An Algorithmic Posterior Approach to the Treatment of Multilevel Degenerative Cervical Spine Disease: A Multicenter Prospective Study.

BACKGROUND: The choice of surgical method for the treatment of multilevel degenerative cervical spine disease is based on the assessment of neurological symptoms and anatomical source of compression. However, such decision-making process remains complex and poorly defined. PURPOSE: To analyze the effectiveness of an algorithmic posterior approach to the surgical treatment of patients with multilevel degenerative disease of the cervical spine based on the preoperative clinical and imaging parameters. STUDY DESIGN: Prospective nonrandomized multicenter cohort study. METHODS: The study included 338 patients with multilevel degenerative disease of the cervical spine. Two groups of patients were evaluated at 3 neurosurgical centers between 2015 and 2019. The prospective group (Group I, n = 214) consisted of patients who were treated using an algorithm to decide whether they should be treated with an instrumented arthrodesis or a nonfusion procedure. The control group (Group II, n = 124) consisted of patients who underwent posterior decompression with or without stabilization between 2007 and 2014. A total of 192 patients in Group I and 112 in Group II had more than 2 years of follow-up. Visual analog scale (VAS) neck pain, Neck Disability Index (NDI), MacNab and Nurick Scales were collected. Perioperative complications were identified. RESULTS: At 2-year follow-up, Group I had significantly better clinical outcomes based on VAS neck pain score (P = 0.02), NDI score (P = 0.01), satisfaction with surgery on the MacNab Scale (P < 0.001), and outcome of surgery based on the Nurick Scale (P < 0.001). Complication rate was lower in Group I, 5.7% compared with 34.8% in Group II, P = 0.004. CONCLUSIONS: The algorithmic posterior approach to the surgical treatment of patients with multilevel degenerative disease of the cervical spine resulted in significant improvement of functional outcomes and a decrease in complications at a minimum 2 years of follow-up.

Impact of Cervical Disc Arthroplasty vs Anterior Cervical Discectomy and Fusion on Driving Disability: Post Hoc Analysis of a Randomized Controlled Trial With 10-Year Follow-Up.

BACKGROUND: Driving an automobile requires the ability to turn the neck laterally. Anecdotally, patients with multilevel fusions often complain about restricted turning motion. The purpose of this study was to compare the effectiveness of cervical disc arthroplasty (CDA) with anterior cervical discectomy and fusion (ACDF) on driving disability improvement at 10-year follow-up after a 2-level procedure. METHODS: In the original randomized controlled trial, patients with cervical radiculopathy or myelopathy at 2 levels underwent CDA or ACDF. The driving disability question from the Neck Disability Index was rated from 0 to 5 years preoperatively and up to 10 years postoperatively. Severity of driving disability was categorized into "none" (score 0), "mild" (1 or 2), and "severe" (3, 4, or 5). Score and severity were compared between groups. RESULTS: Out of 397 patients, 148 CDA and 118 ACDF patients had 10-year follow-up. Driving disability scores were not different between the groups preoperatively (CDA: 2.65; ACDF: 2.71, P = 0.699). Postoperatively, the scores in the CDA group were significantly lower than those in the ACDF group at 5 (0.60 vs 1.08, P ≤ 0.001) and 10 years (0.66 vs 1.07, P = 0.001). Mean score improvement in the CDA group was significantly greater than the ACDF group at 10-year follow-up (-1.94 vs -1.63, P = 0.003). The majority of patients reported severe driving disability (CDA: 56.9%, ACDF: 58.0%, P = 0.968) before surgery. After surgery, a greater proportion of patients in the CDA group had neck pain-free driving compared with the ACDF group at 5 (63.3% vs 41.8%, P < 0.001) and 10 years (61.8% vs 41.2%, P = 0.003). CONCLUSION: In patients with cervical radiculopathy/myelopathy and 2-level disease, CDA provided greater improvements in driving disability as compared with ACDF at 10-year follow-up. This is the first report of its kind. This finding may be attributable to preservation of motion associated with CDA. CLINICAL RELEVENCE: This study provides valuable information regarding the improvement of driving disability after both CDA and ACDF. It demonstrates that both procedures result in significant improvements, with CDA resulting in even better improvements than ACDF, up to 10 year follow-up.

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.

Can standard anterior Smith-Robinson supramanubrial approach be utilized for approach down to T2 or T3?

