Magnetic resonance spectroscopy (MRS) identification of chemically painful lumbar discs leads to improved 6-, 12-, and 24-month outcomes for discogenic low back pain surgeries.

PURPOSE: MRS was shown to reliably quantify relative levels of degenerative pain biomarkers, differentiating painful versus non-painful discs in patients with chronic discogenic low back pain (DLBP), and this correlates with surgical success rates. We now report results based on more patients and longer follow-up. METHODS: Disc MRS was performed in DLBP patients who subsequently received lumbar surgery. Custom post-processing (NOCISCAN-LS®; Aclarion Inc.) calculated disc-specific NOCISCORES® that reflect relative differences in degenerative pain biomarkers for diagnosing chemically painful discs. Outcomes in 78 patients were evaluated using Oswestry Disability Index (ODI) scores. Surgical success (≥ 15-point ODI improvement) was compared between surgeries that were "Concordant" (Group C) versus "Discordant" (Group D) with NOCISCORE-based diagnosis for painful discs. RESULTS: Success rates were higher for Group C versus Group D: 6 months (88% vs. 62%; p = 0.01), 12 months (91% vs. 56%; p < 0.001), and 24 months (85% vs. 63%; p = 0.07). Success rates for Group C surgeries were also higher than Group D surgeries in a variety of sub-group comparisons. Group C had a greater reduction in ODI from pre-operative to follow-up than Group D [absolute change (% change), (p)]: 6 months: - 35 (- 61%) versus - 23 (- 39%), (p < 0.05); 12 months: - 39 (- 69%) versus - 22 (- 39%), (p < 0.01); and 24 months: - 38 (- 66%) versus - 26 (- 48%), (p < 0.05). CONCLUSION: More successful, sustained outcomes were obtained when surgically treating chemically painful discs identified by NOCISCAN-LS post-processed disc MRS exams. Results suggest that NOCISCAN-LS provides a valuable new diagnostic tool to help clinicians better select treatment levels.

Optimizing success with lumbar disc arthroplasty.

PURPOSE: This study aimed at determining the variables that may prove useful in predicting clinical outcomes following lumbar disc arthroplasty. METHODS: Pre- and post-operative imaging assessments were obtained for 99 single-level lumbar disc arthroplasty patients from a prospective IDE study. The assessments and patient demographics were tested to identify variables that were significantly associated with clinical outcomes. RESULTS: Clinical outcome data were available for 85 % of patients at the 5-year follow-up. Numerous assessments made from the pre-operative imaging were found to have statistically significant associations with clinical outcomes at 2 and 5 years. The most notable factors were related to the amount of degeneration at the index level, with patients achieving better outcome scores at 5 years if they have higher grades of degeneration preoperatively. CONCLUSIONS: Several variables may prove effective at optimizing clinical outcomes including a preoperative disc height <8 mm, Modic type 2 changes adjacent to the target disc, a low amount of lordosis present at the treatment level, low levels of fatty replacement of the paraspinal musculature, a prominent amount of facet joint or disc degeneration, and the presence of flat or convex vertebral endplates. There were also post-operative findings associated with better patient outcomes including a larger percent of the endplate covered with the implant, larger implant heights, greater increases in disc space heights, and a larger increase in index level lumbar lordosis. These variables could be explored in other clinical studies to facilitate meta-analyses that could identify effective strategies to optimize clinical outcomes with lumbar disc arthroplasty.

Allogeneic Disc Progenitor Cells Safely Increase Disc Volume and Improve Pain, Disability, and Quality of Life in Patients With Lumbar Disc Degeneration-Results of an FDA-Approved Biologic Therapy Randomized Clinical Trial.

BACKGROUND: Progenitor cells derived from intervertebral disc tissue demonstrated immunomodulatory and regenerative properties in preclinical studies. We report the safety and efficacy results of a US Food and Drug Administration-approved clinical trial of these cells for the treatment of symptomatic degenerative disc disease. METHODS: Sixty patients with symptomatic single-level lumbar degenerative disc disease (mean age 37.9 years, 60% men) were enrolled in a randomized, double-blinded, placebo-controlled Phase I/Phase II study at 13 clinical sites. They were randomized to receive single intradiscal injections of either low-dose cells (N = 20), high-dose cells (N = 20), vehicle alone (N = 10), or placebo (N = 10). The primary endpoint was mean visual analog scale (VAS) pain improvement >30% at 52 weeks. Disc volume was radiologically assessed. Adverse events (AEs), regardless of whether they were related to treatment, were reported. Patients were assessed at baseline and at 4, 12, 26, 52, 78, and 104 weeks posttreatment. RESULTS: At week 52, the high-dose group had a mean VAS percentage decrease from baseline (-62.8%, P = 0.0005), achieving the endpoint of back pain improvement >30%; the mean change was also significantly greater than the minimal clinically important difference of a 20-point decrease (-42.8, P = 0.001). This clinical improvement was maintained at week 104. The vehicle group had a smaller significant decrease in VAS (-52.8%, P = 0.044), while the low-dose and placebo groups showed nonsignificant improvements. Only the high-dose group had a significant change in disc volume, with mean increases of 249.0 mm3 (P = 0.028) at 52 weeks and 402.1 mm3 (P = 0.028) at 104 weeks. A minority of patients (18.3%) reported AEs that were severe. Overall, 6.7% of patients experienced serious AEs, all in the vehicle (n = 1) or placebo (n = 3) groups, none treatment related. CONCLUSIONS: High-dose allogeneic disc progenitor cells produced statistically significant, clinically meaningful improvements in back pain and disc volume at 1 year following a single intradiscal injection and were safe and well tolerated. These improvements were maintained at 2 years post-injection. CLINICAL TRIAL REGISTRATION: NCT03347708-Study to Evaluate the Safety and Preliminary Efficacy of Injectable Disc Cell Therapy, a Treatment for Symptomatic Lumbar Intervertebral Disc Degeneration.

