Choice of plate may affect outcomes for single versus multilevel ACDF: results of a prospective randomized single-blind trial.

Background Context: Conflicting views exist according to the individual philosophy about various plate designs that can be used in anterior cervical discectomy and fusion (ACDF) to achieve clinical and radiological improvement within shortest time period. No prospective randomized study has ever been conducted to clarify the relationship between clinical outcomes, fusion rates, and the choice of plate (static vs. dynamic design).

Purpose: To compare the clinical and radiological outcomes of patients treated with one-level or multiple levels ACDF using cervical plates of dynamic (slotted-holes) versus static (fixed-holes) design.

Study Design: Single masked, prospective, randomized study.

Patient Sample: Over a 4-year period, 66 patients (M:F=37:29) had ACDF using either dynamic (n=33) or static (n=33) plates for intractable radiculopathy as the result of degenerative cervical spine disease. Overall, 28 patients had single-level fusion and 38 had two or three levels fused.

Outcome Measures: Visual Analogue Pain scores (VASs), Neck Disability Index (NDI), and radiological criteria of established fusion.

Methods: The qualifying subjects were randomized to receive ACDF using either fixed-holes (static) or the slotted-holes (dynamic) anterior cervical plates. Clinical and radiographic data were collected and analyzed. Paired-sample t test was used to correlate clinical and radiological outcomes and General Linear Model Analysis of Variance (GLM ANOVA) with repeated measures was used to detect outcome differences between the two groups for single and multiple fusions.

Results: At a mean follow-up of 16 months (range, 12-24), 49 patients (73.7%) had clinical success and 56 (85%) showed radiological fusion. Although clinical success was a predictor of fusion (p=.043), the reverse was not true (p=.61). In single-level fusion, no statistical difference of outcome was observed between the two groups but multilevel fusions with dynamic plate showed significantly lower VAS and NDI than those with static plates (p=.050).

Conclusions: Although clinical improvement is a good predictor of successful ACDF, radiological evidence of fusion alone is not reliable as a parameter of success. The design of plate does not affect the outcomes in single-level fusions but statistics indicate that multiple-level fusions may have better clinical outcome when a dynamic plate design is used.