Prospective Randomized Multi-Center Clinical Trial of Cervical Fusion Cages

Robert Hacker MD,
Joseph Cauthen, MD
Thomas Gilbert, MD (Eugene, OR)

Introduction:

The purpose of this study is to report on the clinical results from a prospective, randomized multi–center IDE trial that compared the BAK/C( (Sulzer SpineTech, Minneapolis MN) threaded fusion cage to non–instrumented bone–only fusions.

Materials and Methods:

Inclusion criteria included radiographic evidence of symptomatic discogenic radiculopathy from one or two contiguous cervical spine segments (C3 to C7); no moderate to severe myelopathy; no previous fusion at the affected level, cervical trauma, or rheumatoid disease. Patient–based outcome was assessed by a 10–point visual analog scale measuring neck and radicular pain, and an SF–36 questionnaire.

Results:

Of the 488 enrolled patients, 288 patients were followed for a minimum of one–year and 140 at two–years. When comparing the two randomized groups, similar outcomes were noted for duration of surgery, hospital stay, improvements in neck pain and radicular pain in the affected limb, improvements in SF–36's Physical Component Subscale (PCS) and Mental Component Subscale (MCS), and the patients' perception of overall surgical outcome. Symptom improvements were generally maintained at the two–years. A lower percentage of BAK/C patients required an iliac crest bone harvest compared to ACDF patients (p less than 0.001, Chi square test). Fusion outcome, assessed by an independent orthoradiologist, for one level cases at 12 months was 86.4% for ACDF and 98.7% for BAK/C. Overall complication rate, defined as the number of patients experiencing one or more events, for the BAK/ C group was 10.1%; for the ACDF group the overall complication incidence was 16.2% with graft collapse/migration in 4.9% of patients. There was no difference in complications requiring a second operative procedure (4.0% for BAK/C and 4.2% for ACDF)

Discussion & Conclusions:

This large multi–center trial demonstrated that outcomes after a cervical fusion procedure with the BAK/C device are comparable to those of an uninstrumented, bone–only anterior discecetomy and interbody fusion. The BAK/C threaded fusion cage represents an alternative that obviates the need for allograft and its inherent potential problems of reduced incorporation, as well as reduces the necessity for autograph harvesting and the associated potential morbidity.