Bryan Cunningham
St. Joseph Medical Center, Baltimore,MD,USA
Dynamic spinal stabilization serves as the nextfrontier in the surgical management of spinalpathology. As we move from an era of spinal arthrodesisto one in which segmental motion is preserved, thispromising new technology offers increasing clinical andresearch challenges in the areas of implant design,spinal kinematics, histologic osseointegration andparticulate wear debris. As an alternative to spinalfusion, dynamic spinal fixation serves to replace thesymptomatic degenerated structures, restore thefunctional biomechanical properties of the motionsegment, and protect neurovascular structures. To thisend, the implanted device should re-establishnear-normal kinematics to the functional spinal unit,encourage osseointegration at the bone-metal interface,minimize particulate wear debris and promote ananterior/posterior column load-sharing environment.
Key Points
1. Dynamic spinal stabilization should preserve thenormal mapping of segmental motion at the operativelevel and adjacent intervertebral levels versusconventional methods of spinal arthrodesis.
2. The selection of implant surface should encourage,or at least not inhibit, trabecular osseointegration atthe endplate interface and at the same time preservesegmental motion. Histopathological analysis of localand reticuloendothelial tissues in response to theimplanted device should be unremarkable.
3. Metallic and polymeric particulate wear debris fromspinal instrumentation may affect the surroundingtissue and potentially compromise long-term biologicperformance. The minimization of particulate weardebris through judicious selection of implant materials,cautious choice of bearing surfaces with minimizationof component interfaces will all likely result inoptimized mechanical and biological performance ofspinal implants.
