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Implant Complications, Fusion, Loss of Lordosis, and Outcome After Anterior Cervical Plating With Dynamic or Rigid Plates: Two-Year Results of a Multi-Centric, Randomized, Controlled Study

Pitzen, Tobias R. MD, PhD*; Chrobok, Jiri MD, PhD†; Štulik, Jan MD, PhD‡; Ruffing, Sabine MD§; Drumm, Joerg MD¶; Sova, Laurentius MD∥; Kučera, Roman MD†; Vyskočil, Tomas MD‡; Steudel, Wolf Ingo MD, PhD¶

doi: 10.1097/BRS.0b013e318198ce10
Randomized Trial

Study Design. Prospective, controlled, randomized, multicenter study.

Objective. To analyze implant complications and speed.

Summary of Background Data. Rigid plate designs, in which the screws are locked to the plate, are in common use and thought to provide more fixation than dynamic designs, in which the screws may glide when the graft is settling. The aim of the study is to analyze (1) implant complications, (2) speed of fusion, (3) loss of lordosis, and (4) clinical outcome in both types of plates.

Methods. One hundred thirty-two patients were included and assigned by randomization to one of the groups in which they received a routine anterior cervical discectomy and autograft fusion with either a dynamic plate (ABC, study group) or a rigid plate (CSLP, control group). At discharge, after 3 and 6 months and finally after 2 years, implant complications, segmental mobility, absence of radiolucencies, absence of bone sclerosis, evidence of bridging trabecular bone, loss of lordosis, Visual Analog Scale (VAS) and Neck Disability Score were recorded. All radiographic measurements were performed by an independent radiologist.

Results. There have been 4 patients with implant complications within the control group and no implant complications within the study group, P = 0.045. Mean segmental mobility before discharge for the study group was 1.7 mm, 1.4 mm after 3 months, 0.8 mm after 6 months, and 0.4 mm after 2 years. For the control group, these values were 1.0, 1.8, 1.6, and 0.5 mm. The difference at 6 months between both groups was significant (P = 0.024). Neither absence of radiolucencies, nor absence of sclerosis, nor evidence of bridging bone showed significant differences between the 2 groups through the postoperative follow-up (P > 0.05). The loss of segmental lordosis for the study group with respect to intraoperative radiograph was 1.3° at discharge and 4.3° after 2 years. For the controlgroup, these values were 0.9°, 0.7°. The difference at 2 years was significant (P = 0.003). Clinical postoperative outcome (VAS and ODI) was not different between the 2 groups through the postoperative follow-up (P > 0.05).

Conclusion. Dynamic cervical plate designs provide less implant complications (no patient) compared with rigid plate designs (4 patients). Speed of fusion was faster in the presence of a dynamic plate. However, loss of segmental lordosis is significantly higher if dynamic plates are used, which did not result in differences regarding clinical outcome between dynamic and constrained plates after 2 years. Thus, dynamic plates should be considered to be the preferred treatment option because of the lower risk for implant failure-related revision surgery.

Dynamic cervical plates provide less implant complications, a faster fusion of the cervical spine, and a higher loss of segmental lordosis when compared with rigid cervical plates. None of these aspects, however, did result in differences regarding clinical outcome between dynamic and rigid plates within the 2-year follow-up period.

From the *SRH Waldklinikum Gera gGmbH, Gera, Germany; †Neurosurgery, Homolka Hospital, Prague, Czech Republic; ‡Spinal Surgery, University Hospital Motol, Prague, Czech Republic; §Radiologie, Bundesknappschaftsklinik Püttlingen, Püttlingen, Germany; ¶Neurosurgical Department, University of the Saarland, Homburg, Germany; and ∥Neurosurgical Department, Bundeswehrkrankenhaus Ulm, Ulm, Germany.

Acknowledgment date: February 21, 2008. First revision date: August 1, 2008. Second revision date: October 20, 2008. Acceptance date: October 20, 2008.

The device(s)/drug(s) is/are FDA-approved or approved by corresponding national agency for this indication.

No funds were received in support of this work. One or more of the author(s) has/have received or will receive benefits for personal or professional use from a commercial party related directly or indirectly to the subject of this manuscript: e.g., honoraria, gifts, consultancies, royalties, stocks, stock options, decision making position.

Address correspondence and reprint requests to Tobias Pitzen, MD, PhD, SRH Waldklinikum Gera gGmbH, Straβe des Friedens 122, 07548 Gera, Germany; E-mail:

© 2009 Lippincott Williams & Wilkins, Inc.