P79. Cervical disc arthroplasty: preliminary results of a randomized prospective study of single level ACDF vs. Prodisc-C for the management of cervical spondylosis

Proceedings of the NASS 20th Annual Meeting / The Spine Journal 5 (2005) 1S–189S OUTCOME MEASURES: In addition to demographics and surgical details, patients were assessed for back pain, leg pain, satisfaction and recommendation (100 mm VAS), functional status (Oswestry), nuerological imporvement, general health (SF-12). METHODS: Patients were placed in a prone position for a posterior approach. The pathological segment(s) were exposed via a mid-line or Wiltse approach. Pedicle screws were placed more anterolaterally than typical and directed convergently. Care was taken to place the screw properly on the first attempt, with the screw head low and at or ventral to the sagittal plane of the facet joints. Stabilizing cords and universal spacers were placed bilaterally and the construct was completed according to manufacturer’s recommendations. RESULTS: 65 segments were instrumented (25 1- and 20 2-level); L4-5 accounted for 55.4% of the instrumented levels. Mean blood loss and surgical time were 421cc and 183min, respectively. Both blood loss and surgical time were less in 1- rather than 2-level cases. Median hospital stay was 4 days. Mean preoperative leg and back pain was 81.8 and 49.3 respectively. Both measures decreased after surgery and were 32.1 and 32.7 at 1 year. Oswestry scores decreased from 56.5 preoperatively to 35.4 one year postoperatively. General health improved with the PCS increasing from 27.3 to 37.1 one year after surgery. The MCS increased from 39.9 to 49.9 at the same time. Neurological assesments 1 year post after surgery, revealed maintainance/improvement for motor testing in 92.9%, sensory testing in 100.0%, SLR in 64.3% and reflex testing for 85.7% of patients. Mean patient satisfaction was 74.8 and likelihood of recommendation was 79.4at 12 months. CONCLUSIONS: The surgery appeared well tolerated. Postoperative outcome measures were noticeably improved in all areas. This is neither inconsistent nor noticeably inferior to other treatments. However, avoiding fusion and the ability to maintain a relatively large amount of natural anatomy may yield greater improvements in outcomes over time. Two surgical aspects have already become apparent. It is clear in some cases the Wiltse approach can be successfully used, causing much less tissue trauma. Also, it appears that there may be cases where stabilization without decompression can alleviate symptoms again minimizing trauma. The limited follow-up length and cohort size suggest careful interpretation of these results. Despite the moderate sample size and follow-up lengths, these preliminary data are optimistic. DISCLOSURES: FDA device/drug: The Dynesys Spinal System. Status: Investigational/not approved. CONFLICT OF INTEREST: Author (RD) Consultant: Zimmer Spine. doi: 10.1016/j.spinee.2005.05.292

P78. Transforaminal lumbar interbody fusion vs. anterior/posterior reconstruction for lumbar disc degeneration and instability Alan Villavicencio, MD1, Sigita Burneikiene, MD1, Ketan Bulsara, MD2, Jeffrey Thramann, MD1; 1Boulder Neurosurgical Associates, Boulder, CO, USA; 2University of Missouri, Columbia, MO, USA BACKGROUND CONTEXT: Multiple various lumbar interbody fusion approaches are used to treat painful degenerative disc disease and spinal instability. Both anterior-posterior (AP) reconstructive surgery and transforaminal lumbar interbody fusion (TLIF) provide a circumferential fusion. However, the TLIF approach is theoretically less invasive and simultaneously allows for decompression of neural structures and relief of a radicular pain. There is currently no data in the literature that directly compares these two approaches. PURPOSE: The purpose of this study was to compare clinical parameters such as surgical blood loss, duration of the procedure, length of hospitalization and complications for the transforaminal lumbar interbody fusion approach versus anterior-posterior (AP) reconstructive surgery for lumbar degenerative disc disease and instability. STUDY DESIGN/SETTING: A retrospective analysis was completed on 167 consecutive cases performed at Boulder Community hospital (Boulder, Colorado) between January of 2002 and March of 2004.

