Journal article
In Vivo Deformation, Surface Damage, and Biostability of Retrieved Dynesys Systems
Spine (Philadelphia, Pa. 1976), v 35(23), pp E1310-E1316
01 Nov 2010
PMID: 20975485
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
Study Design. Retrospective retrieval analysis.
Objective. To evaluate wear, deformation and biodegradation within retrieved polycarbonate urethane (PCU) components of Dynesys systems.
Summary of Background Data. The Dynesys Dynamic Stabilization System (Zimmer Spine) consists of pedicle screws (Ti alloy), polycarbonate urethane (PCU) spacers, and a polyethylene-terephthalate cord. Methods. Seventeen retrieved (mean implantation: 2.5 years, range: 0.7-7.0 years) and 2 exemplar implant systems were available. Reasons for revision were persistent pain (16/17), infection (1/17), and/or screw loosening (11/17), with 1/17 case of implant migration. Optical microscopy, microCT, and scanning electron microscopy were conducted to evaluate PCU spacer wear and deformation. Attenuated total reflectance Fourier transform infrared spectroscopy was used to assess spacer surface chemical composition.
Results. Retrieved spacer components exhibited permanent bending deformation (mean: 4.3, range: 0.0 degrees-15.8 degrees). We observed evidence of PCU spacer contact with pedicle screws, cords, and surrounding bony structures (74/75, 69/75, and 51/75 spacers, respectively). Relatively infrequent damage modes included PCU fracture (1/75 spacers) or cracking (2/75 spacers), as well as pedicle screw fracture (3/103 screws). PCU degradation products were identified in 10/75 spacers, which represented retrievals having significantly longer implantation times (mean: 4.3 years, range: 1.0-7.0 years). Of these spacers, 8/10 had degradation peaks identified along the side of the spacer where the material would have been in contact with bodily fluid.
Conclusion. PCU spacers from retrieved Dynesys systems exhibited permanent deformation, focal regions of in vivo wear and surface damage. Chemical changes associated with PCU biodegradation were associated with longer-term retrievals. The most frequently observed complication was pedicle screw loosening, with 3 incidences of screw breakage in 2 patients. These retrieval data provide a crucial basis for developing in vitro tests to simulate in vivo damage and degradation of posterior dynamic motion preservation implants. Longer-term retrievals, as well as retrievals that include more recent design features (e. g., HA coating), will be useful to provide a greater context for the clinical implications of our short-term observations.
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Details
- Title
- In Vivo Deformation, Surface Damage, and Biostability of Retrieved Dynesys Systems
- Creators
- Allyson Ianuzzi - ExponentSteven M. Kurtz - Exponent (United States)William Kane - Exponent Inc, Philadelphia, PA USAPriyanka Shah - Exponent Inc, Philadelphia, PA USARyan Siskey - Exponent Inc, Philadelphia, PA USAAndre van Ooij - Maastricht Univ, Med Ctr, Dept Orthopaed Surg, Maastricht, NetherlandsRajesh Bindal - Methodist Hosp, Houston, TX 77030 USARaymond Ross - Hope Hosp, Manchester, Lancs, EnglandTodd Lanman - Ctr City Doctors Hosp, Beverly Hills, CA USAKarin Buettner-Janz - Vivantes Clin Ctr, Berlin, GermanyJorge Isaza - Baton Rouge Orthopaed Clin, Baton Rouge, LA USA
- Publication Details
- Spine (Philadelphia, Pa. 1976), v 35(23), pp E1310-E1316
- Publisher
- Lippincott Williams & Wilkins
- Number of pages
- 7
- Grant note
- R01AR056264 / NATIONAL INSTITUTE OF ARTHRITIS AND MUSCULOSKELETAL AND SKIN DISEASES; United States Department of Health & Human Services; National Institutes of Health (NIH) - USA; NIH National Institute of Arthritis & Musculoskeletal & Skin Diseases (NIAMS) R01 AR056264 / NIH; United States Department of Health & Human Services; National Institutes of Health (NIH) - USA
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- School of Biomedical Engineering, Science, and Health Systems
- Web of Science ID
- WOS:000283490100009
- Scopus ID
- 2-s2.0-78149266561
- Other Identifier
- 991019167642604721
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- Collaboration types
- Industry collaboration
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Clinical Neurology
- Orthopedics