Clinical and radiological evaluation of Trabecular Metal and the Smith-Robinson technique in anterior cervical fusion for degenerative disease: a prospective, randomized, controlled study with 2-year follow-up

Comparison of Interbody Fusion Strategies in Anterior Cervical Discectomy and Fusion: A Network Meta-Analysis and Systematic Review

OBJECTIVE

The optimal choice for fusion strategy in Anterior Cervical Discectomy and Fusion (ACDF) remains an unresolved issue. This study aims to perform a network meta-analysis and systematic review of fusion rate and complication rate of various fusion strategies used in ACDF.

METHODS

This study followed Prisma guidelines, and we searched PubMed, Embase, Cochrane Library, and Web of Science from inception to November 11, 2022, for Randomized Controlled trials comparing the efficacy and safety of fusion modalities in ACDF. The primary outcome was the fusion rate and complication rate. The PROSPERO number is CRD42022374440.

RESULTS

This meta-analysis identified 26 Randomized Controlled trial studies with 1789 patients across 15 fusion methods. The cage with autograft + plating showed the highest fusion rate, surpassing other methods like iliac crest bone graft (ICBG) and artificial bone graft (AFG). The stand-alone cage with autograft (SATG) had the second highest fusion rate. Regarding complication rate, the cage with AFG (CAFG) had the highest rate, more than other methods. The ICBG had a higher complication rate compared to ICBG + P, AFG, stand-alone cage with artificial bone graft, SATG, and CALG. The SATG performed well in both fusion and complication rate.

CONCLUSIONS

In this study, we conducted the first network meta-analysis to compare the efficacy and safety of various fusion methods in ACDF. Our findings suggest that SATG, with superior performance in fusion rate and complication rate, may be the optimal choice for ACDF. However, the results should be interpreted cautiously until additional research provides further evidence.

The fusion rates at different times of cortical iliac crest autograft or allograft compared with cages after anterior cervical discectomy and fusion: a meta-analysis

OBJECTIVE

The cortical iliac crest autograft (CICA)/structural allograft (SA) has still been recognized as the gold standard for the ACDF technique for its high degree of histocompatibility and osteoinduction ability though the flourishing and evolving cage development. However, there was no further indication for using CICA/SA in ACDF based on basic information of inpatients. Our operative experience implied that applying CICA/SA has an advantage on faster fusion but not the long-term fusion rate. Therefore, our study aimed to compare the fusion rates between CICA and cage, between SA and cage, and between CICA/CA and cage.

METHODS

Based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), a comprehensive literature search of electronic databases including PubMed, Embase, Cochrane Library and Web of Science was conducted to identify these clinical trials that investigated the postoperative 3, 6, 12 and 24 months fusion rates of CICA/structural SA versus cage. Assessment of risk of bias, data extraction and statistical analysis were then carried out by two independent authors with the resolve-by-consensus method. The primary outcome was fusion rate at 3, 6, 12 and 24 months postoperatively. The secondary outcomes were also meta-analyzed such as hardware complications, operative duration and hospitalization time. Our meta-analysis was registered with PROSPERO (Identifier: CRD42022345247).

RESULT

A total of 3451 segments (2398 patients) derived from 34 studies were included after the screening of 3366 articles. The segmental fusion rates of CICA were higher than cages at 3 (P = 0.184, I2 = 40.9%) and 6 (P = 0.147, I2 = 38.8%) months postoperatively, but not 12 (P = 0.988, I2 = 0.0%) and 24 (P = 0.055, I2 = 65.6%) months postoperatively. And there was no significant difference in segmental fusion rates between SA and cage at none of 3 (P = 0.047, I2 = 62.2%), 6 (P = 0.179, I2 = 41.9%) and 12 (P = 0.049, I2 = 58.0%) months after operations. As for secondary outcomes, the CICA was inferior to cages in terms of hardware complications, operative time, blood loss, hospitalization time, interbody height, disk height and Odom rating. The hardware complication of using SA was significantly higher than the cage, but not the hospitalization time, disk height, NDI and Odom rating.

CONCLUSION

Applying CICA has an advantage on faster fusion than using a cage but not the long-term fusion rate in ACDF. Future high-quality RCTs regarding the hardware complications between CICA and cage in younger patients are warranted for the deduced indication.

Clinical Efficacy and Safety of Surgical Treatments in Patients With Pure Cervical Radiculopathy

Background

Traditionally paired meta-analysis revealed inconsistencies in the safety and effectiveness of surgical interventions. We conducted a network meta-analysis to assess various treatments' clinical efficacy and safety for pure cervical radiculopathy.

Methods

The Embase, PubMed, and Cochrane Library databases were searched for randomized controlled trials (RCTs) comparing different treatment options for patients with pure cervical radiculopathy from inception until October 23, 2021. The primary outcomes were postoperative success rates, postoperative complication rates, and postoperative reoperation rates. The pooled data were subjected to a random-effects consistency model. The protocol was published in PROSPERO (CRD42021284819).

Results

This study included 23 RCTs (n = 1,844) that evaluated various treatments for patients with pure cervical radiculopathy. There were no statistical differences between treatments in the consistency model in terms of major clinical effectiveness and safety outcomes. Postoperative success rates were higher for anterior cervical foraminotomy (ACF: probability 38%), posterior cervical foraminotomy (PCF: 24%), and anterior cervical discectomy with fusion and additional plating (ACDFP: 21%). Postoperative complication rates ranked from high to low as follows: cervical disc replacement (CDR: probability 32%), physiotherapy (25%), ACF (25%). Autologous bone graft (ABG) had better relief from arm pain (probability 71%) and neck disability (71%). Among the seven surgical interventions with a statistical difference, anterior cervical discectomy with allograft bone graft plus plating (ABGP) had the shortest surgery time.

Conclusions

According to current results, all surgical interventions can achieve satisfactory results, and there are no statistically significant differences. As a result, based on their strengths and patient-related factors, surgeons can exercise discretion in determining the appropriate surgical intervention for pure cervical radiculopathy.

Systematic Review Registration: CRD42021284819.

The Clinical Application of Porous Tantalum and Its New Development for Bone Tissue Engineering

Porous tantalum (Ta) is a promising biomaterial and has been applied in orthopedics and dentistry for nearly two decades. The high porosity and interconnected pore structure of porous Ta promise fine bone ingrowth and new bone formation within the inner space, which further guarantee rapid osteointegration and bone-implant stability in the long term. Porous Ta has high wettability and surface energy that can facilitate adherence, proliferation and mineralization of osteoblasts. Meanwhile, the low elastic modulus and high friction coefficient of porous Ta allow it to effectively avoid the stress shield effect, minimize marginal bone loss and ensure primary stability. Accordingly, the satisfactory clinical application of porous Ta-based implants or prostheses is mainly derived from its excellent biological and mechanical properties. With the advent of additive manufacturing, personalized porous Ta-based implants or prostheses have shown their clinical value in the treatment of individual patients who need specially designed implants or prosthesis. In addition, many modification methods have been introduced to enhance the bioactivity and antibacterial property of porous Ta with promising in vitro and in vivo research results. In any case, choosing suitable patients is of great importance to guarantee surgical success after porous Ta insertion.

Clinico-Radiological Outcome of Single-Level and Hybrid Total Disc Replacement with Spineart Baguera®-C for Cervical Myeloradiculopathy: Minimum 2-Year Follow-Up Study in Indian Population

Context

Cervical radiculopathy and myelopathy is one of the most frequent ailments encountered by spine surgeon. Motion-preserving surgeries in cervical spine is a standard of care due to its certain advantages such as biomechanical anatomical conformity, reduced chances of adjacent segment degeneration, and revision surgeries. While there is abundant data from some centers, data from developing countries are still limited.

Aims

The aim was to study the clinico-radiological outcome of single-level and hybrid total disc replacement (TDR) with Spineart Baguera^®-C cervical prosthesis for cervical myeloradiculopathy.

Settings and Design

Retrospective study.

Materials and Methods

Retrospective analysis of the 29 consecutive patient undergoing single level TDR and hybrid fixation (i.e., TDR with anterior cervical discectomy and fusion) with Spineart Baguera^®-C cervical prosthesis for myeloradiculopathy from January 1, 2014 to December 31, 2017, was done. Radiological features and outcome were studied from data collected on Insta-picture archiving and communication system.

Statistical Analysis Used

SAS 9.4 was used for all computations. Results on continuous measurements were presented as mean and standard deviation (min-max) and results on categorical measurements were presented as numbers (n) and percentages.

Results

Twenty-nine patients were included in the study. The mean age was 43.31 ± 9.04 years with 14 males and 15 females. The most common level of TDR was C5-C6 (72.41%). The mean follow-up duration was 3.14 years ± 1.13 years (2-5 years). The mean hospital stay was 4.93 ± 2.12 days. The mean neck disability index (NDI) at admission was 27.24 ± 7.66 which decreased to 6.41 ± 4.29 at final follow-up.

Conclusions

Two-year data on treatment with Spineart Baguera^®-C cervical prosthesis shows significantly improved NDI, visual analog scale (arm) with maintenance of movement of the prosthesis.

Fragility Analysis of Statistically Significant Outcomes of Randomized Control Trials in Spine Surgery: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVES

The aim of this study was to assess the robustness of statistically significant outcomes from randomized control trials (RCTs) in spine surgery using Fragility Index (FI) which is a novel metric measuring the number of events upon which statistical significance of the outcome depends.

