The Outcomes of Revision Anterior Cervical Decompression and Fusion Using a Stand-Alone Implant Versus Traditional Interbody Polyetheretherketone Cage, Titanium Plate, and Screw Instrumentation

INTRODUCTION

Anterior cervical decompression and fusion (ACDF) is the standard surgical procedure for cervical radiculopathy and myelopathy, although ACDF includes risks of adjacent segment disease (ASD) and subsequent revision procedures. Various interbody cage, plate, and screw options can be utilized. Stand-alone devices were designed to overcome undesired complications of hardware prominence and associated dysphagia, soft tissue violation, and adjacent level encroachment. Implants include biomechanical structural support (cage) composed of various materials (polyetheretherketone (PEEK)/titanium) and integral fixation (screws/blades). The purpose was to compare intraoperative, short- and long-term outcomes of revision ACDF using a stand-alone implant (ACDF-ZP group) versus traditional interbody PEEK cage, titanium plate, and screw instrumentation (ACDF-CP group).

METHODS

This was a retrospective, cohort study reviewing charts of patients who underwent revision ACDF. The primary outcome measure was the incidence of postoperative dysphagia. Secondary outcomes included intraoperative, short-term, and long-term outcomes and complications.

RESULTS

Sixty-one patients were included (ACDF-ZP group = 50; ACDF-CP group = 11). In-hospital incidence of dysphagia was significantly less in the ACDF-CP group (P = 0.041). Thrity-one (62.0%) of the ACDF-ZP group reported dysphagia postoperatively, half resolved by 6 weeks, and two persisted for more than 6 months. Five (45.5%) of the ACDF-CP group reported dysphagia with most resolving within 6 weeks. There were no statistically significant differences between groups in short- or long-term complications, dysphonia, or reoperation rates. No statistical significance was seen in blood loss, operative time, hospital stay, local and global alignment, or cage subsidence.

CONCLUSION

Rates of dysphagia were comparable between groups at short and long-term follow-up, despite a greater incidence of postoperative dysphagia in the ACDF-ZP group. All complications and occurrences of cage subsidence were observed in the ACDF-ZP group, which may be attributed to the larger sample size. Given these findings, zero-profile stand-alone implants and traditional interbody PEEK cage, titanium plate, and screw instrumentation appear to be both safe and effective options for revision ACDF.

CT based bone mineral density as a predictor of proximal junctional fractures

Background

Proximal junctional fractures (PJFr) can be a catastrophic complication associated with adult spinal deformity surgery. Osteoporosis can be a major risk factor for the cause of PJFr. Recent studies suggest using surrogate computed tomography (CT) scans in place of spinal dual-energy x-ray absorptiometry (DEXA) scores for bone mineral density (BMD). Investigate the feasibility of using preoperative CT based bone mineral density at upper instrumented vertebrae (UIV) and one level proximally (UIV+1) and distally (UIV-1) to predict the possibility of PJFr risk.

Methods

Retrospective two-academic center case-controlled study, reviewed consecutive adult spinal deformity surgeries; included constructs encompassing at least five fusion levels and fusions to pelvis. Examined demographic, surgical, and radiographic data preoperatively, postoperatively, and final follow-up. Formed groups based on type of proximal junctional deformity (PJD): Control (no PJD), proximal junctional kyphosis (PJK) and PJFr. Preoperative CT BMD values measured in Hounsfield units (HU) for sagittal and axial planes at UIV, UIV+1, and UIV-1 and compared between groups.

Results

N=92 patients. Preoperative CT scan BMD values were significantly lower in PJFr vs. control at: UIV+1 in sagittal (p=0.007), axial (p=0.02) planes; UIV sagittal (p=0.04) and axial (p=0.03) planes; and UIV-1 sagittal (p=0.05) plane. Similarly, lower CT scan BMD values noted in PJFr vs. PJK at: UIV+1 in sagittal (p=0.04) and axial (p=0.03) planes. Trend seen with lower CT scan BMD values at UIV+1 level in PJFr vs. PJK in sagittal (p=0.12) and axial (p=0.10) planes. Preoperative global sagittal imbalance measurements significantly lower in control, but comparable between PJK and PJFr.

