The Telehealth Spine Physical Examination: A Practical Approach Learned During the COVID-19 Pandemic

Background

The COVID-19 pandemic has led to a surge in the use of telehealth visits across the country to minimize in-person visits and to limit the spread of COVID-19. To date, no standards or outlines for telehealth spine examinations have been detailed and many surgeons simply defer the physical examination when performing telehealth visits. Nevertheless, just as physical examination of the spine is an integral part of live clinical encounters, appropriately modified physical examinations should also be part of virtual visits.

Methods

In this study we provide our methodology for guiding providers and patients in efficiently performing telehealth spine examinations.

Results

The study details steps for efficiently performing a physical examination in the telehealth setting. Our written suggestions are supplemented with photographs and video recordings to help streamline the virtual examination.

Conclusions

An effective and efficient spine physical examination can be performed during telehealth visits. Future directions include verifying the findings from our virtual physical examination with in-person examinations.

The Intersection Between Lateral Mass and Inferomedial Edge of the C1 Posterior Arch: A Reference Point for C1 Lateral Mass Screw Insertion

Objective

To determine the ideal Atlas (C1) lateral mass screw placement and trajectory using the intersection between the lateral mass and inferomedial edge of the posterior arch as an easily identifiable and reproducible medial reference point. Selection of an ideal entry point and trajectory of C1 lateral mass screw insertion can help to minimize neurovascular injuries. While various techniques for screw insertion have been proposed in the past, they all require extensive dissection of the C1 lateral mass, which can cause profuse bleeding.

Methods

Ninety-three 3-dimensional computed tomography reconstructed images of C1 lateral masses in adult patients were utilized to simulate the placement of C1 lateral mass screws via 4 entry points and 2 trajectory angles referencing off of a medial reference point using Vero’s VISI 17 software. The safety during screw insertion simulation, as well as the screw length, were evaluated.

Results

We found that C1 lateral mass screws could be safely placed bilaterally at 3 mm lateral to the reference point in both 0° and 15° medial screw angulation without violation of the cortex. The 15° medial angulation allowed for longer (18 mm) screws than the 0° angulation.

Conclusion

We recommend starting C1 lateral mass screws 3 mm lateral to the intersection between the lateral mass and inferomedial edge of the posterior arch at a 15° medial angulation.

Circumferential Operations of the Cervical Spine

Generally, a combined anterior and posterior cervical approach is associated with significant morbidity since it requires an extended operative time, greater intraoperative blood loss, and both anterior- and posterior-related surgical complications. However, there are some instances where a circumferential cervical fusion can be advantageous. Our objective is to discuss the indications for circumferential cervical spine procedures. A narrative review of the literature was performed. We include the indications for circumferential cervical approaches of the senior author (KDR). Indications for circumferential approaches include: (1) high-risk patients for pseudoarthrosis, (2) cervical deformity (e.g., degenerative, posttraumatic, cervicothoracic kyphosis), (3) cervical spine metastases (especially those with multilevel involvement), (4) cervical spine infection, (5) unstable cervical trauma, (6) movement disorders and cerebral palsy, (7) Multiply operated patient (especially postlaminectomy kyphosis and patients with massive ossification of the posterior longitudinal ligament), and when (8) early fusion is desirable. Circumferential procedures may be useful in many different cervical spine conditions requiring surgery. Despite its advantages, particularly with reducing the risk for pseudarthrosis, the benefits of a combined approach must be weighed against the risks associated with a dual approach. With appropriate preoperative planning, intraoperative decision-making, and surgical techniques, excellent clinical outcomes can be achieved.

Revision Surgeries at the Index Level After Cervical Disc Arthroplasty - A Systematic Review

Objective

To perform a systematic literature review on revision surgeries at the index level after cervical disc arthroplasty (CDA) failure.

Methods

A systematic literature review was performed according to the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines. Prospective studies on patients who required a secondary surgery after CDA failure were included for analysis. The minimum follow-up for these studies was 5 years.

Results

Out of 864 studies in the original search group, a total of 20 studies were included. From a total of 4,087 patients, 161 patients required a reoperation at the index level. A total of 170 surgeries were performed, as some patients required multiple surgeries. The most common secondary procedures were anterior cervical discectomy and fusion (ACDF) (68%, N = 61) and posterior cervical fusion (15.5%, N = 14), followed by other reoperation (13.3%, N = 12). The associated outcomes for those who required a revision surgery were rarely mentioned in the included literature.

Conclusion

The long-term revision rate at the index level of failed CDA surgery was 3.9%, with a minimum 5-year follow-up. ACDF was the most commonly performed procedure to salvage a failed CDA. Some patients who required a new surgery after CDA failure may require a more extensive salvage procedure and even subsequent surgeries.

Predictors of neurologic outcome after surgery for cervical ossification of the posterior longitudinal ligament differ based on myelopathy severity: a multicenter study

OBJECTIVE

The purpose of this retrospective multicenter study was to compare prognostic factors for neurological recovery in patients undergoing surgery for cervical ossification of the posterior longitudinal ligament (OPLL) based on their presenting mild, moderate, or severe myelopathy.

METHODS

The study included 372 consecutive patients with OPLL who underwent surgery for cervical myelopathy between 2006 and 2016 in East Asian countries with a high OPLL prevalence. Baseline and postoperative clinical outcomes were assessed using the Japanese Orthopaedic Association (JOA) myelopathy score and recovery ratio. Radiographic assessment included occupying ratio, cervical range of motion, and sagittal alignment parameters. Patient myelopathy was classified as mild, moderate, or severe based on the preoperative JOA score. Linear and multivariate regression analyses were performed to identify patient and surgical factors associated with neurological recovery stratified by baseline myelopathy severity.

RESULTS

The mean follow-up period was 45.4 months (range 25-140 months). The mean preoperative and postoperative JOA scores and recovery ratios for the total cohort were 11.7 ± 3.0, 14.5 ± 2.7, and 55.2% ± 39.3%, respectively. In patients with mild myelopathy, only age and diabetes correlated with recovery. In patients with moderate to severe myelopathy, older age and preoperative increased signal intensity on T2-weighted imaging were significantly correlated with a lower likelihood of recovery, while female sex and anterior decompression with fusion (ADF) were associated with better recovery.

CONCLUSIONS

Various patient and surgical factors are correlated with likelihood of neurological recovery after surgical treatment for cervical OPLL, depending on the severity of presenting myelopathy. Older age, male sex, intramedullary high signal intensity, and posterior decompression are associated with less myelopathy improvement in patients with worse baseline function. Therefore, myelopathy-specific preoperative counseling regarding prognosis for postoperative long-term neurological improvement should include consideration of these individual and surgical factors.

Effect of Ventral vs Dorsal Spinal Surgery on Patient-Reported Physical Functioning in Patients With Cervical Spondylotic Myelopathy: A Randomized Clinical Trial

IMPORTANCE

Cervical spondylotic myelopathy is the most common cause of spinal cord dysfunction worldwide. It remains unknown whether a ventral or dorsal surgical approach provides the best results.

OBJECTIVE

To determine whether a ventral surgical approach compared with a dorsal surgical approach for treatment of cervical spondylotic myelopathy improves patient-reported physical functioning at 1 year.

DESIGN, SETTING, AND PARTICIPANTS

Randomized clinical trial of patients aged 45 to 80 years with multilevel cervical spondylotic myelopathy enrolled at 15 large North American hospitals from April 1, 2014, to March 30, 2018; final follow-up was April 15, 2020.

INTERVENTIONS

Patients were randomized to undergo ventral surgery (n = 63) or dorsal surgery (n = 100). Ventral surgery involved anterior cervical disk removal and instrumented fusion. Dorsal surgery involved laminectomy with instrumented fusion or open-door laminoplasty. Type of dorsal surgery (fusion or laminoplasty) was at surgeon's discretion.