Prospective study on serum metal levels in patients with metal-on-metal lumbar disc arthroplasty.

PURPOSE: Metal-on-metal total disc replacement is a recent alternative treatment for degenerative disc disease. Wear and corrosion of these implants can lead to local and systemic transport of metal debris. This prospective longitudinal study examined the serum chromium and cobalt levels in 24 patients with cobalt-chromium alloy metal-on-metal lumbar disc replacements. METHODS: Serum was assayed for chromium (Cr) and cobalt (Co) using high-resolution inductively-coupled plasma-mass spectrometry. Detection limits were 0.015 ng/mL for Cr and 0.04 ng/mL for Co. RESULTS: Median serum Co levels at pre-op, 3, 6, 12, 24, and 36-months post-op were 0.10, 1.03, 0.96, 0.98, 0.67, and 0.52 ng/mL, respectively. Median serum Cr levels were 0.06, 0.49, 0.65, 0.43, 0.52, and 0.50 ng/mL, respectively. CONCLUSION: In general, these results indicated that serum Co and Cr levels are elevated at all postoperative time points and are of the same order of magnitude as those observed in well-functioning metal-on-metal surface replacements of the hip and in metal-on-metal total hip replacements at similar postoperative time points.

Impact of Cervical Disc Arthroplasty vs Anterior Cervical Discectomy and Fusion on Driving Disability: Post Hoc Analysis of a Randomized Controlled Trial With 10-Year Follow-Up.

BACKGROUND: Driving an automobile requires the ability to turn the neck laterally. Anecdotally, patients with multilevel fusions often complain about restricted turning motion. The purpose of this study was to compare the effectiveness of cervical disc arthroplasty (CDA) with anterior cervical discectomy and fusion (ACDF) on driving disability improvement at 10-year follow-up after a 2-level procedure. METHODS: In the original randomized controlled trial, patients with cervical radiculopathy or myelopathy at 2 levels underwent CDA or ACDF. The driving disability question from the Neck Disability Index was rated from 0 to 5 years preoperatively and up to 10 years postoperatively. Severity of driving disability was categorized into "none" (score 0), "mild" (1 or 2), and "severe" (3, 4, or 5). Score and severity were compared between groups. RESULTS: Out of 397 patients, 148 CDA and 118 ACDF patients had 10-year follow-up. Driving disability scores were not different between the groups preoperatively (CDA: 2.65; ACDF: 2.71, P = 0.699). Postoperatively, the scores in the CDA group were significantly lower than those in the ACDF group at 5 (0.60 vs 1.08, P ≤ 0.001) and 10 years (0.66 vs 1.07, P = 0.001). Mean score improvement in the CDA group was significantly greater than the ACDF group at 10-year follow-up (-1.94 vs -1.63, P = 0.003). The majority of patients reported severe driving disability (CDA: 56.9%, ACDF: 58.0%, P = 0.968) before surgery. After surgery, a greater proportion of patients in the CDA group had neck pain-free driving compared with the ACDF group at 5 (63.3% vs 41.8%, P < 0.001) and 10 years (61.8% vs 41.2%, P = 0.003). CONCLUSION: In patients with cervical radiculopathy/myelopathy and 2-level disease, CDA provided greater improvements in driving disability as compared with ACDF at 10-year follow-up. This is the first report of its kind. This finding may be attributable to preservation of motion associated with CDA. CLINICAL RELEVENCE: This study provides valuable information regarding the improvement of driving disability after both CDA and ACDF. It demonstrates that both procedures result in significant improvements, with CDA resulting in even better improvements than ACDF, up to 10 year follow-up.

Biomechanical assessment of a PEEK rod system for semi-rigid fixation of lumbar fusion constructs.

