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Wear Analysis of a Bilateral Facet Augmentation System Subject to Cyclic Compressive Impact Loading

Abstract Details

2011, Master of Science in Bioengineering, University of Toledo, Bioengineering.

Study Design: An in-vitro study to evaluate the wear profile of a novel percutaneous bilateral facet augmentation system subjected to cyclic impact loading.

Objective: To simulate in-vitro, the long term wear effects due to extension limiting impacts of the surgically shaped facets on to the polycarbonate urethane (PCU) cushion of the PercuDyn¿¿¿¿¿¿¿ (Interventional Spine Inc., Irvine, CA) device and to determine its applicability in-vivo. Wear rate and particulate characterization was determined after subjecting the device to two million cycles of compressive impact loading.

Background Context: Cyclic loading and micro motion in orthopaedic implants at articulating and/or interacting surfaces may produce wear debris in-vivo. Wear debris are known to cause adverse tissue reactions such as osteolysis at the bone-implant junction and consequently device failure due to loss of fixation from the bone. Wear debris also may cause localized tissue inflammation and metallosis. This study was designed to assess wear characteristics of the PercuDyn¿¿¿¿¿¿¿ device, primarily of the polymeric component (PCU), by simulating ‘extension’ limiting impacts of the inferior articular process onto the PCU cushion. The wear rate and size/shape characteristics of the wear debris were evaluated using techniques such as EDS and SEM.

Outcome Measure: Following two million cycles of cyclic loading, the wear particle profile (size/shape/dimension) and the wear rate were established using EDS and SEM. This data is compared to the wear data from the ‘axial rotation’ wear study of the same device and polymer related wear literature on “similar” products.

Methods: In-vitro wear testing on the MTS® Bionix Spine Wear Simulator was performed for 2 million cycles. Wear debris characterization and wear rate were determined using energy dispersive x-ray spectroscopy (EDS), scanning electron microscopy (SEM) and light microscopy techniques. An ‘isolation and recovery’ validation study was performed to assess the efficiency of particulate collection rate.

Results: The wear debris mass measured at the end of 2 million cycles for 7 test samples was 0.219mg based on the worst case recovery rate of 68.2%. The average wear rate was 0.1 mg/million cycles or 0.08 mm3/million cycles. Approximately 92% and 97% of device (PCU) wear debris were less than 10 µm after the first and second million cycles respectively; 98-99% were less than 20µm after both one and two million cycles. Almost 100% of particulates were spherical to ellipsoidal in shape.

Conclusions: The PercuDyn¿¿¿¿¿¿¿ exhibited an average ‘polymeric’ wear rate of 0.1 mg/million cycles which was substantially less than Bryan and Charité artificial disc implants. It was also less than the earlier ‘axial rotation’ wear study (0.33mg/million cycles). Wear debris size and shape configurations were similar to the above mentioned comparisons. The total polymeric wear mass was significantly less than the threshold limit of 4mg tolerable in-vivo. All outcomes indicated a favorable wear profile concluding easy phagocytosis for resulting wear debris and no probabilities of adverse tissue reactions. The in-vivo tolerability of wear debris resulting from implantation of this device was further corroborated from this adjunct study.

Vijay Goel, K (Committee Chair)
Constantine Demetropoulos, K (Committee Member)
Ioan Marinescu, D (Committee Member)
160 p.

Recommended Citations

Citations

  • Nayak, A. N. (2011). Wear Analysis of a Bilateral Facet Augmentation System Subject to Cyclic Compressive Impact Loading [Master's thesis, University of Toledo]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1311394076

    APA Style (7th edition)

  • Nayak, Aniruddh. Wear Analysis of a Bilateral Facet Augmentation System Subject to Cyclic Compressive Impact Loading. 2011. University of Toledo, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=toledo1311394076.

    MLA Style (8th edition)

  • Nayak, Aniruddh. "Wear Analysis of a Bilateral Facet Augmentation System Subject to Cyclic Compressive Impact Loading." Master's thesis, University of Toledo, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1311394076

    Chicago Manual of Style (17th edition)