PURPOSE: The aim of this study was to determine a plain radiographic criterion for determining the feasibility of using the standard anterior Smith-Robinson supramanubrial approach for anterior surgery down to T2 or T3. METHODS: The surgical database (2002-2014) was searched to identify patients with anterior cervical surgery to T2 or T3. A method to determine whether a standard anterior Smith-Robinson approach can be used to operate on the upper thoracic levels was evaluated. The surgeon chose the surgical approach preoperatively using a lateral radiograph by determining if a line from the intended skin incision to the lower instrumented level (LIV) passed above the top of the manubrium. If so, a standard Smith-Robinson approach was selected. Another spine surgeon then analyzed all patients who had anterior thoracic fusion to T2 or below. The lateral radiographs were retrospectively reviewed. RESULTS: A total of 44 patients who underwent anterior surgery down to T2 or T3 vertebrae were identified. T2 was the LIV in 39 patients. T3 was the LIV in five patients. No surgery was abandoned or converted to a difference approach after making the standard Smith-Robinson approach. To increase visualization, T1 corpectomy was necessary in 4 of 39 patients when T2 was the LIV. T2 corpectomy was necessary in 2 of 5 patients when T3 was the LIV. CONCLUSION: If a line from the intended skin incision to the LIV passes over the top of the manubrium, a standard Smith-Robinson approach without sternotomy can be successfully used.

Influence of the Number of Cervical Fusion Levels on Cervical Spine Motion and Health-Related Quality of Life.

STUDY DESIGN: A retrospective study. OBJECTIVE: To analyze the influence of the number of cervical fusion levels on total cervical motion and health-related quality of life (HRQoL) in patients with solid anterior cervical fusions (ACFs). SUMMARY OF BACKGROUND DATA: Few studies have analyzed the degree to which cervical range of motion (ROM) and HRQoL are affected by the number of cervical fusion segments. METHODS: We analyzed a cohort of patients who underwent ACF for degenerative disc disease. To assess the clinical outcomes and HRQoL, preoperative, 1- and 2-year postoperative neck and arm pain, visual-analogue scale, neck disability index, and short form-36 were analyzed. Radiographically, C2-7 and C0-2 ROM, C2-7 sagittal vertical axis (SVA), and Kellgren grade of radiographic adjacent segment pathology (RASP) were evaluated. RESULTS: A total of 105 patients (M:F = 46:59, mean age of 51.4 yr) were enrolled. There were 36 patients who underwent single-level ACF (group 1), 41 patients who had a double level ACF (group 2), and 28 patients who underwent ACF involving 3 or more levels (group 3). There was no decrease in C2-7 motion in group 1, a mean 7-degree decrease in group 2, a mean 18-degree decrease in those who underwent a 3-level ACF, and a mean 22-degree decrease after 4-level ACF. The grade of RASP was not influenced by the number of fusion levels. All HRQoL parameters showed no significant correlation between number of fusion levels, cervical ROM, and SVA. CONCLUSION: Single-level ACF showed no decrease in total cervical motion; multilevel ACF decreased cervical motion by a mean of 7.8 degrees per segment of fusion. Progression of RASP showed no correlation with the number of fusion levels. HRQoLs were not influenced by the number of fusion levels, cervical ROM, or SVA after solid ACF. LEVEL OF EVIDENCE: 3.

Cervical osteotomies for neurological deformities.

PURPOSE: To report our experience and technique for performing cervical osteotomies under the setting of cervical deformity and myelopathy. METHODS: Patients who underwent cervical osteotomies for CD with myelopathy were identified in a 10 year period from 2000 to 2010. Demographics, surgery type, osteotomy type, operative details, and radiographs were collected for pre-operative and ultimate post-operative time points. Cervical lordosis (CL) and basion plumb line were collected to assess angular and translational corrections. RESULTS: In the study period, a total of 35 patients underwent a cervical osteotomy for fixed cervical deformity with a diagnosis of cervical myelopathy or myeloradiculopathy with an average follow-up of 3.4 years (range 1.0-6.3). The cohort was separated into two groups based on the type of surgical approach taken to correct their deformity. Anterior osteotomy with or without posterior instrumentation were performed in 31 patients (Group 1). Pedicle subtraction osteotomies were performed in 4 patients (Group 2). For Group 1, the mean angular correction achieved in this was 27.7° (range 9.0-66.0°) and the mean translational correction was 1.8 cm (range 0.1-2.4 cm). In group 2, the mean angular correction was 48.8° (range 38.4-68.3°) and the mean translational correction was 2.8 cm per PSO (range 0.1-5.6 cm). Similar improvements in pre- and post-operative Neck Disability Index scores were achieved with either osteotomy technique. CONCLUSIONS: We present our series of patients with cervical myelopathy and/or radiculopathy and concurrent cervical deformity who were treated with cervical osteotomies. The re-alignment of the spine was a key step in preventing the progression of myelopathy and protecting the spinal cord from the continued injury.

