Although anterior cervical discectomy and fusion (ACDF) has traditionally been the standard surgical treatment for symptomatic cervical degenerative disc disease (DDD), the literature suggests that the efficacy is decreased and the complication rates increased when ACDF is used at 2 contiguous levels vs 1 level. Few data currently exist that compare the effectiveness of 1-level total disc replacement (TDR) with 2-level TDR.

Hyun W. Bae, MD, Cedars-Sinai Spine Center, Los Angeles, California, USA, presented the 60-month follow-up results from the pivotal LDR Spine USA Mobi-C® Cervical Disc Prosthesis IDE clinical trial [NCT00389597] that compared patient outcomes between 1- and 2-level ACDF and between 1- and 2-level TDR.

The single-blind, prospective, randomized, multicenter trial compared ACDF to TDR in patients who were diagnosed with symptomatic cervical DDD at 1 or 2 levels of the cervical spine with no previous cervical fusions. A Food and Drug Administration (FDA) Investigational Device Exemption was obtained to conduct the study.

The trial was conducted at 24 sites in the United States, with all sites performing both 1- and 2-level procedures and both TDR and ACDF procedures. In the phase 3 trial, the patients were randomized in a 2:1 fashion in the 1-level arm (TDR = 164; ACDF = 81) and in the 2-level arm (TDR = 225; ACDF = 105).

The outcomes measured included the neck disability index (NDI), neck and arm pain as measured with the visual analog scale (VAS), patient satisfaction, patient recommendation to others for this surgery, SF-12 Mental and Physical Health Composite Scores, adverse events representing major complications, subsequent surgery rates, and overall success rate. Outcome measurements were collected prior to surgery and after surgery at week 6, and months 3, 6, 12, 18, 24, 36, 48, and 60. The follow-up rate at 60 months was 88.5% in the TDR group and 83.1% in the ACDF group.

The NDI scores were nearly equivalent for 1-level and 2-level TDR and 1-level ACDF. However, for 2-level ACDF, at about 24 months the scores became worse and this became significant at months 36, 48, and 60 (P < .05). The VAS scores were also higher at months 36, 48, and 60 with 2-level ACDF. Although patient satisfaction was high (> 90%) for all groups at all time points, it was somewhat lower for 2-level ACDF, as was the likelihood the patient would recommend the operation.

There was no difference in the rate of complications with TDR in the patients who had it performed at 1 or 2 levels. The overall success rate was higher with TDR than with ACDF performed at 1 or 2 levels at months 24, 36, 48, and 60, while the success rate with ACDF declined when it was performed at 2 levels vs 1 (P < .05).

In this trial, there was no significant reduction in efficacy with TDR as the number of levels treated with Mobi-C increased from 1 to 2 levels. However, in patients treated with ACDF, there was a reduction in treatment effect when the number of levels increased from 1 to 2. The long-term results of this trial continue to demonstrate the Mobi-C is safe and effective, concluded Dr Bae.