Heterotopic ossification is related to change in disc space angle after Prestige-LP cervical disc arthroplasty.

PURPOSE: To investigate the influence of the immediate post-operative change in disc space angle relative to preoperation on heterotopic ossification (HO) occurrence following cervical disc arthroplasty (CDA) and on clinical and radiographic outcomes. METHODS: Eighty-four patients with single-level Prestige-LP arthroplasty were retrospectively reviewed. HO was assessed based on McAfee classification. Radiological parameters, including index disc space angle (DSA), functional spinal unit angle, cervical lordosis, segmental range of motion (SROM), migration and subsidence of the prosthesis, prosthesis-endplate coverage ratio, and complications, were evaluated. Clinical features and outcome scores were also evaluated. RESULTS: A significant association between immediate post-operative DSA change and HO occurrence was found. Patients with a more than 5° increase in immediate post-operative DSA lordosis had a significantly higher incidence of HO and more severe HO than patients with a less than 5° DSA increase after CDA. No correlation was observed between clinical outcomes and post-operative DSA increase or HO occurrence. Both groups maintained cervical sagittal alignment. However, patients with a more than 5° DSA increase exhibited larger anterior migration amount and lower prosthesis-endplate coverage ratio compared to a less than 5° increase in DSA, and more lordotic DSA and less SROM at the final follow-up compared with those at preoperation. No significant difference in other complications was found between the groups. CONCLUSION: Patients with a more than 5° increase in immediate post-operative DSA showed adverse effects on HO formation. Overcorrected DSA was associated with poor prosthesis stability, inadequate endplate coverage, and limited SROM, although it did not affect the clinical outcomes. These slides can be retrieved under Electronic Supplementary Material.

Clinical and radiographic outcomes of cervical disc arthroplasty with Prestige-LP Disc: a minimum 6-year follow-up study.

BACKGROUND: Cervical disc arthroplasty (CDA) has been considered as an alternative to cervical arthrodesis in the treatment of cervical degenerative disc diseases (CDDD). The aim of this study was to assess the long-term clinical and radiographic outcomes of CDA with Prestige-LP Disc. METHODS: A total of 61 patients who underwent single- or two-level CDA with Prestige-LP Disc were retrospectively investigated at a minimum of 6-year follow-up. Clinical assessments included visual analogue scale (VAS) for neck and arm pain, Neck Disability Index (NDI), and Japanese Orthopedic Association (JOA) score. Radiological evaluations included range of motion (ROM) of the index and adjacent levels, segmental angle, cervical sagittal alignment, heterotopic ossification (HO) and adjacent segment degeneration (ASD). RESULTS: Significant and maintained improvement in VAS for neck and arm, NDI and JOA were observed after a mean follow-up of 82.3 months (p < 0.001). The preoperative ROM of the index level was 9.7°, which was maintained at 2-and 4-year follow-up (9.3°, p = 0.597; 9.0°, p = 0.297), but was decreased to 8.0° at final follow-up (p = 0.019). Mobility was maintained in 80.5% (62/77) of the implanted prostheses at final follow-up. ROM of the superior and inferior adjacent segments, cervical sagittal alignment and cervical angel were all maintained. The incidence of HO was 42.9% at final follow-up, but it did not influence the clinical outcome. Radiographic ASD were detected in 29.5% of the patients. However, the incidence of symptomatic ASD was only 6.6%. CONCLUSION: Cervical disc arthroplasty with Prestige-LP Disc demonstrated a maintained and satisfactory clinical outcome at a minimal of 6-year follow-up, with majority of the prostheses remained mobile. Cervical disc arthroplasty with Prestige-LP Dis can be considered as an effective surgical method in treating CDDD.

Comparison of the effects of different artificial discs on hybrid surgery: A finite element analysis.

