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Gregory F. Jost, Erica F. Bisson and Meic H. Schmidt

Object

Placement of transarticular facet screws is one option for stabilization of the subaxial cervical spine. Small clinical series and biomechanical data support their role as a substitute for other posterior stabilization techniques; however, the application of transarticular facet screws in the subaxial cervical spine has not been widely adopted, possibly because of surgeon unfamiliarity with the trajectory. In this study, the authors' objective is to define insertion points and angles of safe trajectory for transarticular facet screw placement in the subaxial cervical spine.

Methods

Thirty fine-cut CT scans of cervical spines were reconstructed in the multiplanar mode and evaluated for safe transarticular screw placement in the subaxial cervical spine (C2–3, C3–4, C4–5, C5–6, C6–7). As in placement of lateral mass screws, the vertebral artery and exiting nerve root were bypassed posterolaterally. The entry point was set 1 mm medial and 1 mm caudal to the center of the lateral mass. From this entry point, the sagittal angulation was set to traverse the facet joint plane approximately perpendicularly. For the axial angulation, the exit point was set posterolaterally to the transverse process. After ideal insertion angles and screw lengths were identified, the trajectory was simulated on CT scans of 20 different cervical spines to confirm safe screw placement.

Results

The mean optimal mediolateral insertion angles (± SD) were as follows: 23° ± 5° at C2–3; 24° ± 4° at C3–4; 25° ± 5° at C4–5; 25° ± 4° at C5–6; and 33° ± 6° at C6–7. The mean sagittal insertion angles measured to the sagittal projection of the facet joint space were as follows: 77° ± 10° at C2–3; 77° ± 10° at C3–4; 80° ± 11° at C4–5; 81°± 8° at C5–6; and 100° ± 11° at C6–7. The mean trajectory lengths were 15 ± 2 mm at C2–3; 14 ± 1 mm at C3–4; 15 ± 1 mm at C4–5; 16 ± 2 mm at C5–6; and 23 ± 4 mm at C6–7. Simulation of these insertion angles on 20 different cervical spine CTs yielded a safe trajectory in 85%–95% of spines for C2–3, C3–4, C4–5, C5–6, and C6–7.

Conclusions

The calculated optimal insertion angles and lengths for each level may guide the safe placement of subaxial cervical transfacet screws.

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Erica F. Bisson, Deshpande V. Rajakumar and Praveen V. Mummaneni

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Marcus D. Mazur, Sara McEvoy, Meic H. Schmidt and Erica F. Bisson

OBJECT

Patient satisfaction scores have become a common metric for health care quality. Because satisfaction scores are right-skewed, even small differences in mean scores can have a large impact. Little information, however, is available on the specific factors that play a role in satisfaction in patients with spinal disorders. The authors investigated whether disability severity and the surgeon's recommendation for or against surgical intervention were associated with patient satisfaction scores.

METHODS

The authors conducted a retrospective cohort study involving adult patients who were referred to a spine surgeon for an outpatient evaluation of back pain. Patients completed the Oswestry Disability Index (ODI) before their clinic appointment and a Press Ganey patient satisfaction survey after their visit. Patients were grouped by self-assessed disability severity: mild to moderate (ODI < 40%) and severe (≥ 40%). Satisfaction scores were graded from 0 (very poor) to 100 (very good). Nonparametric tests were used to evaluate the association between patient satisfaction and current disability self-assessment. The authors also investigated whether the surgeon's recommendation against surgery negatively affected patient satisfaction.

RESULTS

One hundred thirty patients completed the ODI questionnaire before and satisfaction surveys after seeing a spine surgeon for a new outpatient back pain consultation. Of these, 68 patients had severe disability, 62 had mild to moderate disability, 67 received a recommendation for surgery, and 63 received a recommendation against surgery. Composite satisfaction scores were lower among patients who had severe disability than among those with mild to moderate disability (median [interquartile range]: 91.7 [83.7–96.4] vs 95.8 [91.0–99.3], respectively; p = 0.0040). Patients who received a recommendation against surgery reported lower satisfaction scores than those who received a recommendation for surgery (91.7 [83.5–95.8] vs 95.8 [88.5–99.8]; p = 0.0059).