MAIN OUTCOMES AND MEASURES

The primary outcome was 1-year change in the Short Form 36 physical component summary (SF-36 PCS) score (range, 0 [worst] to 100 [best]; minimum clinically important difference = 5). Secondary outcomes included 1-year change in modified Japanese Orthopaedic Association scale score, complications, work status, sagittal vertical axis, health resource utilization, and 1- and 2-year changes in the Neck Disability Index and the EuroQol 5 Dimensions score.

RESULTS

Among 163 patients who were randomized (mean age, 62 years; 80 [49%] women), 155 (95%) completed the trial at 1 year (80% at 2 years). All patients had surgery, but 5 patients did not receive their allocated surgery (ventral: n = 1; dorsal: n = 4). One-year SF-36 PCS mean improvement was not significantly different between ventral surgery (5.9 points) and dorsal surgery (6.2 points) (estimated mean difference, 0.3; 95% CI, -2.6 to 3.1; P = .86). Of 7 prespecified secondary outcomes, 6 showed no significant difference. Rates of complications in the ventral and dorsal surgery groups, respectively, were 48% vs 24% (difference, 24%; 95% CI, 8.7%-38.5%; P = .002) and included dysphagia (41% vs 0%), new neurological deficit (2% vs 9%), reoperations (6% vs 4%), and readmissions within 30 days (0% vs 7%).

CONCLUSIONS AND RELEVANCE

Among patients with cervical spondylotic myelopathy undergoing cervical spinal surgery, a ventral surgical approach did not significantly improve patient-reported physical functioning at 1 year compared with outcomes after a dorsal surgical approach.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02076113.

Comparison of adverse events between cervical disc arthroplasty and anterior cervical discectomy and fusion: a 10-year follow-up

BACKGROUND CONTEXT

Cervical disc arthroplasty (CDA) has been advocated as an alternative to anterior cervical discectomy and fusion (ACDF) with the added potential to reduce the risk of adjacent level disc degeneration and segmental instability. However, the long-term adverse events of arthroplasty have yet to be fully reported.

PURPOSE

To investigate the 10-year follow-up adverse events rates between CDA and ACDF.

STUDY DESIGN/SETTING

The study was a randomized, prospective, multicenter Investigational Device Exemption (IDE) trial and its continued follow-up as a postapproval study (PAS). Single level surgeries were performed for cervical disc pathologies between May 2002 and October 2004.

PATIENT SAMPLE

n=463 patients.

OUTCOME MEASURES

Adverse events comparison of CDA and ACDF from self-reported and physiologic measures.

METHODS

At each evaluation time point, subjects were queried for adverse events since their last visit; and all adverse events were documented, regardless of whether or not they appeared related to the surgery or device. Adverse events were recorded, categorized, and assessed for severity and relationship to the study device and/or surgical procedure. The 10-year cumulative rates for each type of adverse events were summarized using a life-table method for the time-to-event analysis. A log-rank test was used to compare the two treatment groups.

RESULTS

A total of 242 patients received CDA and 221 patients received ACDF. At 10-year follow-up, 54% (130/242) of CDA patients and 47% (104/221) of the ACDF subjects were evaluated. At up to 10-year follow-up, 231 patients in the CDA group (cumulative rate 98.4%) and 199 patients in the ACDF group (cumulative rate 98.7%) had at least one adverse event. Overall, the difference in the cumulative rate of all adverse events over 10 years was not statistically different (p=0.166). The cumulative rates of the following adverse events were not different between the two groups for cancer, cardiovascular, death, dysphonia/dysphagia, gastrointestinal, infection, urogenital, respiratory, implant displacement/loosening, implant malposition, neck and arm pain, neurological, other pain, spinal events, and intraoperative vascular injury. However, there were more adverse events in the CDA group resulting from trauma (p=.012) and more spinal events at the index level (p=.006). The ACDF group had significantly more nonunion events (p=.019), and nonunion outcome pending (p=.034), adjacent level spinal events (p=.033), and events that fell into the "other" category (p=.015).

CONCLUSIONS

The cumulative rates of patients who had any adverse events were not different between the artificial cervical disc and the anterior cervical arthrodesis groups. In addition, the cumulative rates were not different between the two groups for the majority of categories as well.

Development of Neuromonitoring Pedicle Screw - Results of Electrical Resistance and Neurophysiologic Test in Pig Model

Objective

To analyze the electrical resistance of a newly developed neuromonitoring pedicle screw (Neuro-PS) and to verify the electrophysiologic properties of the Neuro-PS in a pig model.

Methods

We developed 2 types of the Neuro-PS in which a gold lead was located internally (type I) and externally (type II). We measured the electrical resistance of the Neuro-PS and the conventional screw and analyzed the electrical thresholds of triggered EMG (t-EMG) of each screw by intentionally penetrating the medial pedicle wall and contacting the exiting nerve root in a pig model.

Results

The electrical resistances of the Neuro-PS were remarkably lower than that of the conventional screw. In electrophysiologic testing, only the type II Neuro-PS under the leadnerve contact condition showed a significantly lower stimulation threshold as compared to the conventional screw.

Conclusion

The Neuro-PS demonstrated lower electrical resistances than the conventional screw. The type II Neuro-PS under the lead-nerve contact condition showed a significantly lower stimulation threshold compared to that of the other screws in the t-EMG test.

Does screw length for primary two-level ACDF influence pseudarthrosis risk?

BACKGROUND CONTEXT

Pseudarthrosis remains a major complication for patients undergoing anterior cervical discectomy and fusion (ACDF; 0%-15% at 1-year follow-up). Potentially modifiable risk factors are known in literature, such as smoking and osteoporosis. Biomechanical studies suggest that plates with locking screws can enhance the fixation rigidity and pull-out strength. Although longer screws are known to be correlated with increased pull-out strength, deeper screw depths can increase the risk for intraoperative complications. An important factor that has yet to be studied is the minimum screw length relative to the diameter of the vertebral body (VB) necessary to achieve successful fusion. In this study, we hypothesize that screws with shorter depths relative to the VB will increase the risk for radiographic pseudarthrosis and result in poor patient reported outcomes (PROs).

PURPOSE

To examine the impact of ACDF screw length on pseudarthrosis risk.

STUDY DESIGN

A review of prospectively collected data.

PATIENT SAMPLE

A total of 85 patients were included in this study. The mean age ±standard deviation was 58.9±10.3 and 42.4% of patients were female. The mean follow-up was 21.6±8.3 months.

OUTCOME MEASURES

The neck disability index (NDI) was used to assess PROs up to 2-years after surgery. For each ACDF level, the screw length and VB% (screw length divided by the anterior-posterior VB diameter) were measured. Radiographic pseudarthrosis (interspinous motion [ISM] ≥1 mm) was recorded at 6-weeks, 6-months, and 1-year for each patient. The positive and negative predictive values (PPV, NPV) for ISM ≥ 1mm were measured for different VB% thresholds. A VB% of <75% was found to have the highest PPV (93%) and NPV (70%) for radiographic pseudarthrosis. This threshold of <75% was then assessed in our bivariate and multivariate analyses.

METHODS

We reviewed a database (2015-2018) of adult (≥18 years old) patients who underwent a primary two-level ACDF with or without corpectomy. All ACDF constructs involved fixed angle screws. The minimum follow-up period was 1 year. Multivariate analyses were performed to determine if screw VB% was an independent risk factor for radiographic pseudarthrosis.

RESULTS

By 1-year, overall fusion success was achieved in 92.9% of patients. The 1-year revision rate was 4.7%. Patients with any screw VB% <75% had substantially worse fusion success (64.3%) than those who did not (98.6%) at 1-year. The VB% <75% increased the risk for radiographic pseudarthrosis at every follow up period. In comparison to other time-points, patients with radiographic pseudarthrosis at 6 weeks had significantly worse NDI scores by 2-years (p=.047). The independent risk factors for radiographic pseudarthrosis at 6-weeks included any screw VB% <75% (OR 77, p<.001), prior/current smoker (OR 6.8, p=.024), and corpectomy (OR 0.1, p=.010). Patients with ISM≥1 mm had a higher rate of revision surgery at 1-year (5.9% vs. 3.9%), but this was not statistically significant (p=.656).