In recent years, artificial cervical discs have been used in intervertebral disc replacement surgery and hybrid surgery (HS). The advantages and disadvantages of different artificial cervical discs in artificial cervical disc replacement surgery have been compared. However, few scholars have studied the biomechanical effects of various artificial disc prostheses on the human cervical spine in HS which include the Anterior Cervical Discectomy and Fusion (ACDF) and Cervical Disc Arthroplasty (CDA). This study compared the biomechanical behavior of Mobi-C and Prestige LP in the operative and adjacent segments during two-level hybrid surgery. A three-dimensional finite element model of C2-C7 was first established and validated. Subsequently, clinical surgery was then simulated to establish a surgical model of anterior cervical fusion at the C4-C5 level. Mobi-C and Prestige-LP artificial disc prostheses were implanted at the C5-C6 level to create two hybrid models. All finite element models were fixed on the lower endplate of the C7 vertebra and subjected to a load of 73.6 N and different directions of 1 Nm torque on the odontoid process of the C2 vertebra to simulate human flexion, extension, lateral bending, and axial rotation. This paper compares the ROM, intervertebral pressure, and facet joint force after hybrid surgery with the intact model. The results show that compared with Prestige LP, Mobi-C can improve ROM of the replacement segment and compensate for the intervertebral pressure of the adjacent segment more effectively, but the facet joint pressure of the replacement segment may be higher.

Biomechanical analysis of single- and double-level cervical disc arthroplasty using finite element modeling.

Recently, many different types of artificial discs have been introduced to persevere the biomechanical behavior of the cervical spine. This study compares the biomechanical behavior of single- and double-level cervical disc arthroplasty, that is "Prestige LP and Mobi-C" on the index and adjacent segment. A three-dimension finite element model of C2-C7 was developed and validated. In single-level prostheses, the Prestige LP or Mobi-C was implanted in the segment C5-C6, while the double-level arthroplasty was integrated at both segments C4-C5 and C5-C6 in the FE model. The intact FE and prosthesis-modified models were constrained from the inferior endplate of the vertebra C7 and applied a compressive load of 73.6 N with a moment load of 1 Nm on the odontoid process of the vertebra C2 to produce flexion/extension, lateral bending, and axial rotation. The prosthesis-modified model's range of motion and intradiscal pressure were determined and compared to the intact model. Also examined the impact of the prostheses on the stress at the bone-implant interface. The range of motion of the implanted segments in both single- and double-levels arthroplasty was increased while that of the adjacent segment of implanted segments decreased. The intradiscal pressure in both levels of arthroplasty was greater than in the intact model. In conclusion, Mobi-C's cervical prostheses could better preserve the normal range of motion and maintain intradiscal pressure than the Prestige LP.

Late complication of cervical disc arthroplasty: heterotopic ossification causing myelopathy after 10 years. Illustrative case.

BACKGROUND: Heterotopic ossification (HO) is a well-documented complication of cervical disc arthroplasty (CDA), although it rarely causes adverse clinical effects. Despite high-grade HO possibly limiting segmental mobility, it is reportedly seldom associated with symptoms. OBSERVATIONS: The authors report a case of a 46-year-old male patient who underwent hybrid CDA and anterior cervical discectomy and fusion for 3-level cervical disc herniation that caused myeloradiculopathy. The surgery was successful; the patient experienced nearly complete recovery postoperatively. The follow-up images, including computed tomography and magnetic resonance imaging scans, showed satisfactory decompression at the indexed levels without residual osteophytes or ossification of the posterior longitudinal ligament. However, 10 years later, the patient presented with symptomatic compressive myelopathy caused by severe HO that prompted a secondary surgery. LESSONS: Although it is generally reported in the literature that HO is clinically innocuous, in this patient, it gradually and progressively developed and caused myelopathy, requiring a secondary surgery. Symptomatic HO can be expected over time, and patients with a high risk of HO deserve long-term follow-up after CDA. Further investigations are warranted to corroborate these risk factors, including multilevel calcified disc herniation, severe spondylosis, and suboptimal placement of the device during primary CDA surgery.

Cervical Alignment After Cervical Arthroplasty with Prestige-LP Disc at C5-C6 Level.