The concept of semi-rigid fixation (SRF) has driven the development of spinal implants that utilize nonmetallic materials and novel rod geometries in an effort to promote fusion via a balance of stability, intra- and inter-level load sharing, and durability. The purpose of this study was to characterize the mechanical and biomechanical properties of a pedicle screw-based polyetheretherketone (PEEK) SRF system for the lumbar spine to compare its kinematic, structural, and durability performance profile against that of traditional lumbar fusion systems. Performance of the SRF system was characterized using a validated spectrum of experimental, computational, and in vitro testing. Finite element models were first used to optimize the size and shape of the polymeric rods and bound their performance parameters. Subsequently, benchtop tests determined the static and dynamic performance threshold of PEEK rods in relevant loading modes (flexion-extension (F/E), axial rotation (AR), and lateral bending (LB)). Numerical analyses evaluated the amount of anteroposterior column load sharing provided by both metallic and PEEK rods. Finally, a cadaveric spine simulator was used to determine the level of stability that PEEK rods provide. Under physiological loading conditions, a 6.35 mm nominal diameter oval PEEK rod construct unloads the bone-screw interface and increases anterior column load (approx. 75% anterior, 25% posterior) when compared to titanium (Ti) rod constructs. The PEEK construct's stiffness demonstrated a value lower than that of all the metallic rod systems, regardless of diameter or metallic composition (78% < 5.5 mm Ti; 66% < 4.5 mm Ti; 38% < 3.6 mm Ti). The endurance limit of the PEEK construct was comparable to that of clinically successful metallic rod systems (135N at 5 × 10(6) cycles). Compared to the intact state, cadaveric spines implanted with PEEK constructs demonstrated a significant reduction of range of motion in all three loading directions (> 80% reduction in F/E, p < 0.001; > 70% reduction in LB, p < 0.001; > 54% reduction in AR, p < 0.001). There was no statistically significant difference in the stability provided by the PEEK rods and titanium rods in any mode (p = 0.769 for F/E; p = 0.085 for LB; p = 0.633 for AR). The CD HORIZON(®) LEGACY(™) PEEK Rod System provided intervertebral stability comparable to currently marketed titanium lumbar fusion constructs. PEEK rods also more closely approximated the physiologic anteroposterior column load sharing compared to results with titanium rods. The durability, stability, strength, and biomechanical profile of PEEK rods were demonstrated and the potential advantages of SRF were highlighted.

Cervical Disc Arthroplasty for Axial Neck Pain: Comparison of Outcomes to 2 Other Common Cervical Conditions.

BACKGROUND: Cervical disc arthroplasty (CDA) is an established treatment for degenerative disc disease with radiculopathy and/or myelopathy. There is, however, little published evidence of its effectiveness to relieve pain and improve function in patients with a primary diagnosis of axial neck pain. Such patients were excluded from all previous Food and Drug Administration clinical trials for CDA. We compare the outcomes of patients who underwent CDA for 3 common cervical conditions from 2003 to 2018. METHODS: Seven hundred and eighty-two CDA patients at a single site were grouped by primary diagnosis: predominant axial neck pain (ANP) (n = 257), predominant radiculopathy (RAD) (n = 331), or a combination of both (ANP + RAD) (n = 195). Mixed models for repeated measures predicted and analyzed scores at all time points, adjusting for diagnosis group, time point, and, if statistically significant, number of operative levels and demographic characteristics. Outcome measures included the Neck Disability Index, numerical pain scales (intensity plus frequency), the Veterans RAND 12 Item Health Survey (VR-12) Physical Component Score, the Mental Component Score, and reoperations. Patients were assessed preoperatively and postoperatively at 6 weeks, 3 months, 6 months, 1 year, and annually thereafter. RESULTS: At baseline, arm pain scores in the ANP group were statistically lower (P = .0002) than in the RAD and ANP + RAD groups, consistent with preoperative diagnoses. Surgeries included 40.8% 1-level, 41.6% 2-level, 14.7% 3-level, and 2.9% 4-level. For all outcome measures, improvements were statistically significant from baseline to each postoperative time point without statistical difference between the 3 diagnosis groups. In total, 45/782 patients (5.8%) underwent a secondary surgery: 3.5% ANP, 5.8% RAD, and 8.7% ANP + RAD. Days to reoperation did not statistically differ between groups (P = .489). CONCLUSIONS: Appropriately selected patients with predominant axial neck pain treated with CDA may achieve clinical and functional outcomes comparable to patients with a primary diagnosis of radiculopathy or of axial neck pain with concomitant radiculopathy. CLINICAL RELEVANCE: This study provides information that should help clinicians decide whether to offer CDA for patients with a primary diagnosis of axial neck pain and to appropriately counsel such patients about expected outcomes. LEVEL OF EVIDENCE: 4.

Multilevel Cervical Disc Arthroplasty: Long-Term Outcomes at 3 and 4 Levels.

BACKGROUND: Multilevel cervical degenerative disc disease in 2 or more segments poses treatment challenges. Anterior cervical discectomy and fusion is a viable treatment option, but one with high rates of adjacent segment disease and pseudoarthrosis. Cervical disc arthroplasty (CDA) is approved by the US Food and Drug Administration for the treatment of 1- and 2-level cervical pathology, with established long-term safety and effectiveness. Limited evidence exists for CDA at more than 2 levels. This study investigates the long-term outcomes of 3- and 4-level CDA out to 7 years. METHODS: In a retrospective review of prospectively collected data, patient demographics and surgical characteristics were collected. Patient-reported outcomes (PROs) were collected preoperatively and at 6 weeks, 3 months, 6 months, and 12 months postoperatively, and annually thereafter, including: Neck Disability Index (NDI), numeric rating scales for neck pain and arm pain, the Veterans Rand 12-item Health Survey physical component summary (PCS) score and mental component summary (MCS) score, and patient satisfaction scores. Secondary surgery data were also collected. Predictive methods using mixed-effects regression models were used to analyze the data. RESULTS: Data for 139 CDAs were available for evaluation (n = 116 three-level and n = 23 four-level). Statistical improvement was shown for all PRO scores at all postoperative intervals (P < .001). From preoperatively to 7 years postoperatively, mean NDI decreased from 57.9 to 31.3 (45.9% improvement), mean neck pain decreased from 15.6 to 7.9 (49.4% improvement), mean arm pain decreased from 12.2 to 5.6 (54.1% improvement), mean PCS increased from 29.2 to 41.4 (41.8% improvement), and mean MCS increased from 37.1 to 44.5 (19.9% improvement). Five (3.6%) 3-level patients underwent secondary surgery. Patient satisfaction exceeded 88% 7 years after surgery. CONCLUSION: Statistical improvement in PROs, with a low rate of secondary surgeries out to 7 years, demonstrates that 3- and 4-level CDA may be performed safely and effectively in appropriately selected patients. LEVEL OF EVIDENCE: 4.

