Comparison of nanoparticular hydroxyapatite pastes of different particle content and size in a novel scapula defect model

Abstract

Nanocrystalline hydroxyapatite (HA) has good biocompatibility and the potential to support bone formation. It represents a promising alternative to autologous bone grafting, which is considered the current gold standard for the treatment of low weight bearing bone defects. The purpose of this study was to compare three bone substitute pastes of different HA content and particle size with autologous bone and empty defects, at two time points (6 and 12 months) in an ovine scapula drillhole model using micro-CT, histology and histomorphometry evaluation. The nHA-LC (38% HA content) paste supported bone formation with a high defect bridging-rate. Compared to nHA-LC, Ostim® (35% HA content) showed less and smaller particle agglomerates but also a reduced defect bridging-rate due to its fast degradation The highly concentrated nHA-HC paste (48% HA content) formed oversized particle agglomerates which supported the defect bridging but left little space for bone formation in the defect site. Interestingly, the gold standard treatment of the defect site with autologous bone tissue did not improve bone formation or defect bridging compared to the empty control. We concluded that the material resorption and bone formation was highly impacted by the particle-specific agglomeration behaviour in this study.

A large animal model for standardized testing of bone regeneration strategies

“…These results for nBV/TV have been used in the publication by Hruschka et al [ 19 ] as control groups in comparison to several bone substitute materials but were not described in greater detail. They are presented here more extensively in order to illustrate the quantitative healing properties of the experimental model.…”

“…The products or substances that are about to be tested in the defects should be subjected to identical physiological influences by being implanted in the same narrow anatomical region where conditions are constant. We describe here the establishment of this standardized model from selection of animals to surgery to the histologic and morphometric evaluation as it has been proven in a recently published study on the preclinical testing of hydroxyapatite biomaterials [ 19 ].…”

Porous Titanium Granules in comparison with Autogenous Bone Graft in Femoral Osseous Defects: A Histomorphometric Study of Bone Regeneration and Osseointegration in Rabbits

“…As new bone tissue can only be laid down in areas where there is no bone substitute material (PTG or AGM) present, the size of this available space between the particles has great influence on the amount of bone neoformation. erefore, the percentage of newly formed bone in the available space between the bone substitute materials (newly formed bone per available volume; nBV/Av.V) was also calculated [40]. To characterize the total amount of material which is potentially biomechanically active, the percentage of newly formed bone plus bone substitute material in the region of interest (composite volume per tissue volume; Co.V/TV) was determined [40].…”

“…erefore, the percentage of newly formed bone in the available space between the bone substitute materials (newly formed bone per available volume; nBV/Av.V) was also calculated [40]. To characterize the total amount of material which is potentially biomechanically active, the percentage of newly formed bone plus bone substitute material in the region of interest (composite volume per tissue volume; Co.V/TV) was determined [40]. As a measure of the quality of integration of grafted materials, the percentage of bone substitute surface that was in contact with newly formed bone (bone-to-bonesubstitute contact; BBSC) was quantified.…”

Thermal analysis of pure and multisubstituted hydroxyapatite pastes

“…The hydroxyapatite, Са 10 (PO 4 ) 6 (OH) 2 (HAP), composition is similar to bone, has good biocompatibility and bioactivity therefore is increasingly used in medicine, especially in repairing bone defects as bone grafts, coating material for metallic implants, dental implants, and drug delivery systems [1][2][3]. Nanocrystalline HAP paste is suitable bone substitute in dental and orthopedic surgery for filling bone defects in minimally invasive surgery.…”