Fiducial markers made from tantalum are suitable for marking of PEEK implants and for direct implantation in the human body. Tantalum (Ta) has a high density (16 g per cm3), offers good radio-opacity and requires a low x-ray dose for examination. The metal are therefore the perfect option as fiducial marker in a low density material medical device. Tantalum metal is further highly biocompatible and has been used for surgery for more than 30 years without any severe events reported. Tantalum x-ray markers is among the safest options currently available.
Tantalum PEEK Markers in Implants
For x-ray marking purposes, tantalum indicators are suitable for.g. spinal cages and joint implants made from polymers. The markers allow exact determination of the position of the implant during surgery by digital imaging in combination with tantalum reference markers during RSA. For PEEK implants the tantalum component may be used in different forms as shown below. Often a marker set is used (e.g. a pin together with spherical beads) to allow three dimensional determination of the medical device.
Typical Tantalum Marker Shapes
Pins made from tantalum wire or tantalum rod material may be inserted in different lengths in e.g. spinal cages allowing the surgeon to determine the type of implant inserted.
Tantalum beads or balls are commonly used for insertion in human tissue (as the may be inserted by a gun) and in various shapes in the implant (e.g. hip, knee, spinal etc). The advantage by the spherical markers is that they show up as points in the radio graphs and it is possible to determine to what extend the PEEK implant migrates in the body. Implant migration may be determined by RSA techniques where x-rays images obtained from the patient allow surgeons to make precise measurements on prosthesis migration down to approximately 0.1 mm.
Literature on Tantalum Markers in PEEK used for RSA