Lumbar Interbody Fusion Devices: A Comparative Study

Purpose: The use of metal cage fixation has become a widely accepted alternative for posterior lumbar interbody fusion (PLIF). This is a preliminary report on a prospective, randomized concurrently on-going IDE study comparing the clinical outcomes of the rectangular CONTACT Fusion cage, "CFC" (Synthes Spine®) and the commercially available cylindrical Ray Threaded Fusion Cage (TFC)™ (Surgical Dynamics, Inc) when used as stand-alone PLIF devices.

Materials and Methods: Patients at each center were randomized in a 1:1 ratio to receive either the CFC or the Ray TFC device. All implants were packed with autologous bone. No additional anterior/posterior instrumentation was used. Patient data were recorded preoperatively and for minimum of 24 months post-surgery. Patients were followed clinically with the Oswestry Low Back Pain Disability Questionnaire, Visual Analog Scale, and independently viewed radiographs.

Results: This report summarizes preliminary clinical outcome data on 188 evaluable patients implanted at 23 centers with the CFC (n=98) or the Ray (n=90) between 1997 and 1999. The mean age was 46 years and 54% of the patients were male. Thirty-nine percent were smokers and 28% were on workman's compensation in both groups. At 6 months, mean back scores dropped 19.7 points (P<0 .001, n="55)" in the CFC group and 21.3 points (P<0.001, Ray group. Radiographic results to date show no significant differences between two study groups. A two-sided Fisher's Exact Test revealed treatments. Twenty-two percent of patients received surgical intervention for complications (14% device-related, 24% procedure-related) 16% underwent (7% 15% procedure-related).

Conclusion: On preliminary review, the clinical outcomes for patients undergoing PLIF with cage fixation using the CFC or Ray TFC appear equivalent. There was a significant improvement in pain and functional disability in both treatment groups.