The Effect of ACDF or Arthroplasty on Cervicogenic Headaches: A Post Hoc Analysis of a Prospective, Multicenter Study With 10-Year Follow-up.

STUDY DESIGN: This was a post hoc analysis of a prospective FDA-IDE study. OBJECTIVE: The purpose of this study is to determine the effectiveness of a 2-level anterior cervical discectomy and fusion (ACDF) or cervical disk arthroplasty (CDA) at relieving headaches associated with cervical radiculopathy or myelopathy at 10 years postoperative. BACKGROUND: To our knowledge, there is no large, prospective study that has examined the efficacy of cervical spine surgery for relieving headaches associated with radiculopathy or myelopathy at 10 years postoperative. MATERIALS AND METHODS: This was a post hoc analysis of a prospective FDA-IDE study for the Prestige LP versus ACDF for radiculopathy or myelopathy due to 2 levels. Preoperatively and out to 10 years, their Neck Disability Index documented if they had headaches (0: no headaches; 1: infrequent slight; 2: infrequent moderate; 3: frequent moderate; 4: frequent severe; 5: nearly constant). RESULTS: Three hundred ninety-seven patients were randomized to CDA (209) or ACDF (188). Preoperatively 86% had headaches and 55.9% (52.2% of CDA, 60.1% of ACDFs) had frequent moderate, severe, or nearly constant headache (grades 3-5). By 6 weeks postoperative, 64.4% had headaches and only 12.5% had grades 3-5 headaches (9.3% of CDA and 16% of ACDFs). The benefit lasted to the 10-year follow-up such that 60.3% had any headaches and 16.8% had grades 3-5 headaches (10.9% CDA; 24.3% ACDF). CONCLUSIONS: These results suggest that 86% of patients with radiculopathy or myelopathy complain of headaches preoperatively, with 55.9% having frequent or constant, moderate to severe headaches (grades 3-5). By 6 weeks postoperative, only 12.5% had grades 3-5 headaches. At 10-year follow-up, 16.8% had grades 3-5 headaches. Both arthroplasty and ACDF are often effective at alleviating headaches associated with radiculopathy or myelopathy.

Occurrence and clinical implications of heterotopic ossification after cervical disc arthroplasty with the Prestige LP Cervical Disc at 2 contiguous levels.

OBJECTIVE: The authors sought to assess the impact of heterotopic ossification (HO) on clinical outcomes and angular range of motion (ROM) after cervical disc arthroplasty (CDA) performed with the Prestige LP Cervical Disc (Prestige LP disc) at 2 levels. METHODS: HO was assessed and graded from 0 to IV for increasing severity on lateral neutral radiographs at each visit in 209 patients who underwent implantation of Prestige LP discs at 2 cervical levels in a clinical trial with extended 10-year follow-up. ROM was compared by using HO grade, and clinical outcomes were compared between HO subgroups (grade 0-II vs III/IV) based on HO severity at 2 and 10 years after surgery. RESULTS: The grade III/IV HO incidence at either or both index levels was 24.2% (48/198) at 2 years and 39.0% (57/146) at 10 years. No statistical difference was found in overall success; neurological success; or Neck Disability Index (NDI), neck pain, arm pain, or SF-36 Physical Component Summary (PCS) scores between the HO subgroups (grade 0-II vs III/IV) at either 2 or 10 years. The cumulative rate of possible implant-related adverse events (AEs) was higher in patients having grade III/IV HO at 2 years (56.3%) and 10 years (47.8%) compared with those having grade 0-II HO at 2 years (24.4%) and 10 years (17.9%), specifically in 2 subcategories: spinal events and HOs reported by the investigators. No statistical difference was found between the HO subgroups in possible implant-related serious AEs or secondary surgeries at the index or adjacent levels. The average angular ROMs at index levels were lower in subjects with higher-grade HO at 2 and 10 years. The average ROMs at the superior level were 8.8°, 6.6°, 3.2°, and 0.3°, respectively, for the HO grade 0/I, II, III, and IV groups at 10 years, and 7.9°, 6.2°, 3.7°, and 0.6°, respectively, at the inferior level. CONCLUSIONS: Radiographically severe (grade III or IV) HO after CDA with the Prestige LP disc at 2 levels did not significantly affect efficacy or safety outcomes (severe AEs or secondary surgeries). However, severe HO, particularly grade IV HO, significantly limited ROM, as expected.

Lumbar disc arthroplasty versus anterior lumbar interbody fusion: 5-year outcomes for patients in the Maverick disc investigational device exemption study.

