Clinical Outcome of Lumbar Hybrid Surgery in a Consecutive Series of Patients with Long-term Follow-up.

STUDY DESIGN: This was a retrospective study combined with attempted prospective patient contact to collect current data. OBJECTIVE: The purpose of this study was to investigate long-term clinical outcome of patients undergoing lumbar hybrid surgery (total disc replacement (TDR) at one level and fusion at an adjacent level. SUMMARY OF BACKGROUND DATA: Many patients with symptomatic lumbar disc degeneration are affected at more than one level. Lumbar TDR was introduced as a fusion alternative; however, some disc levels are not amenable to TDR and fusion is preferable at such levels. Hybrid surgery was introduced as an option to fusing multiple levels. METHODS: A consecutive series of 305 patients undergoing lumbar hybrid surgery was identified beginning with the first case experience in 2005. Operative and clinical outcome data including visual analog scales (VAS) assessing back and leg pain, Oswestry Disability Index (ODI), and re-operations were collected. The mean follow-up duration was 67.1 months. RESULTS: There were statistically significant improvements (P<0.01) in the mean values of all three clinical outcome measures: VAS back pain scores improved from 6.7 to 3.3; leg pain improved from 4.3 to 2.0; and ODI scores improved from 45.5 to 24.6. There were no significant differences in pain and function scores for patients with minimum 10-year follow-up vs. those with shorter follow-up duration. Re-operation occurred in 16.1% of patients, many of which involved removal of posterior instrumentation at the fusion level (6.2% of study group, 38.8% of re-operations). Re-operation involving the TDR level occurred in 9 patients (2.9%), only 3 of which (1.0%) involved TDR removal/revision. CONCLUSION: This study supports that for many patients with multilevel symptomatic disc degeneration, hybrid surgery is a viable surgical option. Significant improvements were demonstrated in pain and function scores with no diminished improvement in scores among patients with more than 10-year follow-up.

Removals and Revisions of Cervical Total Disc Replacement Devices in a Consecutive Series of 1,626 Patients Beginning with the First Case Experience in 2003.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: The purpose of this study was to investigate the rate of cervical total disc replacement (TDR) device removal or revision. SUMMARY OF BACKGROUND DATA: Cervical TDR has gained acceptance as an alternative to anterior cervical discectomy and fusion (ACDF) in appropriately selected patients. There have been concerns over device safety, one measure of which is subsequent surgery related to device problems. METHODS: A consecutive series of 1,626 cervical TDR patients from 2003 to June 2021 were included, consisting of TDRs up to 3 levels and hybrids (TDR and fusion). TDR removal or revision surgeries and reasons for these surgeries, procedures performed, and duration from index procedure were recorded. Data were analyzed to determine removal/revision rate and factors possibly related to these events. RESULTS: There were 24 removals/revisions (1.48%) in the 1,626 patients. Removal was performed in 23 cases (1.41%) and revision in 1 (0.06%). Among removal cases, ACDF was performed in 18 and TDR was replaced with another TDR in 5. Removals with fusion included 5 cases of osteolysis with/without C. acnes, 4 device displacement/migration, 4 posterior spinal pathology, and one for each of the following: metal allergy, approach-related complications, malpositioning, subsidence, and hypermobility. The revision involved TDR repositioning 3 days after index surgery. There were 66 patients for whom minimum of 10year follow-up was confirmed, and none had removal/revision surgery 10 or more years after index surgery. There was no relationship between occurrence of removal/revision and age, gender, body mass index, or physician experience (learning curve). The removal/revision rate was significantly higher in FDA trials vs. post-approval (4.1% vs. 1.3%, P<0.05). CONCLUSION: In this large consecutive series of patients, 1.48% of cervical TDRs were removed/revised. The low rate of removals/revisions over a long period of time provides support for the devices' safety.

Lumbar Total Disk Replacement Device Removals and Revisions Performed During a 20-Year Experience with 2141 Patients.

STUDY DESIGN: This was a retrospective study with prospective patient contact attempted to collect current data. OBJECTIVE: The purpose was to investigate the incidence and reasons for lumbar total disk replacement (TDR) removal or revision. SUMMARY OF BACKGROUND DATA: A concern regarding lumbar TDR was safety, particularly the need for device removal or revision. This may be particularly important considering removal/revision requires repeat anterior exposure with an increased risk of vascular injury. METHODS: Data were collected for a series of 2141 lumbar TDR patients, beginning with the first case experience in 2000. The mean follow-up was 78.6 months. For each case of device removal/revision, the reason, duration from index surgery, and procedure performed were recorded. RESULTS: Of 2141 patients, 27 (1.26%) underwent TDR removal or revision. Device removal was performed in 24 patients (1.12%), while three patients underwent revision (0.14%). Of the 24 removals, 12 were due to migration and/or loosening, three developed problems post-trauma, two developed lymphocytic reaction to device materials, two had ongoing pain, and there was one case of each: TDR was too large, vertebral body fracture (osteoporosis), lytic lesion, device subsidence and facet arthrosis, and infection seeded from a chest infection 146 months post-TDR. The three revisions were for Core repositioning (technique error), device repositioning after displacement, and core replacement due to wear/failure. With respect to timing, 37.0% of removals/revisions occurred within one-month postimplantation. Of note, 40.7% of removals/revisions occurred in the first 25 TDR cases performed by individual surgeons. There was one significant vascular complication occurring in a patient whose TDR was removed due to trauma. This was also the only patient among 258 with ≥15-year follow-up who underwent removal/revision. CONCLUSION: In this large consecutive series, 1.26% of TDRs were removed/revised. The low rate over a 20 year period supports the safety of these devices.