SUMMARY OF BACKGROUND DATA

Many trials in Spine surgery were characterized by fewer outcome events along with small sample size. FI helps us identify the robustness of the results from such studies with statistically significant dichotomous outcomes.

METHODS

We conducted independent and in duplicate, a systematic review of published RCTs in spine surgery from PubMed Central, Embase, and Cochrane Database. RCTs with 1:1 prospective study design and reporting statistically significant dichotomous primary or secondary outcomes were included. FI was calculated for each RCT and its correlation with various factors was analyzed.

RESULTS

Seventy trials met inclusion criteria with a median sample size of 133 (interquartile range [IQR]: 80-218) and median reported events per trial was 38 (IQR: 13-94). The median FI score was 2 (IQR: 0-5), which means if we switch two patients from nonevent to event, the statistical significance of the outcome is lost. The FI score was less than the number of patients lost to follow-up in 28 of 70 trials. The FI score was found to positively correlated with sample size (r = 0.431, P = 0.001), total number of outcome events (r = 0.305, P = 0.01) while negatively correlated with P value (r = -0.392, P = 0.001). Funding, journal impact-factor, risk of bias domains, and year of publication did not have a significant correlation.

CONCLUSION

Statistically significant dichotomous outcomes reported in spine surgery RCTs are more often fragile and outcomes of the patients lost to follow-up could have changed the significance of results and hence it needs caution before transcending their results into clinical application. The addition of FI in routine reporting of RCTs would guide readers on the robustness of the statistical significance of outcomes. RCTs with FI ≥5 without any patient lost to follow-up can be considered to have clinically robust results.Level of Evidence: 1.

Surgical Interventions for Cervical Radiculopathy without Myelopathy: A Systematic Review and Meta-Analysis

BACKGROUND

The effectiveness of surgical interventions for cervical degenerative disorders has been investigated in multiple systematic reviews. Differences in study population (e.g., patients with myelopathy and/or radiculopathy) were often neglected. Therefore, the objective of this study was to investigate the effectiveness of surgical interventions for patients with symptoms of cervical radiculopathy without myelopathy by conducting a systematic review and meta-analysis based on randomized controlled trials (RCTs).

METHODS

A comprehensive systematic search was conducted in MEDLINE, Embase, and CENTRAL (Cochrane Central Register of Controlled Trials) to identify RCTs that investigated the effectiveness of surgical interventions using an anterior or posterior approach compared with other interventions for patients with pure cervical radiculopathy. Outcomes were success rates (Odom criteria, similar rating scales, or percentage of patients who improved), complication and reoperation rates, work status, disability (Neck Disability Index), and pain (arm and neck). The Cochrane risk-of-bias tool was used to assess the likelihood of the risk of bias. A random-effects model was used. Heterogeneity among study results (I2 ≥ 50% or p < 0.05) was explored by conducting subgroup analyses. Funnel plots were used to assess the likelihood of publication bias.

RESULTS

A total of 21 RCTs were included, comprising 1,567 patients. For all outcomes, among all surgical techniques, only 1 pooled estimate showed a significant effect on success rate, which was in favor of anterior cervical discectomy with fusion compared with anterior cervical discectomy without an intervertebral spacer (p = 0.02; risk ratio [RR] = 0.87; 95% confidence interval [CI] = 0.77 to 0.98). Complication rates were higher when autologous bone graft from the iliac crest was used as an intervertebral spacer (p < 0.01; RR = 3.40; 95% CI = 1.56 to 7.43), related to donor-site morbidity.

CONCLUSIONS

This meta-analysis demonstrated consistent results regarding clinical outcome for pure cervical radiculopathy among all studied interventions. Complication and reoperation rates were also similar, with the exception of higher complication rates in patients in whom autologous bone grafts were used. On the basis of clinical outcome and safety, there is no superior surgical intervention for pure cervical radiculopathy.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

The Role of Anterior Cervical Discectomy and Fusion on Relieving Axial Neck Pain in Patients With Single-Level Disease: A Systematic Review and Meta-Analysis

STUDY DESIGN

Systematic review and meta-analysis.

OBJECTIVES

This study aims to evaluate the effects of anterior cervical decompression and fusion (ACDF) on axial neck pain in adult patients receiving surgery for myelopathy, radiculopathy, or a combination of both.

METHODS

Two independent reviewers completed a librarian-assisted search of 4 databases. Visual Analogue Scale (VAS) and Neck Disability Index (NDI) scores were extracted preoperatively and at 3, 6, 12, 24, 36, 48, and 48+ months postoperatively for ACDF groups and pooled using a random-effects model.

RESULTS

Of 17 850 eligible studies, 37 were included for analysis, totaling 2138 patients analyzed with VAS and 2477 with NDI score. Individual VAS mean differences were reduced at 6 weeks (-2.5 [95% confidence interval (CI): -3.5 to -1.6]), 3 months (-2.9 [-3.7 to -2.2]), 6 months (-3.2 [-3.9 to -2.6]), 12 months (-3.7 [-4.3 to -3.1]), 24 months (-4.0 [-4.4 to -3.5]), 48 months (-4.6 [-5.5 to -3.8]), and >48 months (-4.7 [-5.8 to -3.6]) follow-up (P < .0001 for all endpoints). Individual NDI mean differences were reduced at 6 weeks (-26.7 [-30.9 to -22.6]), 3 months (-29.8 [-32.7 to -26.8]), 6 months (-31.2 [-35.5 to -26.8)], 12 months (-29.3 [-33.2 to -25.4]), 24 months (-28.9 [-32.6 to -25.2]), 48 months (-33.1 [-37.4 to -28.7]), and >48 months (-37.6 [-45.9 to -29.3]) follow-up (P < .0001 for all endpoints).

CONCLUSIONS

ACDF is associated with a significant reduction in axial neck pain compared with preoperative values in patients being treated specifically for myelopathy or radiculopathy. This influences the preoperative discussions surgeons may have with patients regarding their expectations for surgery. The effects seen are stable over time and represent a clinically significant reduction in axial neck pain.

Tantalum: the next biomaterial in spine surgery?

Tantalum is a porous metal, whose elastic modulus, high frictional properties and biocompatibility make it an ideal construct to facilitate adequate bony fusion in spine surgery. Since 2015, the published literature on clinical outcomes of tantalum in spine surgery has more than doubled. A review of the literature was performed on the PubMed (MEDLINE) database on January 27, 2019, for papers pertinent to the use of tantalum metal in spine surgery. Thirteen studies were included in this review. For cervical spine, we found increased fusion rates in autograft alone compared to tantalum standalone (92.8% vs. 89.0%, P=0.001) and tantalum cages plus autograft (92.8% vs. 64.8%, P<0.0001). Complication rates in cervical fusion were lower in patients treated with tantalum standalone versus those treated with autograft (7.4% vs. 13.7%, P<0.0001), and autograft and anterior plate (7.4% vs. 33%, P=0.001). Autograft patients had higher rates of revision surgery compared to tantalum standalone (12.8% vs. 2.8%, P<0.0001) and tantalum ring with autograft (12.8% vs. 7.7%, P<0.001). For lumbar spine, we found autograft had lower fusion rate compared to tantalum standalone (80.0% vs. 93.4%, P<0.0001). Use of tantalum metal in spine fusion surgery shows promising results in fusion, complication and revision rates, and clinical outcomes compared to autograft. Although, fusion rates in short-term studies evaluating tantalum in the cervical spine are conflicting, long-term series beyond 2 years show excellent results. This early finding may be related difficulties in radiographic evaluation of fusion in the setting of tantalum cage use. Further studies are needed to further delineate the timing of fusion with the implementation of tantalum in the cervical and lumbar spine.

Scientific, Clinical, Regulatory, and Economic Aspects of Choosing Bone Graft/Biological Options in Spine Surgery

Spinal arthrodesis is a major element of the spinal surgeon's practice. To attain successful fusion rates, attention must be paid to spinal segment immobilization and proper selection of bone graft. Autogenous bone graft (ie, ICBG), the "gold standard," with or without graft extenders and enhancers provides the foundation for most spinal fusions. ABG is the only graft option containing all 3 factors of new bone growth: osteoconductivity, osteoinductivity, and osteogenicity. While many bone graft alternatives function well as bone graft extenders, only growth factors proteins (ie, rhBMP-2 or OP-2) function as bone graft enhancers and substitutes. The search for optimal hybrid interbody cages, bone graft substitutes, autogenous or allogenic stem cells, and nanostructure scaffolds for release of growth factors continues.

Tantalum Fusion Device in Anterior Cervical Discectomy and Fusion For Treatment of Cervical Degeneration Disease: A Systematic Review and Meta-Analysis

STUDY DESIGN

This is a systematic review and meta-analysis study.

OBJECTIVE

The purpose of this systematic review and meta-analysis study is to evaluate the outcomes of a tantalum fusion device in anterior cervical discectomy and fusion (ACDF) for the treatment of cervical degeneration disease.

SUMMARY OF BACKGROUND DATA

A great interest has raised for porous tantalum in cervical fusion, but several studies reported the divergent clinical outcome and fusion rate. No systematic review and meta-analysis has been conducted up to present to evaluate the outcomes of the tantalum fusion device.