CONCLUSIONS

In primary two-level ACDF, VB% <75% is significantly associated with increased ISM (≥1 mm) at all time points for this study. As an intraoperative guide, spine surgeons can use the screw VB% threshold of <75% to avoid unnecessarily short screws. This threshold can be easily measured pre- and intraoperatively, and has been found to be strongly correlated to radiographic pseudarthrosis in the early postoperative period.

Recent trends in medicare utilization and reimbursement for anterior cervical discectomy and fusion

BACKGROUND CONTEXT

Anterior cervical discectomy and fusion (ACDF) has been considered the gold standard for treating various cervical spine pathologies stemming from cervical degenerative disorders. While cervical artificial disc replacement has emerged as an alternative in select cases, ACDF still remains a commonly performed procedure.

PURPOSE

This study seeks to define the costs of ACDF and identify trends and variations in ACDF volume, utilization, and surgeon and hospital reimbursement rates.

STUDY DESIGN/SETTING

Retrospective analysis of patients undergoing ACDF PATIENT SAMPLE: Medicare patients undergoing ACDF between 2012 and 2017 OUTCOME MEASURES: ACDF volume, utilization rates, and surgeon/hospital reimbursement rates METHODS: This study tracked annual Medicare claims and payments to ACDF surgeons using publicly-available databases and aggregated data at the county level. Descriptive statistics and multivariate regression models were used to evaluate trends in procedure volume, utilization rates (per 10,000 Medicare beneficiaries), and reimbursement rates, and to examine associations between county-specific variables (ie, urban or rural, average household income, poverty rate, percent Medicare population, race/ethnicity demographics), and ACDF utilization and reimbursement rates.

RESULTS

A total of 264,673 ACDF surgeries were performed in the Medicare population from 2012 to 2017, with a 24.2% increase in annual procedure volume. Utilization also increased by 6.5% from 8.0 surgeries per 10,000 Medicare beneficiaries in 2012 to 8.5 in 2017. Hospital reimbursements for cervical spine fusion surgeries without complications or co-morbidities experienced nominal and inflation-adjusted increases of 9.5% and 0.7%, respectively, from $12,030.11 in 2012 to $13,167.64 in 2017. Surgeon reimbursements for single-level and multilevel ACDF each nominally decreased from $958.11 and $1,173.01, respectively, in 2012 to $950.34 and $1,138.41 in 2017 (a 0.8% and 2.9% decrease, respectively), but after adjusting for inflation, reimbursements per case fell by an average of 8.7% and 10.7%, respectively. In contrast, mean reimbursements per case for hospitals rose by 7.1% (1.5% inflation-adjusted decrease). A significant upward yearly trend in ambulatory surgical centers volume, resulted in a net increase of 184.5% between 2015 and 2017 (p<.001).

CONCLUSIONS

While ACDF volume and utilization has continued to increase since 2012, Medicare payments to hospitals and surgeons have struggled to keep up with inflation. Our study confirms that Medicare reimbursement per case continues to decrease at a disproportionate rate for surgeons, compared to hospitals. The increasing trend in procedures performed at ambulatory surgical centers shows promise for a future model of cost-efficient and value-based care.

Symptomatic cervical spinal stenosis in spastic cerebral palsy

AIM

To describe the prevalence of symptomatic cervical spinal stenosis (CSS) in spastic cerebral palsy (CP) and associated characteristics.

METHOD

This cross-sectional study of adults (>18y) with CP (2006-2016) at a single institution compared the patient characteristics (demographics, comorbidities, surgical history, medications, Gross Motor Function Classification System [GMFCS] level, and CP type) of patients with and without CSS.

RESULTS

Of 424 patients (mean age 33y 4mo, SD 13y 6mo, range 18-78y; 225 females, 199 males), 32 patients (7.5%) had symptomatic CSS. GMFCS levels in the study cohort were distributed as follows: level I, 25%; level II, 25%; level III, 22%; level IV, 19%; level V, 9%. Twenty-five out of 32 (78.1%) patients had spastic CP, two (6.3%) had dystonic CP, and one (3.1%) had mixed characteristics. Individuals with CSS were older (mean age 54y 6mo, SD 10y 5mo vs mean age 31y 7mo, SD 12y 1mo, p<0.05) and had a higher body mass index (26.1, SD 4.8 vs 23.4, SD 6.2, p<0.05) than those without CSS. Presentations included upper-extremity symptoms (73%), ambulation decline (70%), neck pain (53%), and incontinence (30%). Common stenosis levels were C5-C6 (59%), C4-C5 (56%), and C6-C7 (53%).

INTERPRETATION

Symptomatic CSS was identified in 7.5% of this adult cohort during the 2006 to 2016 period. Diagnosis in CP is difficult due to impaired communication and pre-existing gait abnormalities and spasticity. Given the high prevalence of symptomatic CSS in adults, we propose developing screening guidelines. Physicians must maintain a high level of suspicion for CSS if patients present with changes in gait or spasticity.

Timing of Surgery in Thoracolumbar Spine Injury: Impact on Neurological Outcome

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

We aimed to evaluate the improvement in neurological deficit following early versus late decompression and stabilization of thoracolumbar junctional fractures.

METHODS

This is a retrospective evaluation of all patients with a traumatic spinal cord injury (SCI) from T11 to L2 treated at a teaching hospital between 2010 and 2017. Grouped analysis was performed comparing the cohort of patients who received early surgery within 24 hours (group 1) with those operated within 24 to 72 hours (group 2) and more than 72 hours after SCI (group 3). The primary outcome was the change in ASIA (American Spinal Injury Association) motor score at 12-month follow-up.

RESULTS

There were 317 patients (225 males and 92 females with mean age of 31.55 ± 12.43 years). A total of 144, 77, and 96 patients belonged to groups 1, 2, and 3 respectively. Improvement of at least 1 grade on ASIA classification was observed in 80, 45, and 33 patients in groups 1, 2, and 3 respectively (P = .001). Overall, 32, 12, and 10 patients improved ≥2 grades on ASIA classification in groups 1, 2, and 3, respectively (P = .069). On logistic regression analysis, early surgery and severity of initial injury (complete [ASIA A] vs incomplete SCI [ASIA B-D]) were found to significantly influence the potential for neurologic improvement (P = .004 and P < .0001, respectively).

CONCLUSION

We believe that the earlier the decompression, the better. The 72-hour cutoff represents the most promising time window during which surgical decompression has the potential to confer a neuroprotective effect in the setting of incomplete SCI (ASIA B-D) in the distal region of the spinal cord (conus medullaris).

Osteolysis after cervical disc arthroplasty

PURPOSE

Cervical disc arthroplasty (CDA) has become an increasingly popular treatment for cervical degenerative disc disease. One potential complication is osteolysis. However, current literature on this topic appears limited. The purpose of this study is to elucidate the incidence, aetiology, consequence, and subsequent treatment of this complication.

METHODS

A systematic literature review was performed according to the PRISMA guidelines. Studies discussing the causes, incidence and management of osteolysis after a CA were included.

RESULTS

A total of nine studies were included. We divided these studies into two groups: (1) large case series in which an active radiological evaluation for osteolysis was performed (total = six studies), (2) case report studies, which discussed symptomatic cases of osteolysis (total = three). The incidence of asymptomatic osteolysis ranged from 8 to 64%; however, only one study reported an incidence of < 10% and when this case was excluded the incidence ranged from 44 to 64%. Severe asymptomatic bone loss (exposure of the implant) was found in less than 4% of patients. Bone loss from osteolysis appeared to occur early (< 1 year) after surgery and late (> 1 year) as well. Symptomatic patients with osteolysis often required revision surgery. These patients required removal of implant and conversion to fusion in the majority of the cases.