Prosthesis design and likelihood of achieving physiological range of motion after cervical disc arthroplasty: analysis of range of motion data from 1,173 patients from 7 IDE clinical trials.

BACKGROUND CONTEXT: The functional goals of cervical disc arthroplasty (CDA) are to restore enough range of motion (ROM) to reduce the risk of accelerated adjacent segment degeneration but limit excessive motion to maintain a biomechanically stable index segment. This motion-range is termed the "Physiological mobility range." Clinical studies report postoperative ROM averaged over all study subjects but they do not report what proportion of reconstructed segments yield ROM in the Physiological mobility range following CDA surgery. PURPOSE: To calculate the proportion of reconstructed segments that yield flexion-extension ROM (FE-ROM) in the Physiological mobility range (defined as 5°-16°) by analyzing the 24-month postoperative data reported by clinical trials of various cervical disc prostheses. STUDY DESIGN/SETTING: Analysis of 24-month postoperative FE-ROM data from clinical trials. PATIENT SAMPLE: Data from 1,173 patients from single-level disc replacement clinical trials of 7 cervical disc prostheses. OUTCOME MEASURES: 24-month postoperative index-level FE-ROM. METHODS: The FE-ROM histograms reported in Food and Drug Administration-Investigational Device Exemption (FDA-IDE) submissions and available for this analysis were used to calculate the frequencies of implanted levels with postoperative FE-ROM in the following motion-ranges: Hypomobile (0°-4°), Physiological (5°-16°), and Hypermobile (≥17°). The ROM histograms also allowed calculation of the average ROM of implanted segments in each of the 3 motion-ranges. RESULTS: Only 762 of 1,173 patients (implanted levels) yielded 24-month postCDA FE-ROM in the physiological mobility range (5°-16°). The proportions ranged from 60% to 79% across the 7 disc-prostheses, with an average of 65.0%±6.2%. Three-hundred and two (302) of 1,173 implanted levels yielded ROM in the 0°-4° range. The proportions ranged from 15% to 38% with an average of 25.7%±8.9%. One-hundred and nine (109) of 1,173 implanted levels yielded ROM of ≥17° with a range of 2%-21% and an average proportion of 9.3%±7.9%. The prosthesis with built-in stiffness due to its nucleus-annulus design yielded the highest proportion (103/131, 79%) of implanted segments in the physiological mobility range, compared to the cohort average of 65% (p<.01). Sixty-five of the 350 (18.6%) discs implanted with the 2 mobile-core designs in this cohort yielded ROM≥17° as compared to the cohort average of 9.3% (109/1,173) (p<.05). At 2-year postCDA, the "hypomobile" segments moved on average 2.4±1.2°, those in the "physiological-mobility" group moved 9.4±3.2°, and the hypermobile segments moved 19.6±2.6°. CONCLUSIONS: Prosthesis design significantly influenced the likelihood of achieving FE-ROM in the physiological mobility range, while avoiding hypomobility or hypermobility (p<.01). Postoperative ROM averaged over all study subjects provides incomplete information about the prosthesis performance - it does not tell us how many implanted segments achieve physiological mobility and how many end up with hypomobility or hypermobility. We conclude that the proportion of index levels achieving postCDA motions in the physiological mobility range (5°-16°) is a more useful outcome measure for future clinical trials.

Impact of previous lumbar spine surgery on the outcome of lumbar total disc replacement: analysis of prospective 5-year follow-up study data.

PURPOSE: It is sometimes anticipated that patients with prior spine surgery will have a compromised outcome from future procedures. The purpose of this study was to compare TDR outcomes in patients with prior lumbar spine surgery to those with no previous surgery. METHODS: Post hoc analysis was performed on 5-year follow-up data collected prospectively in the multi-centre FDA-regulated trial for the activL® Artificial Disc which involved 376 patients treated for single-level symptomatic disc degeneration. Clinical outcome measures included the Oswestry Disability Index (ODI), visual analog scales (VAS) assessing back and leg pain, SF-36, adverse events, and re-operations. Radiographic outcomes included flexion/extension range of motion (ROM) and translation of the operated segment. Patients were divided into two groups: Prior Lumbar Surgery (PLS, n = 92) and No Prior Lumbar Surgery (NPLS, n = 284). RESULTS: Baseline demographics were similar in the two groups. ODI, VAS, and SF-36 Physical Component Scale scores improved significantly (p < 0.05) from baseline in both groups with improvements maintained through 5-year post-TDR with no significant differences between groups. There were no statistically significant differences in rates of serious device-related events, procedure-related events, or re-operations. While ROM was significantly less prior to TDR surgery in the PLS group, there was no significant difference in ROM at post-operative points. CONCLUSION: Prior lumbar spine surgery was not associated with compromised outcomes following TDR. These results are in line with reports from earlier studies with shorter follow-up, finding that non-destabilizing prior surgery is not a contra-indication for TDR provided that selection criteria are met. LEVEL OF EVIDENCE I: Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.

