Category: Spine

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Comparison of Outcomes Following Anterior vs Posterior Fusion Surgery for Patients With Degenerative Cervical Myelopathy

Neurosurgery, 84 (4) 919–926. 2019

The choice of anterior vs posterior approach for degenerative cervical myelopathy that spans multiple segments remains controversial.

OBJECTIVE: To compare the outcomes following the 2 approaches using multicenter prospectively collected data.

METHODS: Quality Outcomes Database (QOD) for patients undergoing surgery for 3 to 5 level degenerative cervicalmyelopathywas analyzed. The anterior group (anterior cervical discectomy [ACDF] or corpectomy [ACCF] with fusion) was compared with posterior cervical fusion. Outcomes included: patient reported outcomes (PROs): neck disability index (NDI), numeric rating scale (NRS) of neck pain and arm pain, EQ-5D, modified Japanese Orthopedic Association score for myelopathy (mJOA), and NASS satisfaction questionnaire; hospital length of stay (LOS), 90-d readmission, and return to work (RTW). Multivariable regression models were fitted for outcomes.

RESULTS: Of total 245 patients analyzed, 163 patients underwent anterior surgery (ACDF- 116, ACCF-47) and 82 underwent posterior surgery. Patients undergoing an anterior approach had lower odds of having higher LOS (P < .001, odds ratio 0.16, 95% confidence interval 0.08-0.30). The 12-moNDI, EQ-5D,NRS,mJOA, and satisfaction scores aswell as 90-d readmission and RTW did not differ significantly between anterior and posterior groups.

CONCLUSION: Patients undergoing anterior approaches for 3 to 5 level degenerative cervical myelopathy had shorter hospital LOS compared to those undergoing posterior decompression and fusion. Also, patients in both groups exhibited similar long-term PROs, readmission, and RTW rates. Further investigations are needed to compare the differences in longer term reoperation rates and functional outcomes before the clinical superiority of one approach over the other can be established.

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Comparing the diagnostic accuracies of F-18 FDG PET and MRI for the detection of spondylodiscitis: A meta-analysis

Spine. 44(7):E414-E422, April 1, 2019

The aim of this study was to compare the diagnostic accuracies of F-18 fluorodeoxyglucose (F-18 FDG) positron emission tomography (PET) and magnetic resonance imaging (MRI) for the detection of spondylodiscitis through a meta-analysis.

Summary of Background Data. There is no meta-analysis study that compares the diagnostic accuracies of F-18 FDG PET and MRI for the detection of spondylodiscitis.

Methods. The MEDLINE and EMBASE databases were searched from the earliest available date of indexing to January 10, 2018 for studies comparing the diagnostic performance F-18 FDG PET with that of MRI for the detection of spondylodiscitis. We determined the sensitivities and specificities across studies, calculated the positive and negative likelihood ratios (LR+ and LR-), and constructed the summary receiver operating characteristic curves.

Results. In the seven studies (212 patients) selected, the pooled sensitivity and specificity of F- 18 FDG PET were 0.95 (95% confidence interval [CI]: 0.87-0.98) and 0.88 (95% CI: 0.73-0.95), respectively. The LR syntheses showed an overall LR+ of 7.6 (95% CI: 3.4-17.2) and LR- of 0.05 (95% CI: 0.02-0.14). The pooled diagnostic odds ratio (DOR) was 141 (95% CI: 44-444). The pooled sensitivity and specificity of MRI were 0.85 (95% CI: 0.65-0.95) and 0.66 (95% CI: 0.48-0.80), respectively. The LR syntheses showed an overall LR+ of 2.5 (95% CI: 1.5-4.2) and LR- of 0.22 (95% CI: 0.08-0.60). The pooled DOR was 11 (95% CI: 3-42). In the metaregression analysis, no variable was identified as the source of the study heterogeneity.

Conclusions. The current meta-analysis shows that F-18 FDG PET has better diagnostic accuracy than MRI for the detection of spondylodiscitis. Further large multicenter studies would be necessary to substantiate the diagnostic accuracies of F-18 FDG PET and MRI for spondylodiscitis.

Level of Evidence: 2

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Correlation of magnetic resonance diffusion tensor imaging parameters with American Spinal Injury Association score for prognostication and long-term outcomes

Neurosurg Focus 46 (3):E2, 2019

Conventional MRI is routinely used to demonstrate the anatomical site of spinal cord injury (SCI). However, quantitative and qualitative imaging parameters have limited use in predicting neurological outcomes. Currently, there are no reliable neuroimaging biomarkers to predict short- and long-term outcome after SCI.

