implanted in porcine mandibular continuity defects (Herford et al, ), sheep femoral plug defects (Talley, Kalpakci, Shimko, et al, ; Talley, Kalpakci, Zienkiewicz, et al, ), and posterolateral fusion in non‐human primates (Akamaru et al, ). Additionally, block‐type biphasic calcium phosphates supported local delivery of rhBMP‐2 and new bone growth in a rabbit calvarial defect (Kim et al, ).…”