Evaluation of Anterior Lumbar Interbody Fusion Performed Using a Stand-Alone, Integrated Fusion Cage.

BACKGROUND: Anterior lumbar interbody fusion (ALIF) has been performed for many years. Often, posterior supplemental fixation has been used to provide additional stability to the operated segment. Interbody implants have evolved to incorporate unique designs, polyetheretherketone, integrated screws, and surface texture. With these changes, the need for supplemental posterior fixation has been debated. The purpose of this study was to evaluate the clinical outcome of stand-alone ALIF. METHODS: A surgery log was reviewed to identify the consecutive series of 58 patients undergoing ALIF using a STALIF stand-alone cage from March 2011 (first case) to December 2018 (minimum 24 months postoperative) with a mean follow-up of 30.6 months. All patients were treated for symptomatic degenerative conditions. Charts were reviewed to collect general patient information, operative data, and patient-reported outcomes, including the Oswestry Disability Index (ODI), visual analog scales (VAS) separately assessing back pain and leg pain, and re-operations. For patients who were not seen recently in clinic for follow-up, current outcome data were collected through mailings. RESULTS: The mean operative blood loss was 52.1 mL. There was a statistically significant improvement in mean ODI scores from 41.7 preoperatively to 21.0 at follow-up (P < 0.01). There was also significant improvement (P < 0.01) in VAS back pain (6.0-2.5) and leg pain (4.1-1.3). Subsequent surgery was performed on 9 patients. Reasons for re-operation were pseudoarthrosis (n = 3), progressive cage subsidence (n = 1), foraminal stenosis at the index level (n = 1), metal allergy reaction (n = 2), adjacent segment degeneration (n = 1), and ongoing pain (n = 1). There were no cases of device failure, vertebral body fracture, or screws backing out of the implant. DISCUSSION: Stand-alone ALIF was associated with statistically significant improvements in ODI scores, back pain, and leg pain. The re-operation rate for clear pseudoarthrosis or cage subsidence was 6.8%. These results support that stand-alone ALIF produces good outcomes in patients treated for symptomatic disc degeneration while avoiding the use of posterior fixation and its complication risk and cost. CLINICAL RELEVANCE: The results of this study support that stand-alone ALIF is a viable procedure for the treatment of symptomatic disc degeneration unresponsive in patients who have failed nonoperative care and who do not have specific indications for supplemental posterior instrumentation.

In which cases do surgeons specializing in total disc replacement perform fusion in patients with symptomatic lumbar disc degeneration?

PURPOSE: The purpose of this study was to investigate reasons and their frequency for why spine surgeons subspecializing in total disc replacement (TDR) performed lumbar fusion rather than TDR. METHODS: The study was based on a consecutive series of 515 patients undergoing lumbar TDR or fusion during a 5-year period by three surgeons specializing in TDR. For each fusion patient, the reason for not performing TDR was recorded. RESULTS: TDR was performed in 65.4% (n = 337) of patients and the remaining 34.6% (n = 178) underwent anterior lumbar interbody fusion (ALIF ± posterior instrumentation). Of the 178 fusion patients, the most common reason for fusion was combined factors related to severe degenerative changes (n = 59, 11.5% of the study population). The second most common reason was > Grade 1 spondylolisthesis (n = 32, 6.2%), followed by insurance non-coverage (n = 24, 4.7%), and osteopenia/osteoporosis (n = 13, 2.5%). Fusion patients were significantly older than TDR patients (52.5 vs. 41.6 years; p < 0.01). There was no significant difference with respect to gender (41.2% female vs. 43.8% female, p > 0.05) or the percentage of patients with single-level surgery (61.2% vs. 56.7%, p > 0.05). CONCLUSION: The most common reason for not performing lumbar TDR was related to anatomic factors that may compromise stability of the operated segment and/or TDR functionality. The older age of fusion patients may be related to these factors. This study found that many patients are appropriate candidates for lumbar TDR. However, even among TDR subspecialists, fusion is preferred when there are factors that cannot be addressed with TDR and/or may compromise implant functionality.

Segmental Motion of Cervical Arthroplasty Leads to Decreased Adjacent-Level Degeneration: Analysis of the 7-Year Postoperative Results of a Multicenter Randomized Controlled Trial.