METHODS A prospective cohort of 23 patients with SCI (19 with cervical SCI [CSCI] and 4 with thoracic SCI [TSCI]) treated between 2007 and 2014 was included in the study. The American Spinal Injury Association (ASIA) score was determined at the time of arrival and at 1-year follow-up. Only 15 patients (12 with CSCI and 3 with TSCI) had 1-year follow-up. Whole-cord fractional anisotropy (FA) was determined at C1–2, following which C1–2 was divided into upper, middle, and lower segments and the corresponding FA value at each of these segments was calculated. Correlation analysis was performed between FA and ASIA score at time of arrival and 1-year follow-up.

RESULTS Correlation analysis showed a positive but nonsignificant correlation (p = 0.095) between FA and ASIA score for all patients (CSCI and TCSI) at the time of arrival. Additional regression analysis consisting of only patients with CSCI showed a significant correlation (p = 0.008) between FA and ASIA score at time of arrival as well as at 1-year follow-up (p = 0.025). Furthermore, in case of patients with CSCI, a significant correlation between FA value at each of the segments (upper, middle, and lower) of C1–2 and ASIA score at time of arrival was found (p = 0.017, p = 0.015, and p = 0.002, respectively).

CONCLUSIONS In patients with CSCI, the measurement of diffusion anisotropy of the high cervical cord (C1–2) correlates significantly with injury severity and long-term follow-up. However, this correlation is not seen in patients with TSCI. Therefore, FA can be used as an imaging biomarker for evaluating neural injury and monitoring recovery in patients with CSCI.

 

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Nanotechnology in Spine Surgery: A Current Update and Critical Review of the Literature

World Neurosurg. (2019) 123:142-155

Nanotechnology is a promising field with numerous applications across various branches of medicine. The unique innate physical, chemical, and biological properties of nanoparticles enable them to serve as appropriate agents performing diverse functions at cellular and subcellular levels. Spinal pathologies constitute one major field where its applications are being explored.

METHODS: A critical review of literature was performed to identify the cur- rent role of nanotechnology in spine surgery. A PubMed search was done using the following key words: “nanotechnology in neurosurgery,” “nanotechnology in surgery,” “nanotechnology in spine,” “nanotechnology in spine surgery,” “nanotechnology in disc regeneration,” “nanotechnology in spinal injury,” “nanotechnology in spinal cord regeneration,” “nanotechnology in spine fusion,” “nanotechnology in osteoporosis,” “nanotechnology in spinal drug delivery,” and “nanotechnology in spinal infection.” Initial search revealed 347 articles. Articles were further screened. Duplicate articles, articles on non- nanotechnologic topics, nonspine articles, or articles with details not pertaining to the current field of interest and non-English language studies were excluded.

RESULTS: A total of 76 articles were finally included. Nanotechnologic ad- vancements in spine surgery include applications in spinal fusion, central nervous system drug delivery, neuronal regeneration, disk regeneration, spinal infection prophylaxis, management of osteoporosis, sutureless vascular anas- tomosis, molecular imaging, and theranostic medicine.

CONCLUSIONS: Nanotechnology in spine surgery is still in its early stages. Eventually, we may see the implementation of nanotechnology as an alternative to existing treatment options. Concerns regarding safety of this technology need to be addressed through future research projects. Although promising, the exact role of nanotechnology in spine surgery remains to be seen.

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Surgical management of spinal meningiomas

J Neurosurg Spine 30:308–313, 2019

Spinal meningiomas (sMNGs) are relatively rare in comparison to intracranial MNGs. sMNGs localized anterior to the denticulate ligament (aMNGs) represent a surgically challenging subgroup. A high perioperative complication rate due to the need for complex surgical approaches has been described. In the present study, the authors report on their surgical experience that involves two institutions in which 207 patients underwent surgery for sMNGs. Special focus was placed on patients with aMNGs that were treated via a unilateral posterior approach (ULPA).

METHODS Between 2005 and 2017, 207 patients underwent resection of sMNGs at one of two institutions. The following characteristics were assessed: tumor size and localization, surgical approach, duration of surgery, grade of resection, peri- and postoperative complication rates, and neurological outcome. Data were compared between the subgroups of patients according to the lesion’s relationship to the denticulate ligament and to surgical approach.

RESULTS The authors identified 48 patients with aMNGs, 86 patients with lateral MNGs, and 76 patients with posterior MNGs (pMNGs). Overall, 66.6% of aMNGs and 64% of pMNGs were reached via a ULPA. aMNGs that were approached via a ULPA showed reduced duration of surgery (131 vs 224 minutes, p < 0.0001) and had surgical complication rates and neurological outcomes comparable to those of lesions that were approached via a bilateral approach. No significant differences in complication rate, outcomes, and extent of resection were seen between aMNGs and pMNGs.

CONCLUSIONS The duration of surgery, extent of resection, and outcomes are comparable between aMNGs and pMNGs when removed via a ULPA. Thus, ULPA represents a safe route to achieve a gross-total resection, even in cases of aMNG.

