Faculty Bibliography

Study Design. Retrospective analysis.Objective. To determine patient demographics, incidence of comorbidities and procedure-related complications, and identify risk factors associated with morbidity and mortality after spinal surgery for cauda equina syndrome (CES).Summary of Background Data. To our knowledge, no study has provided nationwide estimates of patient characteristics and procedure-related complication rates after spinal surgery for CES relative to an unaffected population.Methods. Nationwide Inpatient Sample data collected between 2001 and 2010 was analyzed. Discharges with procedural codes for lumbar spinal fusion, decompression, or discectomy were included. The CES cohort included diagnoses of CES, and the unaffected cohort included lumbar spinal pathology diagnoses. Patient demographics, incidence of comorbidities and procedure-related complications, and risk factors associated with morbidity and mortality were compared.Results. Discharges for 11,207 CES and 689,799 unaffected patients were identified. Differences between cohorts were found for demographic and hospital data. Average comorbidity indices for the CES cohort were found to be increased (0.23 vs.0.13, p< 0.0001), as well as the incidence of total procedure-related complications (18.63% vs. 13.12%, p< 0.0001). In-hospital mortality rate was significantly increased for the CES cohort (0.30% vs. 0.08%, p< 0.0001). A number of comorbidities associated with additional risk for morbidity and mortality among the CES cohort were identified.Conclusion. Relative to an unaffected population undergoing similar treatment, CES patients were more likely to have increased associated comorbidities on presentation, as well as increased complication rates with a prolonged hospital course postoperatively. CES was found to carry an increased incidence of procedure-related complications as well as in-hospital mortality. A number of comorbidities associated with additional risk for morbidity and mortality among the CES cohort were identified. This study provides clinically useful data for surgeons to educate patients at risk for morbidity and mortality as well as direct future research to improve patient outcomes.

BACKGROUND: Cervical drains have historically been used to avoid postoperative wound and respiratory complications such as excessive edema, hematoma, infection, re-intubation, delayed extubation, or respiratory distress. Recently, some surgeons have ceased using drains because they may prolong hospital stay, operative time, or patient discomfort. The objective of this retrospective case-control series is to investigate the effectiveness of postoperative drains following one- and two-level cervical fusions. METHODS: A chart review was conducted at a single institution from 2010-2013. Outcome measures included operative time, hospital stay, estimated blood loss and incidence of wound complications (infection, hematoma, edema, and complications with wound healing or evacuation), respiratory complications (delayed extubation, re-intubation, and respiratory treatment), and overall complications (wound complications, respiratory complications, dysphagia, and other complications). Statistical analyses including independent samples t-test, chi-square, analysis of covariance, and linear regression were used to compare patients who received a postoperative drain to those who did not. RESULTS: The study population included 39 patients who received a postoperative drain and 42 patients who did not. There were no differences in demographics between the two groups. Patients with drains showed increased operative time (100.1 vs 69.3 min, p < 0.001), hospital stay (38.9 vs. 31.7 hrs, p = 0.021), and blood loss (62.7 vs 29.1 mL, p < 0.001) compared to patients without drains. The frequency of wound complications, respiratory complications, and overall complications did not vary significantly between groups. CONCLUSIONS/LEVEL OF EVIDENCE: Cervical drains may not be necessary for patients undergoing one- and two-level cervical fusion. While there were no differences in incidence of complications between groups, patients treated with drains had significantly longer operative time and length of hospital stay. CLINICAL RELEVANCE: This could contribute to excessive costs for patients treated with drains, despite the lack of compelling evidence of the advantages of this treatment in the literature and in the current study.