CONCLUSIONS

Osteolysis after CDA is common; however, the majority of cases have only mild or asymptomatic presentations that do not require revision surgery. The timing of osteolysis varies significantly. This may be due to differences in the aetiology of osteolysis.

Addressing a national crisis: the spine hospital and department's response to the COVID-19 pandemic in New York City

In a very brief period, the COVID-19 pandemic has swept across the planet leaving governments, societies, and healthcare systems unprepared and under-resourced. New York City now represents the global viral epicenter with roughly one-third of all mortalities in the United States. To date, our hospital has treated thousands of COVID-19 positive patients and sits at the forefront of the United States response to this pandemic. The goal of this paper is to share the lessons learned by our spine division during a crisis when hospital resources and personnel are stretched thin. Such experiences include management of elective and emergent cases, outpatient clinics, physician redeployment, and general health and wellness. As peak infections spread across the United States, we hope this article will serve as a resource for other spine departments on how to manage patient care and healthcare worker deployment during the COVID-19 crisis.

Safety of Outpatient Anterior Cervical Discectomy and Fusion: A Systematic Review and Meta-Analysis

BACKGROUND

Anterior cervical discectomy and fusion (ACDF) is being increasingly offered on an outpatient basis. However, the safety profile of outpatient ACDF remains poorly defined.

OBJECTIVE

To review the medical literature on the safety of outpatient ACDF.

METHODS

We systematically reviewed the literature for articles published before April 1, 2018, describing outpatient ACDF and associated complications, including incidence of reoperation, stroke, thrombolytic events, dysphagia, hematoma, and mortality. A random-effects analysis was performed comparing complications between the inpatient and outpatient groups.

RESULTS

We identified 21 articles that satisfied the selection criteria, of which 15 were comparative studies. Most of the existing studies were retrospective, with a lack of level I or II studies on this topic. We found no statistically significant difference between inpatient and outpatient ACDF in overall complications, incidence of stroke, thrombolytic events, dysphagia, and hematoma development. However, patients undergoing outpatient ACDF had lower reported reoperation rates (P < .001), mortality (P < .001), and hospitalization duration (P < .001).

CONCLUSION

Our meta-analysis indicates that there is a lack of high level of evidence studies regarding the safety of outpatient ACDF. However, the existing literature suggests that outpatient ACDF can be safe, with low complication rates comparable to inpatient ACDF in well-selected patients. Patients with advanced age and comorbidities such as obesity and significant myelopathy are likely not suitable for outpatient ACDF. Spine surgeons must carefully evaluate each patient to decide whether outpatient ACDF is a safe option. Higher quality, large prospective randomized control trials are needed to accurately demonstrate the safety profile of outpatient ACDF.

Occipitocervical Fixation: General Considerations and Surgical Technique

STUDY DESIGN

Narrative literature review.

OBJECTIVE

To review and present details on the occipitocervical fixation (OCF) technique as well as considerations for planning the procedure.

METHODS

We present the surgical technique of OCF in a step-by-step didactic and practical manner with surgical tips and tricks, including C1 and C2 screw fixation techniques. Additionally, we discuss complications, the extension of fusion, types of OCF, and how to avoid common side effects associated with OCF.

RESULTS

The complex and mobile anatomy of the craniocervical junction, when requiring fixation and fusion, warrants rigid instrumentation that can be achieve using a modern screw-plate-rod construct. Indications for OCF are craniocervical instability, and atlantoaxial instability when selective atlantoaxial fusion is not feasible. OCF generally involves occiput-C2 fusion. C1 fixation is generally unnecessary, since it increases the surgical time and is associated with the risk of vascular complications. Selective occiput-C2 fusion is recommended when there is no need for including the cervical subaxial region (eg, when stenosis or fractures coexist in the subaxial spine), and good fixation is achieved at C2. Most instrumentation systems now have occipital plates that are not pre-integrated to rods, making fixation much simpler. Surgical steps, from position to wound closure, are presented in detail, with pearls for practice and discussion of cervical alignment.

CONCLUSIONS

OCF is a challenging procedure, with potential risk of severe adverse effects. Understanding the surgical indications, as well as the nuances of the surgical technique, is required to improve patient outcomes and avoid complications.

Perioperative Anticoagulation Management in Spine Surgery: Initial Findings From the AO Spine Anticoagulation Global Survey

STUDY DESIGN

Cross-sectional, international survey.

OBJECTIVES

This study addressed the global perspectives concerning perioperative use of pharmacologic thromboprophylaxis during spine surgery along with its risks and benefits.

METHODS

A questionnaire was designed and implemented by expert members in the AO Spine community. The survey was distributed to AO Spine's spine surgeon members (N = 3805). Data included surgeon demographic information, type and region of practice, anticoagulation principles, different patient scenarios, and comorbidities.

RESULTS

A total of 316 (8.3% response rate) spine surgeons completed the survey, representing 64 different countries. Completed surveys were primarily from Europe (31.7%), South/Latin America (19.9%), and Asia (18.4%). Surgeons tended to be 35 to 44 years old (42.1%), fellowship-trained (74.7%), and orthopedic surgeons (65.5%) from academic institutions (39.6%). Most surgeons (70.3%) used routine anticoagulation risk stratification, irrespective of geographic location. However, significant differences were seen between continents with anticoagulation initiation and cessation methodology. Specifically, the length of a procedure (P = .036) and patient body mass index (P = .008) were perceived differently when deciding to begin anticoagulation, while the importance of medical clearance (P < .001) and reference to literature (P = .035) differed during cessation. For specific techniques, most providers noted use of mobilization, low-molecular-weight heparin, and mechanical prophylaxis beginning on postoperative 0 to 1 days. Conversely, bridging regimens were bimodal in distribution, with providers electing anticoagulant initiation on postoperative 0 to 1 days or days 5-6.

CONCLUSION

This survey highlights the heterogeneity of spine care and accentuates geographical variations. Furthermore, it identifies the difficulty in providing consistent perioperative anticoagulation recommendations to patients, as there remains no widely accepted, definitive literature of evidence or guidelines.

Curved versus straight-cut hinges for open-door laminoplasty: A finite element and biomechanical study

In this study, the stabilities of the hinge sides of plate-augmented open-door laminoplasties based on cutting in a curved or straight line were compared using a finite element (FE) model and an experimental assessment. Using FE models generated from CT scans of a human subject, straight and curved techniques for cutting the hinge side were evaluated. Compressive forces were applied to both simulated models, and the stress distributions on the respective hinge sites were evaluated by comparing the maximum von Mises stresses. Biomechanical testing procedures were then carried out on porcine cervical vertebrae, with straight- and curved-cut groups loaded to failure, and the corresponding reaction forces on the hinge sites were recorded using a loading cell. The FE analysis results revealed no significant differences between the straight- and curved-cut groups in terms of maximum stress forces on the superior, middle, or inferior portions of the hinge sites. In the experimental study, the curved-cut group withstood higher loads to failure at the hinge site than the straight-cut group. The ability of the curved-cut laminoplasty hinges to withstand higher compressive loading to failure than straight-cut hinges suggests the potential of the proposed technique to reduce the risk of hinge fracture and displacement.

Anterior osteotomy for rigid cervical deformity correction

Rigid deformities of the cervical spine can be associated with significant pain, disability, and impaired quality of life. Historical treatments generally utilized posterior approaches including the opening wedge osteotomy and pedicle subtraction osteotomy (PSO). Translation can occur during osteoclasis of the opening wedge osteotomy, making it inherently less stable than a PSO. The PSO is limited to lower cervical or upper thoracic levels due to the vertebral artery and sensitivity of cervical nerve roots to compression during osteotomy closure. The anterior osteotomy, defined as an osteotomy through the cervical disc space and uncovertebral joints back to the level of the transverse foramen bilaterally, is a powerful correction technique that can be applied throughout the cervical spine. It can also be used to correct deformities in the coronal plane. This review will summarize the technical nuances of the anterior osteotomy including patient selection, preoperative planning, and surgical technique.

