In Vivo Deformation, Surface Damage, and Biostability of Retrieved Dynesys Systems

• DOI: 10.1097/brs.0b013e3181d6f84f
• Publication Date: 2010-10-23T05:43:51Z
• Authors: Allyson Ianuzzi; Steven M. Kurtz; William Kane; Priyanka Shah; Ryan Siskey; Andre van Ooij; Rajesh Bindal; Raymond Ross; Todd Lanman; Karin Büttner-Janz; Jorge Isaza
• Keywords: Polycarbonate

In Brief Study Design. Retrospective retrieval analysis. Objective. To evaluate wear, deformation and biodegradation within retrieved polycarbonate urethane (PCU) components of Dynesys systems. Summary Background Data. The Dynamic Stabilization System (Zimmer Spine) consists pedicle screws (Ti alloy), spacers, a polyethylene-terephthalate cord. Methods. Seventeen (mean implantation: 2.5 years, range: 0.7–7.0 years) 2 exemplar implant systems were available. Reasons for revision persistent pain (16/17), infection (1/17), and/or screw loosening (11/17), with 1/17 case migration. Optical microscopy, microCT, scanning electron microscopy conducted to PCU spacer wear deformation. Attenuated total reflectance Fourier transform infrared spectroscopy was used assess surface chemical composition. Results. Retrieved exhibited permanent bending (mean: 4.3°, 0.0°–15.8°). We observed evidence contact screws, cords, surrounding bony structures (74/75, 69/75, 51/75 respectively). Relatively infrequent damage modes included fracture (1/75 spacers) or cracking (2/75 spacers), as well (3/103 screws). degradation products identified in 10/75 which represented retrievals having significantly longer implantation times 4.3 1.0–7.0 years). Of these 8/10 had peaks along the side where material would have been bodily fluid. Conclusion. spacers from deformation, focal regions vivo damage. Chemical changes associated longer-term retrievals. most frequently complication loosening, 3 incidences breakage patients. These data provide crucial basis developing vitro tests simulate posterior dynamic motion preservation implants. Longer-term retrievals, that include more recent design features (e.g., HA coating), will be useful greater context clinical implications our short-term observations. stabilization (Dynesys, Zimmer Spine; n = 17) studied. Revision reasons fracture. Wear, degradative observed. motion-preservation