OBJECTIVE: Despite evidence of its safety and effectiveness, the use of lumbar disc arthroplasty has been slow to expand due in part to concerns about late complications and the risks of revision surgery associated with early devices. More recently, FDA approval of newer devices and improving reimbursements have reversed this trend in the United States. Additional long-term data on lumbar disc arthroplasty are still needed. This study reports the 5-year results of the FDA investigational device exemption clinical trial of the Medtronic Spinal and Biologics' Maverick total disc replacement. METHODS: Patients with single-level degenerative disc disease from L4 to S1 were randomized 2:1 at 31 investigational sites. In the period from April 2003 to August 2004, 405 patients received the investigational device and 172 patients underwent the control procedure of anterior lumbar interbody fusion. Outcome measures included the Oswestry Disability Index (ODI), numeric rating scales (NRSs) for back and leg pain, the SF-36, disc height, interbody motion, heterotopic ossification (investigational device), adverse events (AEs), additional surgeries, and neurological status. Treatment was considered an overall success when all of the following criteria were met: 1) ODI score improvement ≥ 15 points over the preoperative score; 2) maintenance or improvement in neurological status compared with preoperatively; 3) disc height success, that is, no more than a 2-mm reduction in anterior or posterior height; 4) no serious AEs caused by the implant or by the implant and the surgical procedure; and 5) no additional surgery classified as a failure. RESULTS: Compared to that in the control group, improvement in the investigational group was statistically greater according to the ODI and SF-36 Physical Component Summary (PCS) at 1, 2, and 5 years; the NRS for back pain at 1 and 2 years; and the NRS for leg pain at 1 year. The rates of heterotopic ossification increased over time: 1.0% (4/382) at 1 year, 2.6% (9/345) at 2 years, and 5.9% (11/187) at 5 years. Investigational patients had fewer device-related AEs and serious device-related AEs than the control patients at both 2 and 5 years postoperatively. Noninferiority of the composite measure overall success was demonstrated at all follow-up intervals; superiority was demonstrated at 1 and 2 years. CONCLUSIONS: Lumbar disc arthroplasty is a safe and effective treatment for single-level lumbar degenerative disc disease, resulting in improved physical function and reduced pain up to 5 years after surgery.Clinical trial registration no.: NCT00635843 (clinicaltrials.gov).

Cervical disc arthroplasty: 10-year outcomes of the Prestige LP cervical disc at a single level.

OBJECTIVE: Food and Drug Administration-approved investigational device exemption (IDE) studies have provided level I evidence supporting cervical disc arthroplasty (CDA) as a safe and effective alternative to anterior cervical discectomy and fusion (ACDF). Long-term CDA outcomes continue to be evaluated. Here, the authors present outcomes at 10 years postoperatively for the single-level CDA arm of an IDE study (postapproval study). METHODS: The primary endpoint was overall success, a composite variable composed of five criteria: 1) Neck Disability Index score improvement ≥ 15 points; 2) maintenance or improvement in neurological status; 3) no decline in anterior or posterior functional spinal unit (FSU) height of more than 2 mm compared to 6 weeks postoperatively; 4) no serious adverse event (AE) caused by the implant or the implant and the surgical procedure; and 5) no additional surgery classified as a failure. Additional safety and effectiveness measures included numeric rating scales for neck pain and arm pain, SF-36 quality-of-life physical and mental components, patient satisfaction, range of motion, and AEs. RESULTS: From the reported assessments at 7 years postoperatively to the 10-year postoperative follow-up, the scores for all patient-reported outcomes, rate of overall success (without FSU), and proportion of patients at least maintaining their neurological function remained stable for the CDA group. Nine patients had secondary surgery at the index level, increasing the secondary surgery cumulative rate from 6.6% to 10.3%. In that same time frame, four patients experienced a serious implant or implant/surgical procedure-related AE, for a 10-year cumulative rate of 7.8%. Seven patients had any second surgery at adjacent levels, for a 10-year cumulative rate of 13.8%. Average angular motion at both the index and adjacent levels was well maintained without creating hypermobility. Class IV heterotopic ossification increased from 1.2% at 2 years to 4.6% at 7 years and 9.0% at 10 years. Patient satisfaction was > 90% at 10 years. CONCLUSIONS: CDA remained safe and effective out to 10 years postoperatively, with results comparable to 7-year outcomes and with high patient satisfaction.Clinical trial registration no.: NCT00667459 (clinicaltrials.gov).

One-Level Versus 2-Level Treatment With Cervical Disc Arthroplasty or Fusion: Outcomes Up to 7 Years.

BACKGROUND: Anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA) have been used to treat degenerative disc disease at single as well as multiple cervical levels. This study compares the safety and efficacy of 1-level versus 2-level CDA and ACDF. METHODS: In total, 545 and 397 patients with degenerative disc disease were studied in 1-level and 2-level Food and Drug Administration (FDA)-approved clinical trials, respectively: CDA (n = 280 and 209), ACDF (n = 265 and 188). Data from these studies were used to compare 1- versus 2-level procedures: the propensity score method was used to adjust for potential confounding effects, and adjusted mean outcome safety and efficacy scores at 2 and 7 years postsurgery were compared between 1-level and 2-level procedures within treatment type. RESULTS: One-level and 2-level procedures had similar rates of improvement in overall success and patient-reported outcomes scores for both CDA and ACDF. There were no statistical differences in rates of implant-related adverse events (AEs) or serious implant-related AEs between 1-level and 2-level CDA. The 7-year rate of implant-related AEs was higher for 2-level than 1-level ACDF (27.7% vs 18.9%, P ≤ .036), though the rates of serious implant-related AEs between ACDF groups did not differ significantly. Secondary surgery rates were not statistically different between 1-level and 2-level procedures (CDA or ACDF) at the index or adjacent levels at 2 or 7 years. Grade IV heterotopic ossification at 7 years was reported in 4.6% of 1-level CDA patients and 8.6%/7.3% at the superior/inferior levels, respectively, of 2-level CDA patients. CONCLUSIONS: One- and 2-level CDA appear equally safe and effective in the treatment of cervical degenerative disc disease. Two-level ACDF appears to be as effective as 1-level ACDF but with a higher rate of some AEs at long-term follow-up. LEVEL OF EVIDENCE: 2. CLINICAL TRIALS: clinicaltrials.gov: NCT00667459, NCT00642876, and NCT00637156.