Conclusions

Higher preoperative global sagittal imbalance with lower preoperative CT BMD values at UIV and UIV+1 vertebral body may increase the risk of proximal junctional fractures after adult spine deformity surgery. Proximal junctional hooks may supplement the pathogenesis. Readers should note the small sample size.

Level of Evidence: 3

Distal Ventral Iliac Pathway for Spinopelvic Fixation: Technique Description and Case Series

BACKGROUND

Pelvic fixation improves the stability of spinal instrumentation and can be used in high-grade degenerative disease, trauma, deformity, and destabilizing invasive pathologies, such as infection and tumor. Classic techniques for spinopelvic fixation include traditional iliac screws and S2-Alar-Iliac screws. We present a case series describing the distal ventral iliac pathway (DVIP) for spinopelvic fixation and discuss surgical indications and merits of this technique. We describe the use of the DVIP for spinopelvic fixation in the setting of degenerative and traumatic pathologies, compare this technique with existing approaches, and summarize literature to support this approach.

METHODS

One hundred twenty-eight cases of DVIP screws were identified at 1 academic medical center, and 3 cases were chosen as representative examples for technique demonstration.

RESULTS

Patient ages ranged from 19 to 81 (mean 62) years. Intraoperative and postoperative complications include 12 incidental durotomies, 3 suprafascial infections, and 2 compressive hematomas. There were 22 instances of hardware failure and 8 instances of pseudoarthrosis. Overall, 26 patients underwent revision surgery. Mean estimated blood loss, operative time, and time under fluoroscopy were 1959 mL, 386 minutes, and 3.19 minutes, respectively.

CONCLUSIONS

The DVIP is both safe and effective as a treatment for patients with degenerative and traumatic lumbosacral pathology. Spinopelvic fixation provides improved soft tissue coverage and fewer hardware complications at minimum of 1 year follow up. This case series demonstrates a novel surgical technique for spinopelvic fixation in the setting of numerous spinal pathologies.

LEVEL OF EVIDENCE

4.

CLINICAL RELEVANCE

This surgical technique is less technically challenging than current approaches, minimizes radiation exposure, and obviates the need for horizontal connector rods. In addition, in highly destabilizing pathologies, this technique also allows for multiple screw placement within the ilium, while maintaining the ability to connect to a single rod construct. This technique is safe, technically approachable, and broadly applicable to an array of spinopelvic pathologies.

Perioperative Intravenous Corticosteroids and Radiographic Prevertebral Soft Tissue Swelling in Anterior Cervical Fusion for Degenerative Disease

OBJECTIVE

Prevertebral soft tissue swelling (PSTS) is a known complication of anterior cervical fusion (ACF). Prior studies have shown that perioperative steroids may reduce PSTS after ACF. We retrospectively evaluated the role of perioperative intravenous (IV) corticosteroid administration in minimizing radiographic PSTS measurements in patients undergoing ACF for degenerative disease.

METHODS

Records of 100 consecutive patients undergoing ACF for degenerative disease (Current Procedural Terminology code 63075) from January 2010 through December 2012 by 2 orthopedic spine fellowship-trained surgeons at a single institution were retrospectively reviewed. Patients were included on the basis of specific criteria. They were then separated into comparison and IV steroid groups. Demographic and surgical data were collected. Last, measurements of PSTS, which included PSTS ratio and PSTS index (PSTSI), were obtained from plain radiographs preoperatively and at 3 postoperative time points.

RESULTS

Eighty patients were included; 26 received IV steroids at the surgeon's discretion (12 intraoperatively, 11 postoperatively and 3 at both time periods). With the exception of a history of prior anterior cervical spine surgery (3.70% comparison vs. 23.08% IV steroid, P = 0.01), there was no statistically significant demographic characteristic. Furthermore, there was no statistically significant surgical characteristic. Last, there was no statistically significant difference between groups at any time point for either PSTS ratio at any level or PSTSI.

CONCLUSIONS

There does not appear to be a role for perioperative IV steroid administration in minimizing radiographic PSTS in patients undergoing ACF for degenerative disease. The relationship between perioperative IV steroid administration and PSTS requires further investigation.