Improvements in Neck Pain and Disability Following C1-C2 Posterior Cervical Instrumentation and Fusion for Atlanto-Axial Osteoarthritis

OBJECTIVE

Symptomatic Atlanto-axial (C1-2) osteoarthritis (AAOA) is a common phenomenon in elderly patients; however, there is a paucity of data on the effectiveness of posterior atlanto-axial fusion (PAAF) for this condition. To this end, here we assess changes in patient-reported outcomes and neck-related disability in adult patients undergoing PAAF for symptomatic C1-2 AAOA.

METHODS

In this retrospective study, the clinical records of consecutive patients with symptomatic AAOA who underwent PAAF between 2004 and 2017 were reviewed. Patient demographics, comorbidities, intraoperative and postoperative variables, and complication rates were collected. Neck Disability Index (NDI) scores were recorded at baseline and 6 weeks, 6 months, 1 year, and 2 years postoperatively.

RESULTS

Forty-two patients (average age, 72.04 ± 8.56 years; 26.19% males) met the study's inclusion criteria. In this cohort, 19.04% had previous subaxial cervical spine surgery, 35.71% had a history of smoking (all had stopped smoking before surgery), and 11.90% had type II diabetes. At baseline, the majority of patients had a normal neurologic exam. The average preoperative NDI score was 26.88 ± 24.85, which improved to 10.59 ± 14.88 at the 1-year follow-up and 13.20 ± 14.96 at the 2-year follow-up (P = 0.004). At baseline, 18% of the patients reported severe disability based on NDI score; this percentage decreased to 2% at 1 year and 0 at 2 years (P = 0.01). Importantly, a high percentage (11.90%) of patients had undergone previous subaxial cervical fusion for their pain due to a mistaken diagnosis for this condition, without symptom relief.

CONCLUSIONS

In appropriately selected patients, PAAF may decrease neck pain and improve functional disability in patients with AAOA. Future prospective longitudinal studies are needed to corroborate these findings.

Safety and efficacy of direct nerve root decompression via anterior cervical discectomy and fusion with uncinectomy for cervical radiculopathy

Cervical radiculopathy is a common spinal condition associated with pain, sensory disturbances, and motor weakness. Symptoms often can be attributable to either disc herniation and/or bony foraminal stenosis due to uncinate hypertrophy. Posterior cervical foraminotomy and conventional anterior cervical discectomy and fusion (ACDF) represent the mainstay of treatment. In patients with severe bony foraminal stenosis, posterior foraminotomy and standard ACDF without complete resection of uncinate process may result in incomplete decompression. ACDF with uncinectomy allows for complete and direct decompression of the exiting nerve root, and may lead to improved clinical outcome in appropriately selected patients. We describe the technique for ACDF with uncinectomy and report the clinical outcome in a consecutive series of patients.

Posterior screw fixation in the subaxial cervical spine: a technique and literature review

Posterior cervical spine fixation is a key component in achieving spinal arthrodesis for treating various cervical spine pathologies including neoplastic, inflammatory, traumatic and degenerative diseases. Historically, various wiring techniques had played major roles in posterior cervical spine fixation. Today, posterior cervical screw fixation is utilized by most spine surgeons instead of wiring for its superior biomechanical strength. A review of lateral mass, pedicle, intralaminar and transfacet screw fixation techniques in the subaxial cervical spine is presented in a detailed fashion. A comparison among different posterior cervical subaxial fixation techniques is also included. Although the safety of freehand techniques was demonstrated in the majority of the existing studies, real-time navigation is becoming increasingly utilized for cervical screw insertion, especially for cervical pedicle screws, where the freehand technique is technically demanding and may carry a higher risk of neurovascular injury. Several different posterior screw fixation techniques exist for the subaxial cervical spine with generally low complication rate. Spine surgeons should be familiar with these techniques and choose the optimal technique based on each patient's individual anatomy and surgical needs.

Infection prevention in cervical spine surgery

Surgical site infections (SSI) following cervical spine surgery can lead to significant patient morbidity and costs. Prevention of SSIs is multifactorial and can be divided in to preoperative patient optimization and intraoperative surgical factors. We performed a literature review to identify methods that can be used to prevent SSI development specifically in the cervical spine. We also present specific surgical pearls and techniques that have the potential to significantly decrease rates of cervical SSIs.

Restoration of Global Sagittal Alignment After Surgical Correction of Cervical Hyperlordosis in a Patient with Emery-Dreifuss Muscular Dystrophy: A Case Report

CASE

We report a rare cervical hyperlordotic deformity in a 19-year-old woman with Emery-Dreifuss muscular dystrophy and concomitant scoliosis. After standard posterolateral instrumentation and fusion of C2-T1 and extensive soft-tissue release, her neck pain improved and unassisted maintenance of cervical alignment and horizontal gaze were preserved through an 8-year follow-up. More importantly, she exhibited reciprocal correction of compensatory global sagittal malalignment, including lumbar lordosis.

CONCLUSIONS

This case highlights the importance of full-spine analysis for all patients with spinal deformity to identify and differentiate primary driver(s) of deformity from compensatory mechanisms to individualize treatment toward what truly drives the patient's disability.

Surgical Site Infection Prevention Following Spine Surgery

STUDY DESIGN

Literature review.

OBJECTIVES

Surgical site infection (SSI) following spine surgery leads to significant patient morbidity, mortality, and increased health care costs. The purpose of this article is to identify risk factors and strategies to prevent SSIs following spine surgery, with particular focus on avoiding infections in posterior cervical surgery.

METHODS

We performed a literature review and synthesis to identify methods that can be used to prevent the development of SSI following spine surgery. Specific pearls for preventing infection in posterior cervical spine surgery are also presented.

RESULTS

SSI prevention can be divided into patient and surgeon factors. Preoperative patient factors include smoking cessation, tight glycemic control, weight loss, and nutrition optimization. Surgeon factors include screening and treatment for pathologic microorganisms, skin preparation using chlorhexidine and alcohol, antimicrobial prophylaxis, hand hygiene, meticulous surgical technique, frequent irrigation, intrawound vancomycin powder, meticulous multilayered closure, and use of closed suction drains.

CONCLUSION

Prevention of SSI following spine surgery is multifactorial and begins with careful patient selection, preoperative optimization, and meticulous attention to numerous surgical factors. With careful attention to various patient and surgeon factors, it is possible to significantly reduce SSI rates following spine surgery.

Minimizing Blood Loss in Spine Surgery

STUDY DESIGN

Broad narrative review.

OBJECTIVE

To review and summarize the current literature on guidelines, outcomes, techniques and indications surrounding multiple modalities of minimizing blood loss in spine surgery.

METHODS

A thorough review of peer-reviewed literature was performed on the guidelines, outcomes, techniques, and indications for multiple modalities of minimizing blood loss in spine surgery.

RESULTS

There is a large body of literature that provides a consensus on guidelines regarding the appropriate timing of discontinuation of anticoagulation, aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), and herbal supplements prior to surgery. Additionally, there is a more heterogenous discussion the utility of preoperative autologous blood donation facilitated by erythropoietin and iron supplementation for healthy patients slated for procedures with high anticipated blood loss and for whom allogeneic transfusion is likely. Intraoperative maneuvers available to minimize blood loss include positioning and maintaining normothermia. Tranexamic acid (TXA), bipolar sealer electrocautery, and topical hemostatic agents, and hypotensive anesthesia (mean arterial pressure (MAP) <65 mm Hg) should be strongly considered in cases with larger exposures and higher anticipated blood loss. There is strong level 1 evidence for the use of TXA in spine surgery as it reduces the overall blood loss and transfusion requirements.