OBJECTIVE: We explored the effects of implantation of the Prestige-LP disc at the C5-C6 level on cervical alignment and the association between the cervical alignment and clinical outcomes. METHODS: Patients with C5-C6 level cervical disc arthroplasty were consecutively reviewed. The Japanese Orthopaedic Association score, neck disability index, visual analog scale (VAS) for neck pain, and VAS for arm pain were used to evaluate the clinical outcomes. The range of motion (ROM) and cervical alignment, including the C2-C7 angle and C5-C6 angle, were measured. RESULTS: Seventy-seven patients were included, with a mean follow-up of 42.6 months. Most patients achieved a significant reduction in VAS scores and the neck disability index but had a significant increase in the Japanese Orthopaedic Association scores. The C5-C6 ROM, C2-C7 ROM, and C2-C7 angle were preserved and the C5-C6 angle had changed significantly. The C2-C7 angle increased significantly from 15.2° ± 11.5° preoperatively to 19.4° ± 10.2° at the 12-month follow-up visit (P < 0.001) and had decreased to 16.8° ± 10.4° at the last follow-up visit (P = 0.45). The C5-C6 angle had increased significantly from 0.07° ± 5.2° preoperatively to 2.8° ± 5.8° at the 3-month follow-up visit (P < 0.001) and had stabilized at 2.2° ± 5.8° at the last measurement (P = 0.003). No significant correlation was found between the C2-C7 angle and the clinical outcomes. A significant correlation was found between the C5-C6 angle and VAS score for arm pain (r = -0.38; P = 0.02). CONCLUSIONS: The C2-C7 angle was preserved and the C5-C6 angle was restored to lordosis after cervical disc arthroplasty. It seems that segmental lordosis was associated with less arm pain.

Incidence of bone loss after Prestige-LP cervical disc arthroplasty: a single-center retrospective study of 396 cases.

BACKGROUND CONTEXT: The development of bone loss (BL) at the operated level after cervical disc arthroplasty (CDA) has not been well recognized. The incidence of BL may be correlated with the prosthesis type. Currently, no study has reported the incidence of BL after CDA with the Prestige-LP disc, and this remains an active area of research. PURPOSE: To determine the incidence of BL after Prestige-LP CDA and evaluate the impact of BL on clinical and radiological outcomes. STUDY DESIGN: This is an observational study. PATIENT SAMPLE: A total of 396 patients were reviewed. OUTCOME MEASURES: The Japanese Orthopedics Association (JOA), Visual Analogue Scale (VAS), and Neck Disability Index (NDI) scores were evaluated. Cervical lordosis, disc angle, global and segmental range of motion (ROM), heterotopic ossification (HO), and BL were measured. METHODS: We retrospectively reviewed patients who underwent Prestige-LP disc from January 2008 to October 2018 at our institution. Clinical outcomes were evaluated using JOA, VAS, and NDI scores. Radiological variables, including cervical lordosis, disc angle, global and segmental ROM, HO, and BL, were retrieved. RESULTS: A total of 396 patients and 483 CDAs were evaluated. BL occurred in 56.6% of patients and 52.8% of CDA segments. Mild BL occurred in 30.2%, moderate BL in 37.3%, and severe BL in 32.5% of CDA segments. Notably, 88.2% of CDA segments developed BL within the first 3 months, and 19.1% of them progressed at 6 months. However, no progressive BL after 12 months was seen. About 50.2% of CDAs showed superior and inferior endplates involvement. The incidence of BL was associated with age, surgery type, level distribution, and incidence and grade of HO. Patients with BL had a better segmental ROM, but no relationships between patients with or without BL were found in clinical outcomes. CONCLUSIONS: BL was a common but self-limited phenomenon after CDA at the early postoperative stage. It occurred more often in relatively young age patients, two-level CDA, and C5/6 segment. However, patients suffering from BL showed no deterioration of the clinical outcomes, more exceptional motion preservation at the arthroplasty level, and lower incidence with a lower grade of HO.

Does preoperative inferior endplate morphology influence the outcomes of cervical disc arthroplasty at C5-C6 level: A retrospective study.