Assessment of Coronal Spinal Alignment for Adult Spine Deformity Cases After Intraoperative T Square Shaped Use

STUDY DESIGN

Retrospectively reviewed surgeries between 2011 and 2015 of patients who underwent posterior spinal deformity instrumentation with constructs involving fusions to pelvis and encompassing at least five levels.

OBJECTIVE

Measure the radiographic outcomes of coronal malalignment (CM) after use of an intraoperative T square shaped instrument in posterior spinal deformity surgeries with at least five levels of fusion and extension to pelvis.

BACKGROUND

Neuromuscular children found to benefit from intraoperative T square technique to help achieve proper coronal spinal balance with extensive fusions. This intraoperative technique used in our posterior spine deformity instrumentation surgeries with the aforementioned parameters.

METHODS

There were 50 patients: n = 16 with intraoperative T square and n = 34 no-T square shaped device. Subgroups divided based on greater than 20 mm displacement and greater than 40 mm displacement of the C7 plumb line to the central sacral vertical line on either side in preoperative radiographs. We analyzed the demographics and the pre- and postoperative radiographic parameters of standing films: standing CM (displacement of C7 plumb line to central sacral vertical line), and major coronal Cobb angles in total sample and subgroups and compared T square shaped device with no-T square shaped device use by analysis of variance. A p value ≤.05 is statistically significant.

RESULTS

In the total sample, though postoperative CM mean was not statistically different, we observed greater CM corrections in patients where a T square shaped device was used (70%) versus no-T square shaped device used (18%). In >20 mm and >40 mm subgroups, the postoperative mean CM values were statistically lower for the patients where a T square shaped device was used, p = .016 and p = .003, respectively. Cobb corrections were statistically higher for T square shaped device use in both >20 mm and >40 mm subgroups, 68%, respectively.

CONCLUSION

The intraoperative T square shaped device technique had a positive effect on the amount of spine coronal malalignment correction after its use and for lumbar and thoracic coronal Cobb angles.

LEVEL OF EVIDENCE

Level III.

Assessment of Inter- and Intraobserver Reliability and Accuracy to Evaluate Apical Vertebral Rotation Using Four Methods: An Experimental Study Using a Saw Bone Model

STUDY DESIGN

After placing a thoracic three-vertebra segment saw bones model on a standardized turntable, a series of anteroposterior (AP) radiographs were obtained and then set in increments to 90° rotation. Then the specimen was instrumented with 35-mm pedicle screws bilaterally and the rotation process and image acquisition were repeated.

OBJECTIVE

Assess reliability and accuracy of spine surgeons evaluating apical vertebral rotation (AVR) through surgeon's visual x-ray estimation, Nash-Moe system, Upasani trigonometric method, and Upasani grading system.

BACKGROUND CONTEXT

Accurate assessment of AVR is one measure surgeons can evaluate the success of intervention and potential loss of correction in scoliotic deformities.

METHODS

Eighty-four representative images of uninstrumented and instrumented vertebral segments were blinded. AVR was estimated by five experienced spinal deformity surgeons using the four techniques. The surgeons' grading, estimates, and errors compared to actual rotation were calculated. Inter- and intraobserver reliability were calculated using interclass correlation (ICC).

RESULTS

Each surgeon's error for simple visual estimation for uninstrumented segments was 8.7° to 17.4° (average error = 12.4°), and for instrumented segments it was 7.7° to 11.3° (average error = 9.5°). Error for the Upasani trigonometric method was -6.7° to 11.6° (average error = 0.9°). There was relatively poor accuracy for Nash-Moe system (38.2%-53.9%) compared with the Upasani grading system (76.74%-80.23%). Interobserver reliability using the Nash-Moe method was good (0.844), with intraobserver reliability from fair to excellent (0.684-0.949). Interobserver reliability for the Upasani grading method was good (0.829), with intraobserver reliability from fair to good (0.751-0.869). We found excellent interobserver reliability for Upasani trigonometric classification (0.935) with fair to excellent intraobserver reliability (0.775-0.991). The interobserver reliability of surgeons' visual estimates was good (0.898) and the intraobserver reliability from good to excellent (0.866-0.99) without pedicle screws, and interobserver reliability was excellent (0.948) and intraobserver reliability also excellent (0.959-0.986) with pedicle screws.