Two-level cervical disc arthroplasty versus anterior cervical discectomy and fusion: 10-year outcomes of a prospective, randomized investigational device exemption clinical trial.

OBJECTIVE: The authors assessed the 10-year clinical safety and effectiveness of cervical disc arthroplasty (CDA) to treat degenerative cervical spine disease at 2 adjacent levels compared to anterior cervical discectomy and fusion (ACDF). METHODS: A prospective, randomized, controlled, multicenter FDA-approved clinical trial was conducted comparing the low-profile titanium ceramic composite-based Prestige LP Cervical Disc (n = 209) at two levels with ACDF (n = 188). Ten-year follow-up data from a postapproval study were available on 148 CDA and 118 ACDF patients and are reported here. Clinical and radiographic evaluations were completed preoperatively, intraoperatively, and at regular postoperative follow-up intervals for up to 10 years. The primary endpoint was overall success, a composite variable that included key safety and efficacy considerations. Ten-year follow-up rates were 86.0% for CDA and 84.9% for ACDF. RESULTS: From 2 to 10 years, CDA demonstrated statistical superiority over ACDF for overall success, with rates at 10 years of 80.4% versus 62.2%, respectively (posterior probability of superiority [PPS] = 99.9%). Neck Disability Index (NDI) success was also superior, with rates at 10 years of 88.4% versus 76.5% (PPS = 99.5%), as was neurological success (92.6% vs 86.1%; PPS = 95.6%). Improvements from preoperative results in NDI and neck pain scores were consistently statistically superior for CDA compared to ACDF. All other study effectiveness measures were at least noninferior for CDA compared to ACDF through the 10-year follow-up period, including disc height. Mean angular ranges of motion at treated levels were maintained in the CDA group for up to 10 years. The rates of grade IV heterotopic ossification (HO) at the superior and inferior levels were 8.2% and 10.3%, respectively. The rate of severe HO (grade III or IV) did not increase significantly from 7 years (42.4%) to 10 years (39.0%). The CDA group had fewer serious (grade 3-4) implant-related or implant/surgical procedure-related adverse events (3.8% vs 8.1%; posterior mean 95% Bayesian credible interval [BCI] of the log hazard ratio [LHR] -0.92 [-1.88, -0.01]). The CDA group also had statistically fewer secondary surgical procedures at the index levels (4.7%) than the ACDF group (17.6%) (LHR [95% BCI] -1.39 [-2.15, -0.61]) as well as at adjacent levels (9.0% vs 17.9%). CONCLUSIONS: The Prestige LP Cervical Disc, implanted at two adjacent levels, maintains improved clinical outcomes and segmental motion 10 years after surgery and is a safe and effective alternative to fusion.Clinical trial registration no.: NCT00637156 (clinicaltrials.gov).

Reliability and accuracy of fine-cut computed tomography scans to determine the status of anterior interbody fusions with metallic cages.

BACKGROUND CONTEXT: Computed tomography (CT) scan has been shown to be more accurate than radiographs in evaluating anterior interbody fusion but may still over-read the extent of fusion. PURPOSE: To assess the reliability and accuracy of fine-cut CT scans with reconstructions in evaluating anterior lumbar interbody fusion (ALIF) with metallic cages using surgical exploration as the reference standard. STUDY DESIGN: Accuracy of a diagnostic test referenced to the gold standard. PATIENT SAMPLE: A total of 49 patients and 69 surgical levels. OUTCOME MEASURES: Evaluation of fine-cut CT scans for evidence of fusion with subsequent surgical exploration as the reference standard. METHODS: Forty-nine patients who underwent ALIF with metallic cages over 69 levels, who had a fine-cut CT scan before revision were included. Five spine surgeons unaware of the findings on surgical exploration evaluated pre-revision CT scans, classified these as fused or not; and determined the presence of a "sentinel sign" and a "posterior sentinel sign." Kappa coefficients for interobserver reliability, sensitivity, and specificity to detect fusion were determined. RESULTS: There were 26 males and 23 females with a mean age of 43 years. There were 27 smokers. Average time from index to revision surgery was 22 months. Interobserver kappa for classification as fused or not was 0.25 with 70% to 97% sensitivity and 28% to 85% specificity. The interobserver kappa for the sentinel sign was 0.34 with 13% to 33% sensitivity and 77% to 92% specificity. The interobserver kappa for the posterior sentinel sign was 0.23 with 33% to 87% sensitivity and 56% to 90% specificity. CONCLUSIONS: Raters generally overstated fusion with low specificities across raters and low consensus specificity. Overall accuracy of the posterior sentinel sign (74%) was higher than the sentinel sign (61%). The low kappa value indicates fair reliability. In patients with metallic interbody devices, surgeons should be cautious about interpreting the findings on fine-cut CT scans whether using a general assessment of the fusion, the sentinel sign, or the posterior sentinel sign.