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The role of diffusion tensor imaging in the diagnosis, prognosis, and assessment of recovery and treatment of spinal cord injury: a systematic review

Neurosurg Focus 46 (3):E7, 2019

Diffusion tensor imaging (DTI) is an MRI tool that provides an objective, noninvasive, in vivo assessment of spinal cord injury (SCI). DTI is significantly better at visualizing microstructures than standard MRI sequences. In this imaging modality, the direction and amplitude of the diffusion of water molecules inside tissues is measured, and this diffusion can be measured using a variety of parameters. As a result, the potential clinical application of DTI has been studied in several spinal cord pathologies, including SCI. The aim of this study was to describe the current state of the potential clinical utility of DTI in patients with SCI and the challenges to its use as a tool in clinical practice.

METHODS A search in the PubMed database was conducted for articles relating to the use of DTI in SCI. The citations of relevant articles were also searched for additional articles.

RESULTS Among the most common DTI metrics are fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity. Changes in these metrics reflect changes in tissue integrity. Several DTI metrics and combinations thereof have demonstrated significant correlations with clinical function both in model species and in humans. Its applications encompass the full spectrum of the clinical assessment of SCI including diagnosis, prognosis, recovery, and efficacy of treatments in both the spinal cord and potentially the brain.

CONCLUSIONS DTI and its metrics have great potential to become a powerful clinical tool in SCI. However, the current limitations of DTI preclude its use beyond research and into clinical practice. Further studies are needed to significantly improve and resolve these limitations as well as to determine reliable time-specific changes in multiple DTI metrics for this tool to be used accurately and reliably in the clinical setting.

 

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The Patient-Reported Outcomes Measurement Information System in spine surgery: a systematic review

J Neurosurg Spine 30:405–413, 2019

The Patient-Reported Outcomes Measurement Information System (PROMIS) was developed to provide a standardized measure of clinical outcomes that is valid and reliable across a variety of patient populations. PROMIS has exhibited strong correlations with many legacy patient-reported outcome (PRO) measures. However, it is unclear to what extent PROMIS has been used within the spine literature. In this context, the purpose of this systematic review was to provide a comprehensive overview of the PROMIS literature for spine-specific populations that can be used to inform clinicians and guide future work. Specifically, the authors aimed to 1) evaluate publication trends of PROMIS in the spine literature, 2) assess how studies have used PROMIS, and 3) determine the correlations of PROMIS domains with legacy PROs as reported for spine populations.

METHODS Studies reporting PROMIS scores among spine populations were identified from PubMed/MEDLINE and a review of reference lists from obtained studies. Articles were excluded if they did not report original results, or if the study population was not evaluated or treated for spine-related complaints. Characteristics of each study and journal in which it was published were recorded. Correlation of PROMIS to legacy PROs was reported with 0.1 ≤ |r| < 0.3, 0.3 ≤ |r| < 0.5, and |r| ≥ 0.5 indicating weak, moderate, and strong correlations, respectively.

RESULTS Twenty-one articles were included in this analysis. Twelve studies assessed the validity of PROMIS whereas 9 used PROMIS as an outcome measure. The first study discussing PROMIS in patients with spine disorders was published in 2012, whereas the majority were published in 2017. The most common PROMIS domain used was Pain Interference. Assessments of PROMIS validity were most frequently performed with the Neck Disability Index. PROMIS domains demonstrated moderate to strong correlations with the legacy PROs that were evaluated. Studies assessing the validity of PROMIS exhibited substantial variability in PROMIS domains and legacy PROs used for comparisons.

CONCLUSIONS There has been a recent increase in the use of PROMIS within the spine literature. However, only a minority of studies have incorporated PROMIS for its intended use as an outcomes measure. Overall, PROMIS has exhibited moderate to strong correlations with a majority of legacy PROs used in the spine literature. These results suggest that PROMIS can be effective in the assessment and tracking of PROs among spine populations.

 

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Artificial disc replacement versus fusion in patients with cervical degenerative disc disease and radiculopathy: a randomized controlled trial with 5-year outcomes

J Neurosurg Spine 30:323–331, 2019

The method of artificial disc replacement (ADR) has been developed as an alternative treatment to fusion surgery after decompression for cervical degenerative disc disease (DDD) with radiculopathy. Preserving the motion of ADR devices aims to prevent immobilization side effects such as adjacent-segment pathology (ASP). However, longterm follow-up evaluations using MRI are needed to investigate if this intent is achieved.