OBJECTIVES: Despite encouraging clinical results, the postoperative segmental kyphosis was observed in many cervical disc arthroplasty (CDA) studies. Most studies discussed technical factors related to kyphosis. However, the cervical endplate, which contacted directly with prostheses and distributed the compressive load across the vertebral body, was seldom investigated. The purpose of the study was to investigate the effects of the inferior endplate morphology on clinical and radiological outcomes after C5/C6-level CDA with Prestige-LP Disc. PATIENTS AND METHODS: One hundred and thirty-two patients with C5/C6-level CDA were retrospectively reviewed. Their preoperative inferior endplates on the mid-sagittal plane were visually classified into 3 types: type I with the endplate concavity apex located posteriorly, type II with the apex located in the middle and type III with the apex located anteriorly. Sagittal diameter of endplate, endplate concavity depth and endplate concavity apex location were measured. Japanese Orthopedic Association (JOA), visual analogue scale (VAS) and Neck Disability Index (NDI) scores were used to evaluate clinical outcomes. Range of motion (ROM) and sagittal alignment including C2-7 and C5-6 angle were assessed. RESULTS: The type I, type II and type III endplates accounted for 25.00 %, 51.52 % and 23.48 % of 132 individuals. Most patients achieved significant reduction in VAS scores and NDI but the significant increase in JOA scores. No substantial differences in clinical outcomes were found among the 3 endplate types. Compared with preoperative values, the C5-6 ROM, C2-7 ROM and C2-7 angle were preserved, while the C5-6 angle increased significantly from kyphosis to lordosis. At the last follow-up, type I endplate had the least C5-6 angle (2.03°, 3.94° and 4.46° for type I, II and III endplates) and the highest incidence of segmental kyphosis at C5-C6 level (33.30 %, 14.70 % and 9.70 % in the same order, P = 0.028). CONCLUSIONS: Patients achieved satisfactory clinical outcomes after C5/C6-level CDA without significant differences among three endplate types. Type I endplate had a high incidence of segmental kyphosis at C5-C6 level.

Artificial Discs in Cervical Disc Replacement: A Meta-Analysis for Comparison of Long-Term Outcomes.

BACKGROUND: Cervical disc replacement (CDR) has emerged as an alternative to anterior cervical discectomy and fusion for the surgical treatment of degenerative cervical disc disease. Although comparison of the 2 techniques has been studied in the literature, a thorough assessment of all artificial discs between each has not been performed. The objective of the present study was to examine the long-term outcomes of 5 artificial discs. METHODS: An electronic literature search was conducted for studies of CDR devices for all years available. Only articles in English were included. Heterotopic ossification, adjacent segment disease, and reoperation comprised the primary outcomes of interest. Pooled descriptive statistics with effect size (ES) and 95% confidence interval were used to synthesize the outcomes for each device. RESULTS: Sixty-five studies (n = 5785) were included in the analysis. Comparison of the incidence of grade III/IV heterotopic ossification showed a significant variability between the 5 devices (P < 0.001) with ProDisc-C (ES, 38%; 95% confidence interval [CI], 24%-54%) having the highest incidence rate. Overall rate of adjacent segment disease was 14% (95% CI, 7%-23%) with significant associated heterogeneity (P < 0.001). Regarding 2-year reoperation risk, the overall incidence rate was 2% (95% CI, 1%-3%), with nonsignificant variability between devices (P = 0.63). The highest rate was observed in the Discover group (ES, 4%; 95% CI, 0%-13%). CONCLUSIONS: The results of the present meta-analysis indicate that surgical and clinical outcomes may differ among different CDR devices. These findings may assist surgeons in tailoring their decision making to specific patient profiles. Future multicenter efforts are needed to validate associations found in this study.

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.

Quality of Life Following Prestige LP Cervical Disc Arthroplasty in a Prospective Multicountry Study.