Assessment of health-related quality of life in spine treatment: conversion from SF-36 to VR-12.

BACKGROUND CONTEXT: Health-related quality-of-life outcomes have been collected with the Medical Outcomes Study (MOS) Short Form 36 (SF-36) survey. Boston University School of Public Health has developed algorithms for the conversion of SF-36 to Veterans RAND 12-Item Health Survey (VR-12) Physical Component Summary (PCS) and Mental Component Summary (MCS) scores. PURPOSE: The purpose of the present study is to investigate the conversion of the SF-36 to VR-12 PCS and MCS scores. STUDY DESIGN: Preoperative and postoperative SF-36 were collected from patients who underwent lumbar or cervical surgery from a single surgeon between August 1998 and January 2013. METHODS: Short Form 36 PCS and MCS scores were calculated following their original instructions. The SF-36 answers were then converted to VR-12 PCS and MCS scores following the algorithm provided by the Boston University School of Public Health. The mean score, preoperative to postoperative change, and proportions of patients who reach the minimum detectable change were compared between SF-36 and VR-12. RESULTS: A total of 1,968 patients (1,559 lumbar and 409 cervical) had completed preoperative and postoperative SF-36. The values of the SF-36 and VR-12 mean scores were extremely similar, with score differences ranging from 0.77 to 1.82. The preoperative to postoperative improvement was highly significant (p<.001) for both SF-36 and VR-12 scores. The mean change scores were similar, with a difference of up to 0.93 for PCS and up to 0.37 for MCS. Minimum detectable change (MDC) values were almost identical for SF-36 and VR-12, with a difference of 0.12 for PCS and up to 0.41 for MCS. The proportions of patients whose change in score reached MDC were also nearly identical for SF-36 and VR-12. About 90% of the patients above SF-36 MDC were also above VR-12 MDC. CONCLUSIONS: The converted VR-12 scores, similar to the SF-36 scores, detect a significant postoperative improvement in PCS and MCS scores. The calculated MDC values and the proportions of patients whose score improvement reach MDC are similar for both SF-36 and VR-12.

Comparison of Lumbar Total Disc Replacement With Surgical Spinal Fusion for the Treatment of Single-Level Degenerative Disc Disease: A Meta-Analysis of 5-Year Outcomes From Randomized Controlled Trials.

STUDY DESIGN: Meta-analysis. OBJECTIVES: To evaluate the long-term efficacy and safety of total disc replacement (TDR) compared with fusion in patients with functionally disabling chronic low back pain due to single-level lumbar degenerative disc disease (DDD) at 5 years. METHODS: PubMed and Cochrane Central Register of Controlled Trials databases were searched for randomized controlled trials reporting outcomes at 5 years for TDR compared with fusion in patients with single-level lumbar DDD. Outcomes included Oswestry Disability Index (ODI) success, back pain scores, reoperations, and patient satisfaction. All analyses were conducted using a random-effects model; analyses were reported as relative risk (RR) ratios and mean differences (MDs). Sensitivity analyses were conducted for different outcome definitions, high loss to follow-up, and high heterogeneity. RESULTS: The meta-analysis included 4 studies. TDR patients had a significantly greater likelihood of ODI success (RR 1.0912; 95% CI 1.0004, 1.1903) and patient satisfaction (RR 1.13; 95% CI 1.03, 1.24) and a significantly lower risk of reoperation (RR 0.52; 95% CI 0.35, 0.77) than fusion patients. There was no association with improvement in back pain scores whether patients received TDR or fusion (MD -2.79; 95% CI -8.09, 2.51). Most results were robust to sensitivity analyses. Results for ODI success and patient satisfaction were sensitive to different outcome definitions but remained in favor of TDR. CONCLUSIONS: TDR is an effective alternative to fusion for lumbar DDD. It offers several clinical advantages over the longer term that can benefit the patient and reduce health care burden, without additional safety consequences.

Safety and Efficiency of Cervical Disc Arthroplasty in Ambulatory Surgery Centers vs. Hospital Settings.

BACKGROUND: Outpatient surgery has been shown safe and effective for anterior cervical discectomy and fusion (ACDF), and more recently, for 1-level cervical disc arthroplasty (CDA). The purpose of this analysis is to compare the safety and efficiency of 1-level and 2-level CDA performed in an ambulatory surgery center (ASC) and in a hospital setting. METHODS: The study was a retrospective collection and analysis of data from consecutive CDA patients treated in ASCs compared to a historical control group of patients treated in hospital settings who were classified as outpatient (0 or 1-night stay) or inpatient (2 or more nights). Surgery time, blood loss, return to work, adverse events (AEs), and subsequent surgeries were compared. RESULTS: The sample consisted of 145 ASC patients, 348 hospital outpatients, and 65 hospital inpatients. A greater proportion of 2-level surgeries were performed in hospital than ASC. Surgery times were significantly shorter in ASCs than outpatient or inpatient 1-level (63.6 ± 21.6, 86.5 ± 35.8, and 116.7 ± 48.4 minutes, respectively) and 2-level (92.4 ± 37.3, 126.7 ± 43.8, and 140.3 ± 54.5 minutes, respectively) surgeries. Estimated blood loss was also significantly less in ASC than outpatient and inpatient 1-level (18.5 ± 30.6, 43.7 ± 35.9, and 85.7 ± 98.0 mL, respectively) and 2-level (21.1 ± 12.3, 67.8 ± 94.9, and 64.9 ± 66.1 mL). There were no hospital admissions and no subsequent surgeries among ASC patients. ASC patients had 1 AE (0.7%) and hospital patients had 10 AEs (2.4%). Working patients returned to work after a similar number of days off, but fewer ASC patients had returned to work by the end of the 90-day period. CONCLUSIONS: Both 1- and 2-level CDA may be performed safely in an ASC. Surgeries in ASCs are of shorter duration and performed with less blood loss without increased AEs.