METHODS The authors performed a randomized controlled trial with 153 patients (mean age 47 years) undergoing surgery for cervical radiculopathy. Eighty-three patients received an ADR and 70 patients underwent fusion surgery. Outcomes after 5 years were assessed using patient-reported outcome measures using the Neck Disability Index (NDI) score as the primary outcome; motion preservation and heterotopic ossification by radiography; ASP by MRI; and secondary surgical procedures.

RESULTS Scores on the NDI were approximately halved in both groups: the mean score after 5 years was 36 (95% confidence interval [CI] 31–41) in the ADR group and 32 (95% CI 27–38) in the fusion group (p = 0.48). There were no other significant differences between the groups in six other patient-related outcome measures. Fifty-four percent of the patients in the ADR group preserved motion at the operated cervical level and 25% of the ADRs were spontaneously fused. Seventeen ADR patients (21%) and 7 fusion patients (10%) underwent secondary surgery (p = 0.11), with 5 patients in each group due to clinical ASP.

CONCLUSIONS In patients with cervical DDD and radiculopathy decompression as well as ADR, surgery did not result in better clinical or radiological outcomes after 5 years compared with decompression and fusion surgery.

Clinical trial registration no.: 44347115 (ISRCTN).

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Anterior Reduction and Fusion of Cervical Facet Dislocations

Neurosurgery 84:388–395, 2019

Cervical facet dislocations are among the most common traumatic spinal injuries. Posterior, anterior, and combined surgical approaches have been described and are widely debated.

OBJECTIVE: To demonstrate efficacy in anterior-only surgical management for subaxial cervical facet dislocations.

METHODS: A consistent surgical algorithm for cervical facet dislocation was applied over a 19-yr period and analyzed retrospectively in adults with acute unilateral or bilateral facet dislocation of the subaxial cervical spine. The primary endpoint was maintenance of early cervical alignment. The need for additional posterior instrumented fusion was determined.

RESULTS: A database search identified 96 patients (mean age = 37.9, range = 14-74 yr, 68 (70%) male. The most common affected levels were C4-C5 (30), C5-C6 (29), and C6-C7 (30). Bilateral dislocation occurred in 51 patients (53%). Seventy-eight (81%) patients had neurological deficits, 31 (32%) being complete (Abbreviated Injury Score A) spinal cord injuries. Preoperative closed reductionwas attempted in 60 (63%) patients, with 33 (55%) achieving satisfactory alignment. After anterior cervical discectomy, reduction, allograft placement, and instrumentation, a total of 92 (96%) patients had achieved satisfactory realignment. Median time to surgery was 13.27 h. Eight (8%) patients required posterior fixation due to intraoperative determination of incomplete realignment (4; 4%) and development of early progressive deformity (4; 4%). Mean follow-up was 4.5 mo (range 0.5-24 mo) with 33 (34%) patients lost to follow-up.

CONCLUSION: Anterior approaches are viable for reduction and stabilization of cervical facet dislocations. Further prospective studies are required to evaluate clinical and longterm success.

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Robot-assisted intravertebral augmentation corrects local kyphosis more effectively than a conventional fluoroscopy-guided technique

J Neurosurg Spine 30:289–295, 2019

Intravertebral augmentation (IVA) is a reliable minimally invasive technique for treating Magerl type A vertebral body fractures. However, poor correction of kyphotic angulation, the risk of cement leakage, and significant exposure to radiation (for the surgeon, the operating room staff, and the patient) remain significant issues. The authors conducted a study to assess the value of robot-assisted IVA (RA-IVA) for thoracolumbar vertebral body fractures.

METHODS The authors performed a retrospective, single-center study of patients who had undergone RA-IVA or conventional fluoroscopy-guided IVA (F-IVA) for thoracolumbar vertebral body fractures. Installation and operating times, guidance accuracy, residual local kyphosis, degree of restoration of vertebral body height, incidence of cement leakage, rate of morbidity, length of hospital stay, and radiation-related data were recorded.

RESULTS Data obtained in 30 patients who underwent RA-IVA were compared with those obtained in 30 patients who underwent F-IVA during the same period (the surgical indications were identical, but the surgeons were different). The mean ± SD installation time in the RA-IVA group (24 ± 7.5 minutes) was significantly shorter (p = 0.005) than that in the F-IVA group (26 ± 8 minutes). The mean operating time for the RA-IVA group (52 ± 11 minutes) was significantly longer (p = 0.026) than that for the F-IVA group (30 ± 11 minutes). All RA-IVAs and F-IVAs were Ravi’s scale grade A (no pedicle breach). The mean degree of residual local kyphosis (4.7° ± 3.15°) and the percentage of vertebral body height restoration (63.6% ± 21.4%) were significantly better after RA-IVA than after F-IVA (8.4° ± 5.4° and 30% ± 34%, respectively). The incidence of cement leakage was significantly lower in the RA-IVA group (p < 0.05). The mean length of hospital stay after surgery was 3.2 days for both groups. No surgery-related complications occurred in either group. With RA-IVA, the mean radiation exposure was 438 ± 147 mGy × cm for the patient and 30 ± 17 mGy for the surgeon.