METHODS

We comprehensively searched multiple databases for studies that investigated the tantalum fusion device in ACDF. The retrieved results were last updated on February 15, 2018. Outcomes of interest comprised of operative parameters, fusion rate, the incidence of adverse events as well as patient-reported outcomes, including the Neck Disability Index (NDI) score, Visual Analog Scale (VAS) score, Short Form-36 Physical Component Scores and complications.

RESULTS

Ten studies included were included in this review and 6 randomized controlled trial studies included. All studies were pooled to evaluate the outcome of fusion rate, NDI, and VAS after tantalum fusion treatment. The results of the meta-analysis showed that implantation of the tantalum fusion device is associated with significantly shorter operative and fewer adverse events when compared with autologous iliac crest bone graft. However, no difference was found with regards to the fusion rate, NDI, VAS, and global assessment.

CONCLUSIONS

Through this systemic review and meta-analysis, no significant difference was found with regards to fusion rate, postoperative NDI, and VAS between tantalum fusion and iliac crest bone graft in ACDF. More longer-term and randomized studies with large samples are warranted to validate any association found in this study.

LEVEL OF EVIDENCE

Level II.

Tantalum implants for posterior lumbar interbody fusion: A safe method at medium-term follow-up?

INTRODUCTION

Intervertebral implants increase stability and improve results in lumbar interbody fusion (LIF). The aim of the present study was to assess clinical and radiological results of posterior lumbar interbody fusion (PLIF) using a tantalum intervertebral implant without associated interbody bone graft.

MATERIEL AND METHODS

A single-center retrospective study included 52 cases of single-level PLIF, using 2 tantalum intervertebral cages, without interbody bone graft: 42 for degenerative disc disease, 10 for isthmic spondylolisthesis. Minimum follow-up was 2 years. Clinical assessment used a visual analog (pain) scale (VAS), the Oswestry Disability Index (ODI) and the Roland Morris (RM) scale. Tantalum osseointegration and intersegment mobility were assessed on static and dynamic X-ray.

RESULTS

Forty-nine patients were included, with a mean 55months' follow-up (range, 25-74months). VAS, ODI and RM scores showed significant improvement at last-follow-up, at 4, 30 and 28 points respectively. There was no mechanical failure on static X-ray; all patients had less than 5° mobility on dynamic X-ray at last follow-up.

DISCUSSION

PLIF with tantalum intervertebral implant without interbody bone graft provided satisfactory clinical and radiological results at medium-term follow-up. The present findings showed reliable primary stability and osseointegration of the tantalum implant.

LEVEL OF EVIDENCE

IV.

Correlation Between Different Interbody Grafts and Pseudarthrosis After Anterior Cervical Discectomy and Fusion Compared with Control Group: Systematic Review

BACKGROUND

Cervical spine degenerative disease is one of the main causes of myelopathy. Anterior cervical discectomy and fusion (ACDF) is the most common surgical procedure used to treat cervical myelopathy. Therefore, it is important to study pseudarthrosis rates after ACDF and correlate them with the graft used.

METHODS

We performed a systematic review to evaluate the relationship between pseudarthrosis after ACDF and the interbody graft used.

RESULTS

A total of 3732 patients were evaluated in 46 studies. The mean age of the included patients was 51.5 ± 4.18 years (range, 42-59.6 years). ACDF is most often perforemd as single-level surgery and the level most impaired is C5-C6. The use of titanium cages, zero profile, recombinant human bone morphogenetic protein 2, and carbon cages was seen as a protective factor for pseudarthrosis compared with the autograft group (control group); with an odds ratio of 0.29, 0.51, 0.03, and 0.3, respectively; the results were statistically relevant. The use of polyetheretherketone, poly(methyl methacrylate), and trabecular metal was a risk factor for development of pseudarthrosis compared with the control group, with an odds ratio of 1.7, 8.7, and 6.8, respectively; the results were statistically relevant. Radiologic follow-up was an important factor for the pseudarthrosis rate; paradoxically, a short follow-up (<1 year) had lower rates of pseudarthrosis and follow-up >2 years increased the chance of finding pseudarthrosis.

CONCLUSIONS

Different types of grafts lead to a significant difference in pseudarthrosis rates. Follow-up time is also an important factor that affects the rate of pseudarthrosis after ACDF.

Application of a novel porous tantalum implant in rabbit anterior lumbar spine fusion model: in vitro and in vivo experiments

BACKGROUND

Some porous materials have been developed to enhance biologic fusion of the implants to bone in spine fusion surgeries. However, there are several inherent limitations. In this study, a novel biomedical porous tantalum was applied to in vitro and in vivo experiments to test its biocompatibility and osteocompatibility.

METHODS

Bone marrow-derived mesenchymal stem cells (BMSCs) were cultured on porous tantalum implant. Scanning electron microscope (SEM) and Cell Counting Kit-8 assay were used to evaluate the cell toxicity and biocompatibility. Twenty-four rabbits were performed discectomy only (control group), discectomy with autologous bone implanted (autograft group), and discectomy with porous tantalum implanted (tantalum group) at 3 levels: L3-L4, L4-L5, and L5-L6 in random order. All the 24 rabbits were randomly sacrificed at the different post-operative times (2, 4, 6, and 12 months; n = 6 at each time point). Histologic examination and micro-computed tomography scans were done to evaluate the fusion process. Comparison of fusion index scores between groups was analyzed using one-way analysis of variance. Other comparisons of numerical variables between groups were made by Student t test.

RESULTS

All rabbits survived and recovered without any symptoms of nerve injury. Radiographic fusion index scores at 12 months post-operatively between autograft and tantalum groups showed no significant difference (2.89 ± 0.32 vs. 2.83 ± 0.38, F = 244.60, P = 0.709). Cell Counting Kit-8 assay showed no significant difference of absorbance values between the leaching liquor group and control group (1.25 ± 0.06 vs. 1.23 ± 0.04, t = -0.644, P = 0.545), which indicated the BMSC proliferation without toxicity. SEM images showed that these cells had irregular shapes with long spindles adhered to the surface of tantalum implant. No implant degradation, wear debris, or osteolysis was observed. Histologic results showed solid fusion in the porous tantalum and autologous bone implanted intervertebral spaces.

CONCLUSION

This novel porous tantalum implant showed a good biocompatibility and osteocompatibility, which could be a valid biomaterial for interbody fusion cages.

Comparison between porous tantalum metal implants and autograft in anterior cervical discectomy and fusion: a meta-analysis

Aim: The objective of this study was to systematically compare the safety and efficacy of porous tantalum metal (TM) implants and autograft in single-level anterior cervical discectomy and fusion. Methods: Potential academic articles were acquired from the Cochrane Library, Medline, PubMed, Embase, Science Direct and other databases. The time range used was from the inception of the electronic databases to March 2018. Gray studies were identified from the references of included literature reports. STATA version 11.0 (Stata Corporation, TX, USA) was used to analyze the pooled data. Results: Four randomized, controlled trials (RCTs) were identified according to the retrieval process. There were significant differences in operation time (mean difference [MD]: -28.846, 95% confidence interval [CI: -47.087, -10.604], p = 0.002) and satisfaction rate (odds ratio [OR]: 2.196, 95% CI: [1.061-4. 546]; p = 0.034). However, no significant difference was detected in blood loss (MD: -73.606, 95% CI: [-217.720, 70.509], p = 0.317), hospital stay (MD: -0.512, 95% CI [-1.082, 0.058]; p = 0.079), fusion rate (OR: 0.497, 95% CI [0.079, 3.115]; p = 0.455), visual analog scale (MD: -0.310, 95% CI [-0.433, -0.186]; p < 0.001) or complication rate (risk difference [RD]: -0.140, 95% CI: [-0.378, 0.099]; p = 0.251). Conclusion: Porous TM implants are equally as effective and safe as autograft in anterior cervical discectomy and fusion processes. In addition, porous TM implants could reduce operation time and improve clinical satisfaction significantly.

What is the most accurate radiographic criterion to determine anterior cervical fusion?

BACKGROUND CONTEXT

The accuracy of radiographic criteria for determining anterior cervical fusion remains controversial, and inconsistency in the literature makes a comparison of published clinical results problematic. The descriptions of bridging bone are still lacking and subjective, and the interpretation of images can be influenced by the type of graft or cage used.

PURPOSE

To assess and validate the diagnostic accuracies of four radiographic fusion criteria using the results of surgical exploration.

STUDY DESIGN

Retrospective, radiographic, and comparative study.

PATIENT SAMPLE

This study included patients who required anterior or posterior exploration of a previous anterior cervical arthrodesis level(s) ranging from C3-C4 to C7-T1 for suspected pseudarthrosis or adjacent-segment pathologies. They underwent radiologic examinations to determine the four fusion criteria. We included patients whose images were taken at least 1 year after the index surgery, and 82 patients with 151 cervical segments were enrolled.

OUTCOME MEASURES

The inter- and intra-rater reliabilities and validity that correlated with the results of surgical exploration for the four fusion criteria were assessed using data (fusion or not) that were collected by two raters.

