#362 Predictors of Success after Cervical Disc Arthoplasty

General Session: Best Papers Session

Presented by: M. Gornet

Author(s):

M.F. Gornet (1)
B.A. Taylor (1)
F.W. Schranck (1)
B. Kopjar (2)

(1) The Orthopedic Center of Saint Louis, Spine Research Center, Saint Louis, MO, USA
(2) University of Washington Seattle, Department of Health Services, Seattle, WA, USA

Abstract

Introduction: Anterior cervical discectomy and fusion (ACDF) remains the surgical standard of care for degenerative disc disease unresponsive to nonoperative treatment. Anderson et al(1) reported on 488 ACDF patients from two IDE trials that pending litigation, workers' compensation (WC), and dermatomal sensory loss were predictors of poor outcome; employment, poor functional status as measured by Neck Disability Index (NDI), and increased age were associated with favorable outcomes. Cervical disc arthroplasty (CDA) is an alternative to ACDF for appropriately selected patients. There is a paucity of information regarding the factors that contribute to successful CDA.

Methods: We evaluated preoperative patient characteristics associated with successful two-year outcomes after CDA in a large prospective consecutive case series treated by two fellowship-trained spine surgeons using validated patient reported outcome measures. Success was defined using the literature-established(2) thresholds for substantial clinical benefit from cervical spine surgery. Patients were considered a success if they improved at least 9.5 points on NDI and at least 6.5 points on the SF-36 Physical Component Score (PCS), and did not have a re-operation or new cervical spine surgery. The data were analyzed by an independent statistician using multivariate logistic analysis of the following predictors: age, gender, baseline SF-36 PCS and Mental Component Score (MCS), numeric scale scores for neck pain and arm pain, operative level, single or multiple levels, smoking, body mass index (BMI) and WC status. We first ran a full model including all predictors. In a second step we only kept predictors with p-value < 0.05.

Results: The analysis included 166 patients with 2-year data available (81.4% follow-up rate) out of 204 eligible subjects. Average age was 45.1 years (standard deviation (SD),8.8). 41.6% were females, 39.8% had multi-level CDA, 51.8% were smokers, 67.5% involved WC claims. 90 patients (54.2%) were classified as a success at 2 years. Average BMI was 29.0 (SD,5.9). Preoperative neck pain and SF-36 MCS were significantly associated with a successful outcome of CDA. The higher the pre-operative neck pain score (i.e. higher neck pain intensity), the higher the odds of treatment success (OR=1.39; 95% C.I., 1.15--1.69). Also, the higher the baseline SF-36 MCS (i.e. better mental health status), the higher the odds of success (OR=1.04, 95% C.I., 1.01--1.06).

Conclusion: In this large case series of community-based practice patients undergoing CDA, the predictors of substantial clinical benefit from surgery at two years post-op were higher intensity of preoperative neck pain, and better preoperative mental health status. Age, gender, number of operated levels, arm pain scores, BMI and WC were not significantly associated with clinical outcome. Patients with poor mental health status appear to be poor CDA candidates.

1 Anderson PA, Subach BR, Riew KD. Predictors of outcome after anterior cervical discectomy and fusion: A multivariate analysis. Spine (Phila Pa 1976). 2009;34(2):161-166.

2 Carreon LY, Glassman SD, Campbell MJ, Anderson PA. Neck Disability Index, short form-36 physical component summary, and pain scales for neck and arm pain: the minimum clinically important difference and substantial clinical benefit after cervical spine fusion. Spine J. 2010 Jun;10(6):469-74.

Epub 2010 Apr 1.