BACKGROUND: Cervical artificial disc replacement (C-ADR) has become a common and accepted surgical treatment for many patients with cervical disc degeneration/herniation and radiculopathy who have failed nonoperative treatment. Midterm follow-up studies of the original investigational device exemption trials comparing C-ADR to traditional anterior cervical discectomy and fusion (ACDF) have revealed C-ADR patients have less adjacent-level disease and fewer reoperations at 5 to 7 years. The purpose of this study was to examine the relationship of radiographic adjacent-level disease (R-ALD) with the amount of index-level segmental range of motion (ROM) in C-ADR patients using the long-term follow-up data from the ProDisc-C investigational device exemption trial. METHODS: This was a post hoc analysis of a 1:1 randomized controlled trial. The initial previously described Food and Drug Administration-approved 2-year study was extended, and consenting patients in the original study were followed at annual intervals up to 7 years. Logistic regression was used to assess any progression in adjacent-level disease (ALD). Ordinal logistic regression was also used to assess the relationship between any progressive R-ALD and final flexion extension (F/E) ROM in C-ADR patients. Spearman's rank-order correlation was used when R-ALD was kept as an ordinal variable to assess the same relationship. RESULTS: At the last follow-up visit, the rate of progressive R-ALD was significantly higher in ACDF patients than in C-ADR patients. When C-ADR patients were divided into 3 groups based on final F/E ROM, those with 0° to 3° (n = 19), 4° to 6° (n = 15), and 7° (n = 42) of segmental motion at the index procedure level, the rate of progressive R-ALD trended significantly with final ROM (P = 0.01). CONCLUSIONS: C-ADR leads to a significant decrease in R-ALD compared to ACDF. The difference in R-ALD is related to the preservation of motion at the index level and resultant preservation of kinematics and forces across the adjacent disc space.

Cervical Disc Arthroplasty: Rationale and History.

Biomechanical studies have demonstrated that cervical fusion results in increased motion and intradiscal pressures at adjacent levels. Cervical disc arthroplasty (CDA) is an alternative treatment for cervical radiculopathy and myelopathy resulting from degenerative disc disease. By maintaining segmental motion, surgeons hope to avoid some of the primary drawbacks of anterior cervical discectomy and fusion (ACDF), such as pseudoarthrosis and adjacent segment disease. First introduced in the 1960s, CDA has evolved over the years with changes to implant geometry and materials. Early devices produced suboptimal outcomes, but more recent generations of implants have shown long-term outcomes rivaling or even surpassing those of ACDF. In this article, the rationale for CDA as well as the history of such devices is reviewed.

Analysis of re-operations after cervical total disc replacement in a consecutive series of 535 patients receiving the ProDisc-C device.

INTRODUCTION: One important factor in evaluating the safety of an implant is the rate of subsequent surgery and the reasons for surgery, particularly those that are related to possible problems with the implant. The purpose of this study was to determine the overall re-operation rate (including revisions, removals, device-related, procedure-related, adjacent segment, and others) for a large consecutive series of cervical TDR patients beginning with the first case experience, using a single device at a single institution. METHODS: Surgery records were reviewed to identify cervical TDR patients and those who underwent subsequent surgery. Cervical TDR cases involving ProDisc-C were identified, beginning with the first case performed in 2003 at a multisite spine specialty centre. Only patients who were at least 2 years post-operative were included, producing a consecutive series of 535 patients. There were 115 hybrids in the series (TDR at one level and fusion at an adjacent segment). Data collected included general demographics and level(s) operated. A surgery log through 12-31-18 was reviewed to identify re-operations occurring in the TDR patients. For each re-operation, the reason, duration from index surgery, and procedure were recorded. The mean duration from the index surgery to the search of the surgery log for re-operations was 78.3 months, range 24 to 181 months. RESULTS: Re-operation occurred in 30 patients (5.6%). These included: 3 TDR removals and revision to anterior discectomy and fusion (1 for migration, 1 for subsidence, and 1 for spondylosis), 1 TDR repositioning, 21 secondary surgeries for adjacent segment degeneration (5 of which were adjacent to fusion levels in hybrid procedures), 1 wound infection, 1 hematoma, and 2 received stimulators for pain control. There were no re- operations for device failure. In cases of re-operation for adjacent segment degeneration, the mean duration between the index surgery and re-operation was 47.3 months. CONCLUSION: The re-operation rate was 5.6%. No surgeries were performed for device failure. These results support the safety of the TDR device.

Screw-Related Complications After Instrumentation of the Osteoporotic Spine: A Systematic Literature Review With Meta-Analysis.