CONCLUSION

As the volume and complexity of spinal procedures rise, intraoperative blood loss management has become a pivotal topic of research within the field. There are many tools for minimizing blood loss in patients undergoing spine surgery. The current literature supports combining techniques to use a cost- effective multimodal approach to minimize blood loss in the perioperative period.

Review of Subaxial Cervical Spine Injuries Presenting to a Tertiary-Level Hospital in Nepal: Challenges in Surgical Management in a Third World Scenario

STUDY DESIGN

Epidemiological retrospective study.

OBJECTIVE

To describe the demographics, timing to surgery, delay, short-term neurological recovery, and complications in surgically treated subaxial cervical trauma in a resource-constrained country.

METHODS

Thirty consecutive subaxial cervical trauma patients presenting to a trauma hospital in Nepal between December 2015 and August 2017 were analyzed as a retrospective cohort. Patients were segregated into 4 groups based on the timing to surgery: within 2 days, 3 to 7 days, 8 to 30 days, and >31 days.

RESULTS

There were 27 male and 3 female patients with mean age 40 years. Twenty-four sustained fall injury, and 27 patients were from outside Kathmandu. No patients were treated within the first 48 hours; only 9 were treated between 3 and 7 days, 16 between 8 and 30 days, and 5 a month later. Major delay was finance and operating room availability. Thirteen patients had a C6C7 involvement followed by C5C6 in 6 patients. Seven patients had complete neurological deficit while 18 patients had incomplete deficit. A total of 46.7% improved their neurology in 6 months. No neurological recovery was observed in complete deficit patients.

CONCLUSION

Seventy percent of our patients were treated longer than 1 week after injury, which would likely be considered unacceptable in most first world countries. As expected, the outcomes for many of these patients were far worse than reported in North American centers with early access to medical care and insurance. Despite this, nearly half of our patients improved neurologically following treatment; hence, surgery holds hope of some restoration of neurologic deficits.

Transoral and Endoscopic Endonasal Odontoidectomies – Surgical Techniques, Indications, and Complications

Odontoidectomy is indicated for some cases of ventral compression in the upper cervical spine. In this paper, we discuss the indications, surgical steps, and nuances of transoral odondoidectomy (TO) and endoscopic endonasal (EE) odontoidectomy. We compare both approaches and discuss the advantages and disadvantages of each. A broad narrative literature review was performed. We also added tips and surgical pearls of the senior author (KDR) in performing odontoidectomies. Surgical techniques were presented. EE is performed in patients where the dens is located above the nasopalatine line. Although technically more demanding, EE has less soft tissue injury and potentially less risk of dysphonia and dysphagia. The TO approach provides a wider exposure and is not limited by the nasopalatine line. Additionally, the TO approach allows the ability for a more extensive resection of C2; these could include the C2 body and the C2–3 disc space. Ventral reconstructions with cages and plates are also feasible via the TO approach. However, there are additional risks of prolonged intubation and tracheostomy with the TO approach. Surgeons who manage upper cervical spine disease should be comfortable performing both approaches, and selecting the best approach should be determined using patient-specific characteristics.

C1 Stenosis - An Easily Missed Cause for Cervical Myelopathy

C1 stenosis is often an easily missed cause for cervical myelopathy. The vast majority of cervical myelopathy occurs in the subaxial cervical spine. The cervical canal is generally largest at C1/2, explaining the relatively rare incidence of neurological deficits in patients with odontoid fractures. However, some subjects have anatomical anomalies of the atlas, which may cause stenosis and result in clinical symptoms similar to subaxial cord compression. Isolated pure atlas hypoplasia leading to stenosis is quite rare and may be associated with other anomalies, such as atlas clefts or transverse ligament calcification. It may also be more commonly associated with syndromic conditions such as Down or Turner syndrome. Although the diagnosis can be easily made with a cervical magnetic resonance imaging, the C3/2 spinolaminar test using a lateral cervical plain radiograph is a useful and sensitive tool for screening. Surgical treatment with a C1 laminectomy is generally necessary and any atlantoaxial or occipito-atlanto instability must be treated with spinal stabilization and fusion.

Preoperative Narcotic Use, Impaired Ambulation Status, and Increased Intraoperative Blood Loss Are Independent Risk Factors for Complications Following Posterior Cervical Laminectomy and Fusion Surgery

OBJECTIVE

This retrospective cohort study seeks to identify risk factors associated with complications following posterior cervical laminectomy and fusion (PCLF) surgery.

METHODS

Adults undergoing PCLF from 2012 through 2018 at a single center were identified. Demographic and radiographic data, surgical characteristics, and complication rates were compared. Multivariate logistic regression models identified independent predictors of complications following surgery.

RESULTS

A total of 196 patients met the inclusion criteria and were included in the study. The medical, surgical, and overall complication rates were 10.2%, 23.0%, and 29.1% respectively. Risk factors associated with medical complications in multivariate analysis included impaired ambulation status (odds ratio [OR], 2.27; p=0.02) and estimated blood loss over 500 mL (OR, 3.67; p=0.02). Multivariate analysis revealed preoperative narcotic use (OR, 2.43; p=0.02) and operative time (OR, 1.005; p=0.03) as risk factors for surgical complication, whereas antidepressant use was a protective factor (OR, 0.21; p=0.01). Overall complication was associated with preoperative narcotic use (OR, 1.97; p=0.04) and higher intraoperative blood loss (OR, 1.0007; p=0.03).

CONCLUSION

Preoperative narcotic use and estimated blood loss predicted the incidence of complications following PCLF for CSM. Ambulation status was a significant predictor of the development of a medical complication specifically. These results may help surgeons in counseling patients who may be at increased risk of complication following surgery.

Prospective Multicenter Assessment of All-Cause Mortality Following Surgery for Adult Cervical Deformity

BACKGROUND

Surgical treatments for adult cervical spinal deformity (ACSD) are often complex and have high complication rates.

OBJECTIVE

To assess all-cause mortality following ACSD surgery.

METHODS

ACSD patients presenting for surgical treatment were identified from a prospectively collected multicenter database. Clinical and surgical parameters and all-cause mortality were assessed.

RESULTS

Of 123 ACSD patients, 120 (98%) had complete baseline data (mean age, 60.6 yr). The mean number of comorbidities per patient was 1.80, and 80% had at least 1 comorbidity. Surgical approaches included anterior only (15.8%), posterior only (50.0%), and combined anterior/posterior (34.2%). The mean number of vertebral levels fused was 8.0 (standard deviation [SD] = 4.5), and 23.3% had a 3-column osteotomy. Death was reported for 11 (9.2%) patients at a mean of 1.1 yr (SD = 0.76 yr; range = 7 d to 2 yr). Mean follow-up for living patients was 1.2 yr (SD = 0.64 yr). Causes of death included myocardial infarction (n = 2), pneumonia/cardiopulmonary failure (n = 2), sepsis (n = 1), obstructive sleep apnea/narcotics (n = 1), subsequently diagnosed amyotrophic lateral sclerosis (n = 1), burn injury related to home supplemental oxygen (n = 1), and unknown (n = 3). Deceased patients did not significantly differ from alive patients based on demographic, clinical, or surgical parameters assessed, except for a higher major complication rate (excluding mortality; 63.6% vs 22.0%, P = .006).

CONCLUSION

All-cause mortality at a mean of 1.2 yr following surgery for ACSD was 9.2% in this prospective multicenter series. Causes of death were reflective of the overall high level of comorbidities. These findings may prove useful for treatment decision making and patient counseling in the context of the substantial impact of ACSD.

Prevalence and Predictive Factors of Concurrent Cervical Spinal Cord Compression in Adult Spinal Deformity

STUDY DESIGN

Retrospective cross-sectional cohort.

OBJECTIVE

To investigate the prevalence and predictive factors of concurrent cervical spinal cord compression (CSCC) in patients with adult spinal deformity (ASD).