Does whole-spine lateral radiograph with clavicle positioning reflect the correct cervical sagittal alignment?

PURPOSE: To evaluate the differences of cervical alignment between standing cervical lateral radiograph and whole-spine lateral radiograph with clavicle position. METHODS: We prospectively evaluated 101 asymptomatic adults from whom standing cervical lateral radiograph with hands on both side followed by whole-spine lateral radiographs with clavicle position were obtained from April 2012 to December 2013. On two radiographs, cervical sagittal alignment from C2 to C7 was analyzed by Gore angle (GA) and Cobb angle (CA); head position was evaluated using the translation distance (TD, distance of the anterior tubercle of C1 compared with the vertical line through the posterior-inferior body of C7) and McGregor angle (MA, angle between the McGregor and horizontal lines). T1-slope was also evaluated. RESULTS: Cervical alignment on the cervical radiograph (GA -13.59° [-15.58 to -11.60], CA -9.76° [-11.65 to -7.86]) was significantly more lordotic than that on whole-spine radiographs (GA -6.28° [-8.65 to -3.91] and -4.14° [-6.40 to -1.89]). TD and MA on cervical radiographs (TD 34.98 mm [33.22-36.75]; MA 7.20° [6.35-8.35]) were meaningfully higher than those on whole-spine radiographs (TD 31.31 mm [29.47-33.16]; MA 6.32° [5.25-7.39]), but the MA values were not significant (p = 0.064). T1-slope was significantly lower in whole-spine radiographs (20.11° [18.88-21.35]) than in cervical radiographs (24.37° [23.14-25.6]). Values are expressed as mean (95 % confidence interval). CONCLUSIONS: Clavicle position during whole-spine radiograph caused a substantial decrease in the T1-slope; head position posteriorly translated followed by the cervical sagittal alignment became more hypo-lordotic, with slight downward gazing in comparison with the cervical radiograph.

Optimal entry points and trajectories for cervical pedicle screw placement into subaxial cervical vertebrae.

The present study was performed to determine the optimal entry points and trajectories for cervical pedicle screw insertion into C3-7. The study involved 40 patients (M:F = 20:20) with various cervical diseases. A surgical simulation program was used to construct three-dimensional spine models from cervical spine axial CT images. Axial, sagittal, and coronal plane data were simultaneously processed to determine the ideal pedicle trajectory (a line passing through the center of the pedicle on coronal, sagittal, and transverse CT images). The optimal entry points on the lateral masses were then identified. Horizontal offsets and vertical offsets of the optimal entry points were measured from three different anatomical landmarks: the lateral notch, the center of the superior edge and the center of lateral mass. The transverse angle and sagittal angles of the ideal pedicle trajectory were measured. Using those entry points and trajectory results, virtual screws were placed into the pedicles using the simulation program, and the outcomes were evaluated. We found that at C3-6, the optimal entry point was located 2.0-2.4 mm medial and 0-0.8 mm inferior to the lateral notch. Since the difference of 1 mm is difficult to discern intra-operatively, for ease of remembrance, we recommend rounding off our findings to arrive at a starting point for the C3-6 pedicle screws to be 2 mm directly medial to the lateral notch. At C7, by contrast, the optimal entry point was 1.6 mm lateral and 2.5 mm superior to the center of lateral mass. Again, for ease of remembrance, we recommend rounding off these numbers to use a starting point for the C7 pedicle screws to be 2 mm lateral and 2 mm superior to the center of lateral mass. The average transverse angles were 45° at C3-5, 38° at C6, and 28° at C7. The entry points for each vertebra should be adjusted according to the transverse angles of pedicles. The mean sagittal angles were 7° upward at C3, and parallel to the upper end plate at C4-7. The simulation study showed that the entry point and ideal pedicle trajectory led to screw placements that were safer than those used in other studies.

The utility of somatosensory evoked potential monitoring during cervical spine surgery: how often does it prompt intervention and affect outcome?