CONCLUSIONS RA-IVA provided better vertebral body fracture correction than the conventional F-IVA. However, RAIVA requires more time than F-IVA.

 

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Effects of smoking on cervical disc arthroplasty

J Neurosurg Spine 30:168–174, 2019

Cigarette smoking can adversely affect bone fusion in patients who undergo anterior cervical discectomy and fusion. However, there is a paucity of data on smoking among patients who have undergone cervical disc arthroplasty (CDA). The present study aimed to compare the clinical and radiological outcomes of smokers to those of nonsmokers following CDA.

METHODS The authors retrospectively reviewed the records of consecutive patients who had undergone 1- or 2-level CDA for cervical disc herniation or spondylosis and had a minimum 2-year follow-up. All patients were grouped into a smoking group, which consisted of those who had consumed cigarettes within 6 months prior to the CDA surgery, or a nonsmoking group, which consisted of those who had not consumed cigarettes at all or within 6 months of the CDA. Clinical outcomes were evaluated according to the visual analog scale for neck and arm pain, Neck Disability Index, Japanese Orthopaedic Association Scale, and Nurick Scale at each time point of evaluation. Radiological outcomes were assessed using radiographs and CT for multiple parameters, including segmental range of motion (ROM), neutral lordotic curve, and presence of heterotopic ossification (HO).

RESULTS A total of 109 patients completed at least 2 years of follow-up and were analyzed (mean follow-up 42.3 months). There were 89 patients in the nonsmoking group and 20 in the smoking group. The latter group was younger and predominantly male (both p < 0.05) compared to the nonsmoking group. The two groups had similar improvements in all clinical outcomes after CDA compared to preoperatively. Radiological evaluations were also very similar between the two groups, except for two factors. The smoking group had well-preserved segmental ROM after CDA at an average of 8.1° (both pre- and postoperation). However, while the nonsmoking group remained mobile, segmental ROM decreased significantly (8.2° to 6.9°, p < 0.05) after CDA. There was a trend toward more HO development in the nonsmoking group than in the smoking group, but the difference was without significance (59.6% vs 50.0%, p = 0.43).

CONCLUSIONS During an average 3.5 years of follow-up after 1- and 2-level CDA, cigarette smokers and nonsmokers had similar improvements in clinical outcomes. Moreover, segmental mobility was slightly better preserved in smokers. Since smoking status did not negatively impact outcomes, CDA may be a reasonable option for selected patients who have smoked.

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Association between payer status and patient-reported outcomes in adult patients with lumbar spinal stenosis treated with decompression surgery

J Neurosurg Spine 30:198–210, 2019

Insurance disparities can have relevant effects on outcomes after elective lumbar spinal surgery. The aim of this study was to evaluate the association between private/public payer status and patient-reported outcomes in adult patients who underwent decompression surgery for lumbar spinal stenosis.

METHODS A sample of 100 patients who underwent surgery for lumbar spinal stenosis from 2012 to 2014 was evaluated as part of the prospectively collected Quality Outcomes Database at a single institution. Outcome measures were evaluated at 3 months and 12 months, analyzed in regard to payer status (private insurance vs Medicare/Veterans Affairs insurance), and adjusted for potential confounders.

RESULTS At baseline, patients had similar visual analog scale back and leg pain, Oswestry Disability Index, and EQ- 5D scores. At 3 months postintervention, patients with government-funded insurance reported significantly worse quality of life (mean difference 0.11, p < 0.001) and more leg pain (mean difference 1.26, p = 0.05). At 12 months, patients with government-funded insurance reported significantly worse quality of life (mean difference 0.14, p < 0.001). There were no significant differences at 3 months or 12 months between groups for back pain (p = 0.14 and 0.43) or disability (p = 0.19 and 0.15). Across time points, patients in both groups showed improvement at 3 months and 12 months in all 4 functional outcomes compared with baseline (p < 0.001).

CONCLUSIONS Both private and public insurance patients had significant improvement after elective lumbar spinal surgery. Patients with public insurance had slightly less improvement in quality of life after surgery than those with private insurance but still benefited greatly from surgical intervention, particularly with respect to functional status.

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The impact of adding posterior instrumentation to transpsoas lateral fusion

J Neurosurg Spine 30:211–221, 2019

Transpsoas lateral interbody fusion is one of the lateral minimally invasive approaches for lumbar spine surgery. Most surgeons insert the interbody cage laterally and then insert pedicle or cortical screw and rod instrumentation posteriorly. However, standalone cages have also been used to avoid posterior instrumentation. To the best of the authors’ knowledge, the literature on comparison of the two approaches is sparse.