CONCLUSIONS

We confirm that both techniques described by Upasani have good reliability and accuracy, appearing more accurate than surgeon's visual estimates or Nash-Moe system.

LEVEL OF EVIDENCE

Level III.

Early Lumbar Nerve Root Deficit After Three Column Osteotomy for Fixed Sagittal Plane Deformities in Adults

Background

Three-column osteotomy is an effective means of correcting fixed sagittal plane deformities. Deformity correction surgeries may be associated with early postoperative neurological deficits often presenting as palsies involving the lumbar roots. The objective was to retrospectively assess a subset of our series of adult deformity correction surgeries and analyze neurological deficits and associated patient and surgical factors.

Methods

Hospital records of 17 patients from a single center were examined. Inclusion criterion were adults (>18 years) who underwent a 3-column osteotomy (pedicle subtraction osteotomy) at the lumbar level for fixed sagittal plane deformities including positive sagittal balance, flat back syndrome, and posttraumatic kyphosis. These also included cases with associated degenerative lumbar scoliosis. Patients were divided in 2 groups: Group 1 with lumbar root deficit and Group 2 with no deficits. We examined the surgical details of the osteotomy, complications during surgery, and observed if the magnitude of correction in the sagittal or coronal plane bore any influence on the nerve deficit.

Results

All 17 patients had a single-level resection except 1 patient who had 2-level osteotomy; 23.5% (4 of 17) developed nerve deficit. Nerve deficit presented as bilateral foot drop (1); unilateral extensor hallucis longus (EHL) weakness (2); and unilateral quadriceps weakness (1). The patient with quadriceps weakness partially recovered to functional strength. Two patients with EHL weakness fully recovered; however, the patient with bilateral foot drop did not improve. L5-S1 interbody fusion was done in 3 of 4 cases in Group 1 and 4 of 13 cases in Group 2.

Conclusions

Nerve deficits after 3-column corrective osteotomies occurred in 23% cases. All but 1 case had significant improvement. Most nerve palsies are neuropraxia and unilateral and tend to recover. L5 weakness appears most common after high lumbar osteotomies. Significant correction of scoliosis at the osteotomy level (>50%) may be a reason for nerve palsy.

Surgeon Reliability for the Assessment of Lumbar Spinal Stenosis on MRI: The Impact of Surgeon Experience

Background

Treating surgeon's visual assessment of axial MRI images to ascertain the degree of stenosis has a critical impact on surgical decision-making. The purpose of this study was to prospectively analyze the impact of surgeon experience on inter-observer and intra-observer reliability of assessing severity of spinal stenosis on MRIs by spine surgeons directly involved in surgical decision-making.

Methods

Seven fellowship trained spine surgeons reviewed MRI studies of 30 symptomatic patients with lumbar stenosis and graded the stenosis in the central canal, the lateral recess and the foramen at T12-L1 to L5-S1 as none, mild, moderate or severe. No specific instructions were provided to what constituted mild, moderate, or severe stenosis. Two surgeons were "senior" (>fifteen years of practice experience); two were "intermediate" (>four years of practice experience), and three "junior" (< one year of practice experience). The concordance correlation coefficient (CCC) was calculated to assess inter-observer reliability. Seven MRI studies were duplicated and randomly re-read to evaluate inter-observer reliability.

Results

Surgeon experience was found to be a strong predictor of inter-observer reliability. Senior inter-observer reliability was significantly higher assessing central(p<0.001), foraminal p=0.005 and lateral p=0.001 than "junior" group.Senior group also showed significantly higher inter-observer reliability that intermediate group assessing foraminal stenosis (p=0.036). In intra-observer reliability the results were contrary to that found in inter-observer reliability.

Conclusion

Inter-observer reliability of assessing stenosis on MRIs increases with surgeon experience. Lower intra-observer reliability values among the senior group, although not clearly explained, may be due to the small number of MRIs evaluated and quality of MRI images.Level of evidence: Level 3.

