Spine. Volume 34(19), 1 September 2009, pp 2001-2007

Sagittal Cervical Alignment After Cervical Disc Arthroplasty and Anterior Cervical Discectomy and Fusion: Results of a Prospective, Randomized, Controlled Trial

Anakwenze, Okechukwu A. MD*; Auerbach, Joshua D. MD†; Milby, Andrew H. BS‡; Lonner, Baron S. MD§; Balderston, Richard A. MD¶

From the *Department of Orthopaedic Surgery, The University of Pennsylvania, Philadelphia, PA; †Department of Orthopaedic Surgery, Bronx-Lebanon Hospital Center, Albert Einstein College of Medicine, Bronx, NY; ‡The University of Pennsylvania School of Medicine, Philadelphia, PA; §Department of Orthopaedic Surgery, NYU-Hospital for Joint Diseases, New York, NY; and ¶Division of Spine Surgery, Pennsylvania Hospital, The University of Pennsylvania, Philadelphia, PA.
Supported by Synthes Spine, West Chester, PA.
Acknowledgment date: April 29, 2008. First revision date: March 1, 2009. Second revision date: March 16, 2009. Acceptance date: March 17, 2009.
The device(s)/drug(s) is/are FDA-approved or approved by corresponding national agency for this indication.
Corporate/Industry funds were received in support of this work. One or more of the author(s)has/have received or will be received 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.
Address correspondence and reprint requests to Joshua D. Auerbach, MD, 408 South 19th St, Philadelphia, PA 19146; E-mail: joshua.auerbach (at) aya.yale.edu

Study Design. Radiographic results of a multicenter, prospective randomized study comparing 1-level cervical total disc replacement (TDR-C) with anterior cervical discectomy and fusion (ACDF).

Objective. To evaluate the effect on device-level lordosis, cranial and caudal adjacent level lordosis, and overall cervical sagittal alignment (C2–C6) after TDR-C or ACDF.

Summary of Background Data. Cervical total disc replacement (TDR-C) has emerged as a promising alternative to ACDF in a select group of patients. The maintenance and/or improvement of sagittal balance is essential in preserving functionality after reconstructive spinal procedures. Recent studies have documented changes in spinal alignment after TDR-C, however, no studies have compared these changes to those noted in matched group of patients that have undergone ACDF.

Methods. Radiographic data were obtained from the randomized group of a multicenter, randomized, prospective, controlled study comparing TDR-C (ProDisc-C, Synthes Spine, West Chester, PA) with ACDF in the treatment of 1-level cervical disc disease. Complete radiographic data were available for 89 TDR-C patients (average age: 42.2 years) and 91 ACDF patients (average age: 41.7 years). Cervical lordosis at the device level, cranial and caudal adjacent levels, and total cervical lordosis (C2–C6) were independently measured before surgery and 2 years after surgery using custom image stabilization software (Quantitative Motion Analysis, Medical Metrics, Inc, Houston, TX).

Results. C5–C6 was the most common operative level (TDR-C: 54%; ACDF: 55%). At 2 years after surgery, the TDR-C group experienced statistically significant changes in lordosis of 3.0° (P < 0.001), 0.90° (P = 0.006), and -1.9° (P < 0.001) at the operative, cranial, and caudal adj-acent levels, respectively. ACDF experienced changes in lordosis of 4.2° (P < 0.001), 1.0° (P = 0.001), and -1.5° (P = 0.001), respectively. The between-group differences were significant at the operative level (P = 0.03) and the caudal adjacent level (P = 0.05). Total cervical lordosis increased in both TDR-C and ACDF by 3.1° and 3.8°, respectively (P = 0.49).

Conclusion. In both TDR-C and ACDF, lordosis increased at the device-level, cranial adjacent level, and in total cervical lordosis, while lordosis decreased at the caudal adjacent level. Although ACDF facilitated a greater increase in device level lordosis (+1.25°) and less loss of lordosis at the caudal adjacent level compared with TDR-C (-0.39°), the clinical relevance of the small differences remain unknown.

Copyright: © 2009 Lippincott Williams & Wilkins, Inc.