Cavetto Phusion Metal
Phusion Metal is a proprietary and novel porous intermetallic compound that obtains an irregular open porous structure optimized for bone ingrowth. The elastic modulus of 0.7 – 1.3 GPa lies within the range of human cancellous bone. A low elastic modulus may preserve bone stock and reduce implant subsidence. Surface friction allows for initial stability and reduces the risk of implant migration. This unique and osteoconductive porous structure allows bone to grow throughout the irregular pores resulting in a more rapid and robust fusion.
Poly-ether-ether-ketone (PEEK), a high-performance radiolucent thermoplastic material with an elastic modulus of 4.1 GPa has been widely used for interbody cage devices over the past decade. However, PEEK is nonporous, provides limited cell response, has been known to form a fibrous connective interface and does not integrate well with bone.
The main objective of this study was to compare a proprietary Phusion Metal interbody fusion cage to a commercially available PEEK interbody fusion cage in an ovine lumbar interbody fusion model. We hypothesized that this open-celled and fully interconnected porous structure would encourage superior bone-to-implant contact and allow bone ingrowth throughout the pores in all directions with substantial implant incorporation, thus, resulting in a more rapid and robust fusion.
Eight sheep underwent an instrumented 2-level lumbar intervertebral fusion at L2-L3 and L4-L5. Each animal was implanted with two different types of interbody fusion cages: commercially approved PEEK cage with autologous bone graft; Phusion Metal cage with autologous bone graft. The animals were evenly divided into 2 time points on the basis of follow-up period; 4 months and 6 months.
Soft tissues (n=42) from heart, liver, lung, spleen, lymph node, and kidney were fixed, dehydrated, cleared, infiltrated, and embedded using standard paraffin histology techniques and equipment.
Sheep underwent lateral and dorsoventral lumbar radiographs as well as computed tomographic scans of the lumbar spine following immediate post-op and euthanasia.
Histological sections were stained with Sanderson’s Rapid Bone stain which provided differentiation of cells and allowed detection of cartilage within the tissue. Slides were then counterstained using a Van Gieson bone stain that allows differentiation of collagen and detection of bone. Histomorphometric measurements were made to quantify the area of new bone + fibrous reactive tissue + osteoid filling the pores of Phusion Metal.
Both the protocol and qualifications of the personnel involved in the study were reviewed and approved by the Institutional Animal Care and Use Committee (IACUC). This preclinical study has been performed in compliance with Good Laboratory Practice for Nonclinical Laboratory Studies (GLP) defined in the current FDA, 21 CFR 58.
No animals were lost or showed signs of infection, lameness or neurologic deficits throughout the study period. Histological analysis of soft tissues (n=42), including heart, liver, lung, spleen, kidney and lymph node was normal for conventionally raised sheep. There were no changes that were considered as potential toxic effects of the implants or procedures. Neither implant related issues nor migrations occurred throughout the study.
With regards to undecalcified bone sections, Phusion Metal demonstrated new reactive bone completely capping the vertebral endplates adjacent to the implants at 4-month and 6-month time points. Phusion Metal implants had less fibrous encapsulation compared to PEEK and had variable amounts of reactive bone directly in contact with the implant surface replacing the fibrous capsule (Figure 2 & Figure 3).
A comparison of radiographs and computed tomographic examinations at time=0 and at euthanasia showed neither signs of implant related issues nor migrations at 4 months and 6 months (Figure 5).
Surgical implantation was achieved in all animals without any adverse events. The wounds were all well-healed and normal ambulation recovery was noted in all animals. There were no adverse reactions to the organs. Radiographic and CT scan evaluation confirmed there was neither evidence of migration nor implant related issues at all time points. No evidence of any adverse reactions to the implants was noted throughout the study.
In an attempt to increase the bone remodeling properties of PEEK, a number of surface technologies have been recently introduced to the market. Although plasma-sprayed titanium coatings on PEEK have been shown to improve bone formation at the implant-bone interface, wear debris and delamination may occur during impaction. Solid titanium cages with a nano-textured surface improves bone ongrowth, however, they obtain high material stiffness with an elastic modulus of 110-115 GPa which may lead to increased subsidence rates.
Phusion Metal has several unique properties and potential advantages compared to PEEK and other surface coated intervertebral fusion cage materials. Phusion Metal® has an irregular porous structure with interconnected passageways that facilitates bone integration throughout the pores, thus, the material actively participates during the entire fusion process.
As seen in the histology images, this intermetallic compound promotes substantial through-growth of bone during the early stages of the healing cascade.
The preclinical GLP study demonstrates the osteoconductive and osseointegrative nature of Phusion Metal used in an interbody fusion ovine model. Unlike PEEK, the proprietary and novel Phusion Metal intermetallic material allowed for early osseointegration at the implant surface adjacent to both endplates and osteoconduction throughout the pores. Phusion Metal, a biocompatible and bone-friendly porous intermetallic compound, holds promise of more rapid and complete bone growth to improve overall spinal fusion outcomes.
Refer to the Phusion Metal Instructions for Use for proper use, precautions, warnings, indications, and labeling.
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NeuroStructures, Inc., is proud to announce it is now certified as ISO 13485 compliant. The certification is accredited by Lloyd’s Register Quality Assurance, Inc. (LRQA). To become certified as ISO 13485 compliant, NeuroStructures, Inc. underwent a thorough evaluation process that included quality management system development, a management system documentation review, pre-audit, initial assessment, and clearance of non-conformances, all of which work to identify corrective actions that elimination non-conformance to the quality management standard. NeuroStructures received its ISO 13485 certificate of registration on September 11, 2015. The certification of compliance with ISO 13485 recognizes that the policies, practices and procedures of our company ensure consistent quality in the services and work product we provide our customers. With this certification, our clients can be confident that Neurostructures is dedicated to maintaining the highest efficiency and responsiveness in achieving our ultimate goal – guaranteed customer satisfaction. To maintain our certification, LRQA will perform annual audits to ensure compliance and to assess initiatives for continued improvement. Our customers can be confident that NeuroStructures will continue to provide the high quality services they have come to expect well into the future. We believe that our decision to become ISO 13485 Certified is a proactive one that not only anticipates the demands of our customers, but also demonstrates our commitment to providing quality services to all our customers in the medical industry.