STUDY DESIGN: Systematic literature review with meta-analysis. OBJECTIVE: Osteoporosis is common in elderly patients, who frequently suffer from spinal fractures or degenerative diseases and often require surgical treatment with spinal instrumentation. Diminished bone quality impairs primary screw purchase, which may lead to loosening and its sequelae, in the worst case, revision surgery. Information about the incidence of spinal instrumentation-related complications in osteoporotic patients is currently limited to individual reports. We conducted a systematic literature review with the aim of quantifying the incidence of screw loosening in osteoporotic spines. METHODS: Publications on spinal instrumentation of osteoporotic patients reporting screw-related complications were identified in 3 databases. Data on screw loosening and other local complications was collected. Pooled risks of experiencing such complications were estimated with random effects models. Risk of bias in the individual studies was assessed with an adapted McHarm Scale. RESULTS: From 1831 initial matches, 32 were eligible and 19 reported screw loosening rates. Studies were heterogeneous concerning procedures performed and risk of bias. Screw loosening incidences were variable with a pooled risk of 22.5% (95% CI 10.8%-36.6%, 95% prediction interval [PI] 0%-81.2%) in reports on nonaugmented screws and 2.2% (95% CI 0.0%-7.2%, 95% PI 0%-25.1%) in reports on augmented screws. CONCLUSIONS: The findings of this meta-analysis suggest that screw loosening incidences may be considerably higher in osteoporotic spines than with normal bone mineral density. Screw augmentation may reduce loosening rates; however, this requires confirmation through clinical studies. Standardized reporting of prespecified complications should be enforced by publishers.

In which cases do surgeons specializing in total disc replacement perform fusion in patients with cervical spine symptoms?

PURPOSE: The purpose was to investigate reasons and their frequency for why total disc replacement (TDR) specialty surgeons performed anterior cervical discectomy and fusion (ACDF) rather than TDR. METHODS: A consecutive series of 464 patients undergoing cervical spine surgery during a 5-year period by three TDR specialty surgeons was reviewed. For each ACDF, the reason for not performing TDR was recorded. RESULTS: TDR was performed in 76.7% of patients (n = 356) and ACDF in 23.3% (n = 108). The most common reason for ACDF versus TDR was anatomical (conditions that may not be adequately addressed with TDR and/or may interfere with device function), which occurred in 64 of 464 patients (13.79%). The second most common reason was insurance (denial/lack of coverage n = 17, 3.23%), and deformity/kyphosis not addressable with TDR was noted in 13 (2.80%). Pseudoarthrosis repair led to ACDF in three patients (0.65%), two did not receive TDR due to osteoporosis (0.43%), and in two others (0.43%) ACDF was undertaken due to high risk of heterotopic ossification. There was one case (0.22%) each of: nickel allergy, trauma with posterior element fracture, TDR removal, multiple prior cervical spine surgeries, concern about artifact on future imaging studies, benign osteoblastic bone, and limitation to adequate surgical approach for TDR. ACDF patients' mean age was significantly greater than TDR patients' (55.3 vs. 46.7 years; p < 0.01). TDR group had significantly more single-level procedures than ACDF (60.8% vs. 43.5%; p < 0.05). CONCLUSION: The most common reason for ACDF versus TDR was anatomy that may compromise segmental stability and/or TDR functionality. Older age and greater number of operated levels may be related to anatomical factors, primarily significant osteophytes and severely degenerated facets. These factors, as well as deformity/kyphosis, are more common in older patients and require multi-level treatment. This study found that many patients are good cervical TDR candidates; however, even among TDR specialists, ACDF may be preferred where it is prudent to not take undue risks. These slides can be retrieved under Electronic Supplementary Material.

Prospective, Randomized Comparison of One-level Mobi-C Cervical Total Disc Replacement vs. Anterior Cervical Discectomy and Fusion: Results at 5-year Follow-up.

INTRODUCTION: There is increasing interest in the role of cervical total disc replacement (TDR) as an alternative to anterior cervical discectomy and fusion (ACDF). Multiple prospective randomized studies with minimum 2 year follow-up have shown TDR to be at least as safe and effective as ACDF in treating symptomatic degenerative disc disease at a single level. The purpose of this study was to compare outcomes of cervical TDR using the Mobi-C(®) with ACDF at 5-year follow-up. METHODS: This prospective, randomized, controlled trial was conducted as a Food and Drug Administration regulated Investigational Device Exemption trial across 23 centers with 245 patients randomized (2:1) to receive TDR with Mobi-C(®) Cervical Disc Prosthesis or ACDF with anterior plate and allograft. Outcome assessments included a composite overall success score, Neck Disability Index (NDI), visual analog scales (VAS) assessing neck and arm pain, Short Form-12 (SF-12) health survey, patient satisfaction, major complications, subsequent surgery, segmental range of motion, and adjacent segment degeneration. RESULTS: The 60-month follow-up rate was 85.5% for the TDR group and 78.9% for the ACDF group. The composite overall success was 61.9% with TDR vs. 52.2% with ACDF, demonstrating statistical non-inferiority. Improvements in NDI, VAS neck and arm pain, and SF-12 scores were similar between groups and were maintained from earlier follow-up through 60 months. There was no significant difference between TDR and ACDF in adverse events or major complications. Range of motion was maintained with TDR through 60 months. Device-related subsequent surgeries (TDR: 3.0%, ACDF: 11.1%, p<0.02) and adjacent segment degeneration at the superior level (TDR: 37.1%, ACDF: 54.7%, p<0.03) were significantly lower for TDR patients. CONCLUSIONS: Five-year results demonstrate the safety and efficacy of TDR with the Mobi-C as a viable alternative to ACDF with the potential advantage of lower rates of reoperation and adjacent segment degeneration, in the treatment of one-level symptomatic cervical degenerative disc disease. CLINICAL RELEVANCE: This prospective, randomized study with 5-year follow-up adds to the existing literature indicating that cervical TDR is a viable alternative to ACDF in appropriately selected patients. LEVEL OF EVIDENCE: This is a Level I study.