SUMMARY OF BACKGROUND DATA

In patients with ASD undergoing major thoracolumbar realignment surgery, concurrent CSCC potentially increases the risk of progression of myelopathy or cervical cord injury due to various perioperative factors including poor intraoperative neck positioning and hypotension. However, the prevalence of CSCC in ASD patients has not been previously studied.

METHODS

This study included ASD patients who were indicated for major thoracolumbar corrective surgery (>5 levels). The presence of CSCC was determined using the modified Cord Compression Index (Grades 0-3) based on the cervical magnetic resonance imaging (MRI). Significant CSCC was defined as Grade>2, and the distribution of compression level as well as the number of Grade>2 segments were investigated in each patient. A multivariate regression analysis was performed to identify the predictors of CSCC with variables being the patients' characteristics including radiographic sagittal alignment parameters.

RESULTS

Of 121 patients with ASD, 41 patients (33.8%) demonstrated significant CSCC on MRI. Intramedullary T2 hyper-intensity (myelomalacia) was present in eight patients (6.6%). Thirty-five of 41 patients were asymptomatic or with myelopathy that is difficult to detect. Significant CSCC was most commonly observed at C4/5 level. Four patients (3.3%) underwent cervical decompression and fusion prior to thoracolumbar reconstruction. Multivariate regression analysis revealed old age, increased body mass index (BMI), and PI-LL mismatch independently predicted the CSCC grade.

CONCLUSION

The prevalence of concurrent significant cervical cord compression in patients with ASD is relatively high at 33.8%. Preoperative evaluation of cervical MRI and examinations for signs/symptoms of myelopathy are essential for patients with (1) older age, (2) increased BMI, and (3) high PI-LL mismatch to avoid progressive myelopathy or cord injury during ASD surgery.

LEVEL OF EVIDENCE

4.

Dynamic Cord Compression Causing Cervical Myelopathy

The diagnosis of cervical spondylotic myelopathy (CSM) is made based on clinical signs and symptoms, and then confirmed with magnetic resonance imaging (MRI) or CT myelogram. Due to the highly mobile nature of the cervical spine, and the fact that most MRIs and CTs are obtained only in one single position, dynamic cord compression can be an elusive diagnosis that is often missed and not well-understood. In this context, dynamic MRI (dMRI) has been utilized to improve the diagnostic accuracy of cervical stenosis in cases where static MRI does not provide enough information to establish a diagnosis or to provide additional information. We performed a literature review on dynamic cord compression in the context of CSM, with particular emphasis on the role of dynamic MRI (dMRI). Cadaveric studies report that the spinal cord lengthens in flexion and the spinal canal dimension increases, whereas the spinal cord relaxes and shortens in extension and the spinal canal decreases. These changes may lead to biomechanical stress in the spinal cord with movement, especially in patients with critical cervical stenosis. The majority of the studies using dMRI in CSM reported that this imaging modality is more sensitive at detecting cervical cord compression compared to routine MRIs done in a neutral position, especially with the neck in extension. Occult anterior compression has also been reported by some authors in flexion, but occurs less frequently. DMRI was also useful to diagnose dynamic cervical cord compression after laminectomies in patients with clinical deterioration without evident cord compression on neutral static MRI. Finally, dMRI are more sensitive in detecting stenosis in patients with CSM than in those with OPLL, likely because OPLL patients often have a more limited ROM than CSM patients. Thus, dMRI is a promising new tool that can help spine surgeons in diagnosing and treating CSM. However, further studies are needed to establish the utilization criteria and the clinical value of dMRI.

Dynamic Cord Compression Causing Cervical Myelopathy

Due to the highly mobile nature of the cervical spine, and the fact that most magnetic resonance imagings (MRIs) and computed tomography scans are obtained only in one single position, dynamic cord compression can be an elusive diagnosis that is often missed and not well-understood. In this context, dynamic MRI (dMRI) has been utilized to improve the diagnostic accuracy of cervical stenosis. We performed a literature review on dynamic cord compression in the context of cervical spondylotic myelopathy (CSM), with particular emphasis on the role of dMRI. Cadaveric studies report that the spinal cord lengthens in flexion and the spinal canal dimension increases, whereas the spinal cord relaxes and shortens in extension and the spinal canal decreases. These changes may lead to biomechanical stress in the spinal cord with movement, especially in patients with critical cervical stenosis. The majority of the studies using dMRI in CSM reported that this imaging modality is more sensitive at detecting cervical cord compression compared to routine MRIs done in a neutral position, especially with the neck in extension. Dynamic MRI was also useful to diagnose dynamic cervical cord compression after laminectomies in patients with clinical deterioration without evident cord compression on neutral static MRI. Finally, dMRI is more sensitive in detecting stenosis in patients with CSM than in those with ossification of the posterior longitudinal ligament (OPLL), likely because OPLL patients often have a more limited range of motion than CSM patients. Thus, dMRI is a promising new tool that can help spine surgeons in diagnosing and treating CSM.

Degenerative Cervical Myelopathy: A 7-Letter Coding System That Supports Decision-Making for the Surgical Approach

Objective

To validate with a prospective study a decision-supporting coding system for the surgical approach for multilevel degenerative cervical myelopathy.

Methods

Ten cases were presented on an internet platform, including clinical and imaging data. A single-approach (G1), a choice between 2 (G2), or 3 approaches (G3) were options. Senior and junior spine surgeons analyzed 7 parameters: location and extension of the compression of the spinal cord, C-spine alignment and instability, general morbidity and bone diseases, and K-line and multilevel corpectomy. For each parameter, an anterior, posterior, or combined approach was suggested. The most frequent letter or the last letter (if C) of the resulting 7-letter code (7LC) suggested the surgical approach. Each surgeon performed 2 reads per case within 8 weeks.

Results

G1: Interrater reliability between junior surgeons improved from the first read (κ = 0.40) to the second (κ = 0.76, p < 0.001) but did not change between senior surgeons (κ = 0.85). The intrarater reliability was similar for junior (κ = 0.78) and senior (κ = 0.71) surgeons. G2: Junior/senior surgeons agreed completely (58%/62%), partially (24%/23%), or did not agree (18%/15%) with the 7LC choice. G3: junior/senior surgeons agreed completely (50%/50%) or partially (50%/50%) with the 7LC choice.

Conclusion

The 7LC showed good overall reliability. Junior surgeons went through a learning curve and converged to senior surgeons in the second read. The 7LC helps less experienced surgeons to analyze, in a structured manner, the relevant clinical and imaging parameters influencing the choice of the surgical approach, rather than simply pointing out the only correct one.

Does index level sagittal alignment determine adjacent level disc height loss?

OBJECTIVE

The authors sought to compare the effect of index level sagittal alignment on cephalad radiographic adjacent segment pathology (RASP) in patients undergoing cervical total disc arthroplasty (TDA) or anterior cervical discectomy and fusion (ACDF).

METHODS

This was a retrospective study of prospectively collected radiographic data from 79 patients who underwent TDA or ACDF and were enrolled and followed prospectively at two centers in a multicenter FDA investigational device exemption trial of the Bryan cervical disc prosthesis used for arthroplasty. Neutral lateral radiographs were obtained pre- and postoperatively and at 1, 2, 4, and up to 7 years following surgery. The index level Cobb angle was measured both pre- and postoperatively. Cephalad disc degeneration was determined by a previously described measurement of the disc height/anteroposterior (AP) distance ratio.

RESULTS

Sixty-eight patients (n = 33 ACDF; n = 35 TDA) had complete radiographs and were included for analysis. Preoperatively, there was no difference in the index level Cobb angle between the ACDF and TDA patients. Postoperatively, the ACDF patients had a larger segment lordosis compared to the TDA patients (p = 0.002). Patients who had a postoperative kyphotic Cobb angle were more likely to have undergone TDA (p = 0.01). A significant decrease in the disc height/AP distance ratio occurred over time (p = 0.035), by an average of 0.01818 at 84 months. However, this decrease was not influenced by preoperative alignment, postoperative alignment, or type of surgery.

