The efficacy of a nanosynthetic bone graft substitute as a bone graft extender in rabbit posterolateral fusion

Abstract

BACKGROUND CONTEXT: Synthetic bone graft substitutes are commonly used in spinal fusion surgery. Preclinical data in a model of spinal fusion to support their efficacy is an important component in clinical adoption to understand how these materials provide a biological and mechanical role in spinal fusion. PURPOSE: To evaluate the in vivo response of a nanosynthetic silicated calcium phosphate putty (OstP) combined with autograft compared to autograft alone or a collagen-biphasic calcium phosphate putty (MasP) combined with autograft in a rabbit spinal fusion model. STUDY DESIGN: Efficacy of a nanosynthetic silicated calcium phosphate putty as an extender to autograft was studied in an experimental animal model of posterolateral spinal fusion at 6, 9, 12 and 26 weeks, compared to a predicate device. METHODS: Skeletally mature female New Zealand White rabbits (70) underwent single level bilateral posterolateral intertransverse process lumbar fusion, using either autograft alone (AG), a nanosynthetic silicated calcium phosphate putty (OstP) combined with autograft (1:1), or a collagen-biphasic calcium phosphate putty (MasP) combined with autograft (1:1). Iliac crest autograft was harvested for each group, and a total of 2 cc of graft material was implanted in the posterolateral gutters per side. Fusion success was assessed at all time points by manual palpation, radiographic assessment, micro-CT and at 12 weeks only using nondestructive range of motion testing. Tissue response, bone formation and graft resorption were assessed by decalcified paraffin histology and by histomorphometry of PMMA embedded sections. RESULTS: Assessment of fusion by manual palpation at the 12 week endpoint showed 7 out of 8 (87.5%) bilateral fusions in the OstP extender group, 4 out of 8 (50%) fusions in the MasP extender group, and 6 out of 8 (75%) fusions in the autograft alone group. Similar trends were observed with fusion scores of radiographic and micro-CT data. Histology showed a normal healing response in all groups, and increased bone formation in the OstP extender group at all timepoints compared to the MasP extender group. New bone formed directly on the OstP granule surface within the fusion mass while this was not a feature of the Collagen-Biphasic CaP material. After 26 weeks the OstP FDA device/drug status: Osteo 3 ZP Putty (Approved for this indication), Mastergraft Putty (Approved for this indication).

"First-in-Patient Case Study of a Novel Nanosynthetic Bone Graft Substitute: OssDsign Catalyst™"

“…These results are very encouraging, however, the results must be considered preliminary as this was a single case and bone healing rates can be variable depending on the individual patient's general health and risk factors. As evidenced by the encouragingly positive pre-clinical studies with this bone graft substitute [1,2], if OssDsign Catalyst is also shown to be osteoinductive in humans, it would be interesting to assess its potential for use in metabolically challenged patients (e.g., osteoporotic, immobilization, nutritional deficiencies, diabetic or heavy smokers), which are known to be slower healers and difficult to fuse with lower expectations of a good clinical outcome [8] The surgeon in this case was pleased with the handling characteristics of this synthetic bone graft and indicated its ease of use in placement in the various areas of the surgical construct (within the interbody cage, along the posterolateral gutters). The risk of graft migration and heterotopic bone formation are minimized by suspending the OssDsign Catalyst granules in a gel carrier to create a malleable putty formulation.…”

“…The level of substituted silicate (5.8% wt% silicon) is the highest level achieved in any bone graft. Also, the high surface area of the nanoscale, porous granules promotes consistent and rapid bone ingrowth, remodeling, and cell-mediated resorption during the bone healing process [1,2] OssDsign Catalyst™ is osteoinductive, osteoconductive, resorbable, porous and is 100% synthetic without the need for adding any biological materials or natural proteins. This novel bone graft contains nanoscale silicate-substituted calcium phosphate granules suspended in a resorbable gel carrier, which enables direct implantation from the packaging without any further preparation time.…”

“…OssDsign Catalyst™ can be used as a standalone bone graft or combined with autograft for use as a bone graft extender. The high surface area of the nanoscale granules has been designed to deliver consistent and rapid bone ingrowth, remodeling and cell-mediated resorption during the bone healing process, as shown in clinically relevant animal studies [1,2].…”

Transforming Natural Eggshell and Diatomite into Bioactive Calcium Silicate Material for Bone Regeneration

“…4,5 Although allogeneic bone grafts of animal origin are abundant, they are prone to immune rejection and carry a potential risk of disease transmission. 6 As a result, new bone graft replacement materials offering good biocompatibility and osteoinductivity are of great interest.…”

“…Over 2.2 million bone graft procedures are performed every year globally to repair bone defects during neurological, oral and maxillofacial, and orthopedic surgeries . While autologous bone grafts are the gold standard for bone repair, their use is limited due to the scarcity of suitable sources and high rate of complications in the bone extraction area, such as infection, pain, and hematoma. , Although allogeneic bone grafts of animal origin are abundant, they are prone to immune rejection and carry a potential risk of disease transmission . As a result, new bone graft replacement materials offering good biocompatibility and osteoinductivity are of great interest.…”