Comparison of 1-Level Versus 2-Level Anterior Cervical Discectomy and Fusion: Clinical and Radiographic Follow-Up at 60 Months.

STUDY DESIGN: This study represents a posthoc analysis of data collected from 2 control arms of a prospective, randomized study. OBJECTIVE: The purpose of this study was to compare results of patients undergoing 1- versus 2-level anterior cervical discectomy and fusion (ACDF). SUMMARY OF BACKGROUND DATA: For single-level ACDF, reported outcomes have generally been good; however, results for 2 levels have been less consistent. METHODS: This 60-month follow-up study was based on data from the prospective Food and Drug Administration regulated Mobi-C artificial disc trial. Serving as the control, ACDF was performed at 1 level in 81 patients and 2 levels in 105 patients. Study selection criteria, fusion technique, and outcome measures were identical, with the only exception being the number of levels that were pathological and operated. RESULTS: Neck Disability Index (NDI) scores, visual analog scales assessing neck and arm pain, and SF-12 scores improved significantly in both groups. Significant differences were observed between groups on NDI and SF-12 PCS scores through 60 months. Fusion rates were 93.3% in the 1-level group and 86.1% in the 2-level (60 months, not significantly different). Adjacent segment degeneration occurred in 54.7% of patients at the superior level and 44.7% at the inferior segment in the 1-level group and 70.8%, and 55.0% respectively in 2-level patients (trend at superior level; 0.05 < P < 0.10). Subsequent index level surgery was performed in 11.1% of single-level patients versus 16.2% of the 2-level group (not significantly different). CONCLUSION: One- and 2-level ACDF groups improved significantly and maintained improvement throughout 60 month follow-up. When comparing groups, outcomes were often similar, though the 1-level group demonstrated higher fusion rates at 6 and 12 months, greater improvement in NDI scores from 18 to 60-month follow-up, and greater improvement in SF-12 PCS from 12 to 60 months.

Evaluation of Decompression and Interlaminar Stabilization Compared with Decompression and Fusion for the Treatment of Lumbar Spinal Stenosis: 5-year Follow-up of a Prospective, Randomized, Controlled Trial.

INTRODUCTION: If nonoperative treatment for lumbar stenosis fails, surgery may be considered. This traditionally includes decompression often combined with fusion. Desire for less extensive surgery led to developing new techniques and implants, including an interlaminar device designed with the goal of providing segmental stability without fusion, following decompression. The purpose of this study was to investigate 5-year outcomes associated with an interlaminar device. METHODS: This prospective, randomized, controlled trial was conducted at 21 centers. Patients with moderate to severe lumbar stenosis at one or two contiguous levels and up to Grade I spondylolisthesis were randomized (2:1 ratio) to decompression and interlaminar stabilization (D+ILS; n=215) using the coflex(®) Interlaminar Stabilization(®) device (Paradigm Spine, LLC) or decompression and fusion with pedicle screws (D+PS; n=107). Clinical evaluations were made preoperatively and at 6 weeks and 3, 6, 12, 18, 24, 36, 48, and 60 months postoperatively. Overall Food and Drug Administration success criteria required that a patient meet 4 criteria: 1) >15 point improvement in Oswestry Disability Index (ODI) score; 2) no reoperation, revision, removal, or supplemental fixation; 3) no major device-related complication; and 4) no epidural steroid injection after surgery. RESULTS: At 5 years, 50.3% of D+ILS vs. 44% of D+PS patients (p>0.35) met the composite success criteria. Reoperation/revision rates were similar in the two groups (16.3% vs. 17.8%; p >0.90). Both groups had statistically significant improvement through 60 months in ODI scores with 80.6% of D+ILS patients and 73.2% of D+PS patients demonstrating >15 point improvement (p>0.30). VAS, SF-12, and ZCQ scores followed a similar pattern of maintained significant improvement throughout follow-up. On the SF-12 and ZCQ, D+ILS group scores were statistically significantly better during early follow-up compared to D+PS. In the D+ILS group, foraminal height, disc space height, and range of motion at the index level were maintained through 5 years. CONCLUSION: Both treatment groups achieved and maintained statistically significant improvements on multiple outcome assessments throughout 5-year follow-up. On some clinical measures, there were statistically significant differences during early follow-up favoring D+ILS. At no point were there significant differences favoring D+PS. Results of this 5-year follow-up study demonstrate that decompression and interlaminar stabilization with coflex is a viable alternative to traditional decompression and fusion in the treatment of patients with moderate to severe stenosis at one or two lumbar levels. LEVEL OF EVIDENCE AND ETHICAL STATEMENTS: This is a Level I study. Institutional approval was received at each of the sites participating in the trial. Each patient gave informed consent to participate in the trial.