CONCLUSIONS

High self-assessment of disability and a surgeon's recommendation against surgical intervention are associated with lower satisfaction scores in patients with spinal disorders.

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Erica F. Bisson, José-Carlos Sauri-Barraza, Toba Niazi and Meic H. Schmidt

Synovial cysts are uncommon pathological entities in patients with cervical degenerative spinal disease, and there are only a few reports in the literature. Treatment typically involves decompression; however, biomechanical data indicate that laminectomies in the cervical spine also result in cervical instability, specifically within the cervicothoracic junction, supporting the use of fusion as well. The authors describe the use of fusion with decompression in the treatment of 3 patients with cervicothoracic synovial cysts that presented in an acute fashion with associated myelopathy and neurological decline, and they review the diagnostic elements, histopathology, and treatment of these cysts. All 3 of the patients did well with decompression via a posterior approach with a single-level instrumented fusion from C-7 to T-1. Each patient regained complete neurological function and had no residual neurological deficits. These results are promising, although the sample size of 3 cases is too small to make any conclusive evaluations. Future studies incorporating Class I and Class II data are imperative to make firm conclusions regarding general management of this rare entity.

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Ziyad L. Khaleel, David A. Besachio, Erica F. Bisson and Lubdha M. Shah

Object

Posterior odontoid process inclination has been associated with Chiari malformation Type I in the pediatric population. There are varying reports to support a reliable range of odontoid inclination angles in control adults. The purpose of this study is to estimate the normal measurements in adults for odontoid retroflexion, retroversion, height, and the pB–C2 line (a line drawn through the odontoid tip from the ventral dura perpendicular to a second line from drawn the basion to the inferoposterior aspect of C-2 vertebral body) to establish a normative reference in this population.

Methods

After obtaining institutional review board approval, the authors performed a retrospective analysis of non–contrast enhanced cervical spine CT scans obtained in 150 consecutive control adults. Three neuroradiologists measured odontoid retroflexion, odontoid retroversion, odontoid height, and the pB–C2 line. The cohort was divided into sex and two age groups. Comparisons of the means with unpaired 2-tailed t-test were performed.

Results

A total of 125 subjects met the inclusion criteria; 80 were men and 45 were women (mean age 52 years, range 18–89 years). The odontoid retroflexion angle ranged from 70° to 89° (mean 79.3° ± 4.9°), and the odontoid retroversion angle ranged from 57° to 87° (mean 71.9° ± 5.3°). The range and mean of odontoid height were 17–27 mm and 22 ± 1.8 mm, respectively. The mean pB–C2 line was 6.5 ± 2.1 mm with a range of 0–11.2 mm. The results were also compared with previously published pediatric data.

Conclusions

The current study demonstrates that the odontoid process in adults is anatomically different from that in children: it is longer, more posteriorly inclined, and has a greater pB–C2 line. Therefore, utilization of these parameters with previously published cutoffs in the pediatric population is not appropriate for surgical planning in adults.

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Spencer Twitchell, Michael Karsy, Jared Reese, Jian Guan, William T. Couldwell, Andrew Dailey and Erica F. Bisson

OBJECTIVE

Efforts to examine the value of care—combining both costs and quality—are gaining importance in the current health care climate. This thrust is particularly evident in treating common spinal disease where both incidences and costs are generally high and practice patterns are variable. It is often challenging to obtain direct surgical costs for these analyses, which hinders the understanding of cost drivers and cost variation. Using a novel tool, the authors sought to understand the costs of posterior lumbar arthrodesis with interbody devices.

