Additive Medical Polymer Dimensional Verification Using X-Ray Tomography
Micro-CT verification of additive medical polymers requires physical pre-filtering, local adaptive thresholding, and ISO 15530-3 uncertainty budgeting.
Porous Interbody Fusion Cages
Meaning
Orthopaedic implants designed with open-pore structures to encourage bone ingrowth are used in spinal surgery to maintain spacing between adjacent vertebrae. In the medical device industry, porous interbody fusion cages provide a stable environment for bone tissue to grow through the implant. These devices are placed directly into the cleared disc space during a fusion procedure.
Implant Design
Latticed patterns within the titanium body of the implant mimic the natural structure of cancellous bone. This open architecture allows blood flow and bone cells to populate the interior of the cage. Incorrect pore sizing prevents successful fusion.
Manufacturing Method
Printing these implants with selective laser melting allows for the customisation of the pore size, density and overall shape to fit the anatomy of the patient. The laser melts titanium powder layer by layer to build the complex internal geometries that traditional machining cannot produce. Removing unmelted powder from the finished cage is necessary to ensure safety.
Mechanical Strength
Static and dynamic compression tests evaluate the implant’s ability to withstand the heavy loads of the human spine without failing. The porous structure must balance the need for low stiffness to prevent bone resorption with the need for high yield strength to prevent collapse. Rushing to market without fully testing the fatigue limit of these printed lattices can lead to catastrophic implant failure during daily patient activities.