Lumbar total disc arthroplasty utilizing the ProDisc prosthesis in smokers versus nonsmokers: a prospective study with 2-year minimum follow-up.

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 degrees to 7 degrees (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.

The treatment of disabling multilevel lumbar discogenic low back pain with total disc arthroplasty utilizing the ProDisc prosthesis: a prospective study with 2-year minimum follow-up.

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 degrees to 7 degrees (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 extrusion of 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 single-level lumbar discogenic low back pain with total disc arthroplasty utilizing the Prodisc prosthesis: a prospective study with 2-year minimum follow-up.

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 degrees to 7 degrees (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.

Early results after ProDisc-C cervical disc replacement.

OBJECT: Cervical anterior decompression and total-disc replacement is currently being investigated as an alternative treatment in patients with symptomatic intervertebral cervical spondylosis with and without radiculopathy. The authors prospectively investigated the safety and efficacy of using the ProDisc-C disc for cervical arthroplasty in the treatment of symptomatic cervical spondylosis. METHODS: Sixteen patients in whom a diagnosis of symptomatic cervical spondylosis had been established were prospectively treated with complete anterior cervical discectomy and ProDisc-C cervical disc arthroplasty. Overall 12 single- and four two-level procedures were performed (20 prostheses). Patients underwent pre- and multiple postoperative assessments (3 and 6 weeks and 3, 6, and 12 months). The median age of all patients was 50 years (range 32-60 years). Levels of surgery included seven C5-6, six C6-7, and three C4-5. Neck and arm pain as well as disability scores were significantly improved by 3 months and remained significantly improved at 1 year. No additional fusion surgeries were necessary at the affected or unaffected levels. Radiography revealed an affected disc motion from 4 to 12 degrees. No surgery- or device-related complications were documented. CONCLUSIONS: Analysis of preliminary results involving ProDisc-C arthroplasty indicates significant improvement in pain and functional outcome scores. No spontaneous fusions at the level of surgery or at adjacent levels were noted. Long-term follow-up studies will be necessary before more definitive treatment recommendations can be formulated.

Critical properties of loop percolation models with optimization constraints.

We study loop percolation models in two and in three space dimensions, in which configurations of occupied bonds are forced to form a closed loop. We show that the uncorrelated occupation of elementary plaquettes of the square and the simple cubic lattice by elementary loops leads to a percolation transition that is in the same universality class as the conventional percolation. In contrast to this, an optimization constraint for the loop configurations, which then have to minimize a particular generic energy function, leads to a percolation transition that constitutes a universality class for which we report the critical exponents. Implication for the physics of solid-on-solid and vortex glass models are discussed.