STUDY DESIGN: Retrospective review of the results of somatosensory evoked potentials (SSEP) performed in cervical spine surgery. PURPOSE: To evaluate the utility of spinal cord monitoring during cervical spine surgery in a single surgeon's practice, based on how often it prompted an intraoperative intervention. OVERVIEW OF LITERATURE: Intraoperative monitoring during cervical spine surgery is not a universally accepted standard of care. This is due in part to the paucity of literature regarding the impact of monitoring on patient management or outcome. METHODS: SSEP for tibial, median, and ulnar nerves were monitored in 809 consecutive cervical spine operations performed by a single surgeon. The average patient age was 52 years (range, 2 to 88 years), with 472 males and 339 females. Cases were screened for significant degradation or loss of SSEP data. Specific attention was paid to 1) what interventions were performed in response to the SSEP degradation with subsequent improvement, and 2) whether SSEP changes corresponded with postoperative neurological deficits. RESULTS: Seventeen of 809 patients (2.1%) had SSEP degradation that met warning criteria and therefore prompted intervention. Release of shoulder tape (8) or traction (4) most often resulted in SSEP improvement. Failure of SSEP data to return to within acceptable limits of baseline was associated with neurological deficit (p=0.04). Two patients awoke with new postoperative neurological deficits, which resolved in 6 hours and 2 months respectively. Patients with ossification of the posterior longitudinal ligament (OPLL) were at seven-fold greater risk of intraoperative SSEP degradation. CONCLUSIONS: SSEP monitoring in this surgical population proved sensitive to perioperative factors which may increase the risk of postoperative neurologic deficit, and probably prevented neurological deficits in 15 of 809 patients (1.9%). Improvement in data following intervention appears to correlate well with unchanged neurologic status. Experience with intraoperative monitoring in this patient series has led to incorporation of these techniques as a standard of care in cervical spine surgeries performed by this surgeon.

Long-term complications in adult spinal deformity patients having combined surgery a comparison of primary to revision patients.

STUDY DESIGN: This is a comparison of primary (N = 18) to revision (N = 26) combined (anterior and posterior surgery) adult spinal deformity patients with regard to late (>6 months) complications and radiographic/functional outcomes at a minimum 2-year follow-up. OBJECTIVES: To determine whether revision status increases the risk of late complications or offers a poor prognosis for functional outcome in adult deformity patients. SUMMARY OF BACKGROUND DATA: It is known that patients who have combined surgery for adult deformity have a high incidence of perioperative complications. Long-term complications and the effect of revision status have not been clarified in the literature. The functional outcomes for these patients are unclear as to whether or not there is a difference between primary and revision patients. Outside the arena of adult spinal deformity the functional outcomes for revision cases have been disappointing. METHODS: A consecutive series of 44 patients who underwent combined procedures for adult spinal deformity were followed for a minimum of 2 years (average follow-up 42 months). Clinical data were obtained by chart and radiographic review. Major complications were considered to be deep wound infection, pseudarthrosis, transition syndrome, neurologic deficit, and death. Minor complications considered were asymptomatic instrumentation failure (without loss of correction), instrumentation prominence requiring removal, and proximal or distal junctional segmental kyphosis (5-10 degrees ) or subsequent disc space narrowing of 2-5 mm without clinical symptoms. The patients also completed the AAOS Lumbar/Scoliosis MODEMS questionnaires aimed at assessing pain, function, and satisfaction. RESULTS: Minor complications were comparable in both groups: 4 of 18 (22%) in the primary group and 6 of 26 (23%) in the revision group. Major complications were slightly more frequent in the primary group with five complications in 4 patients (4 of 18 patients) (22%) compared with 3 of 26 patients (12%) in the revision group. The incidence of pseudarthrosis was 22% (4 of 18) for the primary group and 4% (1 of 26) for the revision group (P< 0.14). Forty of 44 patients completed the questionnaires. The primary patients functioned at a slightly higher level after surgery than the revision group. The level of pain was also slightly lower at final follow-up in the primary group. Despite these differences, the revision group had a higher level of patient satisfaction. CONCLUSION: At a minimum 2-year follow-up the late complications were not higher in the revision patients than in the primary group. The rate of major long-term complications, specifically pseudarthroses, was higher in the primary group. Patient satisfaction was higher in the revision patients, probably because they were experiencing a greater level of perceived pain and dysfunction at the time of their reconstruction.