Biostability of an orthopaedic device and its long-term implantable biomaterials

Lawless, Bernard Michael (2019). Biostability of an orthopaedic device and its long-term implantable biomaterials. University of Birmingham. Ph.D.

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Abstract

The BDyn device is a bilateral posterior dynamic stabilisation spinal implant used to treat degenerative disc disease. The BDyn device consists of a polycarbonate urethane (PCU) component, a silicone component, a mobile titanium alloy rod, a fixed titanium alloy rod and it is fixed to the vertebrae by titanium alloy pedicle screws.

The viscoelastic properties, chemical structure and surface morphological changes of the untreated, in vitro degraded and in vivo degraded were compared. The macro and micro-scale viscoelastic properties, chemical structure and surface morphology of five long-term implantable PCU biomaterials, which were in vitro degraded by four separate degradation methods were also investigated.

No resonant frequencies were reported for the untreated and in vitro degraded components and devices however, resonance was detected in the frequency sweep test of BDyn Explant 2 with the sharp increase of the loss stiffness occurred at 4 Hz; this highlights the importance of evaluating orthopaedic devices with frequency dependent mechanical testing techniques. The biomaterials were viscoelastic throughout the frequency range tested and were significantly different at specific frequencies when comparing untreated specimens to specimens degraded by a specific degradation method; this further highlights the need to evaluate elastomeric biomaterials with frequency dependent mechanical testing techniques.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):