Rahul V. Shah

In Brief Study Design. Prospective, longitudinal minimum 2-year follow-up. Objective. To assess the efficacy and safety of the Prodisc implant in patients with disabling single-level discogenic low back pain (LBP). Summary of Background Data. The treatment of debilitating discogenic LBP has been controversial and varied. To date, a longitudinal prospective study of the treatment of single-level incapacitating discogenic LBP using the Prodisc total disc arthroplasty technique has not been described. Methods. A prospective analysis was performed on 118 patients treated with single-level lumbar Prodisc total disc arthroplasty. Patients 18 to 60 years of age with disabling and recalcitrant discogenic LBP with or without radicular pain secondary to single-level discogenic LBP from L3 to S1 were included. Patients were assessed before surgery, and outcome measurements were after surgery administered at 3, 6, 12, and 24 months. Results. A total of 104 patients (88%) fulfilled all follow-up criteria. The median age of all patients was 47 years (range, 36–60 years). Statistical improvements in VAS, Oswestry, and patient satisfaction scores occurred 3 months postoperatively. These improvements were maintained at the 24-month follow-up. Radicular pain also decreased significantly. Full-time and part-time work rates increased from 10% to 35% and 3% to 24%, respectively. No additional fusion surgeries were necessary either at the affected or unaffected levels. Radiographic analysis revealed an affected disc height increase from 4 mm to 13 mm (P < 0.001) and an affected disc motion from 3° to 7° (P < 0.004). Conclusions. Single-level Prodisc lumbar total disc arthroplasty is a safe and efficacious treatment method for debilitating lumbar discogenic LBP. Significant improvements in patient satisfaction and disability scores occurred after surgery by 3 months and were maintained at the 2-year follow-up. No device-related complications occurred. Patients with severe to moderate disc height loss as well as those with symptomatic posterior anular defects with minimal disc height loss achieve functional gains and significant pain relief. Careful and appropriate patient selection is essential in ensuring optimal surgical outcomes. The treatment of debilitating discogenic low back pain has been controversial and varied. The purpose of this study is to assess the efficacy and safety of the Prodisc implant in patients with disabling single-level discogenic low back pain. Single-level Prodisc lumbar total disc arthroplasty is a safe and efficacious treatment method for debilitating lumbar spondylosis without significant facet arthropathy. In our analysis, statistically significant improvement in patient satisfaction and disability scores occurred after surgery in 96% of patients by 3 months and were maintained at the 2-year follow-up. No device-related complications occurred.

In Brief Study Design. Retrospective review of articles published in the journal Spine. Objectives. To evaluate potential correlations between research sponsorship and study outcome. Summary of Background Data. Industry sponsorship has traditionally been associated with more positive results than non-funded or peer-reviewed funded projects in other areas of medicine. The association of such sponsorship and study outcome has not been addressed previously in spine research. Methods. Articles from the journal Spine from January 2002 to July 2003 were reviewed. These were examined for the subject evaluated, type of study design, funding source, and conclusion reached. Results. Of 1143 articles, 527 met inclusion criteria of having abstract, materials/methods, and conclusion sections. Industry support was reported for 84 (15.9%), foundation support for 67 (12.7%), government support for 54 (10.2%), institution support for 17 (3.2%), and no funding was reported for 304 (57.9%). The odds ratio of industry funded reporting positive results was 3.3 times that of studies with any other funding sources (P < 0.001). Conclusions. Industry funded studies demonstrated a statistically greater likelihood to report positive results than studies with other funding sources. Potential explanations for this are biased study design, biased experimental technique, biased result interpretation, or publication bias. Although the expense of research and limited funding sources have forced an increased reliance on industry support for funding basic science and clinical spine research, this does introduce the potential for bias and must be recognized by the reader. This retrospective study of 527 articles published in the journal Spine assessed potential corrections between research sponsorship and study outcome. Positive results were statistically correlated with industry funding in comparison with other funding sources. Although industry funding is often necessary given the expense of clinical research, the potential for bias must be appreciated.

In Brief Study Design. Prospective, longitudinal minimum 2-year follow-up. Objective. To assess the efficacy and safety of the Prodisc implant in patients with disabling multilevel discogenic low back pain (LBP). Summary of Background Data. Few, if any, alternatives have been proposed to treat recalcitrant and debilitating multilevel lumbar discogenic low back pain. To date, a prospective study specifically examining the use of multilevel Prodisc total disc arthroplasty has not been described Methods. A prospective analysis was performed on 25 patients (63 prostheses) treated with multilevel lumbar ProDisc total disc arthroplasty. Minimum follow-up was 2 years. Patients 18 to 60 years of age with disabling discogenic low back pain and minimal radicular pain secondary to multiple level lumbar spondylosis from L1 to S1 were included. Preoperative and postoperative disability and pain scores were measured using Oswestry and visual analog scores. Preoperative and postoperative neurologic, radiographic, and pain medication assessments were also performed at similar postoperative intervals. Results. A total of 29 patients (72 prostheses) were enrolled in the prospective analysis. Twenty-five patients (63 prostheses) fulfilled all follow-up criteria and are included for final analysis. Fifteen bisegmental and 10 trisegmental level cases were performed. Visual analog pain, Oswestry, and patient satisfaction scores were significantly reduced at the 3-month as well as at 48-month follow-up. Radiographic analysis revealed an affected disc height increases from 5 mm to 12 mm (P < 0.05) and affected disc motions from 3° to 7° (P < 0.05). No change in adjacent level disc heights was seen. Complications included a single case of subsidence of the inferior endplate of the L4–L5 segment in a bisegmental L4–L5/L5–S1 case. We also report a delayed case of anterior extrusionof a polyethylene component in a patient who had sustained a fall of a bicycle. Conclusions. Our preliminary data on multisegmental ProDisc lumbar total disc arthroplasty appear to be a safe and efficacious treatment method for debilitating lumbar spondylosis without significant facet arthropathy. In our select (non-Workers Compensation and/or medical legal) cohort of patients, we demonstrate a patient satisfaction rate of 93%. Careful and appropriate patient selection is essential in ensuring optimal surgical outcomes. The treatment of disabling multilevel degenerative disc disease has been varied and controversial. The goal of the present study is to explore an alternative treatment method, multilevel lumbar total disc replacement surgery using the ProDisc prosthesis, in the treatment of multilevel discogenic low back pain. Our prospective, minimum 2-year follow-up data indicate that this alternative treatment method can achieve high patient satisfaction rates (93%) when appropriate patient selection and meticulous surgical technique are used. Careful evaluation of bone density and preparation of vertebral endplates is mandatory in multilevel lumbar disc replacement surgery.