METHODS

The four published radiographic fusion criteria were interspinous motion (ISM) < 1 mm and superjacent ISM ≥ 4 mm, seen on dynamic radiographs; conventional bridging bone, as seen on computed tomography (CT) scans; and extra-graft bridging bone (ExGBB) and intragraft bridging bone (InGBB), observed on multi-axial reconstructed CT scans. The criteria were evaluated by two raters (spine surgeons with 5 and 7 years of experience). The raters evaluated each criterion twice at two different time points, 3 to 4 weeks apart. First, ISM and conventional bridging bone on CT scans were evaluated, followed by ExGBB and InGBB, with a time interval of 4 months. This Research was supported by the Chung-Ang University Research Grants (less than 5,000 US dollars) in 2016.

RESULTS

The inter- and intra-rater reliability values of the ExGBB (0.887-0.933) criteria were the highest, followed by those for the ISM (0.860-0.906), bridging bone (0.755-0.907), and InGBB (0.656-0.695) criteria. The validity values that correlated with the exploration results were the highest for the ExGBB criteria (k=0.889), followed by the ISM (k=0.776), bridging bone (k=0.757), and InGBB (k=0.656) criteria and ExGBB showed the highest sensitivity (91.7%) and specificity (98.4%). Regarding the graft materials that were used, all criteria had the highest values in the auto-cortical group and lowest values in the cage group. Of note, sensitivity and specificity of ExGBB were 100% in autocortical group. In the cage group, the validity values for the ExGBB (k=0.663) and ISM (k=0.666) criteria were higher than those for the bridging bone (k=0.504) and InGBB (k=0.308) criteria CONCLUSION: The presence of ExGBB (anterior, posterior, or lateral to the graft or cage) correlated the best with surgical exploration. The ISM criteria demonstrated a similar accuracy to that of conventional bridging bone criteria on CT scans. In arthrodesed segments with auto-cortical bone, criteria showed the highest validity values. In cage group, ISM and ExGBB had acceptable accuracy, but the conventional bridging bone and InGBB were worse than guessing. We recommend that ISM and ExGBB criteria should be used to increase accuracy in patients who undergo arthrodesis with cages.

Comparative Study of Functional Outcome of Anterior Cervical Decompression and Interbody Fusion With Tricortical Stand-Alone Iliac Crest Autograft Versus Stand-Alone Polyetheretherketone Cage in Cervical Spondylotic Myelopathy

STUDY DESIGN

Retrospective analysis of prospectively collected data.

OBJECTIVE

The aim of the study was to compare the outcome of anterior cervical decompression and fusion (ACDF) with stand-alone tricortical iliac crest autograft versus stand-alone polyetheretherketone (PEEK) cage in cases of cervical spondylotic myelopathy.

METHODS

Prospectively collected data of 60 patients in each group were compared.

RESULTS

There was statistically significant improvement noted in postoperative Modified Japanese Orthopaedic Association (MJOA) follow-up scores with comparison pairs of preoperative versus 6 months, preoperative versus 1 year, and 3 months versus 6 months, 3 months versus 1 year in both groups. But improvements in MJOA scores were statistically insignificant between 6 months and 1 year (P = .0639) for the autograft group when compared with PEEK cage group (P = 0001). The mean loss of segmental lordosis on follow-up X-ray for the autograft group was (5.89 ± 2.90°), which was significantly higher (1.88 ± 2.77°) than the mean loss seen in the PEEK cage group (P = .01). This was most evident between 6 months and 1 year, resulting in plateauing of the improvement in MJOA score between 6 months to 1 year in the autograft group. While there was no statistical difference between fusion rates between the groups for 1 and 2 levels of ACDF, overall fusion rates were significantly better for 1-level ACDF (95.74%) when compared with 2-level ACDF (76.00%).

CONCLUSION

ACDF with PEEK cage is the fusion technique of choice for cervical fusion with fewer complications and better functional recovery in the treatment of cervical spondylotic myelopathy.

Eleven-Year Follow-Up of Two Cohorts of Patients Comparing Stand-Alone Porous Tantalum Cage Versus Autologous Bone Graft and Plating in Anterior Cervical Fusions

BACKGROUND

Anterior cervical discectomy and fusion with a porous tantalum cage is an accepted method to treat degenerated cervical discs, with good results, similar to those with autologous bone graft and plating at short- and mid-term follow-up. However, to date, long-term follow-up studies have been performed.

METHODS

We performed a retrospective, single-center study to evaluate the outcomes of 2 cohorts from a previous prospective randomized controlled trial comparing stand-alone tantalum cage (group 1, 27 patients) with autologous bone graft and plating (group 2, 30 patients) for single-level anterior cervical discectomy and fusion at 11 years of follow-up. The usual clinical and radiological outcomes and "overall success," proposed by the Food and Drug Administration, were evaluated.

RESULTS

The improvement in clinical outcomes achieved postoperatively was maintained similarly in the 2 cohorts at 11 years of follow-up. In group 1, the cage had subsided 2-3 mm in 12 patients (44%), segmental lordosis was maintained in 16 patients (59%), adjacent segment degeneration had developed or progressed in 27 of the adjacent segments (50%) in 15 patients (56%), and postoperative nonprogressive deformation of the anterior aspect of the cage was observed in 7 (26%) and minor fragmentation in 3 (11%) patients. In group 2, segmental lordosis was maintained in 90% of the patients and adjacent segment degeneration had developed or progressed in 15 patients (50%).

CONCLUSIONS

These results show that the clinical and radiological outcomes achieved at mid-term follow-up using a tantalum cage for single-level anterior cervical discectomy and fusion will be maintained for 11 years postoperatively, similar to the results with autologous bone graft and plating.

Diagnosing Pseudoarthrosis After Anterior Cervical Discectomy and Fusion

Radiographic confirmation of fusion after anterior cervical discectomy and fusion (ACDF) surgery is a critical aspect of determining surgical success. However, there is a lack of established diagnostic radiographic parameters for pseudoarthrosis. The purpose of this study is to summarize the findings of previous studies, review the advantages and disadvantages of frequently employed diagnostic criteria, and present our recommended protocol of fusion assessment. This study identified randomized controlled trials, case-control studies, and prospective and retrospective cohort studies reporting on spinal fusion and how successful fusion after ACDF. Among the 39 articles reviewed, bridging bone across the operated levels on static radiographs was the most commonly used criteria to confirm fusion (31 of 39, 79%). Dynamic flexion-extension radiographs were used to assess for interspinous movement (ISM) (22 of 39, 56.4%) and change in Cobb angle (12 of 39, 30.8%). Computed tomography (CT) based findings (21 of 39, 53.8%) were employed in ambiguous cases with improved sensitivity and specificity. Reconstructed CT scans were used to assess for intragraft bridging bone and extragraft bridging bone (ExGBB). ExGBB were proved to have the highest diagnostic sensitivity and specificity for pseudoarthrosis detection when compared to all other radiographic criteria. The ISM <1 mm on dynamic flexion-extension radiographs had high diagnostic sensitivity and specificity as well. After our reviewing, we recommend using dynamic lateral flexion-extension cervical spine radiographs at 150% magnificationin which the interspinous motion <1 mm and superjacent interspinous motion ≥4 mm confirms fusion. In ambiguous cases, we recommend using reconstructed CT scans to evaluate for ExGBB.

Electrochemical Impedance and Polarization Corrosion Studies of Tantalum Surface Modified by DC Plasma Electrolytic Oxidation

Tantalum has recently become an actively researched biomaterial for the bone reconstruction applications because of its excellent corrosion resistance and successful clinical records. However, a bare Ta surface is not capable of directly bonding to the bone upon implantation and requires some method of bioactivation. In this study, this was realized by direct current (DC) plasma electrolytic oxidation (PEO). Susceptibility to corrosion is a major factor determining the service-life of an implant. Therefore, herein, the corrosion resistance of the PEO coatings on Ta was investigated in Ringer’s solution. The coatings were formed by galvanostatic anodization up to 200, 300 and 400 V, after which the treatment was conducted potentiostatically until the total process time amounted to 5 min. Three solutions containing Ca(H₂PO₂)₂, Ca(HCOO)₂ and Mg(CH₃COO)₂ were used in the treatment. For the corrosion characterization, electrochemical impedance spectroscopy and potentiodynamic polarization techniques were chosen. The coatings showed the best corrosion resistance at voltages low enough so that the intensive sparking was absent, which resulted in the formation of thin films. The impedance data were fitted to the equivalent electrical circuits with two time constants, namely R(Q[R(QR)]) and R(Q[R(Q[RW])]). The inclusion of W in the circuit helped to fit the low-frequency part of the samples PEO-ed at 400 V, hinting at the important role of diffusion in the corrosion resistance of the PEO coatings described in the research.

Novel Osteobiologics and Biomaterials in the Treatment of Spinal Disorders

Spinal osteobiologics have evolved substantially in this century after the development of many product categories such as growth factors, allograft, and stem cells. The indications for the use of novel biologics within spine surgery are rapidly expanding as the mechanism of each is elucidated. While the knowledge base of bone morphogenetic protein increases with each subsequent year, the application of new nanotechnology and cell-based strategies are being reported. This review will discuss the most recent data in novel osteobiologics, and where we could use future study.

Degenerative Cervical Disc Disease: Long-term Changes in Sagittal Alignment and Their Clinical Implications After Cervical Interbody Fusion Cage Subsidence: A Prospective Study With Standalone Lordotic Tantalum Cages

STUDY DESIGN

A retrospective, observational study of prospectively collected outcomes.

OBJECTIVE

To investigate the long-term clinical course of anterior cervical discectomy and fusion with interbody fusion cages (ACDF-IFC) with lordotic tantalum implants and to correlate the radiologic findings with the clinical outcomes, with special emphasis on the significance and the influence of implant subsidence.