Safety and Efficacy of the Use of Intrathecal Morphine for Spinal Three Column Osteotomy

Introduction

The use of intrathecal morphine has the potential to help alleviate the pain that patients experience undergoing spinal surgeries. Complications can cause immobilization, which can lead to vascular thrombosis and ileus. Studies have shown epidural analgesia significantly lowered postoperative pain scores in scoliosis surgeries. Intrathecal anesthesia has been shown to have good pain control over the initial 24-hour postoperative period.

Purpose

Determine if intrathecal morphine would reduce postoperative pain with minimal side effects.

Methods

The surgical case logs from three spinal deformity surgeons from a single academic medical center were reviewed retrospectively. This included cases where more than five levels of fusion occurred and surgery involved an osteotomy. The records of 17 patients were queried, and patient and surgical data were collected. The patients were divided into two groups: eight patients were administered intrathecal morphine and nine patients received no morphine. Postoperative pain scores were obtained hourly over the initial 24 hours postoperatively by nurses trained to obtain pain scores from the Numeric Pain Rating Scale. In addition, the rates of any noted side effects were recorded. Analysis of variance (ANOVA) and Fisher’s exact tests were used to calculate any statistical significance with p < 0.05 considered to be significant.

Results

The maximum and total 24-hour postoperative pain scores had a mean of 5.6 (standard deviation = 4.2; p = 0.4266) and 69.3 (standard deviation = 57.8; p = 0.9189), respectively, for patients administered intrathecal morphine. The patients who did not receive intrathecal morphine had total pain scores of 3.9 (standard deviation = 4.5) and 65.7 (standard deviation = 79.7), respectively. Though the results were not statistically significant, there was a potential trend toward decreased in pain mean scores in the first 10 hours for the intrathecal morphine group. There was no statistical difference in the rate of side effects between patients.

Conclusions

The use of intrathecal morphine did not significantly appear to reduce postoperative pain in patients when compared to intravenous or oral narcotics. There was a potential trend in a reduction in postoperative pain during the first 10 hours postoperatively, but this did not reach a statistically significant value and did not hold up after the first 10 hours postoperatively. However, it was noted that intrathecal morphine was safe to use in postoperative spinal deformity surgery as no statistical significance in side effects was noted.

Analysis of instrumentation failures after three column osteotomies of the spine

Background

Correction of fixed spinal imbalance in a sagittal and/or coronal plane frequently needs a tricolumnar wedge resection when the deformity is rigid. Complications associated with deformity correction surgery are pseudoarthrosis and implant failure located along the construct. The purposes of this study were to assess comparative rates of pseudoarthrosis (implant failure) at weaker points along lumbosacral junction and level of osteotomy, estimate overall incidence of implant failure, and comparatively analyze failures at different points along the construct.

Methods

This was an IRB approved, single center study retrospective analysis. Twenty-six patients who underwent three column osteotomies were grouped according to procedure: pedicle subtraction osteotomy (PSO, (n = 18)); vertebral column resection (VCR, (n = 4)); hemivertebra excision (HE, (n = 2)); and extracavitary corpectomy (EC, (n = 2)). Follow-up data is presented on all of the study patients. Number of levels of fusion, anchors, percent saturation of fixation levels, type of bone graft and graft substitutes, and rod material and diameter were recorded. Radiographical data was reviewed preoperatively and postoperatively at 2 weeks and 3, 6, and 12 months and annually to determine sagittal and coronal balance, lumbopelvic parameters, presence or absence of interbody structural support, laterality or rod failure, and time to implant failure.

Results

Twenty-seven percent (7/26) patients demonstrated rod breakage either unilaterally (N = 2) or bilaterally (N = 5) during follow-up. Seventy-one percent had increasing back pain or worsening sagittal balance, while remaining failures found incidentally. No failures in children were seen.

Conclusion

Tricolumnar osteotomy by posterior approach is a valuable tool. Rod failures found approximately 1 year from surgery, with 86% located at level of osteotomy and 14% at lumbosacral junction. Possible reasons are increased stress in the rod at this point and relatively deficient bone stock secondary to wide laminectomy. The low rate of rod breakage at lumbosacral junction may be related to adoption of structural interbody graft and stronger iliac screws. Additional biomechanical studies needed to assess the importance of these factors. This was a level IV study.