METHODS

The Value Driven Outcomes (VDO) database at the University of Utah was used to evaluate the care of patients who underwent open or minimally invasive surgery (MIS), 1- and 2-level lumbar spine fusion (Current Procedural Terminology code 22263). Patients treated from January 2012 through June 2017 were included.

RESULTS

A total of 276 patients (mean age 58.9 ± 12.4 years) were identified; 46.7% of patients were men. Most patients (82.2%) underwent 1-level fusion. Thirteen patients (4.7%) had major complications and 11 (4.1%) had minor complications. MIS (β = 0.16, p = 0.002), length of stay (β = 0.47, p = 0.0001), and number of operated levels (β = 0.37, p = 0.0001) predicted costs in a multivariable analysis. Supplies and implants (55%) and facility cost (36%) accounted for most of the expenditure. Other costs included pharmacy (7%), laboratory (1%), and imaging (1%).

CONCLUSIONS

These results provide direct cost accounting for lumbar fusion procedures using the VDO database. Efforts to improve the value of lumbar surgery should focus on high cost areas, i.e., facility and supplies/implant.

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Erica F. Bisson, Gregory F. Jost, Ronald I. Apfelbaum and Meic H. Schmidt

Object

The use of minimally invasive noninstrumented fusions has increased as thoracoscopic approaches to the spine have evolved. The addition of instrumentation is infrequent, in part because of the lack of a minimally invasive implant system. The authors describe a technique for thoracoscopic plating after discectomy and report early clinical outcomes.

Methods

After a standard endoscopic discectomy and partial corpectomy and before exposure of the ventral thecal sac, the authors implanted a polyaxial screw and clamping element under fluoroscopic guidance. Reconstruction involves placement of autograft in the defect and subsequent placement of the remainder of the screw/plate construct with 2 screws per vertebral level.

Results

Twenty-five patients underwent thoracoscopic and thoracoscopy-assisted discectomies and fusion in which the aforementioned plate system was used. Of 19 patients presenting with pain, 10 had 6-month clinical follow-up with a greater than 50% reduction in visual analog scale score, which continued to improve up to 2 years postoperatively. There were 3 cases of pneumonia, 3 CSF leaks, 1 chyle leak, and 1 death due to a massive pulmonary embolus on the 1st postoperative day.

Conclusions

The authors conclude that thoracoscopic discectomy and plate-instrumented fusion can be achieved with acceptable results and morbidity. Further studies should evaluate the role of instrumented fusions after thoracoscopic discectomy in larger groups of patients and during a longer follow-up period.

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Marcus Mazur, Gregory F. Jost, Meic H. Schmidt and Erica F. Bisson

Object

Anterior decompression is an effective way to treat cervical myelopathy associated with ossification of the posterior longitudinal ligament (OPLL); however, this approach is associated with an increased risk of a dural tear and resultant CSF leak because fusion of the dura with the ossified PLL is common in these cases. The authors review the literature and present an algorithm for treatment of CSF leaks in these patients.

Methods

A MEDLINE review was performed to identify papers related to CSF leak after anterior decompression for OPLL, and data were summarized to identify treatment options for various situations. A treatment algorithm was identified based on these findings and the experience of the authors.

Results

Eleven studies were identified that presented data on intra- and postoperative management of a CSF leak during ventral surgery for OPLL. The incidence of cervical dural tears and CSF leaks after anterior decompression procedures for OPLL ranged from 4.3% to 32%. Techniques including preventative measures, intraoperative dural repair with various materials, and postoperative drainage or shunt placement have all been used.

Conclusions

Although direct dural repair is the preferred treatment for CSF leak, this technique is not always technically possible. In these cases, intraoperative adjuncts in combination with postoperative measures can be used to decrease the pressure gradient across the dural tear.

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Jakub Godzik, Vijay M. Ravindra, Wilson Z. Ray, Meic H. Schmidt, Erica F. Bisson and Andrew T. Dailey

OBJECT

The authors’ objectives were to compare the rate of fusion after occipitoatlantoaxial arthrodesis using structural allograft with the fusion rate from using autograft, to evaluate correction of radiographic parameters, and to describe symptom relief with each graft technique.