SUMMARY OF BACKGROUND DATA

Cage subsidence is the most frequently reported complication after ACDF-IFC. However, most reports fail to correlate cage subsidence with lower fusion rates or with unsatisfactory clinical results.

METHODS

Forty-one consecutive patients with symptomatic degenerative cervical disk disease with failure of conservative treatment were included. All patients underwent 1-/2-level ACDF-IFC with lordotic tantalum implants. The mean follow-up was 4.91 years.

RESULTS

The final follow-up fusion rate was 96.96% (32/33). The interspace height (IH) at the affected levels was significantly incremented after implant insertion, and despite a gradual loss in the height over time, the final follow-up IH was significantly higher than that measured preoperatively (P<0.0001). Anterior IH and posterior IH lost 55.8% and 76.2% of the initially incremented height, respectively, with a final increase of 72% in the AIH-PIH height differential. Implant subsidence (>3 mm) occurred in 11 disk spaces (26.82%). Preoperative and postoperative IH were significantly higher in subsidence patients; however, there was no difference in the final follow-up IH (P>0.05). Patients with ≥3 years of follow-up (n=29) did not demonstrate further significant subsidence beyond the second year. Regarding C1-C7 lordosis, the segmental Cobb angle, the cervical Visual Analogue Scale, and Neck Disability Index questionnaires, no difference between patients with or without final follow-up endplate subsidence was encountered.

CONCLUSIONS

Until fusion occurs, tantalum cage settlement into the vertebral body is to be expected. Further subsidence could be the result of segmental adaptative changes. Graft subsidence did not affect the clinical outcome in any of our patients during long-term follow-up. The occurrence of dynamical implant subsidence had a positive effect on cervical lordosis, especially at the posterior IH.

A 5- to 8-year randomized study on the treatment of cervical radiculopathy: anterior cervical decompression and fusion plus physiotherapy versus physiotherapy alone

OBJECTIVE

The aim of this study was to evaluate the 5- to 8-year outcome of anterior cervical decompression and fusion (ACDF) combined with a structured physiotherapy program as compared with that following the same physiotherapy program alone in patients with cervical radiculopathy. No previous prospective randomized studies with a follow-up of more than 2 years have compared outcomes of surgical versus nonsurgical intervention for cervical radiculopathy.

METHODS

Fifty-nine patients were randomized to ACDF surgery with postoperative physiotherapy (30 patients) or to structured physiotherapy alone (29 patients). The physiotherapy program included general and specific exercises as well as pain coping strategies. Outcome measures included neck disability (Neck Disability Index [NDI]), neck and arm pain intensity (visual analog scale [VAS]), health state (EQ-5D questionnaire), and a patient global assessment. Patients were followed up for 5–8 years.

RESULTS

After 5–8 years, the NDI was reduced by a mean score% of 21 (95% CI 14–28) in the surgical group and 11% (95% CI 4%–18%) in the nonsurgical group (p = 0.03). Neck pain was reduced by a mean score of 39 mm (95% CI 26–53 mm) compared with 19 mm (95% CI 7–30 mm; p = 0.01), and arm pain was reduced by a mean score of 33 mm (95% CI 18–49 mm) compared with 19 mm (95% CI 7–32 mm; p = 0.1), respectively. The EQ-5D had a mean respective increase of 0.29 (95% CI 0.13–0.45) compared with 0.14 (95% CI 0.01–0.27; p = 0.12). Ninety-three percent of patients in the surgical group rated their symptoms as “better” or “much better” compared with 62% in the nonsurgical group (p = 0.005). Both treatment groups experienced significant improvement over baseline for all outcome measures.

CONCLUSIONS

In this prospective randomized study of 5- to 8-year outcomes of surgical versus nonsurgical treatment in patients with cervical radiculopathy, ACDF combined with physiotherapy reduced neck disability and neck pain more effectively than physiotherapy alone. Self-rating by patients as regards treatment outcome was also superior in the surgery group. No significant differences were seen between the 2 patient groups as regards arm pain and health outcome.

Tantalum trabecular metal implants in anterior cervical corpectomy and fusion: 2-year prospective analysis

Anterior cervical decompression for two or more cervical spondylotic levels can be performed using either multiple anterior cervical discectomies and fusion or anterior cervical corpectomy and fusion (ACCF). A variety of options for ACCF implants exist but to our knowledge, there is no clinical data for the use of tantalum trabecular metal implants (TTMI) for ACCF. A retrospective review was performed of prospectively collected data for ten patients undergoing ACCF with TTMI between 2011 and 2012. Radiological outcome was assessed by measuring the change in cervical (C) lordosis (fusion Cobb and C2-C7 Cobb), graft subsidence (anterior/posterior, determined by the subsidence of anterior/posterior body height of fused segments; cranial/caudal, determined by the cranial/caudal plate-to-disc distances) and rate of fusion using lateral cervical X-rays of patients at 0, 6, 12 and 24months post-operatively. The Neck Disability Index (NDI) assessed clinical outcome pre-operatively and at 6, 12 and 24months post-operatively. Cervical lordosis (Cobb angle of fused segment) was 5.2° (± 4.2°) at 0months and 6.0° (± 5.7°) at 24months post-operatively. Graft subsidence was observed to occur at 6months post-operatively and continued throughout follow-up. Anterior, posterior and caudal subsidence occurred more in the first 12months post-operatively than in the following 12months (p<0.05). Average pre-operative NDI was 45%. Average NDIs were 18%, 13% and 10% at 6, 12 and 24months post-operatively, respectively. ACCF patients treated with TTMI demonstrated stable cervical lordosis over 2years of follow-up and 100% fusion rates after 2years. Measures of subsidence appeared to decrease with time. Patients experienced improved clinical outcomes over the 2-year period.

The Cost Effectiveness of Polyetheretheketone (PEEK) Cages for Anterior Cervical Discectomy and Fusion

STUDY DESIGN

Cost-effectiveness analysis using a Markov model with inputs from published literature.

OBJECTIVE

To learn which graft or hardware option used in a single-level anterior cervical discectomy and fusion (ACDF) is most beneficial in terms of cost, quality of life, and overall cost effectiveness. Options studied were autograft, allograft, and polyetheretherketone (PEEK) cages for cervical fusion.

SUMMARY OF BACKGROUND DATA

ACDF is commonly used to treat cervical myelopathy and/or radiculopathy. No study has compared the cost effectiveness of autograft, allograft, and PEEK in 1-level ACDF.

MATERIALS AND METHODS

A literature review provided inputs into a Markov decision model to determine the most effective graft or hardware option for 1-level ACDF. Data regarding rate of complications, quality-adjusted life years (QALYs) gained, and cost for each procedure type was collected. The Markov model was first run in a base case, using all currently available data. The model was then tested using 1-way and 2-way sensitivity analyses to determine the validity of the model's conclusions if specific aspects of model were changed. This model was run for 10 years postoperatively.

RESULTS

The cost per QALY for each option in the base case analysis was $3328/QALY for PEEK, $2492/QALY for autograft, and $2492/QALY for allograft. All graft/hardware options are cost effective ways to improve outcomes for patients living with chronic neck pain. For graft/hardware options the most cost-effective option was allograft. The incremental cost-effectiveness ratio for PEEK compared with autograft or allograft was >$100,000/QALY.

CONCLUSIONS

Allograft is the most cost-effective graft/hardware option for ACDF. Compared with living with cervical myelopathy and/or radiculopathy, ACDF using any graft or hardware option is a cost-effective method of improving the quality of life of patients. PEEK is not a cost-effective option compared with allograft or autograft for use in ACDF.

A minimum 2-year comparative study of autologous cancellous bone grafting versus beta-tricalcium phosphate in anterior cervical discectomy and fusion using a rectangular titanium stand-alone cage

Although titanium stand-alone cages are commonly used in anterior cervical discectomy and fusion (ACDF), there are several concerns such as cage subsidence after surgery. The efficacy of β-tricalcium phosphate (β-TCP) granules as a packing material in 1- or 2-level ACDF using a rectangular titanium stand-alone cage is not fully understood. The purpose of this study is to investigate the validity of rectangular titanium stand-alone cages in 1- and 2-level ACDF with β-TCP. This retrospective study included 55 consecutive patients who underwent ACDF with autologous iliac cancellous bone grafting and 45 consecutive patients with β-TCP grafting. All patients completed at least 2-year postoperative follow-up. Univariate and multivariate analyses were performed to examine the associations between study variables and nonunion after surgery. Significant neurological recovery after surgery was obtained in both groups. Cage subsidence was noted in 14 of 72 cages (19.4 %) in the autograft group and 12 of 64 cages (18.8 %) in the β-TCP group. A total of 66 cages (91.7 %) in the autograft group showed osseous or partial union, and 58 cages (90.6 %) in the β-TCP group showed osseous or partial union by 2 years after surgery. There were no significant differences in cage subsidence and the bony fusion rate between the two groups. Multivariate analysis using a logistic regression model showed that fusion level at C6/7, 2-level fusion, and cage subsidence of grades 2-3 were significantly associated with nonunion at 2 years after surgery. Although an acceptable surgical outcome with negligible complication appears to justify the use of rectangular titanium stand-alone cages in 1- and 2-level ACDF with β-TCP, cage subsidence after surgery needs to be avoided to achieve acceptable bony fusion at the fused segments. Fusion level at C6/7 or 2-level fusion may be another risk factor of nonunion.