CONCLUSIONS

In this cohort of patients undergoing TDA and ACDF, the authors found that preoperative and postoperative sagittal alignment have no effect on RASP at follow-up of at least 7 years. They identified time as the only significant factor affecting RASP.

Mental State Can Influence the Degree of Postoperative Axial Neck Pain Following Cervical Laminoplasty

STUDY DESIGN

A retrospective cohort study.

OBJECTIVE

To investigate factors influencing the incidence of moderate to severe postoperative axial neck pain following cervical laminoplasty.

METHODS

We reviewed 125 patients with cervical myelopathy who underwent double-door laminoplasty. The primary outcomes were the Numerical Rating Scale score (NRS score, 0-10) for neck pain, the Short Form 36 (SF-36) Health Survey score (Physical and Mental Component Summary scores [PCS and MCS, respectively]), and satisfaction. Imaging parameters on plain radiographs and magnetic resonance imaging were also evaluated. Patients with moderate to severe postoperative neck pain (NRS ≥ 5) were compared with those with no or mild neck pain (NRS ≤ 4).

RESULTS

One hundred and three patients (82%) with complete data were eligible for inclusion. There were 67 men and 36 women, with a mean age of 65 years (32-89 years). Twenty-five patients (23%) had moderate to severe postoperative axial pain (NRS ≥ 5) and were compared with the other 78 patients (NRS ≤ 4), which revealed several predictive factors, including female sex, the presence of preoperative neck pain, low postoperative PCS, low preoperative and postoperative MCS, and satisfaction with the treatment. Multivariable logistic regression analysis revealed that the postoperative MCS (P = .002) was a risk factor for postoperative neck pain, although the preoperative MCS did not reach statistical significance (P = .06).

CONCLUSIONS

Patients with a low mental state, possibly before surgery, are at a high risk for postoperative axial neck pain. None of the imaging parameters were statistically different.

Comparison of Best Versus Worst Clinical Outcomes for Adult Cervical Deformity Surgery

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

Factors that predict outcomes for adult cervical spine deformity (ACSD) have not been well defined. To compare ACSD patients with best versus worst outcomes.

METHODS

This study was based on a prospective, multicenter observational ACSD cohort. Best versus worst outcomes were compared based on Neck Disability Index (NDI), Neck Pain Numeric Rating Scale (NP-NRS), and modified Japanese Orthopaedic Association (mJOA) scores.

RESULTS

Of 111 patients, 80 (72%) had minimum 1-year follow-up. For NDI, compared with best outcome patients (n = 28), worst outcome patients (n = 32) were more likely to have had a major complication (P = .004) and to have undergone a posterior-only procedure (P = .039), had greater Charlson Comorbidity Index (P = .009), and had worse postoperative C7-S1 sagittal vertical axis (SVA; P = .027). For NP-NRS, compared with best outcome patients (n = 26), worst outcome patients (n = 18) were younger (P = .045), had worse baseline NP-NRS (P = .034), and were more likely to have had a minor complication (P = .030). For the mJOA, compared with best outcome patients (n = 16), worst outcome patients (n = 18) were more likely to have had a major complication (P = .007) and to have a better baseline mJOA (P = .030). Multivariate models for NDI included posterior-only surgery (P = .006), major complication (P = .002), and postoperative C7-S1 SVA (P = .012); models for NP-NRS included baseline NP-NRS (P = .009), age (P = .017), and posterior-only surgery (P = .038); and models for mJOA included major complication (P = .008).

CONCLUSIONS

Factors distinguishing best and worst ACSD surgery outcomes included patient, surgical, and radiographic factors. These findings suggest areas that may warrant greater awareness to optimize patient counseling and outcomes.

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.

Quantitative and qualitative analyses of spinal canal encroachment during cervical laminectomy using the kerrison rongeur versus High-Speed burr

BACKGROUND

Several cervical laminectomy techniques have been described. One commonly used method involves making bilateral trough laminotomies using either a Kerrison rongeur or a high speed burr, and then removing the lamina en-bloc. Alternatively, some surgeons prefer to thin the lamina with the burr, and then remove the lamina in a piecemeal fashion using Kerrison rongeurs. Some surgeons have warned against the potential risk of iatrogenic spinal cord injury from inserting the Kerrison footplate into a stenotic canal. We aim to quantify the amount of canal encroachment for various methods of cervical laminectomies.

METHODS

Three attending spine surgeons and two fellows each performed laminectomies using C5 sawbones models. The canal was completely filled with modeling putty to simulate a stenotic spinal cord. Bilateral trough laminotomies were performed using a 1 mm Kerrison, a 2 mm Kerrison, and a 3 mm matchstick high-speed burr. Piecemeal laminectomies were performed with a 2 mm Kerrison. A blinded spine surgery fellow performed all quantitative measurements. Three blinded researchers qualitatively ranked the amount of "canal encroachment".

RESULTS

The average canal encroachment was 0.50 ± 0.45mm for the burr, 1.37 ± 0.68 mm for the 1 mm Kerrison, and 1.47 ± 0.37 mm for the 2 mm Kerrison (p = .002). There was a statistically significant difference between the burr and 1 mm Kerrison (p = .01) and between the burr and the 2 mm Kerrison (p = .001). There was no statistical difference between the 1 mm and 2 mm Kerrison (p = .78). The mean rank of the burr group, the Kerrison rongeur group, and the piecemeal group were 1.41, 1.94, and 2.65, respectively, on an ordinal scale of 1-3.

CONCLUSION

When performing a trough laminotomy, the high-speed burr results in less canal encroachment compared to 1 mm or 2 mm Kerrison rongeurs. In the setting of a stenotic spinal canal, spine surgeons should consider using the burr to perform laminectomy to minimize the degree of canal encroachment.

Cervical paraspinal muscle compartment pressure after laminoplasty: A cadaveric study

Axial neck pain is a common complaint after cervical laminoplasty and the causes are still not well-understood. We hypothesized that abnormal paracervical muscle compartment pressures might be one of them. The cervical paraspinal muscle compartment pressures of 10 cadavers were measured in six different areas under four different conditions. The posterior cervical area was divided into two sides: open side and hinge side. Then each side was divided into upper, middle, and lower areas. The compartment pressures of each area were measured under four different conditions: before and after dissection of posterior paravertebral (paraspinal) muscles, after laminoplasty and after laminoplasty with removal of the spinous processes. There was a statistically significant difference between the pressures after dissection versus after laminoplasty on the hinge side at all upper, middle and lower areas [p < 0.01, <0.001 and =0.009 respectively]. There was a difference in the pressures after laminoplasty between the open and hinge sides [p < 0.001, <0.001 and =0.023 respectively]. We also found the following significant differences: the pressures between before dissection and after laminoplasty on the hinge side, as well as between after laminoplasty and after removal of the spinous process on the hinge side in the upper and middle areas [p < 0.001, =0.0016 and p = 0.002, =0.023 respectively]. Cervical paraspinal muscle compartment pressures on the hinge side were significantly increased after laminoplasty. This may be a contributor to axial neck pain following laminoplasty. The pressure was then significantly decreased after removal of the spinous processes.

Anterior Cervical Foraminotomy: 2-Dimensional Operative Video

We provide a step-by-step technique guide for performing anterior cervical foraminotomy in this video. An illustrative case was presented with detailed narration and a discussion of surgical nuances. Anterior cervical foraminotomy can be an effective treatment strategy for patients with unilateral cervical radiculopathy without the need for cervical spine fusion. Spine surgeons should be familiar with technique and use it as a motion-preserving surgical option in treating isolated cervical radiculopathy. There is no identifying information in this video. A patient consent was obtained for publishing of the material included in the video.