Oral Posters: Values and Outcomes in Spine Surgery

Presented by: R. Guyer - View Audio/Video Presentation (Members Only)

Author(s):

R. Guyer(1), J. Zigler(1), D. Ohnmeiss(2)

(1) Texas Back Institute, Plano, TX, United States
(2) Texas Back Institute Research Foundation, Plano, TX, United States

Abstract

Introduction: One of the potential benefits of lumbar total disc replacement (TDR) over fusion for the treatment of painful disc degeneration is the possibility of reducing adjacent segment degeneration (ASD). There has been little investigation into this area in large prospective studies. The purpose of this study was to analyze pre- to post-operative changes of the disc adjacent to the level receiving a TDR at 5 year follow-up.

Methods: Patients from 14 sites were enrolled in the study, 218 assigned to the investigational group, activL® and 106 assigned to the control group, ProDisc-L. All patients were treated for single-level symptomatic disc degeneration non-responsive to non-operative care. Flexion/extension, neutral lateral and anteroposterior radiographs were made at each study visit. Pre- and 5-year post-operative radiographs were available for 135 patients in the investigational group and 63 patients in the control group. All radiographs were evaluated by an independent lab specializing in image assessment. Measurements made from the radiographs included adjacent segment degeneration based in the Kellgren-Lawrence scale and the scale described by Zigler et al. (JNS 2012), range of motion, disc height, and translation.

Results: When compared to pre-operative images, 8.8% of the investigational group and 19.0% of the control group had increased ASD scores at 5-year follow-up (p< 0.05). Results were the same using either the Kellgren-Lawrence or the Zigler ASD scale. Figure 1 provides the percentage of patients in the investigational group with increased ASD scores from pre-operative to 5 year post-operative for each degree of range of motion at the TDR level at 5 years. For each additional degree of range of motion, there was a consistent decrease in the percentage of patients with ASD. The rate of ASD was significantly greater in patients more than 40 years of age than those aged 40 years or less (19.6% vs. 5.0%; p< 0.01; data pooled for investigational and control groups).

Discussion: The results of this prospective, 5-year follow-up study found that the rate of adjacent segment degeneration was 8.8% for the activL® device. This is similar to the rate of 9.2% reported in another TDR study with 5-year follow-up (Zigler et al, JNS, 2012). That study found ASD to be significantly less with TDR than with fusion. The rate of ASD declined with increasing range of motion at the TDR level, possibly suggesting a protective effect of motion. The higher rate of ASD among older patients may suggest that some changes in adjacent level discs may be attributable to the aging process. The current study adds further support that increased motion reduces the occurrence of adjacent segment degeneration.

Fig. 1