Polymethylmethacrylate (PMMA) plastic has been a standard cement substance used by orthopedic surgeons to inject into bone for repair of fractures or stabilization of impants. Now Orthovita, a company out of Malvern, Pennsylvania, has received FDA approval for a new substance that plans to give PMMA a run for its money. The CORTOSS bone augmentation material recently completed a clinical trial testing its effectiveness and safety for vertebral compression fractures, producing rather positive results.
CORTOSS Bone Augmentation Material is a blend of cross-linking resins and reinforcing fillers, which include the proprietary bioactive glass found in Orthovita’s VITOSS™ Bioactive FOAM products. Unlike PMMA, CORTOSS does not contain a methylmethacrylate monomer. The composite has a constant, paste-like consistency when being injected and sets quickly to create a load bearing implant with the mechanical properties of human cortical bone. In the pivotal study, CORTOSS demonstrated flow and fill into the existing intra-vertebral anatomy rather than displacing it like PMMA, which may reduce the volume of material required for clinical success. Pre-clinical in vitro and in vivo studies show that, after implantation, a bioactive response occurs at the implant’s surface which promotes the deposition of calcium phosphate, thereby strengthening the implant-bone interface. The unique flow characteristics of CORTOSS allow low-pressure, manual delivery through Orthovita’s ALIQUOT™ Delivery System. CORTOSS’ mix-on-demand preparation allows clinicians to stop material injection for an indeterminate amount of time, thus providing a high degree of procedural flexibility.
In April 2009, Orthovita submitted the 2-year follow-up clinical data for patients enrolled in the company’s prospective, randomized, multi-center study comparing the efficacy of PMMA to CORTOSS. In this 256-patient pivotal trial conducted under an investigational device exemption, CORTOSS achieved its primary end-point of non-inferiority to the PMMA control at 24-months using a composite endpoint success rate reflecting improvement in the Visual Analogue Pain Scale (VAS) pain score, maintenance or improvement in Oswestry Disability Index (ODI) function assessment, maintenance of vertebral height and alignment, and no subsequent device-related surgical intervention at the index treatment level. In the pivotal study at 24 months:
• The composite endpoint success rate was 76.9% for patients treated with CORTOSS and 73.4% for PMMA patients.
• With an ODI success rate of 96.7%, the CORTOSS patient group experienced a statistically significant benefit in function success over the PMMA group, which had an ODI success rate of 88.4%.
Early patient outcomes were also assessed in the pivotal study at 3 months:
• The composite endpoint success rate was 82.8% for patients treated with CORTOSS and 73.7% for PMMA patients.
• With a VAS success rate of 86.6%, the CORTOSS patient group experienced a statistically significant benefit in pain success over the PMMA group, which had a VAS success rate of 75.0%.
In addition to the statistically significant benefit in pain success at three months and function success at 24 months, the CORTOSS population experienced measurable benefits over the PMMA cohort in the following outcomes:
-A 43.4% reduction in subsequent, adjacent level fractures in CORTOSS patients treated for a primary fracture at one level, as measured at the end of the 24-month follow-up period.
-The CORTOSS patients required an average of 30% less material to achieve fracture fill.
Product page: Cortoss Bone Augmentation Material