METHODS The authors performed a systematic review and meta-analysis of the available literature on transpsoas lateral interbody fusion by an electronic search of the PubMed, EMBASE, and Scopus databases using PRISMA guidelines. They compared patients undergoing transpsoas standalone fusion (TP) with those undergoing transpsoas fusion with posterior instrumentation (TPP).

RESULTS A total of 28 studies with 1462 patients were included. Three hundred and seventy-four patients underwent TPP, and 956 patients underwent TP. The mean patient age ranged from 45.7 to 68 years in the TP group, and 50 to 67.7 years in the TPP group. The incidence of reoperation was found to be higher for TP (0.08, 95% confidence interval [CI] 0.04–0.11) compared to TPP (0.03, 95% CI 0.01–0.06; p = 0.057). Similarly, the incidence of cage movement was found to be greater in TP (0.18, 95% CI 0.10–0.26) compared to TPP (0.03, 95% CI 0.00–0.05; p < 0.001). Oswestry Disability Index (ODI) and visual analog scale (VAS) scores and postoperative transient deficits were found to be comparable between the two groups.

CONCLUSIONS These results appear to suggest that addition of posterior instrumentation to transpsoas fusion is associated with decreased reoperations and cage movements. The results of previous systematic reviews and meta-analyses should be reevaluated in light of these results, which seem to suggest that higher reoperation and subsidence rates may be due to the use of the standalone technique.

 

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Artificial disc replacement versus fusion in patients with cervical degenerative disc disease with radiculopathy: 5-year outcomes from the National Swedish Spine Register

J Neurosurg Spine 30:159–167, 2019

The long-term efficacy of artificial disc replacement (ADR) surgery compared with fusion after decompression for the treatment of cervical degenerative disc disease and radiculopathy has not previously been investigated in a population-based setting.

METHODS All patients with cervical degenerative disc disease and radiculopathy who were in the national Swedish Spine Registry (Swespine) beginning in January 1, 2006, were eligible for the study. Follow-up information was obtained up to November 15, 2017. The authors compared, using propensity score matching, patients treated with anterior decompression and insertion of an ADR with patients who underwent anterior decompression combined with fusion surgery.
The primary outcome was the Neck Disability Index (NDI), a patient-reported function score ranging from 0% to 100%, with higher scores indicating greater disability and a minimum clinically important difference of > 15%.

RESULTS A total of 3998 patients (2018:1980 women/men) met the inclusion criteria, of whom 204 had undergone arthroplasty and 3794 had undergone fusion. After propensity score matching, 185 patients with a mean age of 49.7 years remained in each group. Scores on the NDI were approximately halved in both groups after 5 years, but without a significant mean difference in NDI (3.0%; 95% CI -8.4 to 2.4; p = 0.28) between the groups. There were no differences between the groups in EuroQol–5 Dimensions or in pain scores for the neck and arm.

CONCLUSIONS In patients with cervical degenerative disc disease and radiculopathy, decompression plus ADR surgery did not result in a clinically important difference in outcomes after 5 years, compared with decompression and fusion surgery.

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Symptomatic Adjacent Level Disease Requiring Surgery: Analysis of 10-Year Results From a Prospective, Randomized, Clinical Trial Comparing Cervical Disc Arthroplasty to Anterior Cervical Fusion

Neurosurgery 84:347–354, 2019

Ten-year follow-up data from the US Food and Drug Administration investigational device exemption trial comparing BRYAN  Cervical Disc (Medtronic, Dublin, Ireland) arthroplasty to anterior cervical discectomy and fusion (ACDF) demonstrated that disc arthroplasty maintained range of motion and improvements in overall success and neck disability.

OBJECTIVE: To compare the 10-yr rates of symptomatic adjacent level disease requiring surgery (SALDRS).

METHODS: Prospective randomized trial data were analyzed comparing BRYANR  Cervical Disc arthroplasty to ACDF for single-level cervical disc disease with concordant radiculopathy or myelopathy with clinicoradiographic analysis at 10 yr. Secondarily, 84-mo data were pooled with PRESTIGE   Cervical Disc arthroplasty (Medtronic) study data to provide overall rates of SALDRS.

RESULTS: Significantly greater overall success was maintained at every postoperative interval with an overall success rate of 81.3% with BRYAN  disc and 66.3% with ACDF (P = .005) without loss of motion preservation (8.69◦ vs 0.60◦). Reoperation at adjacent levels up to the 120-mo visit was 9.7% in the arthroplasty group and 15.8% in the ACDF group (P = .146). The combined data from BRYAN and Prestige ST demonstrate that BRYAN  and Prestige disc groups had a lower rate of second surgeries at the adjacent levels, up to the 84-mo visit, compared to the combined ACDF groups (6.9% vs 11.7%; P = .023).