Treatment of Cervical Myelopathy: Long-term Outcomes of Arthroplasty for Myelopathy Versus Radiculopathy, And Arthroplasty Versus Arthrodesis for Myelopathy.

STUDY DESIGN: Analysis of 2- and 7-year outcomes from a clinical trial comparing 2-level cervical disk arthroplasty (CDA) to anterior cervical discectomy and fusion (ACDF) in 287 patients with radiculopathy alone, and 110 patients with myelopathy alone or myelopathy with radiculopathy. OBJECTIVE: To compare the long-term safety and effectiveness of CDA for myelopathy versus radiculopathy. SUMMARY OF BACKGROUND DATA: CDA for myelopathy is safe and effective in short term. MATERIALS AND METHODS: We analyzed Neck Disability Index (NDI), neck/arm pain, SF-36, neurological status, adverse events (AEs), and secondary surgeries at index and adjacent levels. RESULTS: All groups improved significantly for NDI, neck/arm pain, and physical component summary (PCS) scores from preoperative to postoperative. CDA Myelopathy versus CDA Radiculopathy: 2- and 7-year improvements were not significantly different. The 7-year score improvements for CDA Myelopathy and CDA Radiculopathy were: NDI (37.8 vs. 35.8, P=0.352), neck pain (12.0 vs. 12.1, P=0.477), arm pain (11.6 vs. 9.6, P=0.480), and PCS (14.1 vs. 13.7, P=0.863). The 2 groups had similar proportions of patients who maintained or improved their neurological status (87.2% vs. 93.5%, P=0.218), similar rates of serious AEs (54.5% vs. 57.5%, P=0.291) and similar rates of secondary surgeries at index (3.7% vs. 4.4%, P=0.839) and adjacent levels (3.7% vs. 7.6%, P=0.367). CDA Myelopathy versus ACDF myelopathy: 2 and 7-year improvements were not significantly different. The 7-year CDA and ACDF score improvements were: NDI (37.8 vs. 31.1, P=0.147), neck pain (12.0 vs. 10.4, P=0.337), arm pain (11.6 vs. 11.4, P=0.791), and PCS (14.1 vs. 11.2, P=0.363). The 2 groups had statistically similar proportions who maintained or improved their neurological status (87.2% vs. 96.2%, P=0.409), statistically similar overall rates of secondary surgeries at the index levels (3.7% vs. 9.4%, P=0.374), and statistically similar rates of secondary surgeries at adjacent levels (3.7% vs. 15.4%, P=0.088). CDA group demonstrated lower rates of serious AEs than ACDF (54.5% vs. 65.9%, P=0.019). CONCLUSIONS: CDA for myelopathy is a safe and effective long-term treatment.

Serum Metal Concentrations in Patients With Titanium Ceramic Composite Cervical Disc Replacements.

STUDY DESIGN: Prospective longitudinal study. OBJECTIVE: The serum titanium (Ti) concentrations were examined in patients implanted with a PRESTIGE LP Cervical Disc System (Medtronic, Inc., Memphis, TN). The metal-on-metal disc with ball-in-trough articulation is made of titanium alloy/titanium carbide composite (Ti-6Al-4 V/TiC). SUMMARY OF BACKGROUND DATA: Cervical disc arthroplasty provides a motion-preserving treatment alternative to anterior cervical discectomy and fusion for degenerative cervical disc disease. The articulating surfaces have a tendency to generate in vivo wear in the form of insoluble particulates (debris) and soluble metal ions. Not much information is available on the long-term metal concentrations observed in cervical disc arthroplasty and how these compare with the metal concentrations in Ti-based posterior fixation devices and other joint replacement implants. METHODS: Thirty patients were enrolled after strict exclusion criteria that included no previous permanent metal implants and no professional exposure to metal particles. High-resolution inductively coupled plasma-mass spectrometry was used to assay blood serum titanium concentrations preoperatively and at 3, 6, 12, 24, 36, 60, and 84 months after surgery. The detection limit for Ti was 0.2 ng/mL. The Friedman test was used to make longitudinal statistical comparisons. RESULTS: The median serum Ti concentrations determined preoperatively, and at 3, 6, 12, 24, 36, 60, and 84 months were 0.10, 1.22, 1.15, 1.27, 1.21, 1.46, 1.34, and 1.42 ng/mL, respectively. The serum Ti concentrations at all postoperative time points were significantly higher than that at the preoperative time point (Friedman P < 0.01). CONCLUSION: The long-term postoperative serum Ti concentrations were significantly higher than the preoperative concentrations. The observed serum Ti concentrations in this study are lower than the reported concentrations in patients receiving posterior spinal instrumentation and metal or ceramic-on-polyethylene hip prostheses with Ti-alloy based stems and acetabular components. LEVEL OF EVIDENCE: 3.