BACKGROUND: To describe routine surgical practice using Prestige LP Cervical Disc (Prestige disc) and patient outcomes for degenerative cervical disc disease in a multicenter 2-year prospective, observational study. METHODS: Patient demographics and intraoperative data were collected; quality of life (QoL) (EQ-5D, EQ-VAS, and neck disability index), average disc height, and adverse events were assessed pre- and postoperatively at 3, 6, 12, and 24 months. RESULTS: One hundred and ninety-four patients were enrolled (190 patients implanted; female: 67%; mean age: 44.0 years; mean body mass index: 25.6). Disc herniation was the most frequent indication for cervical arthroplasty (80.5%). Thirty-seven percent of patients experienced pain for >1 year prior to baseline assessment. Mean procedure duration was 87.1 minutes, and mean blood loss was 43.8 mL. The majority (71.0%) of Prestige discs were implanted at level C5 to C6, while 16.3% of patients received implants at 2 levels. There was a significant improvement from baseline to 3, 6, 12, and 24 months of follow-up in all QoL assessments. After implantation, the mean disc height at the affected level increased by 0.19 from baseline (0.22) to 3 months (0.41) and remained constant up to 24 months (P < .001). Mean disc height of levels above and below the implant remained comparable at baseline and follow-up. A total of 63 adverse events (44 patients) was recorded, of which 7 (11.1%) were related to the Prestige disc, instrumentation, or procedure; 41 (65.1%) were unrelated; and 15 (23.8%) had an unknown relation. CONCLUSIONS: In line with published findings, our study shows significant improvement in outcomes in the first 3 months after Prestige disc implantation with improvements maintained throughout the study.

Five-Year Trends in Center of Rotation After Single-Level Cervical Arthroplasty with the Prestige-LP Disc.

OBJECTIVES: To assess the in vivo longitudinal kinematic performance of the Prestige-LP Disc and describe the 5-year trends in the center of rotation (COR) at the instrumented level. METHODS: Forty-two patients with single-level cervical disc arthroplasty (CDA) were reviewed retrospectively. Lateral static and dynamic cervical radiographs were obtained preoperatively and postoperatively at 1, 3, and 5 years. Kinematic parameters collected included range of motion (ROM), COR, intervertebral disc height (IDH), functional spinal unit (FSU) angle. Japanese Orthopedic Association (JOA), visual analog scale (VAS), and Neck Disability Index (NDI) scores were used to evaluate clinical outcomes. RESULTS: The JOA score was increased significantly and VAS and NDI scores were decreased significantly after CDA. The ROM was preserved, stabilizing at 7.8° at the final follow-up. The mean IDH increased significantly from 4.4 ± 2.6 mm to 7.3 ± 1.9 mm after surgery, and remained unchanged thereafter. The mean FSU increased by nearly 4° from the preoperative value to 3.6° ± 4.4° at the 1-year follow-up but failed to maintain lordosis, decreasing to 0.4° ± 4.7° at the last follow-up. The mean COR-x was calculated as 38.9% preoperatively and remained unchanged throughout the follow-up period. The mean COR-y showed a significant cranial shift after surgery, and an upward trend continued in the subsequent measurements (12.7% at 1 year, 15.4% at 3 years, 19.2% at 5 years); however, there was no significant difference between the 1-year and 5-year measurements. CONCLUSIONS: Single-level CDA with the Prestige-LP Disc achieved favorable clinical outcomes and provided a durable solution for spinal motion at the instrumented level. The COR showed a significant cranial shift after surgery and remained relatively stable during the 5-year follow-up period.

A Comparison of Cervical Disc Arthroplasty and Anterior Cervical Discectomy and Fusion in Patients with Two-Level Cervical Degenerative Disc Disease: 5-Year Follow-Up Results.