CONCLUSION: Compared with ACDF, fewer patients with the BRYAN  disc required surgery for symptomatic adjacent level degeneration, but this did not achieve statistical significance. Analysis of combined study data using Bryan and Prestige discs shows significant differences in SADLRS as early as 7 yr.

 

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Functional Balance Testing in Cervical Spondylotic Myelopathy Patients

Spine 2019;44:103–109

Study Design. A prospective cohort study.

Objective. The aim of this study was to quantify the amount of sway associated with maintaining a balanced posture in a group of untreated cervical spondylotic myelopathy (CSM) patients.

Summary of Background Data. Balance is defined as the ability of the human body to maintain its center of mass (COM) within the base of support with minimal postural sway. Sway is the movement of the COM in the horizontal plane when a person is standing in a static position. CSM patients have impaired body balance and proprioceptive loss.

Methods. Thirty-two CSM patients performed a series of functional balance tests a week before surgery. Sixteen healthy controls (HCs) performed a similar balance test. Patients are instructed to stand erect with feet together and eyes opened in their self-perceived balanced and natural position for a full minute. All test subjects were fitted to a full-body reflective markers set and surface electromyography (EMG).

Results. CSM patients had more COM sway in the anteriorposterior (CSM: 2.87cm vs. C: 0.74 cm; P¼0.023), right-left (CSM: 5.16cm vs. C: 2.51 cm; P¼0.003) directions as well as head sway (anterior-posterior – CSM: 2.17cm vs. C: 0.82 cm; P ¼0.010 and right-left – CSM: 3.66 cm vs. C: 1.69cm; P¼0.044), more COM (CSM: 44.72 cm vs. HC: 19.26 cm, p¼0.001), and head (Pre: 37.87cm vs. C: 19.93 cm, P¼0.001) total sway in comparison to controls. CSM patients utilized significantly more muscle activity to maintain static standing, evidenced by the increased trunk and lower extremity muscle activity (multifidus, erector spinae, rectus femoris, and tibialis anterior, P<0.050) during 1-minute standing.

Conclusion. In symptomatic CSM patients, COM and head total sway were significantly greater than controls. Individuals with CSM exhibit more trunk and lower extremity muscle activity, and thus expend more neuromuscular energy to maintain a balanced, static standing posture. This study is the first effort to evaluate global balance as a dynamic process in this patient population.

Level of Evidence: 3

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Fivefold higher rate of pseudarthrosis with polyetheretherketone interbody device than with structural allograft used for 1-level anterior cervical discectomy and fusion

J Neurosurg Spine 30:46–51, 2019

Common interbody graft options for anterior cervical discectomy and fusion (ACDF) include structural allograft and polyetheretherketone (PEEK). PEEK has gained popularity due to its radiolucency and its elastic modulus, which is similar to that of bone. The authors sought to compare the rates of pseudarthrosis, a lack of solid bone growth across the disc space, and the need for revision surgery with the use of grafts made of allogenic bone versus PEEK.

METHODS The authors retrospectively reviewed 127 cases in which patients had undergone a 1-level ACDF followed by at least 1 year of radiographic follow-up. Data on age, sex, body mass index, tobacco use, pseudarthrosis, and the reoperation rate for pseudarthrosis were collected. These data were analyzed by performing a Pearson’s chi-square test.

RESULTS Of 127 patients, 56 had received PEEK implants and 71 had received allografts. Forty-six of the PEEK implants (82%) were stand-alone devices. There were no significant differences between the 2 treatment groups with respect to patient age, sex, or body mass index. Twenty-nine (52%) of 56 patients with PEEK implants demonstrated radiographic evidence of pseudarthrosis, compared to 7 (10%) of 71 patients with structural allografts (p < 0.001, OR 9.82; 95% CI 3.836–25.139). Seven patients with PEEK implants required reoperation for pseudarthrosis, compared to 1 patient with an allograft (p = 0.01, OR 10.00; 95% CI 1.192–83.884). There was no significant difference in tobacco use between the PEEK and allograft groups (p = 0.586).

CONCLUSIONS The results of this study demonstrate that the use of PEEK devices in 1-level ACDF is associated with a significantly higher rate of radiographically demonstrated pseudarthrosis and need for revision surgery compared with the use of allografts. Surgeons should be aware of this when deciding on interbody graft options, and reimbursement policies should reflect these discrepancies.

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Potential of Human Nucleus Pulposus-Like Cells Derived From Umbilical Cord to Treat Degenerative Disc Disease

Neurosurgery 84:272–283, 2019

Degenerative disc disease (DDD) is a common spinal disorder that manifests with neck and lower back pain caused by the degeneration of intervertebral discs (IVDs). Currently, there is no treatment to cure this debilitating ailment.