Lumbar vertebral body and pars fractures following laminectomy

A 56-year-old alcoholic male incurred L5 vertebral body and bilateral L4 pars fractures with progressive L4 on L5 anterolisthesis following low-energy falls while intoxicated. Recently, he had a L3–S1 laminectomy for lumbar spinal stenosis with claudication. Preoperative imaging and radiographs were negative for pars defects and instability, so an isolated decompressive surgery was performed. Following low-energy falls, his outpatient work-up revealed fractures through the bilateral L4 pedicles and posterior third of L5 vertebral body, with recurrence of axial back pain and bilateral lower extremity radiculopathy. He underwent revision decompression from L4–S1 and posterior instrumented fusion with transforaminal lumbar interbody fusion performed at each revised level. His axial back pain and radiculopathy improved postoperatively. Instability of a lumbar spine fracture pattern can be due to the remote or prior iatrogenic disruption of the posterior ligamentous complex. Our patient benefitted from surgery and his low back pain was resolved.

Stand-alone interspinous spacer versus decompressive laminectomy for treatment of lumbar spinal stenosis

OBJECTIVE

To compare the two-year clinical outcomes of a prospective, randomized controlled trial of an FDA-approved interspinous spacer with the compilation of published findings from 19 studies of decompressive laminectomy for the treatment of lumbar spinal stenosis.

METHODS

Back and leg pain, Oswestry disability index (ODI), and Zurich Claudication Questionnaire (ZCQ) values were compared between spacer- and laminectomy-treated patients preoperatively and at 12 and 24 months.

RESULTS

Percentage improvements between baseline and 24 months uniformly favored patients treated with the spacer for back pain (65% vs. 52%), leg pain (70% vs. 62%), ODI (51% vs. 47%) and ZCQ symptom severity (37% vs. 29%) and physical function (36% vs. 32%).

CONCLUSION

Both treatments provide effective and durable symptom relief of claudicant symptoms. This stand-alone interspinous spacer offers the patient a minimally invasive option with less surgical risk.

The Association of Sacral Table Angle Measurements With Spondylolytic and Spondylolisthetic Defects at the Lumbosacral Articulation: A Radiographic Analysis

STUDY DESIGN

Retrospective radiographic study of 6 patients with L5 spondylolysis observed prospectively before the onset of lysis through adulthood. A radiographic analysis of 50 pediatric control subjects was compared with the study group.

OBJECTIVE

To determine whether sacral table angle (STA) measurements bear etiologic association with the development of spondylolysis and/or subsequent spondylolisthesis.

SUMMARY OF BACKGROUND DATA

Although radiographic parameters in association with spondylolysis and isthmic spondylolisthesis have been studied, no parameter has been shown to definitively have a role in development of this disease process. The STA is a recently described radiographic parameter useful in measuring anatomic changes across the lumbosacral articulation. This measurement's role as a predictor of pars lysis and subsequent slippage remains unknown.

METHODS

The researchers examined the longitudinal plain radiographs of 6 patients observed from childhood, before the development of spondylolysis, through adulthood. Measurements of STA and percent slippage were performed. Fifty pediatric control subjects' radiographs were also examined with STA measurements. Statistical analysis was conducted on results.

RESULTS

Mean STA of the study group before the development of spondylolysis was 95° ± 5.5°. Mean STA from the control group was 97.5° ± 4.3°. No statistical difference was found between groups (p > .05). No index patient had an abnormal STA before spondylolysis (less than 89°, defined as being outside 2 standard deviations from the control mean). Four of 6 index patients with spondylolysis developed spondylolisthesis. A negative correlation (r = .54) was seen for STA as a function of increasing percent slip when assessed longitudinally.

CONCLUSIONS

Abnormal STA measurement was not seen before the development of spondylolysis in this study population. Decreasing STAs were seen secondarily in patients with L5 spondylolisthetic progression. This finding points to anatomic change and secondary remodeling of the upper sacrum as a result of slippage.