In Vivo Magnetic Resonance Imaging Evaluation of Porous Tantalum Interbody Fusion Devices in a Porcine Spinal Arthrodesis Model

STUDY DESIGN

Animal experimental study.

OBJECTIVE

To investigate the use of magnetic resonance (MR) imaging in the assessment of lumbar interbody fusion using porous tantalum implants in a porcine spinal fusion model.

SUMMARY OF BACKGROUND DATA

Porous tantalum has been used successfully as a spinal interbody fusion device. However, to our knowledge, there has been no consensus on the optimal technique for evaluating spinal fusion when using porous tantalum implants.

METHODS

Twelve 12-week-old female Danish Landrace pigs underwent 3 levels of anterior lumbar interbody fusion at L2-3, L4-5 and L6-7. One level was fused using a solid porous tantalum cage with pedicle screw fixation. The other 2 levels were fused using a hollow porous tantalum ring packed with autograft and stabilized anteriorly with staples. Six months postoperatively, T1-weighted, T2-weighted, and gadolinium-DTPA contrast-enhanced MRI were obtained on a GE 1.5-T unit. After sacrifice, conventional radiograph and histological examination were carried out.

RESULTS

Eleven pigs went through the experiment without complications. On all the MR sequences, there were significant higher signal intensity bands at the vertebrae-implant interface of nonfused segments compared with that of fused segments and the vertebral bone and implants themselves (P < 0.001). There was an agreement between histological findings of fibrous tissues surrounding the implants and the high signal intensity band on T1- and T2-weighted MR images respectively (sensitivity 69.6% and 56.5%, specificity 90.7% and 95.3%), both of which were superior to conventional radiograph images (sensitivity 52.2%, specificity 97.7%), especially the T1-weighted MR images.

CONCLUSION

MR imaging could be an effective and noninvasive way to determine the fusion status of tantalum metal implants. Compared with T2-weighted MR imaging and conventional radiograph, T1-weighted spin-echo MR imaging is more sensitive and specific in detecting nonunion via the lucency between the vertebral body and tantalum metal device.

LEVEL OF EVIDENCE

N/A.

The fragility of statistically significant findings from randomized trials in spine surgery: a systematic survey

BACKGROUND CONTEXT

Randomized controlled trials (RCTs) are the most trustworthy source for evaluating treatment effects, but RCTs of spine surgery interventions often produce discordant results. The Fragility Index is a novel metric to inform about the robustness of statistically significant results.

PURPOSE

The aim was to determine the robustness of statistically significant results from RCTs of spine surgery interventions.

STUDY DESIGN/SETTING

This was a systematic survey.

PATIENT SAMPLE

The sample included RCTs of spine surgery interventions.

OUTCOME MEASURES

The Fragility Index is the minimum number of patients in a trial whose status would have to change from a nonevent to an event to change a statistically significant result to a nonsignificant result. Events refer to the occurrence of any dichotomous outcome, such as successful fusion, incident fracture, adjacent segment degeneration, or achievement of a certain functional score. A small Fragility Index indicates that the statistical significance of a result hinges on only a few events, and a large Fragility Index increases one's confidence in the observed treatment effects.

METHODS

We systematically reviewed a database for evidence-based orthopedics and identified all the RCTs that reported at least one positive outcome (ie, p<.05). Two reviewers independently assessed eligibility and extracted data. We used the Fisher exact test to compute Fragility Index values and multivariable linear regression to evaluate potential associated factors.

RESULTS

We identified 40 eligible RCTs with a median sample size of 132 patients (interquartile range [IQR] 79-208) and a median total number of outcome events for the chosen outcome of 31 (IQR 13-63). The median Fragility Index was two (IQR 1-3), which means that adding two events to one of the trial's treatment arms eliminated its statistical significance. The Fragility Index was less than or equal to three events in 75% of the trials, and was less than or equal to the number of patients lost to follow-up in 65% of the trials. Fragility Index values correlated positively with total sample size (r=0.35; p<.05). When adjusted for losses to follow-up and risk of bias, increasing Fragility Index values were associated only with increasingly significant reported p values (p<.01).

CONCLUSIONS

Statistically significant results in spine surgery RCTs are frequently fragile. The addition of only a small number of outcome events can completely eliminate significance. Surgeons, researchers, and other evidence users should exercise caution when interpreting the findings from RCTs with low Fragility Index values and applying these results to patient care.

The Discover artificial disc replacement versus fusion in cervical radiculopathy--a randomized controlled outcome trial with 2-year follow-up

BACKGROUND CONTEXT

Several previous studies comparing artificial disc replacement (ADR) and fusion have been conducted with cautiously positive results in favor of ADR. This study is not, in contrast to most previous studies, an investigational device exemption study required by the Food and Drug Administration for approval to market the product in the United States. This study was partially funded with unrestricted institutional research grants by the company marketing the artificial disc used in this study.

PURPOSE

To compare outcomes between the concepts of an artificial disc to treatment with anterior cervical decompression and fusion (ACDF) and to register complications associated to the two treatments during a follow-up time of 2 years.

STUDY DESIGN/SETTING

This is a randomized controlled multicenter trial, including three spine centers in Sweden.

PATIENT SAMPLE

The study included patients seeking care for cervical radiculopathy who fulfilled inclusion criteria. In total, 153 patients were included.

OUTCOME MEASURES

Self-assessment with Neck Disability Index (NDI) as a primary outcome variable and EQ-5D and visual analog scale as secondary outcome variables.

METHODS

Patients were randomly allocated to either treatment with the Depuy Discover artificial disc or fusion with iliac crest bone graft and plating. Randomization was blinded to both patient and caregivers until time for implantation. Adverse events, complications, and revision surgery were registered as well as loss of follow-up.

RESULTS

Data were available in 137 (91%) of the included and initially treated patients. Both groups improved significantly after surgery. NDI changed from 63.1 to 39.8 in an intention-to-treat analysis. No statistically significant difference between the ADR and the ACDF groups could be demonstrated with NDI values of 39.1 and 40.1, respectively. Nor in secondary outcome measures (EQ-5D and visual analog scale) could any statistically significant differences be demonstrated between the groups. Nine patients in the ADR group and three in the fusion group underwent secondary surgery because of various reasons. Two patients in each group underwent secondary surgery because of adjacent segment pathology. Complication rates were not statistically significant between groups.

CONCLUSIONS

Artificial disc replacement did not result in better outcome compared to fusion measured with NDI 2 years after surgery.

Additively manufactured porous tantalum implants

The medical device industry's interest in open porous, metallic biomaterials has increased in response to additive manufacturing techniques enabling the production of complex shapes that cannot be produced with conventional techniques. Tantalum is an important metal for medical devices because of its good biocompatibility. In this study selective laser melting technology was used for the first time to manufacture highly porous pure tantalum implants with fully interconnected open pores. The architecture of the porous structure in combination with the material properties of tantalum result in mechanical properties close to those of human bone and allow for bone ingrowth. The bone regeneration performance of the porous tantalum was evaluated in vivo using an orthotopic load-bearing bone defect model in the rat femur. After 12 weeks, substantial bone ingrowth, good quality of the regenerated bone and a strong, functional implant-bone interface connection were observed. Compared to identical porous Ti-6Al-4V structures, laser-melted tantalum shows excellent osteoconductive properties, has a higher normalized fatigue strength and allows for more plastic deformation due to its high ductility. It is therefore concluded that this is a first step towards a new generation of open porous tantalum implants manufactured using selective laser melting.

Mid-term results of computer-assisted cervical pedicle screw fixation

Study Design

A retrospective study.

Purpose

The present study aimed to evaluate mid-term results of cervical pedicle screw (CPS) fixation for cervical instability.

Overview of Literature

CPS fixation has widely used in the treatment of cervical spinal instability from various causes; however, there are few reports on mid-term surgical results of CPS fixation.

Methods

Record of 19 patients who underwent cervical and/or upper thoracic (C2-T1) pedicle screw fixation for cervical instability was reviewed. The mean observation period was 90.2 months. Evaluated items included Japanese Orthopaedic Association (JOA) score and C2-7 lordotic angle before surgery and at 5 years after surgery. Postoperative computerized tomography was used to determine the accuracy of screw placement. Visual analog scale (VAS) for neck pain and radiological evidence of adjacent segment degeneration (ASD) at the 5-year follow-up were also evaluated.

Results

Mean JOA score was significantly improved from 9.0 points before surgery to 12.8 at 5 years after surgery (p=0.001). The C2-7 lordotic angle of the neutral position improved from 6.4° to 7.8° at 5 years after surgery, but this was not significant. The major perforation rate was 5.0%. There were no clinically significant complications such as vertebral artery injury, spinal cord injury, or nerve root injury caused by any screw perforation. Mean VAS for neck pain was 49.4 at 5 years after surgery. The rate of ASD was 21.1%.

Conclusions

Our mid-term results showed that CPS fixation was useful for treating cervical instability. Severe complications were prevented with the assistance of a computed tomography-based navigation system.