OBJECTIVE: To investigate the potential of nucleus pulposus (NP)-like cells (NPCs) derived from human umbilical cord mesenchymal stem cells (MSCs) to restore degenerated IVDs using a rabbit DDD model.

METHODS: NPCs differentiated from MSC swere characterized using quantitative real-time reverse transcription polymerase chain reaction and immunocytochemical analysis. MSCs and NPCs were labeled with fluorescent dye, PKH26, and transplanted into degenerated IVDs of a rabbit model of DDD (n = 9 each). Magnetic resonance imaging of the IVDs was performed before and after IVD degeneration, and following cell transplantation. IVDs were extracted 8 wk post-transplantation and analyzed by various biochemical, immunohistological, and molecular techniques.

RESULTS: NPC derivatives of MSCs expressed known NP-specific genes, SOX9, ACAN, COL2, FOXF1, and KRT19. Transplanted cells survived, dispersed, and integrated into the degenerated IVDs. IVDs augmented with NPCs showed significant improvement in the histology, cellularity, sulfated glycosaminoglycan andwater contents of the NP. In addition, expression of human genes, SOX9, ACAN, COL2, FOXF1, KRT19, PAX6, CA12, and COMP, aswell as proteins, SOX9, ACAN, COL2, and FOXF1, suggest NP biosynthesis due to transplantation of NPCs. Based on these results, a molecular mechanism for NP regeneration was proposed.

CONCLUSION: The findings of this study demonstrating feasibility and efficacy of NPCs to regenerate NP should spur interest for clinical studies to treat DDD using cell therapy.

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Lateral Lumbar Interbody Fusion Revisited: Complication Avoidance and Outcomes with the Mini-Open Approach

World Neurosurg. (2019) 121:e647-e653

OBJECTIVE: To discuss lessons learned from an initial lateral lumbar interbody fusion (LLIF) experience with a focus on evolving surgical technique, complication avoidance, and new motor and sensory outcomes after implementation of a modified surgical approach.

METHODS: A retrospective analysis of a prospectively collected series of all patients undergoing LLIF by the senior author (A.D.L.) from January 2010 to January 2018 after implementation of a modified surgical mini-open technique, compared with previously reported institutional results with the originally recommended percutaneous technique. LLIF-specific complications examined included groin/thigh sensory dysfunction, flank bulge/pseudohernia, psoas-pattern weakness, and femoral nerve injury.

RESULTS: The incidence (19%, n [ 98 patients) of groin/ thigh sensory dysfunction in our cohort was significantly lower than that of the historical control (60%, n [ 59) (P < 0.0001). The incidence of abdominal flank bulge/pseudohernia (2.0%, n[98 patients) in our cohort was improved but not significantly lower than that of the historical control (4.2%, n[118) (P[0.36). The incidence of psoas-patternweakness (3.1%, n[98) in our cohort was significantly lower than that of the historical control (23.7%, n [ 59) (P [ 0.0001). The incidence of femoral nerve injury (0%, n[98 patients) in our cohort was improved but was not significantly lower than that of the historical control (1.7%, n [118) (P[0.20).

CONCLUSIONS: The adoption of an exclusive mini-open muscle-splitting approach with first-look inspection of the lumbosacral plexus nerve elements may improve motor and sensory outcomes in general and the incidence of postoperative groin/thigh sensory dysfunction and psoaspattern weakness in particular.

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Cervical Disc Arthroplasty: Current Evidence and Real-World Application

Neurosurgery 83:1087–1106, 2018

Cervical total disc replacement (cTDR) is still considered a developing technology, with widespread clinical use beginning in the early 2000s. Despite being relatively new to the marketplace, the literature surrounding cTDR is abundant.

We conducted a thorough review of literature published in the United States (US) and outside the US to report the current global state of cTDR research and clinical use. Search criteria were restricted to publications with a clinical patient population, excluding finite element analyses, biomechanical studies, cadaver studies, surgical technique-specific papers, and case studies. US publications mostly encompass the results of the highly controlled Food and Drug Administration Investigational Device Exemption trials.

The predominantly level I evidence in the US literature supports the use of cTDR at 1 and 2 surgical levels when compared to anterior cervical discectomy and fusion. In general, the outside the US studies typically have smaller patient populations, are rarely controlled, and include broader surgical indications. Though these studies are of lower levels of evidence, they serve to advance patient indications in the use of cTDR.

Complications such as secondary surgery, heterotopic ossification, and adjacent segment degeneration also remain a focus of studies. Other external challenges facing cTDR technology include regulatory restrictions and health economics, both of which are beginning to be addressed.

Combined, the evidence for cTDR is robust supporting a variety of clinical indications.

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