ProDisc-C Total Disc Replacement Versus Anterior Cervical Discectomy and Fusion for Single-Level Symptomatic Cervical Disc Disease: Seven-Year Follow-up of the Prospective Randomized U.S. Food and Drug Administration Investigational Device Exemption Study.

BACKGROUND: In patients with single-level cervical degenerative disc disease, total disc arthroplasty can relieve radicular pain and preserve functional motion between two vertebrae. We compared the efficacy and safety of cervical total disc arthroplasty with that of anterior cervical discectomy and fusion (ACDF) for the treatment of single-level cervical degenerative disc disease between C3-C4 and C6-C7. METHODS: Two hundred and nine patients at thirteen sites were randomly treated with either total disc arthroplasty with ProDisc-C (n = 103) or with ACDF (n = 106). Patients were assessed preoperatively; at six weeks and three, six, twelve, eighteen, and twenty-four months postoperatively; and then annually until seven years postoperatively. Outcome measures included the Neck Disability Index (NDI), the Short Form-36 (SF-36), postoperative neurologic parameters, secondary surgical procedures, adverse events, neck and arm pain, and satisfaction scores. RESULTS: At seven years, the overall follow-up rate was 92% (152 of 165). There were no significant differences in demographic factors, follow-up rate, or patient-reported outcomes between groups. Both procedures were effective in reducing neck and arm pain and improving and maintaining function and health-related quality of life. Neurologic status was improved or maintained in 88% and 89% of the patients in the ProDisc-C and ACDF groups, respectively. After seven years of follow-up, thirty secondary surgical procedures had been performed in nineteen (18%) of 106 patients in the ACDF group compared with seven secondary surgical procedures in seven (7%) of 103 patients in the ProDisc-C group (p = 0.0099). There were no significant differences in the rates of any device-related adverse events between the groups. CONCLUSIONS: Total disc arthroplasty with ProDisc-C is a safe and effective surgical treatment of single-level symptomatic cervical degenerative disc disease. Clinical outcomes after total disc arthroplasty with ProDisc-C were similar to those after ACDF. Patients treated with ProDisc-C had a lower probability of subsequent surgery, suggesting that total disc arthroplasty provides durable results and has the potential to slow the rate of adjacent-level disease. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Development of a novel radiographic measure of lumbar instability and validation using the facet fluid sign.

BACKGROUND: Lumbar spinal instability is frequently referenced in clinical practice and the scientific literature despite the lack of a standard definition or validated radiographic test. The Quantitative Stability Index (QSI) is being developed as a novel objective test for sagittal plane lumbar instability. The QSI is calculated using lumbar flexion-extension radiographs. The goal of the current study was to use the facet fluid sign on MRI as the "gold standard" and determine if the QSI is significantly different in the presence of the fluid sign. METHODS: Sixty-two paired preoperative MRI and flexion-extension exams were obtained from a large FDA IDE study. The MRI exams were assessed for the presence of a facet fluid sign, and the QSI was calculated from sagittal plane intervertebral rotation and translation measurements. The QSI is based on the translation per degree of rotation (TPDR) and is calculated as a Z-score. A QSI > 2 indicates that the TPDR is > 2 std dev above the mean for an asymptomatic and radiographically normal population. The reproducibility of the QSI was also tested. RESULTS: The mean difference between trained observers in the measured QSI was between -0.28 and 0.36. The average QSI was significantly (P = 0.047, one-way analysis of variance) higher at levels with a definite fluid sign (2.3±3.2 versus 0.60±2.4). CONCLUSIONS: Although imperfect, the facet fluid sign observed may be the best currently available test for lumbar spine instability. Using the facet fluid sign as the "gold standard" the current study documents that the QSI can be expected to be significantly higher in the presence of the facet fluid sign. This supports that QSI might be used to test for sagittal plane lumbar instability. CLINICAL RELEVANCE: A validated, objective and practical test for spinal instability would facilitate research to understand the importance of instability in diagnosis and treatment of low-back related disorders.

Restoration of Cervical Alignment is Associated with Improved Clinical Outcome after One and Two Level Anterior Cervical Discectomy and Fusion.