Comparison between Two Different Cervical Interbody Fusion Cages in One Level Stand-alone ACDF: Carbon Fiber Composite Frame Cage Versus Polyetheretherketone Cage

Objective

The authors conducted a retrospective study to compare the implantation of carbon fiber composite frame cages (CFCFCs) to the implantation of polyetheretherketone (PEEK) cages after anterior cervical discectomy for cervical degenerative disc disease. In addition, the predictive factors that influenced fusion or subsidence were investigated.

Methods

A total of 58 patients with single-level degenerative disc disease were treated with anterior cervical discectomy and implantation of stand-alone cages; CFCFCs were used in 35 patients, and PEEK cages were used in 23 patients. Preoperative and postoperative radiological and clinical assessments were performed.

Results

During the mean follow-up period of 41 months, fusion occurred in 43 patients (74.1%), and subsidence developed in 18 patients (31.0%). Pain decreased in all patients, and the patients' satisfaction rate was 75.9%. Neither fusion nor subsidence was related to the clinical outcome. There were no significant differences in the clinical and radiological outcomes between the CFCFC and the PEEK cage groups. Smoking history (p=0.023) was significantly associated with pseudarthrosis, and cage height (≥7mm) (p=0.037) were significantly associated with subsidence.

Conclusion

The clinical and radiological results were similar between the CFCFC and the PEEK cage groups. Fusion or subsidence did not affect the clinical outcomes. Smoking history and cage height (≥7mm) were predictive factors for pseudarthrosis or subsidence in anterior cervical discectomy and fusion with stand-alone cages.

Dynamic radiographic criteria for detecting pseudarthrosis following anterior cervical arthrodesis

BACKGROUND

While interspinous motion analysis is commonly used to determine the status of an anterior cervical fusion, the accuracy of this technique is unclear. We believed that three questions needed to be answered. What degree of image magnification is ideal? How much motion should be considered "adequate" for making dynamic radiographs? What is the optimal amount of interspinous motion for detecting pseudarthrosis?

METHODS

We performed a retrospective study of 125 patients (109 fused segments and 153 pseudarthrotic segments) who had undergone reexploration with confirmation of fusion status. Interspinous motion at each operatively treated level and one superjacent level was measured by two independent investigators twice. Reliabilities of interspinous motion analysis at different magnification rates (25%, 100%, 150%, and 200%) were evaluated for fifty randomly selected segments to determine the optimal magnification, which we used for the remainder of the measurements. Fusion status was also determined on computed tomography (CT) by two other raters. We compared the intraoperative findings with those based on dynamic radiographs (with use of cutoff values of 1 and 2 mm of interspinous motion as the indication of pseudarthrosis) and CT.

RESULTS

On radiographs, both 150% and 200% magnification yielded higher interobserver and intraobserver reliabilities compared with 25% and 100% magnification, and the reliabilities at 150% and 200% were similar to each other, so subsequent measurements were made at 150%. The cutoff value of interspinous motion for detecting pseudarthrosis was 0.9 mm as determined with receiver operating characteristic curve analysis. Compared with CT, interspinous motion of ≥ 1 mm showed relatively low sensitivity (79.5%) and negative predictive value (77.1%) and similar specificity (97.0%) and positive predictive value (97.4%). Using interspinous motion of ≥ 2 mm as the cutoff decreased the sensitivity and negative predictive value to 46.6% and 56.8%, respectively. Our evaluation of what constituted adequate dynamic motion for making the radiographs showed that, with use of interspinous motion of ≥ 1 mm as the cutoff for detecting pseudarthrosis, superjacent interspinous motion of ≥ 4 mm increased the sensitivity and negative predictive value (86.3% and 83.4%) compared with those associated with alternative cutoffs of superjacent interspinous motion (≥ 3.5, ≥ 5, and ≥ 6 mm), and the specificity (96.1%) and positive predictive value (96.9%) were reasonable.

CONCLUSIONS

Use of interspinous motion of ≥ 1 mm as the cutoff for detection of anterior cervical pseudarthrosis on radiographs magnified 150% and made with superjacent interspinous motion of ≥ 4 mm yielded accuracies comparable with those of CT.

Posterior lumbar interbody fusion with stand-alone Trabecular Metal cages for repeatedly recurrent lumbar disc herniation and back pain

OBJECT

Patients with recurrent sciatica due to repeated reherniation of the intervertebral disc carry a poor prognosis for recovery and create a large burden on society. There is no consensus about the best treatment for this patient group. The goal of this study was to evaluate the 12-month results of the placement of stand-alone Trabecular Metal cages in these patients.

METHODS

The authors performed a retrospective analysis of 26 patients with recurrent disc herniations treated with stand-alone posterior lumbar interbody fusion (PLIF) with Trabecular Metal cages. At 1 year patients were evaluated using the Roland Morris Disability Questionnaire (RMDQ) and a visual analog scale (VAS) for back and leg pain. Furthermore, Likert scores of perceived recovery and satisfaction with the treatment were recorded. Lumbar spine radiographs after 1 year were compared with postoperative radiographs to measure subsidence. Stability of the operated segment was assessed using dynamic radiography.

RESULTS

The patient group consisted of 26 patients (62% male) with a mean age of 45.7 ± 11.4 years (± SD). Patients had a history of 1 (31%), 2 (42%), or more (27%) discectomies at the same level. The mean follow-up period was 15.3 ± 7.3 months. At follow-up the mean VAS score for pain in the affected leg was 36.7 ± 27.9. The mean VAS score for back pain was 42.5 ± 30.2. The mean RMDQ score at follow-up was 9.8 ± 6.2. Twelve (46%) of the 26 patients had a global perceived good recovery. With respect to treatment satisfaction, 18 patients (69%) were content or very content with the operation and would recommend it. Disc height was increased immediately postoperatively, and at the 1-year follow-up it was still significantly higher compared with the preoperative height (mean 41% ± 38.7%, range -25.7 to 126.8, paired t-test, both p < 0.001), although a mean of 7.52% ± 11.6% subsidence occurred (median 2.0% [interquartile range 0.0%-10.9%], p < 0.003). No significant correlation between subsidence and postoperative back pain was found (Spearman's rho -0.2, p = 0.459). Flexion-extension radiographs showed instability in 1 patient.

CONCLUSIONS

Although only 46% of patients reported a good recovery with significant reductions in back and leg pain, 85% of patients reported at least some benefit from the operation, and a marked improvement in working status at follow-up was noted. In view of previously published poor results of instrumented lumbar fusion for patients with failed back surgery syndrome, the present data indicate that Trabecular Metal interbody fusion cages can be used in a stand-alone fashion and should not always need supplemental posterior fixation in patients with recurrent disc herniation without spinal instability, although a long-term follow-up study is warranted.

Risk factors for subsidence in anterior cervical fusion with stand-alone polyetheretherketone (PEEK) cages: a review of 82 cases and 182 levels

INTRODUCTION

To determine risk factors for subsidence in patients treated with anterior cervical discectomy and fusion (ACDF) and stand-alone polyetheretherketone (PEEK) cages.

MATERIALS AND METHODS

Records of patients with degenerative spondylosis or traumatic disc herniation resulting in radiculopathy or myelopathy between C2 and C7 who underwent ACDF with stand-alone PEEK cages were retrospectively reviewed. Cages were filled with autogenous cancellous bone harvested from iliac crest or hydroxyapatite. Subsidence was defined as a decrease of 3 mm or more of anterior or posterior disc height from that measured on the postoperative radiograph. Eighty-two patients (32 males, 50 females; 182 treatment levels) were included in the analysis.

RESULTS

Most patients had 1-2 treatment levels (62.2 %), and 37.8 % had 3-4 treatment levels. Treatment levels were from C2-7. Of the 82 patients, cage subsidence occurred in 31 patients, and at 39 treatment levels. Multivariable analysis showed that subsidence was more likely to occur in patients with more than two treatment levels, and more likely to occur at treatment levels C5-7 than at levels C2-5. Subsidence was not associated with postoperative alignment change but associated with more disc height change (relatively oversized cage).

CONCLUSION

Subsidence is associated with a greater number of treatment levels, treatment at C5-7 and relatively oversized cage use.

Comparative analysis of 3 different construct systems for single-level anterior cervical discectomy and fusion: stand-alone cage, iliac graft plus plate augmentation, and cage plus plating

STUDY DESIGN

A retrospective cohort-nested longitudinal study.

OBJECTIVE

To evaluate radiologic and clinically functional outcomes after single-level anterior cervical discectomy and fusion (ACDF) using 3 different fusion construct systems applying an accurate and reliable methodology.

SUMMARY OF BACKGROUND DATA

ACDF is an established procedure that uses 3 different fusion construct systems: cage alone (CA), iliac tricortical bone block with plate (IP), and cage with plate construct (CP). The outcome of a previous study is quite different and did not correlate with experimental studies.

METHODS

ACDF was performed on 158 patients (90 male and 68 female), who were followed up for >12 months. The patients were divided into the following 3 treatment groups: CA, IP, and CP. Factors related to outcome were also evaluated. Fusion rate, subsidence rate, and cervical angles were used to measure radiologic outcome. The Odom criteria and the visual analog scale were used to evaluate the clinical outcome.

RESULTS

The fusion rate was higher for patients in the IP (87.1%) and CP (79.5%) groups than for those in the CA group (63.2%) after 12 months of follow-up (P=0.019). The subsidence rate was lower for patients in the IP (28.1%) and CP (38.5%) groups than for those in the CA group (58.6%) (P=0.010). Subsidence occurred for the anterior height regardless of constructs. Radiating arm pain showed greater relief in the CP group than in the CA group (P=0.015). It improved more in the CP group than in the IP group, but the differences were not statistically significant (P=0.388). Other clinical outcomes did not show significant differences.

