gms | German Medical Science

German Congress of Orthopedic and Trauma Surgery (DKOU 2017)

24.10. - 27.10.2017, Berlin

Characterization of the in-vivo inflammatory response to polycarbonate-urethane wear debris

Meeting Abstract

  • presenting/speaker Eran Linder Ganz - Active Implants LLC, Netanya, Israel
  • Noa Cohen Mograbi - Active Implants LLC, Netanya, Israel
  • Shmuel Israeli - Emek Medical Center, Afula, Israel
  • Judit Krausz - Emek Medical Center, Afula, Israel
  • Natalia Edison - Emek Medical Center, Afula, Israel
  • Nimrod Rozen - Emek Medical Center, Afula, Israel
  • Jonathan Elsner - Active Implants LLC, Memphis, TN , United States
  • Maoz Shemesh - Active Implants LLC, Netanya, Israel

Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2017). Berlin, 24.-27.10.2017. Düsseldorf: German Medical Science GMS Publishing House; 2017. DocPO25-1000

doi: 10.3205/17dkou812, urn:nbn:de:0183-17dkou8120

Published: October 23, 2017

© 2017 Linder Ganz et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 License. See license information at http://creativecommons.org/licenses/by/4.0/.


Outline

Text

Objectives: The clinical results of a synthetic Polycarbonate-urethane (PCU) meniscus implant (NUsurface®, Active Implants) showed that symptoms associated with synovitis - pain and swelling, secondary to implant wear, are the main cause of short-term revisions (1-4 years). Synovitis typically develops due to direct contact between the implant and exposed bone or osteophytes that were not addressed during surgery. Inflammatory response to foreign body has been investigated for traditional materials (e.g. polyethylene), but limited for PCU. Our study provides systematic analysis of synovial tissues collected during revisions, in order to understand the interaction between PCU and the joint, as well as post-removal joint condition effect on future treatments.

Methods: Ten samples of synovial tissue were collected from retrievals (#0054-11-EMC). In all cases, implant damage was linked to abrasion. Average retrieval time was 30.4 months. Samples were stained with Hematoxylin & Eosin (H&E). Tissue sections were examined by experienced pathologist (JK) using plain and polarized light. Particles were traced using an image processing software and effective diameter was calculated. The implant's articulating surfaces were photographed by ESEM.

Results and Conclusion: Abrasion was observed macroscopically mostly in the device's periphery. ESEM showed uniform morphology with increased roughness, compared to normal surface. Microscopic examination of samples revealed fragments of synovial tissue showing papillary hyperplasia with proliferation of macrophages, fibroblasts and lymphocytic infiltrate. Some of the macrophages and giant cells contained hemosiderin in the cytoplasm. This finding is compatible with old hemorrhage. In addition, a proliferation of small blood vessels was observed with mixoid matrix in the papillary formations, consistent with granulation tissue. Multi-nucleated giant cells containing transparent foreign body material with positive birefringence in polarized light were observed in the samples. These findings are consistent with chronic inflammation due to the presence of foreign body. The PCU particles had a non-smooth surface structure and demonstrated an effective diameter of 8.47±8.81 µm (1.02 to 229.31 µm).

Implant wear was the main cause for short-term revisions due to inflammatory response. Our hypothesis is that a clinical effect is only exerted when particle accumulation exceeds a threshold level. Symptoms were typically eliminated after intra-op synovectmy. Microscopically, the synovial tissue indicated evidences of chronic inflammation. Particles were variable in size and shape and correlated well with previous in-vitro testing. At time of revision, all joints remained in a condition that did not adversely affect future treatments. Based on these findings, direct articulation between the implant and exposed bone should be avoided. Our findings contribute to the understanding of indications-for-use for PCU as a bearing material in orthopedics