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Cervical Disc Replacement in Patients With and Without Previous Adjacent Level Fusion Surgery: A Prospective Study

Phillips, Frank M. MD*; Allen, Todd R. MD, PhD*; Regan, John J. MD†; Albert, Todd J. MD‡; Cappuccino, Andrew MD§; Devine, John G. MD¶; Ahrens, Jeanette E. PhD∥; Hipp, John A. PhD**; McAfee, Paul C. MD††

doi: 10.1097/BRS.0b013e31819b061c
Cervical Spine

Study Design. Prospective 6-center study.

Objective. To evaluate outcomes of cervical disc replacement performed adjacent to a prior cervical fusion.

Summary of Background Data. The use of disc replacement adjacent to a prior anterior cervical decompression and fusion (ACDF) is an attractive reconstructive option, obviating the need for a multilevel fusion. This study reports outcomes from patients with and without previous ACDF receiving the porous coated motion (PCM) artificial cervical disc in a United States Federal Drug Administration Investigational Device Exemption trials.

Methods. Patients between ages of 18 and 65 with single-level cervical radiculopathy and/or myelopathy, unresponsive to at least 6 weeks of nonsurgical therapy, or experiencing progressive neurologic symptoms were enrolled. Clinical outcomes are compared for patients receiving a PCM disc at a level adjacent to a prior ACDF (“adjacent”) and those without having previously had fusion (“primary”).

Results. 126 PCM patients were primary (mean age: 44.4 years.) and 26 patients had previous “adjacent level” fusion surgery (mean age: 46.4 years). Surgery time was similar in both groups (96 minutes and 98 minutes, respectively; P = 0.761), and mean blood loss was 76 mL and 66 mL in the 2 groups, respectively (P = 0.491). Clinical outcomes using Neck Disability Index and Visual Analog Scores neck and arm scores showed significant improvement after surgery and were similar between groups at all time points. Revision surgery occurred in 2 of 126 primary patients, and in 2 of 26 patients in the adjacent-to-fusion group.

Conclusion. Although the level adjacent to a prior cervical fusion is subject to increased biomechanical forces, potentially leading to a higher risk of failure, the PCM disc was well tolerated in the short term. The early clinical results of disc replacement adjacent to a prior fusion are good and comparable to the outcomes after primary disc replacement surgery. However, in view of the small study population and short-term follow-up, continued study is mandatory.

This study confirms that porous coated motion disc replacement adjacent to a prior anterior cervical decompression and fusion is associated with retained motion and excellent clinical outcomes with significant improvement in clinical symptoms and Neck Disability Index. The extent of improvement is comparable with that seen in patients undergoing porous coated motion disc replacement as a primary procedure.

From the *Rush University Medical Center, Chicago, IL; †Pacific Coast Spine Institute, Beverly Hills, CA; ‡Thomas Jefferson University and Hospital, Philadelphia, PA; §Buffalo Spine Surgery, Lockport, NY; ¶Madigan Army Medical Center, Tacoma, WA; ∥Pivotal Research Solutions, Allen, TX; **Medical Metrics, Inc., Houston, TX; and ††Towson Orthopedic Associates, O'Dea Medical Arts Building, Towson, MD.

Acknowledgment date: February 20, 2008. First revision date: August 23, 2008. Acceptance date: September 23, 2008.

The device(s)/drug(s) that is/are the subject of this manuscript is/are being evaluated as part of an ongoing FDA-approved investigational protocol (IDE) or corresponding national protocol for cervical PCM IDE.

Institutional 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 Frank M. Phillips, MD, Rush University Medical Center, 1725 W. Harrison, Suite 1063, Chicago, IL 60612; E-mail: frank.phillips@rushortho.com.

© 2009 Lippincott Williams & Wilkins, Inc.