147S

PATIENT SAMPLE: The TLIF surgical procedure was performed on 124 patients and the AP surgery was performed on 43 patients. Patients were treated for painful degenerative disc disease, facet arthropathy, degenerative instability and spinal stenosis. OUTCOME MEASURES: Clinical parameters such as surgical blood loss, duration of the procedure, length of hospitalization and complications were quantitatively assessed in this study. METHODS: Data were compared for two different TLIF approaches (open versus percutaneous pedicle screw placement) versus AP. Statistical significance was evaluated using the Chi square method. RESULTS: Compared with the AP surgery group, operative time in the TLIF groups was shorter by 233 min in the open (p⫽.0001) and by 200 min in the percutaneous cases (p⫽.0001). Blood loss was 126.5 mL lower in the open (p⫽.03) and 319 mL lower in the percutaneous TLIF group (p⫽.0001) as compared with the AP group. Length of stay was shorter by 1.95 days in the open (p⫽.0001) and by 2.9 days in the percutaneous TLIF group (p⫽.0001). Total number of complications was two times lower in the open or percutaneous TLIF group (62.7% vs. 35.3% and 30.0%) as compared with the AP group. CONCLUSIONS: Anterior-posterior lumbar interbody fusion is associated with approximately two times as many complications, significantly increased blood loss, and longer operative and hospitalization times compared with both percutaneous and open TLIF for lumbar disc degeneration and instability. DISCLOSURES: FDA device/drug: rhBMP-2 off label use. Status: Not approved for this indication. CONFLICT OF INTEREST: No conflicts. doi: 10.1016/j.spinee.2005.05.293 P79. Cervical disc arthroplasty: preliminary results of a randomized prospective study of single level ACDF vs. Prodisc-C for the management of cervical spondylosis Michael Janssen, DO1, Ruth Beckham, NP2, Hugh McPherson, MD2, Douglas Beard, MD2; 1Spine Education and Research Institute, Denver, CO, USA; 2Center for Spinal Disorders, CO, USA BACKGROUND CONTEXT: Single-level anterior cervical discectomy and fusion (ACDF) has proven to be an excellent treatment for various disorders of the cervical spine. However, a concern for adjacent level degeneration and loss of cervical motion has prompted the need to consider motion-sparing disc replacement technology in the cervical spine. The Prodisc-C is a cervical total disc replacement designed to provide the potential for motion at the involved cervical functional spinal unit. PURPOSE: The objective of this study is to clinically compare prospective, randomized preliminary results of patients with subaxial cervical radiculopathy who treated with either ACDF or cervical disc replacement with the ProDisc-C. STUDY DESIGN/SETTING: Under IRB approval, surgeons at a single center performed the surgeries for a total of 46 patients. PATIENT SAMPLE: The ACDF group consisted of 22 patients who underwent a one level cervical fusion with allograft bone and anterior plating. The ProDisc-C group consisted of 24 patients who underwent a one level disc replacement. Patient inclusion criteria for the study included disc herniation, loss of height, or spondylotic changes between C3-7 levels with myelopathy and/or radiculopathy. Patients who had undergone previous cervical surgery were not eligible. The average age in the ProDisc-C group was 44 years (range: 33–56) and the ACDF group was 43 years (range 25–60). OUTCOME MEASURES: Efficacy was assessed by evaluating patients at follow-up by the Neck Disability Index (NDI), SF-12, VAS, and range of motion (ROM). Range of motion was measured using standard radiographic methods. METHODS: Patients will be assigned a treatment, either Prodisc-C or ACDF surgery according to a blocked randomization schedule. During the course of the study, patients are assessed preoperatively and postoperatively at 6 weeks, 3 months, 6 months, 1 year, and 2 years.

148S

Proceedings of the NASS 20th Annual Meeting / The Spine Journal 5 (2005) 1S–189S

RESULTS: The average follow-up for both groups was about 1 year (range 6–18 months). The operative time for the two treatments was similar with ProDisc-C disc replacement averaging 88⫾13 minutes and ACDF surgery at 70⫾7 minutes. Estimated operative blood loss was similar with ProDiscC surgery averaging 85⫾35 ml and ACDF surgery averaging 68⫾24 ml. There were no intra-operative complications in either group. There were no neurologic, vascular, or wound complications. Postoperative complications were similar with both groups reporting patients with dysphagia, dysphonia, and interscapular pain. The quality of life measurements (NDI, SF-12, and VAS) all show similar results between the two groups to the 1-year followup time point. Range of motion shows improvement at 1-year follow-up in comparison to preoperative radiographs in the ProDisc-C group. CONCLUSIONS: Although long-term follow-up is needed to fully assess functionality of cervical disc replacement, the preliminary results of safety and efficacy are encouraging in this randomized prospective ongoing study. There have been no complications related to cervical disc replacement surgery or device related issues. There has been no evidence of heterotopic ossification/spontaneous fusions in the disc arthroplasty group. Since adjacent level disease is a significant issue in cervical fusion and is thought to be related to the loss of motion at the fused level, disc replacement may limit the disease while offering a higher quality of life, compared with standard treatment with arthrodesis. DISCLOSURES: FDA device/drug: Prodisc-C. Status: Investigational/ not approved. CONFLICT OF INTEREST: Author (MJ) Consultant: Synthes; Author (MJ) Grant Research Support: Synthes/Spine Solutions. doi: 10.1016/j.spinee.2005.05.294 P80. Hardware removal surgery in patients with persistent low back pain Paul B. Nottingham, MD, Parveen Sra, MPH, Hieu T. Ball, MD, MPH; Bay Area Spine Institute, Walnut Creek, CA, USA BACKGROUND CONTEXT: Internal fixation is commonly used to stabilize the lumbar spine during arthrodesis. However, segmental instrumentation may be a source of pain in patients with recurrent low back pain after radiographically solid fusion. PURPOSE: The purpose of this study was to report on surgical data and assess improvements in symptoms following removal of retained hardware in patients with persistent pain. STUDY DESIGN/SETTING: This was a retrospective outcomes study of lumbar hardware removal surgery. PATIENT SAMPLE: Patients who underwent elective lumbar hardware removal surgery were identified. Pseudarthroses, adjacent level disease requiring extension of fusion, or greater than 2 level fusions were removed from the analyses. The remaining patients with 1 or 2 level solid fusion with retained hardware served as the study cohort. OUTCOME MEASURES: Visual analog pain scale and questions regarding treatment satisfaction were administered. Surgical data included length of surgery, intraoperative and postoperative complications, estimated blood loss, length of hospital stay, and length of follow-up. METHODS: Hospital charts were reviewed to collect surgical information and to identify the study cohort. Patients were followed clinically and completed questions about their current pain level, previous pain level, and satisfaction with the hardware removal surgery. RESULTS: Data from 41 patients with removal of painful retained hardware for 1- or 2- level lumbar fusion were analyzed. Average time from initial fusion surgery to removal of instrumentation was 1.3 years. Three patients experienced postoperative complications, 2 wound infections and 1 tachycardia. Average estimated blood loss was 250 cc and mean length of stay was 2.5 days. Average length of patient follow-up after hardware removal was 2.2 years. Seventy-three percent of patients had experienced some improvement in their pain and 67% reported overall satisfaction with the surgery. CONCLUSIONS: There is very little reported in the current literature on removal of symptomatic retained lumbar hardware. In this study, patient with