OBJECTIVE: To present a long-term clinical and radiographic comparison between the Prestige LP cervical disc replacement and the Zero-P spacer cervical disc fusion in the treatment of patients with symptomatic 2-level cervical degenerative disease. METHODS: In total, 36 patients in the anterior cervical discectomy and fusion (ACDF) group and 24 patients in the cervical disc arthroplasty (CDA) group were analyzed before surgery and at 1 week and 3, 6, 12, 24, and 60 months after surgery. Clinical assessments included the Japanese Orthopaedic Association score, visual analog scale, and Neck Disability Index scores. Radiographic assessments included cervical lordosis, range of motion (ROM) of the total cervical spine, functional spinal unit (FSU), and superior and inferior adjacent segments. Complications including heterotopic ossification and adjacent-segment degeneration (ASD) at 5-year follow-up were collected as well. RESULTS: Mean follow-up period was 65.6 months. Both the ACDF and CDA groups showed significant clinical improvements in terms of Japanese Orthopaedic Association score, visual analog scale, and Neck Disability Index (P < 0.05), but there was no significant difference between groups at the last follow-up period. A significant increase of cervical lordosis was observed in the CDA group after surgery whereas a significant difference was not observed between groups. ROM of the total cervical spine and FSU were maintained during the follow-up, and a significant decrease was observed in the ACDF group after surgery (P < 0.05). The ROM of the superior adjacent segment did not show any difference whereas the ROM of the inferior adjacent segment in the ACDF group presented a significant increase at 6 months and 1 year after surgery and a significant decrease at the last follow-up period. A total of 8 (33.3%) patients in the CDA group had an occurrence of heterotopic ossification. ASD was observed in 2 (8.3%) patients who underwent CDA surgery and 8 (22.2%) patients who underwent ACDF surgery. CONCLUSIONS: The use of the Prestige-LP and ZERO-P Spacer implantations is safe and effective. At 5 years after surgery, CDA with Prestige-LP is superior in terms of ROM of the total cervical spine, FSU, and inferior adjacent segment. It also has a relatively low occurrence rate of ASD. This procedure may be a suitable choice for the treatment of contiguous 2-level CDDD.

Biomechanical Analysis of the Cervical Spine Following Disc Degeneration, Disc Fusion, and Disc Replacement: A Finite Element Study.

BACKGROUND: Discectomy and fusion is considered the "gold standard" treatment for clinical manifestations of degenerative disc disease in the cervical spine. However, clinical and biomechanical studies suggest that fusion may lead to adjacent-segment disease. Cervical disc arthroplasty preserves the motion at the operated level and may potentially decrease the occurrence of adjacent segment degeneration. The purpose of this study was to investigate the effect of disc generation, fusion, and disc replacement on the motion, disc stresses, and facet forces on the cervical spine by using the finite element method. METHODS: A validated, intact, 3-dimensional finite element model of the cervical spine (C2-T1) was modified to simulate single-level (C5-C6) and 2-level (C5-C7) degeneration. The single-level degenerative model was modified to simulate both single-level fusion and arthroplasty (total disc replacement [TDR]) using the Bryan and Prestige LP discs. The 2-level degenerative model was modified to simulate a 2-level fusion, 2-level arthroplasty, and single-level disc replacement adjacent to single-level fusion (hybrid). The intact models were loaded by applying a moment of ±2 Nm in flexion-extension, lateral bending, and axial rotation. The motion in each direction was noted and the other modified models were loaded by increasing the moment until the primary C2-T1 motion matched that of the intact (healthy) C2-T1 motion. RESULTS: Both Bryan and Prestige discs preserved motion at the implanted level and maintained normal motions at the adjacent nonoperative levels. A fusion resulted in a decrease in motion at the fused level and an increase in motion at the unfused levels. In the hybrid construct, the TDR (both) preserved motion adjacent to the fusion, thus reducing the demand on the other levels. The disc stresses followed the same trends as motion. Facet forces increased considerably at the index level following a TDR. CONCLUSION: The Bryan and Prestige LP TDRs both preserved motion at the implanted level and maintained normal motion and disc stresses at the adjacent levels. The motion patterns of the spine with a TDR more closely resembled that of the intact spine than those of the degenerative or fused models.

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).

Clinical and radiographic comparison of cervical disc arthroplasty with Prestige-LP Disc and anterior cervical fusion: A minimum 6-year follow-up study.