CONCLUSIONS

The trend of excellent radiologic outcome was observed for IP≥CP>CA. Plating may play a key role in the support of anterior height. As a result, plating prevents segmental kyphosis and subsidence and promotes bone fusion. Although the overall clinical outcomes were not different among the 3 groups, except for arm pain, more favorable trends regarding clinical outcome were observed for CP≥IP>CA.

Properties of open-cell porous metals and alloys for orthopaedic applications

One shortcoming of metals and alloys used to fabricate various components of orthopaedic systems, such as the femoral stem of a total hip joint replacement and the tibial plate of a total knee joint replacement, is well-recognized. This is that the material modulus of elasticity (E') is substantially larger than that of the contiguous cancellous bone, a consequence of which is stress shielding which, in turn, has been postulated to be implicated in a cascade of events that culminates in the principal life-limiting phenomenon of these systems, namely, aseptic loosening. Thus, over the years, a host of research programs have focused on the synthesis of metallic biomaterials whose E' can be tailored to match that of cancellous bone. The present work is a review of the extant large volume of literature on these materials, which are called open-cell porous metals/alloys (or, sometimes, metal foams or cellular materials). As such, its range is wide, covering myriad aspects such as production methods, characterization studies, in vitro evaluations, and in vivo performance. The review also includes discussion of seven areas for future research, such as parametric studies of the influence of an assortment of process variables (such as the space holder material and the laser power in the space holder method and the laser-engineered net-shaping process, respectively) on various properties (notably, permeability, fatigue strength, and corrosion resistance) of a given porous metal/alloy, innovative methods of determining fatigue strength, and modeling of corrosion behavior.

Trabecular metal™ shoulder prosthesis in the treatment of complex proximal humeral fractures

PURPOSE

Shoulder arthroplasty is one of the options for the treatment of complex proximal humeral fractures. The purpose of this study was to assess the clinical and radiographic results of the trabecular metal shoulder prosthesis in the treatment of complex proximal humeral fractures.

METHODS

Fifty-one consecutive patients with complex proximal humeral fractures who underwent primary shoulder arthroplasties with the trabecular metal™ prosthesis were enrolled in this study. At the final follow-up appointment, 42 of the patients (82.4% of the total patients enrolled) were available for both clinical and radiographic evaluation. There were 28 women and 14 men with a mean age of 65.4 ± 10.7 years. The dominant arm was involved in 30 of the cases. According to Neer's classification, there were seven three-part fractures, 27 four-part fractures and eight head-splitting fractures. Additionally, there were 37 hemiarthroplasties and five total shoulder arthroplasties.

RESULTS

After a mean follow-up of 37.0 ± 8.4 months (range 24-52 months), the average ranges of motion were: 38.6 ± 15.0° for external rotation, L3 level for internal rotation and 132.3 ± 36.0° for forward elevation. The mean American Shoulder and Elbow Surgeons, visual analogue scale and University of California, Los Angeles scores were 82.1 ± 14.1, 0.4 ± 1.1 and 28.8 ± 5.1, respectively. The post-operative radiographs exhibited an anatomically attached greater tuberosity in 39 of the 42 shoulders. Of the three patients with greater tuberosity complications, as displayed by their radiographs, two were observed with malpositioned tuberosities, while the other greater tuberosity was resorbed. Proximal migration of the prosthesis was observed in all three shoulders with greater tuberosity complications and in two shoulders with an anatomically attached greater tuberosity. No neurovascular injury, infection or prosthetic loosening was identified during the final follow-up appointments.

CONCLUSIONS

Satisfactory results can be expected with the trabecular metal shoulder prosthesis for the treatment of complex proximal humeral fractures. The post-operative radiographs demonstrated an anatomically healed greater tuberosity in 93 % of the patients at a minimum follow-up time of two years.

Effect of various kinds of cervical spinal surgery on clinical outcomes: a systematic review and meta-analysis

The choice of a specific surgical technique should be based on its benefits and harms. Previous reviews have shown that the benefit of surgery over conservative care is not clearly demonstrated in patients with disorders of the cervical spine. Also, no additional benefit of fusion upon anterior decompression techniques could be found. A clear overview of other surgical techniques is lacking. We therefore aimed to assess the benefits and harms of cervical spinal surgery in patients with cervical disorders. We searched MEDLINE, EMBASE, CINAHL, and CENTRAL up to June 2012. Randomized controlled trials (RCTs) were selected which included adults with cervical disorders receiving a surgical intervention and that reported at least 1 clinically relevant outcome measure (eg, pain, function, recovery). Two authors independently assessed the risk of bias using the criteria recommended by the Cochrane Back Review Group and extracted the data. The quality of the evidence was rated using the GRADE method. We included 39 RCTs comparing different surgical interventions. We found low-quality evidence for no difference in effectiveness between various surgical techniques used for anterior discectomy. There is a small, clinically irrelevant benefit on recovery and pain in favour of prosthetic disc surgery when compared with fusion techniques. Unfortunately, in these studies the authors had a clear conflict of interest. The differences in benefits and harms between the various surgical techniques are small. The surgeon, patient, and health care provider can therefore make the choice of any surgical technique based on experience, preferences, or costs.

Comparison of 3 fusion techniques in the treatment of the degenerative cervical spine disease. Is stand-alone autograft really the "gold standard?": prospective study with 2-year follow-up

STUDY DESIGN

A prospective study.

OBJECTIVE

The aim of this study was to compare the 3 different methods of interbody fusion of the cervical spine-autograft in stand-alone technique, autograft with anterior plate, and polyetheretherketone cage supported by anterior plate. The clinical and radiological data obtained were analyzed and discussed.

SUMMARY OF BACKGROUND DATA

Although degenerative cervical spine disease has been treated by an anterior approach for more than 50 years, there is not one generally accepted operative approach. There is a very low-quality evidence of little or no difference in pain relief between each of the techniques. Iliac crest autograft still seems to be the "gold standard" for interbody fusion.

METHODS

Prospective study collecting clinical and radiological data of 81 patients undergoing anterior cervical interbody fusion, in which the interbody fusion of 1 or 2 motion segments from C3 to C7 was done by any of the 3 techniques--stand-alone insertion of autograft (group 1: 28 patients), autograft and anterior plate (group 2: 18 patients), and polyetheretherketone cage filled with beta-tricalcium phosphate and plate (group 3: 29 patients). Patients were followed for 2 years after surgery.

RESULTS

Significant interaction of relative height in the segment and time was found (P < 0.001). The values of the relative height of stand-alone autograft dropped below 95% of initial height and the values of the other 2 groups remained above 105%. Significant interaction of time and group was found for Cobb S angles (P < 0.001). Values of group 1 decreased substantially and remained significantly lower than values of other 2 groups. Fusion rate was 100% in all groups. Neck Disability Index group and time interaction was found (P = 0.023). During postoperative follow-up, group 1 scored in all controls higher than the other 2 groups, but differences were not significant. Visual analogue scale showed effect of time (P < 0.001). This was due to a smaller improvement of patients in group 1 during the whole follow-up in comparison with the other 2 groups. Highest proportion of unsatisfied patients was in group 1 compared with the other 2 groups after 2 years (P = 0.034).

CONCLUSION

Significantly worse radiological and clinical results after 2 years of follow-up were achieved using stand-alone autograft technique in comparison with autograft supported by anterior plating similarly as in comparison with cage implant and anterior plating. Using artificial fusion substrate together with plate and cage can offer the same clinical and radiological results such as iliac autograft and plating. Anterior plating seems to be an important factor influencing the postoperative cervical spine alignment and also the clinical outcome.

Pain from donor site after anterior cervical fusion with bone graft: a prospective randomized study with 12 months of follow-up

INTRODUCTION

Harvesting bone graft from the iliac crest in spinal fusion surgery is a widely used technique. However, complications can occur and there are also reports of patients with persistent graft site pain after surgery. The aim of this study was to evaluate pain from the donor site (DS) over time, and register associated complications and if it affected health-related quality of life (HRQoL).

MATERIAL AND METHODS

One hundred and seven patients participating in an RCT between two different methods of reconstruction after cervical decompression were included in this study. One group underwent surgery with bone graft (BG) from the iliac crest and the other with no bone graft (NBG). All patients were evaluated concerning pain at DS and HRQoL preoperatively, at 4 weeks, 3 months and 1 year. Pain was evaluated with visual analog scale (VAS) and HRQoL with EQ-5D.

RESULTS

A statistically significant difference was found at all times of follow-up in the BG group compared to preoperative levels and the NBG group. The VAS levels at follow-ups at 3 months and 1 year were however of questionable clinical importance. Two patients in the BG group had superficial wound infections postoperatively and five patients still had sensory disturbance in the area of graft site at 12 months. No major complications were registered. No difference could be seen in EQ-5D at any time of follow-up between the groups.

CONCLUSION

Harvesting of iliac crest bone graft is associated with significant pain. However, at 3 months postoperatively, the negative effect of clinical importance seemed to have disappeared compared to when no bone graft was harvested. The pain from bone graft harvesting does not seem to affect the quality of life at 4 weeks postoperatively and onward.