Study: Spinal Fixation Rods Can Improve Patient Outcomes

The results of a study conducted by Spinal Resources Inc., show that Bezier-surfaced continuously tapered spinal fixation rods are better than standard constant diameter rods in correcting spinal deformities. 

“Excessive implant stiffness is known to result in stress shielding-induced implant loosening and failure as well as post-operative proximal junctional issues. To address these issues, stepped and conical fixation rods with reductions in outer diameter have been introduced to gradually transfer additional load to spinal segments proximally,” researcher Dr. Craig Slyfield said. “It is exciting such technologies are being developed in an effort to address Proximal Junction Kyphosis (PJK) and spinal fixation implant failure.”

According to the study data, Bezier-surfaced rods provide advantages to both surgeons and patients over standard constant diameter rods, as well as over stepped-reduction-in-diameter rods in correcting spinal deformities. The larger diameter section of the rod supplies solid support. As the diameter narrows, the rod becomes more flexible which means the spine itself is supporting proportionally more load, gradually transferring all the forces that are held by the rod into the bone instead.
 
Continuously tapered spinal fixation rods give surgeons greater control over rod and screw placement, allowing them to accommodate the geometry of the patient’s spine – not the rod design. The continuous rods showed a reduction in stresses at the diameter transition junctions, better screw-bone contact pressures, and reduced material stresses in screw necks as compared to both constant diameter and stepped rods. The improvement in screw neck stress should lead to a reduced risk of screw neck breakage.
 
“Proximal and distal junctional issues remain one of the main causes of failure in adult deformity surgery in thoracolumbar and cervical deformity surgery,” stated Christopher Ames, M.D., director of Spinal Deformity and Spine Tumor Surgery and co-director of the combined High Risk Spine Service, the Neurospinal Disorders Program, and the UCSF Spine Center. “Further development work in stress transition solutions such as ligament augmentation and improved rod stiffness transitions at proximal and distal junctions are likely to be our best solutions in combination with patient-specific alignment planning. These surgeries tremendously benefit our aging population with spinal problems and, therefore, it’s encouraging to see these types of innovations being developed.”
 
“We anticipate the initial release of the rod-based technology along with the individual diameter 4.75, and 5.0 diameter rods around the third quarter of 2021,” projected Bernie Bedor, president and CEO of Spinal Resources Inc. “We are delighted with the development of our pipeline and look forward to advancing the rod-based technology into a posterior cervical platform in 2022.”