Abstract
BACKGROUND CONTEXT: Cervical total disc replacement (TDR) has been shown as safe and effective as anterior cervical discectomy and fusion (ACDF) at both one and two levels. The relation between the number of treated levels and safety and effectiveness out to 7 years has not previously been investigated.
PURPOSE: To determine the equivalent safety and effectiveness at 7 years in 2-level TDR versus 1 level TDR treated patients.
STUDY DESIGN/SETTING: Randomized, controlled, multicenter clinical trial. There were 575 patients randomized in 2:1 ratio. The 1-level arm had 164 TDR vs 81 ACDF patients; the 2-level arm had 225 TDR vs 105 ACDF patients.
PATIENT SAMPLE: Patients with degenerative disc disease at one or two levels of the cervical spine. The study consisted of 575 patients.
OUTCOME MEASURES: Neck Disability Index (NDI), Visual Analog Scale (VAS), Neck Pain, VAS Arm Pain; 12-Item Short Form Health Survey (SF-12)
METHODS: The study consisted of 575 patients randomized in a 2:1 ratio. The 1-level arm had 164 TDR vs 81 ACDF patients; the 2-level arm had 225 TDR vs 105 ACDF patients. TDR patients received a Mobi-C© Cervical Disc (LDR Spine, Austin TX, USA). The ACDF control group was treated with allograft and anterior plating. Outcome measures were collected pre-operatively and at each follow-up out to 7 years. Fisher’s exact test was used to test for significant differences among categorical outcomes. One-way ANOVA with Tukey’s test for significant differences for continuous variables.
RESULTS: TDR patients had similar overall success (1-level: 55.2%: 2-level: 60.8%; p=.39) while the 2-level CADF group had a lower success rate than the 1-level ACDF (1-level: 50.0%: 2-level: 34.2%; p=.10). NDI score improvement was almost identical between 1-level (35.2±0.6) and 2-level (35.6±19.9) TDR patients. Two-level ACDF patients (1-lecel: 35.3±18.9: 2-level: 27.8±21.8; p=.18), through the difference was not statistically significant. No significant differences were observed between 1- and 2-level treatments for VAS neck or arm pain scores, SF-12 MCS/PCS, major complication rates, subsequent surgery, or patient satisfaction. However, two-level ACDF patients tended toward worse outcomes compared to 1-level ACDF patients for most measures.
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