In Brief Study Design. Prospective nonrandomized clinical series. Objectives. To evaluate the efficacy of ProDisc lumbar artificial disc replacement (ADR) in smokers versus nonsmokers. Summary of Background Data. Smoking is a negative predictor in fusion surgery. To date, a prospective study of the treatment of incapacitating discogenic low back pain using ADR in smokers versus nonsmokers has not been described. Methods. A prospective analysis was performed on 104 patients with disabling discogenic low back pain treated with single-level lumbar ProDisc total disc arthroplasty. Smokers and nonsmokers were assessed before surgery and after surgery using patient satisfaction, Oswestry, and Visual Analog Scores. Additionally, preoperative and postoperative neurologic, radiographic, and pain medication assessments were performed at similar postoperative intervals. Results. Oswestry, Visual Analog Scores, and patient satisfaction scores revealed statistical improvement beginning 3 months after surgery and were maintained at minimum 2-year follow-up. Patient satisfaction scores were higher in smokers (94%) than in nonsmokers (87%) at 2-year follow-up (P = 0.07). Radiographic analysis revealed an affected disc height increase from 4 mm to 13 mm (P < 0.05) and an affected disc motion from 3° to 7° (P < 0.05). No cases of loosening, dislodgment, mechanical failure, infection, or fusion of the affected segment occurred. Conclusions. The results of our study indicate that smokers do equally well compared with nonsmokers when ProDisc ADR is used in the treatment of debilitating lumbar spondylosis. Patient outcome and radiographic scores showed significant improvement compared with preoperative levels. Although not evident in our series, additional surveillance for intraoperative and postoperative vascular spasm and occlusion may be warranted in smokers. Single-level ProDisc lumbar total disc arthroplasty is a safe and efficacious treatment method for debilitating lumbar spondylosis in smokers and nonsmokers. The results of our study indicate that smokers do equally well compared with nonsmokers when ProDisc ADR is used in the treatment of debilitating lumbar spondylosis. Patient outcome and radiographic scores showed significant improvement compared with preoperative levels. Interestingly, patient satisfaction scores showed a statistical trend (P = 0.09) toward greater rates of satisfaction in smokers than in nonsmokers.

OBJECT: The authors conducted a prospective longitudinal study to obtain outcome (minimum follow-up period 2 years) regarding the safety and efficacy of single-level lumbar disc (ProDisc prosthesis) replacement in patients 60 years of age or older. METHODS: This prospective analysis involved 22 patients treated in whom the lumbar ProDisc prosthesis was used for total disc arthroplasty. All patients presented with disabling discogenic low-back pain (LBP) with or without radicular pain. The involved segments ranged from L-2 to S-1. Patients in whom there was no evidence of radiographic circumferential spinal stenosis and with minimal or no facet joint degeneration were included. Patients were assessed preoperatively and outcome was evaluated postoperatively at 3, 6, 12, and 24 months by administration of standardized tests (the visual analog scale [VAS], Oswestry Disability Index [ODI], and patient satisfaction). Secondary parameters included analysis of pre- and postoperative radiographic results of disc height at the affected level, adjacent-level disc height and motion, and complications. Twenty-two (100%) fulfilled all follow-up criteria. The median age of all patients was 63 years (range 61-71 years). There were 17 single-level cases, four two-level cases, and one three-level case. Statistical improvements in VAS, ODI, and patient satisfaction scores were observed at 3 months postoperatively. These improvements were maintained at 24-month follow-up examination. Patient satisfaction rates were 94% at 24 months (compared with 95% reported in a previously reported ProDisc study). Radicular pain also decreased significantly. Patients in whom bone mineral density was decreased underwent same-session vertebroplasty following implantation of the ProDisc device(s). There were two cases involving neurological deterioration: unilateral foot drop and loss of proprioception and vibration in one patient and unilateral foot drop in another patient. Both deficits occurred in patients in whom there was evidence preoperatively of circumferential spinal stenosis. There were two cases of implant subsidence and no thromboembolic phenomena. CONCLUSIONS: Significant improvements in patient satisfaction and ODI scores were observed by 3 months postoperatively and these improvements were maintained at the 2-year follow-up examination. Although the authors' early results indicate that the use of ProDisc lumbar total disc arthroplasty in patients older than 60 years of age reduces chronic LBP and improves clinical functional outcomes, they recommend the judicious use of artificial disc replacement in this age group. Until further findings are reported, the authors cautiously recommend the use of artificial disc replacement in the treatment of chronic discogenic LBP in patients older than age 60 years in whom bone quality is adequate in the absence of circumferential spinal stenosis.