Study design: Analysis of data collected prospectively from the United States Food and Drug Administration Investigational Device Exemption (U.S. FDA IDE) clinical trial for patients who underwent ProDisc-L arthroplasty at 1- and 2- levels performed at 2 study centers.
Objective: To determine if there is any clinical or radiographical differences between patients who received 1-level ProDisc-L and patients who received 2-level ProDisc-L with a minimum follow-up of 5 years.
Summary of background data: Recent prospective U.S. FDA clinical trial results have been published showing efficacy of the ProDisc (DePuy Synthes, West Chester, PA) prosthesis in both single and 2 level surgical procedures. Results of these prospective randomized multicenter FDA IDE clinical trials showed safety, efficacy, and superiority over circumferential fusion.
Methods: Patients were part of the FDA clinical trial for the ProDisc-L versus circumferential fusion study at 2 institutions. We identified 20 patients who received ProDisc-L at 1 level and 21 who received it at 2 levels for a total of 41 patients. Pre- and postoperative pain, clinical function, and range of motion were measured. An unpaired t test was done to compare the 2- versus 1-level disc replacement patients.
Results: All patients had more than 60 months of clinical follow-up. The mean scores on the visual analogue scale were 37.1 and 28.7, respectively (P = 0.33) for 1- and 2-level patients. Oswestry Disability Index scores were 33 and 29.1, respectively for 1- and 2-level patients (P = 0.60); and SF-36 health survey physical scores were 43 and 43.9, respectively for 1- and 2-level patients (P = 0.81); SF-36 health survey mental scores were 46.2 and 46.6, respectively for 1- and 2-level patients (P = 0.923). The average final follow-up postoperative range of motion for 1- and 2-level total disc replacement was 6.0º and 5.4º, respectively (P = 0.632).
Conclusion: This study was unable to identify statistical differences in all clinical and radiographical outcomes for patients who underwent 1- and 2-level ProDisc arthroplasty in a cohort from 2 centers. Future studies with longer-term follow-up are needed to confirm these results.
Level of evidence: 4.