METHODS

The authors assessed radiological fusion at 6 and 12 months after surgery and obtained radiographic measurements of C1–2 and C2–7 lordotic angles, C2–7 sagittal vertical alignments, and posterior occipitocervical angles at preoperative, postoperative, and final follow-up examinations. Demographic data, intraoperative details, adverse events, and functional outcomes were collected from hospitalization records. Radiological fusion was defined as the presence of bone trabeculation and no movement between the graft and the occiput or C-2 on routine flexion-extension cervical radiographs. Radiographic measurements were obtained from lateral standing radiographs with patients in the neutral position.

RESULTS

At the University of Utah, 28 adult patients underwent occipitoatlantoaxial arthrodesis between 2003 and 2010 using bicortical allograft, and 11 patients were treated using iliac crest autograft. Mean follow-up for all patients was 20 months (range 1–108 months). Of the 27 patients with a minimum of 12 months of follow-up, 18 (95%) of 19 in the allograft group and 8 (100%) of 8 in the autograft group demonstrated evidence of bony fusion shown by imaging. Patients in both groups demonstrated minimal deterioration of sagittal vertical alignment at final follow-up. Operative times were comparable, but patients undergoing occipitocervical fusion with autograft demonstrated greater blood loss (316 ml vs 195 ml). One (9%) of 11 patients suffered a significant complication related to autograft harvesting.

CONCLUSIONS

The use of allograft in occipitocervical fusion allows a high rate of successful arthrodesis yet avoids the potentially significant morbidity and pain associated with autograft harvesting. The safety and effectiveness profile is comparable with previously published rates for posterior C1–2 fusion using allograft.

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Jian Guan, Vijay M. Ravindra, Meic H. Schmidt, Andrew T. Dailey, Robert S. Hood and Erica F. Bisson

OBJECTIVE

Recurrent lumbar disc herniation (RLDH) is a significant cause of morbidity in patients undergoing lumbar discectomy and has been reported to occur in up to 18% of cases. While repeat discectomy is often successful in treating these patients, concern over repeat RLDH may lead surgeons to advocate instrumented fusion even in the absence of instability. The authors' goal was to compare clinical outcomes for patients undergoing repeat discectomy versus instrumented fusion for RLDH.

METHODS

The authors used the National Neurosurgery Quality and Outcomes Database (N2QOD) to assess outcomes of patients who underwent repeat discectomy versus instrumented fusion at a single institution from 2012 to 2015. Primary outcomes included Oswestry Disability Index (ODI) score, visual analog scale (VAS) score, and quality-adjusted life year (QALY) measures. Secondary outcomes included hospital length of stay, discharge status, and hospital charges.

RESULTS

The authors identified 25 repeat discectomy and 12 instrumented fusion patients with 3- and 12-month follow-up records. The groups had similar ODI and VAS scores and QALY measurements at 3 and 12 months. Patients in the instrumented fusion group had significantly longer hospitalizations (3.7 days vs 1.0 days, p < 0.001) and operative times (229.6 minutes vs 82.7 minutes, p < 0.001). They were also more likely to be female (p = 0.020) and to be discharged to inpatient rehabilitation instead of home (p = 0.036). Hospital charges for the instrumented fusion group were also significantly higher ($54,458.29 vs $11,567.05, p < 0.001). Rates of reoperation were higher in the repeat discectomy group (12% vs 0%), but the difference was not statistically significant (p = 0.211).

CONCLUSIONS

Repeat discectomy and instrumented fusion result in similar clinical outcomes at short-term follow-up. Patients undergoing repeat discectomy had significantly shorter operative times and length of stay, and they incurred dramatically lower hospital charges. They were also less likely to require acute rehabilitation postoperatively. Further research is needed to compare these two management strategies.