Object Lateral mass screws (LMS) have been used extensively with a low complication rate in the subaxial spine. Recently, cervical pedicle screws (CPS) have been introduced, and are thought to provide more optimal stabilization of the subaxial spine in certain circumstances. However, because of the concern for neurovascular injury, the routine use of CPS in this location remains controversial. Despite this controversy, however, there are no articles directly comparing screw-related complications of each procedure in the subaxial cervical spine. The purpose of this study was to evaluate screw-related complications of LMS and CPS in the subaxial cervical spine. Methods A PubMed/MEDLINE and Cochrane Collaboration Library search was executed, using the key words "lateral mass screw" and "cervical pedicle screw." Clinical studies evaluating surgical procedures of the subaxial cervical spine in which either LMS or CPS were used and complications were reported were included. Studies in which the number of patients who had subaxial cervical spine surgery and the number of screws placed from C-3 to C-7 could not be specified were excluded. Data on screw-related complications of each study were recorded and compared. Results Ten studies of LMS and 12 studies of CPS were included in the analysis. Vertebral artery injuries were slightly but statistically significantly higher with the use of CPS relative to LMS in the subaxial cervical spine. Although the use of LMS was associated with a higher rate of screw loosening, screw pullout, loss of reduction, pseudarthrosis, and revision surgery, this finding was not statistically significant. Conclusions Based on the available literature, it appears that perioperative neurological and late biomechanical complication rates, including pseudarthrosis, are similarly low for both LMS and CPS techniques. In contrast, vertebral artery injuries, although statistically significantly more common when using CPS, are extremely rare with both techniques, which may justify their nonroutine use in select cases. Given the paucity of well-designed studies available, this recommendation may be a reflection of deficiencies in the available studies. Surgeons using either technique should have intimate knowledge of cervical anatomy and an adequate preoperative evaluation for each patient, with the final selection based on individual case requirements and anatomical limitations.

BACKGROUND CONTEXT: Adolescent idiopathic scoliosis (AIS) is a complex multi-plane deformity of the spine that involves a lateral component in the coronal plane in addition to a rotational component affecting all three planes. AIS occurs in otherwise healthy children at or around puberty. The natural history of scoliosis varies significantly depending on curve pattern and pathogenesis. Potential sequelae of untreated AIS include curve progression, back pain, cardiopulmonary problems and psychosocial concerns. Optimal treatment of AIS must weigh the benefits and effectiveness of the intervention against its potential risks. This study aims to better define the risks associated with surgical intervention in AIS patients by comparing the perioperative complications of primary and revision spinal fusions in this population. PURPOSE: The goal of this study is to investigate the rates of perioperative complications of primary and revision spinal fusions for AIS. STUDY DESIGN/SETTING: Retrospective review of national data from a large administrative database. PATIENT SAMPLE: Patients between 10 and 18 years of age with diagnosis of idiopathic scoliosis undergoing primary or revision spinal fusions. OUTCOME MEASURES: Perioperative complications, length of stay, total costs, mortality. METHODS: The national inpatient sample (NIS) database was queried for patients undergoing spinal fusion for AIS between 2001 and 2010. Patients with AIS were identified as those between 10 and 18 years of age with a diagnosis of idiopathic scoliosis as identified with ICD-9 codes. Univariate and multivariate analyses were carried out comparing primary and revision fusions in terms of perioperative complications, length of stay (LOS), total cost of hospitalization and mortality. National estimates of annual total number of procedures were calculated. RESULTS: A total of 48,403 fusions were performed for AIS between 2001 and 2010. Of those fusions 1.3% (630) were revisions. Revision fusions were associated with a higher rat!

