gms | German Medical Science

61st Annual Meeting of the German Society of Neurosurgery (DGNC) as part of the Neurowoche 2010
Joint Meeting with the Brazilian Society of Neurosurgery on the 20 September 2010

German Society of Neurosurgery (DGNC)

21 - 25 September 2010, Mannheim

PIERCE-PEEK trial (Prospective International Evaluation of Radiological and Clinical Effects of PEEK Cages for Cervical Spinal Fusion): Final results of an international prospective multi-centre study

Meeting Abstract

  • Olaf Suess - Neurochirurgische Klinik, Charité Universitätsmedizin Berlin, Deutschland
  • Sven Mularski - Neurochirurgische Klinik, Charité Universitätsmedizin Berlin, Deutschland
  • Markus Schomacher - Neurochirurgische Klinik, Charité Universitätsmedizin Berlin, Deutschland
  • Ullrich Meier - Neurochirurgische Klinik, Unfallkrankenhaus Marzahn, Berlin, Deutschland
  • Marco Danne - Neurochirurgische Klinik, Unfallkrankenhaus Marzahn, Berlin, Deutschland
  • Peter Vajkoczy - Neurochirurgische Klinik, Charité Universitätsmedizin Berlin, Deutschland
  • Theodoros Kombos - Neurochirurgische Klinik, Charité Universitätsmedizin Berlin, Deutschland

Deutsche Gesellschaft für Neurochirurgie. 61. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC) im Rahmen der Neurowoche 2010. Mannheim, 21.-25.09.2010. Düsseldorf: German Medical Science GMS Publishing House; 2010. DocV1604

doi: 10.3205/10dgnc078, urn:nbn:de:0183-10dgnc0785

Published: September 16, 2010

© 2010 Suess et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.



Objective: Anterior cervical discectomy and fusion (ACDF) is accepted as the surgical standard for decompression in cases of degenerative disease of the cervical spine with clinical signs of myelopathy. There is still though a lack of consensus about the best material for intercorporal fusion. Several studies have reported favorable clinical result for the use of PEEK implants. So far though, all these studies have been single-center with modest sample sizes and most have been retrospective. Thus we designed the PIERCE-PEEK trial as a multinational prospective clinical trial to investigate the use of stand-alone PEEK spacers in the treatment of single-level cervical degenerative disc disease.

Methods: PIERCE-PEEK is a prospective, multinational, single-arm surgical trial. It has been registered with Controlled Trials under the number: ISRCTN42774128. Enrollment started in 2006. 356 patients were included in five international study-centers. PEEK implants were used for single level ACDF and not packed with any additional bone grafts. Additional plating was not used in any case. Fusion was evaluated after 6, 12 and 18–24 months follow-up. Clinical evaluation included VAS, NDI, Denis Pain Scale, JOA and Odim scores.

Results: ACDF was performed in segment C3/4 in 52 cases, in C 4/5: 94, in C5/6: 153, and in another 57 cases in C6/7. 36 patients were lost for follow-up after 24 months. The clinical scores improved gradually, showing mean VAS dropping from 7.4 to 1.8, JOA rising to a mean of 15 coming from 10 and mean NDI dropping from 26.5 to 8.5. The radiological exams demonstrated an implant migration of more than 1 mm into the bordering vertebra end plate in 17%, and of more than 3 mm in 8%. Fusion rate, according to the WHO trabecular definition of fusion in X-ray and CT scan, was 73% after 6 months, 82% after 12 months and 94% after 18 months.

Conclusions: PEEK is a semi-crystalline polyaromatic linear polymer with a good combination of strength, stiffness, environmental resistance, and biological inertness. Its major advantage is radiolucency and an elastic modulus that comes close to those of mixed bone. The use of stand-alone PEEK implants in the cervical spine results in good clinical outcome. However, although only minimal migration and subsidence was noticed, fusion seems to be significantly delayed, compared to data from e.g. titanium cages, suggesting distance-osteoneogenesis as the biomechanical type of ingrowth.