persistent low back pain following a solid fusion reported an improvement in symptoms after removal of instrumentation. There was low incidence of postoperative complications and a majority of patients were satisfied with the surgery. Prospective studies may provide further support for the potential benefit of hardware removal in certain patients with recurrent low back pain. DISCLOSURES: No disclosures. CONFLICT OF INTEREST: No conflicts. doi: 10.1016/j.spinee.2005.05.295

P81. Does BMP-2 hasten anterior cervical fusion? K. Daniel Riew, MD1, Jong-Beom Park, MD1, Kyu Jung Cho, PhD, MD1, Rachata Tungsiripat, MD1, Brett Taylor, MD2; 1Washington University School of Medicine in St. Louis, St. Louis, MO, USA; 2 Washington University in St. Louis, St. Louis, MO, USA BACKGROUND CONTEXT: Because the cervical spine is known to fuse well, the added expense of bone morphogenic protein (BMP) is not justifiable, except possibly in pseudarthrosis-prone pts. While the final fusion rates for these pts may approach those of normals, they often have delayed healing, delaying their rehabilitation and return to work. PURPOSE: To determine the cost-effectiveness of BMP use in high-risk pts, one must have the following information: Does BMP accelerate healing, and Does accelerated healing result in improved outcomes, including faster return to work. We undertook this study to answer the first of these questions. STUDY DESIGN/SETTING: Retrospective matched-cohort analysis. PATIENT SAMPLE: From 7/02-4/03, the senior author utilized BMP-2 (Infuse) for pseudarthrosis-prone (smokers &/or diabetics, 3 lv) anterior cervical fusions. BMP grp: 31 pts (13 1-lv, 7 2-lv, 11 3-lv; 31 smokers &/ or diabetics). Control grp: 45 pts (28 1-lv, 7 2-lv, 10 3-lv; 45 smokers &/or diabetics). OUTCOME MEASURES: Surgical technique: 2 allo-fibulae grafts were placed at each level for all 1 and 2-level ACDFs, packed with a small BMP. For 3-levels, we performed a corpectomy-discectomy, packing the local autograft into the uncinates, 2 allografts into the ACDF, and a large BMP into the marrow cavity of all allografts. The controls had an identical procedure, except that demineralized bone matrix was placed in the marrow cavities. METHODS: Two independent, experienced spine surgeons reviewed the records and radiographs of all such patients with adequate 6 wk and 3 mo X-rays and selected co-morbidity matched controls that had been operated on by the same surgeon within 3 yrs of the experimental group. They defined fusion as the absence of any motion and pseudarthrotic lines on A/P, lateral and flex-ext views. RESULTS: p⬍.05 for all comparisons. 1) Comparison of BMP vs. no BMP for 1, 2, and 3 levels in smokers and/or diabetics (Table 1). 2) Comparison of BMP vs. no BMP @ 6 wks and 3 mos for 3 levels in nonsmokers (Table 2). 3) Comparison of smokers and/or diabetic to normals for 3 levels. Both with BMP (Table 3). CONCLUSIONS: Our results suggest that BMP hastens fusion for both smokers and non-smokers. In comparison to controls, BMP used in smokers &/or diabetics hastened fusion for all arthrodeses at 6 wks and 3 mos.

Table 1 Comparison of BMP versus no BMP in smokers and/or diabetics 6 Wks

1 Level 2 Levels 3 Levels

3 Mo

BMP % Fused

No BMP % Fused

BMP % Fused

No BMP % Fused

61.5% 71.4% 36.4%

21.4% 0.0% 0.0%

92.3% 85.7% 63.6%

50.0% 14.3% 22.2%

BMP⫽bone morphogenic protein.