BACKGROUND: Anterior cervical discectomy and fusion (ACDF) remains the standard of care for patients with cervical radiculopathy who are unresponsive to conservative care. However, the maintenance and restoration of cervical alignment as a predictive factor for outcome has not yet been fully evaluated. The purpose of this study was to evaluate the impact of maintaining or restoring cervical alignment on one and two level ACDF patients' outcome. METHODS: Data were collected from 104 patients who underwent one and two level ACDF. Cervical alignment was measured preoperatively and at follow-up visits. The patients were classified into three groups based on the postoperative change of their cervical alignment. Neck pain, arm pain, and Neck Disability Index (NDI) scores were obtained preoperatively and at the latest follow-up visit. Incidences of adjacent segment degeneration (ASD) and reoperations because of ASD were recorded. RESULTS: There were 64 patients in the Maintained group, 17 patients in the Restored group and 23 patients in the Kyphotic group. Pre-operatively, the neck pain scores, arm pain scores and NDI scores were not statistically different among the three groups (p>0.05). On average at 12 months follow-up, the neck pain scores improved by 2.7, 4.2, and 2.7 points respectively in the three groups (p>0.05). The patients' arm pain scores improved by 2.1, 2.4, and 2.8 points respectively (p>0.05). NDI scores improved by 12, 31 and 13.7 points respectively (p<0.05). The incidences of ASD and reoperations because of ASD were 16%, 12% and 35% respectively (p>0.05). CONCLUSIONS: The patients with restored cervical alignment had significantly greater NDI improvement and relatively better neck pain improvement. There was a trend for patients who had unchanged cervical kyphosis to have a higher incidence of ASD. Our study suggests that restoration of cervical alignment will contribute to improved clinical outcome in the patients who have one and two level ACDF surgeries. LEVEL OF EVIDENCE: This is a level III study.

Reoperations in cervical total disc replacement compared with anterior cervical fusion: results compiled from multiple prospective food and drug administration investigational device exemption trials conducted at a single site.

STUDY DESIGN: This study is based on a post hoc analysis of data collected from multiple prospective, randomized studies conducted at the same site. OBJECTIVE: The purpose of this study was to compare the reoperation rates in patients with cervical total disc replacement (TDR) versus patients with anterior cervical fusion (ACF). SUMMARY OF BACKGROUND DATA: One important evaluation of any new technology is the safety, including the need for future surgery. One of the potential benefits of cervical TDR compared with ACF, is the possibility of reducing or eliminating degeneration of the adjacent segment. It is also important to determine if the new technology introduces new problems, not seen with the current standard of care. METHODS: Data were collected prospectively for patients enrolled in 1 of 6 Food and Drug Administration regulated investigational device exemption trials conducted at a single site. Results are based on 136 patients (84 TDR, 52 ACF) with mean follow-up of 55.1 months (range, 24-98 mo). Data collected included general demographics, operative details, length of follow-up, the occurrence of a reoperation, the reason for the reoperation, length of time between the index study procedure and reoperation. For this study, reoperation was defined as any surgical procedure involving the cervical spine. The reoperation rates as well as the length of time after the index surgery the reoperation occurred were compared for the TDR and ACF groups. RESULTS: The reoperation rate in the TDR group was significantly less than in the ACF group (8.3% vs. 21.2%; P < 0.05). There was a trend for the reoperation rate attributed to adjacent segment degeneration to be significantly less in the TDR group than in the ACF group (4.8% vs. 13.5%; 0.05

ProDisc-C and anterior cervical discectomy and fusion as surgical treatment for single-level cervical symptomatic degenerative disc disease: five-year results of a Food and Drug Administration study.

STUDY DESIGN: Randomized controlled trial. OBJECTIVE: Analyze the clinical outcomes at 5 years comparing cervical total disc replacement (TDR) with ProDisc-C (Synthes Spine USA Products; LLC, West Chester, PA) with anterior cervical discectomy and fusion (ACDF). SUMMARY OF BACKGROUND DATA: Previous reports of 2- and 4-year results have shown that ProDisc-C, a TDR for surgical treatment of patients experiencing single-level symptomatic cervical disc disease between C3 and C7, is safe and effective. METHODS: Two hundred nine patients (103 ProDisc-C and 106 ACDF) from 13 sites were randomized and treated. Results including neck disability index, visual analog scale (VAS) neck and arm pain, Short Form-36 (SF-36), neurological examination, device success, adverse event occurrence, and VAS patient satisfaction were analyzed. RESULTS: Demographics were similar between the 2 patient groups (ProDisc-C: 42.1 ± 8.4 yr, 44.7% males; ACDF: 43.5 ± 7.1 yr, 46.2% males). Rates of follow-up at 2 years were 98.1% ProDisc-C and 94.8% ACDF, and at 5 years 72.7% ProDisc-C and 63.5% ACDF. For all clinical outcomes for both groups, there was a statistically and clinically significant improvement at 2 and 5 years compared with baseline. At 5 years, ProDisc-C patients had statistically significantly less neck pain intensity and frequency. Both groups scored high VAS satisfaction scores at 5 years, with ProDisc-C 86.56 and ACDF 82.74. There were no reports of device failures or implant migration with ProDisc-C. The ProDisc-C patients maintained motion at their index level. At 5 years, the ProDisc-C patients had a statistically significantly lower rate of reoperation compared with ACDF patients (2.9% vs. 11.3%). CONCLUSION: Five-year results show that TDR with ProDisc-C is a safe and effective treatment of single-level symptomatic cervical disc disease. Clinical outcomes were comparable with ACDF. ProDisc-C patients maintained motion at the index level and had significantly less neck pain intensity and frequency as well as a lower probability of secondary surgery.