OBJECTIVES: To retrospectively compare the long-term clinical and radiographic outcomes of cervical disc arthroplasty (CDA) with Prestige-LP Disc and anterior cervical discectomy and fusion (ACDF) for single-level cervical degenerative disc disease. PATIENTS AND METHODS: Ninety-eight patients (45 CDA and 53 ACDF) with a minimum 6-year follow-up were included. Clinical evaluations included Japanese Orthopedic Association (JOA), visual analogue scale (VAS), and Neck Disability Index (NDI) scores. Radiographic evaluations included sagittal alignment, range of motion (ROM) at the index and adjacent level, adjacent segment degeneration (ASD), and heterotopic ossification (HO). RESULTS: At the final follow-up, there were no significant differences in JOA, VAS neck, and VAS arm scores between the two groups. However, NDI scores improved more in the CDA group than in the ACDF group. The sagittal alignment was maintained in both groups. The ROM at the index level in the CDA group was decreased from 9.6±4.3° at baseline to 7.8±4.7° at the final follow-up. The ROM at the cranial adjacent level in the ACDF group was increased. The incidence of ASD was lower in the CDA group than in the ACDF group (26.7% vs 49.1%, p=0.023). HO was observed in 46.7% of the patients but did not influence the clinical outcome. CONCLUSION: Both CDA with Prestige-LP Disc and ACDF showed good clinical outcomes at a minimum 6-year follow-up. Compared with ACDF, CDA preserved the motion and reduced the incidence of ASD.

Artificial cervical disc replacement with the Prestige-LP prosthesis for the treatment of non-contiguous 2-level cervical degenerative disc disease: A minimum 24-month follow-up.

OBJECTIVE: We describe the features of non-contiguous 2-level cervical degenerative disc disease (NCDDD), investigate the safety and feasibility of artificial cervical disc replacement (ACDR) for the treatment of NCDDD, and expect that our study will provide spine surgeons with an alternative procedure for NCDDD. METHODS: Twenty-five patients with NCDDD received ACDR with a Prestige-LP prosthesis. Clinical outcomes were evaluated using the 36-Short Form (SF-36, Mental Component Summary [MCS] and Physical Component Summary [PCS]), Visual Analog Scale (VAS), Japanese Orthopedic Association (JOA), and Neck Disability Index (NDI) scores. Radiographic evaluations included cervical lordosis (CL), range of motion (ROM), and disc height (DH). Data regarding complications were collected as well. RESULTS: The mean follow-up period was 32.24 months. Clinical outcomes, including SF-36 MCS and PCS, VAS, JOA, and NDI scores significantly improved at the 24-month follow-up (p<0.05). There were no significant differences in CL and ROM at the 24-month follow-up (p>0.05). Although there was a significant difference between the before and 3-month follow-up (p<0.05), the ROM of the intermediate segment (IS) showed a tendency of returning to the preoperative state. The DH of the IS was maintained at each measurement while the DH of the upper and lower operated segments significantly increased at the 24-month follow-up (p<0.05). One patient, whose prosthesis remained mobile at the last follow-up, showed evidence of heterotopic ossification (HO). CONCLUSION: ACDR with the Prestige-LP prosthesis is a safe and feasible alternative procedure for treatment of NCDDD. In the future, a large-sample, prospective randomized controlled study with long-term follow-up will be needed to further demonstrate noncontiguous ACDR as an optimal surgical option for NCDDD.

Long-term clinical and radiographic outcomes of the Prestige LP artificial cervical disc replacement at 2 levels: results from a prospective randomized controlled clinical trial.

OBJECTIVE The aim of this study was to assess long-term clinical safety and effectiveness in patients undergoing anterior cervical surgery using the Prestige LP artificial disc replacement (ADR) prosthesis to treat degenerative cervical spine disease at 2 adjacent levels compared with anterior cervical discectomy and fusion (ACDF). METHODS A prospective, randomized, controlled, multicenter FDA-approved clinical trial was conducted at 30 US centers, comparing the low-profile titanium ceramic composite-based Prestige LP ADR (n = 209) at 2 levels with ACDF (n = 188). Clinical and radiographic evaluations were completed preoperatively, intraoperatively, and at regular postoperative intervals to 84 months. The primary end point was overall success, a composite variable that included key safety and efficacy considerations. RESULTS At 84 months, the Prestige LP ADR demonstrated statistical superiority over fusion for overall success (observed rate 78.6% vs 62.7%; posterior probability of superiority [PPS] = 99.8%), Neck Disability Index success (87.0% vs 75.6%; PPS = 99.3%), and neurological success (91.6% vs 82.1%; PPS = 99.0%). All other study effectiveness measures were at least noninferior for ADR compared with ACDF. There was no statistically significant difference in the overall rate of implant-related or implant/surgical procedure-related adverse events up to 84 months (26.6% and 27.7%, respectively). However, the Prestige LP group had fewer serious (Grade 3 or 4) implant- or implant/surgical procedure-related adverse events (3.2% vs 7.2%, log hazard ratio [LHR] and 95% Bayesian credible interval [95% BCI] -1.19 [-2.29 to -0.15]). Patients in the Prestige LP group also underwent statistically significantly fewer second surgical procedures at the index levels (4.2%) than the fusion group (14.7%) (LHR -1.29 [95% BCI -2.12 to -0.46]). Angular range of motion at superior- and inferior-treated levels on average was maintained in the Prestige LP ADR group to 84 months. CONCLUSIONS The low-profile artificial cervical disc in this study, Prestige LP, implanted at 2 adjacent levels, maintains improved clinical outcomes and segmental motion 84 months after surgery and is a safe and effective alternative to fusion. Clinical trial registration no.: NCT00637156 (clinicaltrials.gov).

