Comparison of 2 lumbar total disc replacements: results of a prospective, randomized, controlled, multicenter Food and Drug Administration trial with 24-month follow-up.
METHODS
This was a prospective, randomized, controlled multicenter study with 24-month follow-up.


OBJECTIVE
The purpose of this study was to evaluate the safety and efficacy in a Food and Drug Administration Investigation Device Exemption of a new lumbar total disc replacement (TDR) by comparing it to an earlier TDR approved for sale.


BACKGROUND
Randomized trials have reported TDR to produce results similar or superior to lumbar fusion. Results for various TDRs seem to be similar, but differences in study design and outcome measures pose challenges in definitively comparing devices. The purpose of this study was to perform a direct comparison of 2 lumbar TDRs in a prospective, randomized trial.


METHODS
TDR was performed in 457 patients from 21 sites (261 patients in the investigational group (Kineflex-L Disc; metal-on-metal design anchored with keels, 204 randomized and 57 nonrandomized training cases), and 196 in the control group (CHARITE artificial disc; metal with polyethylene core with teeth for anchoring; 190 randomized and 6 nonrandomized training cases). All patients were treated nonoperatively for single-level symptomatic disc degeneration for at least 6 months prior to surgery. Perioperative data were collected. Clinical outcome data were collected prospectively, as approved by the Food and Drug Administration, through 24-month follow-up. Primary outcome measures used were the Oswestry Disability Index, visual analogue scales assessing pain, patient satisfaction, and reoperations. Success was defined to be at least 15-point improvements in Oswestry Disability Index scores, no reoperation, and no major adverse events. Radiographical measures included range of motion, disc space height, and assessment for device migration, subsidence, and fusion at the TDR level.


RESULTS
There were no significant differences between the groups when comparing operative time, blood loss, or length of hospital stay. Both groups improved significantly on Oswestry Disability Index and visual analogue scale scores (P < 0.01) with no differences between the groups. Success rates were similar (68.1% investigational vs. 67.4% control). At 24-month follow-up, 94.1% of the investigational group and 91.9% of controls were satisfied with outcome. Reoperation was performed in 10.3% of the investigational group and 8.4% of the control group.


CONCLUSIONS
This prospective, randomized, controlled study comparing 2 TDRs, the first to the authors' knowledge, found the devices produced very similar clinical outcomes. Both groups improved significantly by 6 weeks postoperatively and remained improved throughout follow-up with a high patient satisfaction rate.
*Texas Back Institute, Plano, TX †Loveland Orthopedic Clinic, Loveland, CO ‡Orthopedics International, Kirkland, WA §Triangle Orthopaedic Associates, Durham, NC ¶Carolina Neurosurgery and Spine Associates, Charlotte, NC ‖Towson Orthopaedic Associates, Scoliosis and Spine Center, Towson, MD; and **Texas Back Institute Research Foundation, Plano, TX.
Richard D
RD
Guyer
Kenneth
K
Pettine
Jeffrey S
JS
Roh
Thomas A
TA
Dimmig
Domagoj
D
Coric
Paul C
PC
McAfee
Donna D
DD
Ohnmeiss
D000293:Adolescent; D000328:Adult; D004185:Disability Evaluation; D004867:Equipment Design; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D017060:Patient Satisfaction; D011183:Postoperative Complications; D011446:Prospective Studies; D011859:Radiography; D016059:Range of Motion, Articular; D012086:Reoperation; D059145:Total Disc Replacement / Q000295:instrumentation*; D016896:Treatment Outcome; D055815:Young Adult