Comparison of the incidence of patient-reported post-operative dysphagia between ACDF with a traditional anterior plate and artificial cervical disc replacement.

PURPOSE: Compared with anterior cervical discectomy and fusion (ACDF), cervical disc replacement (CDR) has provided satisfactory clinical results. The incidence of post-operative dysphagia between ACDF with a traditional anterior plate and CDR remains controversial. Considering the limited studies and knowledge in this area, a retrospective study focusing on post-operative dysphagia was conducted. METHODS: The Bazaz grading system was used to assess the severity of dysphagia at post-operative intervals including 1 week, 1 month, 3 months, 6 months, 12 months and 24 months respectively. The Chi-square test, Student t-test, Mann-Whitney U tests and Ordinal Logistic regression were used for data analysis when appropriate. Statistical significance was accepted at a probability value of <0.05. RESULTS: Two hundred and thirty-one patients in the CDR group and one hundred and fifty-eight patients in Plate group were included in this study. The total incidences of dysphagia in the CDR and plate group were 36.58% and 60.43% at one week, 29.27% and 38.85% at one month, 21.95% and 31.65% at three months, 6.83% and 17.99% at six months, 5.85% and 14.39% at 12 months, and 4.39% and 10.07% at the final follow-up respectively (All P<0.05, Mann-Whitney U test). Ordinal Logistic regression analysis showed that female patients, two-level surgery, C4/5 surgery, and anterior cervical plating were significant risk factors for post-operative dysphagia (all P<0.05). CONCLUSION: Comparing ACDF with a plate, CDR with a Prestige LP can significantly reduce both transient and persistent post-operative dysphagia. Female patients, two-level surgery, C4/5 surgery and anterior cervical plating were associated with a higher incidence of dysphagia. Future prospective, randomized, controlled studies are needed to further validate these findings.

Painless squeaking following cervical disc replacement: A case report.

BACKGROUND: We present a case of painless squeaking following cervical disc replacement which to our knowledge has not previously been reported in the literature. METHODS: A 45 year old gentleman presented with severe right sided C6 radiculopathy. He complained of more than 6 weeks of severe dysaesthesia in the right arm with pain radiating into the hand, thumb, index, middle and ring fingers. MRI confirmed severe impingement of C6 and C7 nerve roots. After trying a period of conservative treatment he underwent anterior cervical decompression with total cervical disc replacement of C5-6 and C6-7. RESULTS: Being a keen athlete he started running at 6 months post operatively. At his 12 month outpatient he presented us with an audio file containing squeaking from his neck. This was recorded immediately following a 9.5 mile hard surface run. The squeak got progressively less in intensity over 12 hours and disappeared after 24 hours. All instances of squeaking occurred after exercise where impact (running) or vibration (cycling) took place. This was first noticed 6 months post operatively when he restarted exercising. All episodes were completely painless. At his 18 month outpatient review the squeaking had reduced in frequency and intensity. At his 24 month review it had abated completely. CONCLUSION: The aetiology of this painless squeaking has been elusive and is likely to be multifactorial. However we hypothesise that the audible squeak associated with the prestige LP disc maybe related to specific design characteristics and needs further evaluation.