PURPOSE: Spinal stenosis at the C2-3 segment is a rare occurrence, and when it occurs myelopathy infrequently results. Furthermore, only a handful of cases involving congenital abnormalities of the posterior arch of the axis have been described resulting in cervical myelopathy many of which described simultaneous congenital abnormalities at adjacent levels and none of which identified ossification of the posterior longitudinal ligament (OPLL) at the same level. We report a case of a previously undescribed combination of abnormalities at the C2-3 segment resulting in clinical myelopathy. METHODS: A 49-year-old Chinese male presented with a progressive cervical myelopathy (C-JOA score 11 immediately pre-op). Segmental OPLL at the C2-3 disk space was visible, together with invagination of the bilaterally hypoplastic C2 lamina into the spinal canal. Signal abnormalities of the spinal cord were evident on both T1 and T2 sequences. RESULTS: The patient underwent a posterior decompression and instrumented fusion at C2-3 using pars screws at C2 and lateral mass screws at C3. Following surgery there was a rapid and significant improvement in the neurological symptoms, with the C-JOA score improving to 14 at final follow-up. A successful fusion was evident. CONCLUSIONS: Deficiencies in the posterior arch of the axis are rare and have not previously been reported in conjunction with OPLL. Advanced imaging is helpful to define the abnormality and site of compression. In the setting of a progressive neurological dysfunction, surgical decompression and stabilization is a reasonable intervention and can be associated with neurological and symptomatic improvement.

STUDY DESIGN.: Prospective case series and radiographical analysis. OBJECTIVE.: This study aimed to characterize the changes in subaxial alignment after surgical correction of occipitoaxial kyphosis, establish normal parameters, and report on clinical outcomes in a population of patients with chronic atlantoaxial dislocation patients presenting with swan neck deformities. SUMMARY OF BACKGROUND DATA.: Swan neck deformity of the cervical spine is a term used to describe the simultaneous development of both abnormal kyphosis and hyperlordosis malalignments. Currently, there are no published series that discuss their outcomes after treatment and, more specifically, the subsequent changes that occur in the subaxial spine after the correction of the primary deformity in cases of chronic hyperkyphosis at the occipitoaxial segment. METHODS.: This was a prospective clinical and radiographical study in a population of patients with chronic atlantoaxial dislocation presenting with swan neck deformities. C0-C2 and C2-C7 angles were measured using plain radiographs pre- and postsurgery. The relationship between the alignment of the occipitoaxial joint and the subaxial cervical spine was evaluated. Japanese Orthopaedic Society scores were used to assess functional outcomes. RESULTS.: C0-C2 improved from a mean of -14.4 degrees (SD, 9.5 degrees ) preoperatively to a mean of 7.8 degrees (SD, 1.0 degrees ) postoperatively (P = 0.02). C2-C7 changed from a mean of 43 degrees (SD, 2.8 degrees ) to a mean of 18.6 degrees (SD, 11.2 degrees ) postoperatively (P = 0.02). A significant correlation was detected between the changes that occurred in the upper and lower cervical alignments (R = 0.133; P < 0.01). Clinically, the Japanese Orthopaedic Society preoperative scores improved significantly to postoperative (P < 0.01). CONCLUSION.: This study reports the novel auto-correction of subaxial abnormalities after treatment of the primary upper cervical deformity and delineates the relationship between these 2 occurrences, thus demonstrating the reversibility of such complex abnormalities. Furthermore, the clinical outcomes after surgical treatment of swan neck deformities secondary to atlantoaxial dislocation are favorable and associated with a low complication rate.

STUDY DESIGN: : Prospective radiographic analysis. OBJECTIVE: : This study aimed to characterize the relationship between the alignment of the occipitoaxial (OA) and the subaxial spine, establish normal parameters, and to determine the influence of upper cervical spine alignment on subaxial degenerative disc disease (DDD) and clinical outcomes in this population. SUMMARY OF BACKGROUND DATA: : Previous studies reported that the alignments of the upper and lower cervical spine are closely interrelated in patients with atlantoaxial dislocations of a rheumatoid etiology. None have focused on congenital etiologies or included patients with OA kyphosis. The influence of the upper cervical alignment on subaxial (DDD) and outcomes is also unclear. METHODS: : Fifty-eight patients with congenital AAD undergoing surgical reduction and fusion were included. C0-C2 and C2-C7 angles were measured and DDD was assessed using plain radiographs. The relationship between the alignment of the OA joint and the subaxial cervical spine was evaluated, as well as the relationships between the cervical alignment, outcomes, and cervical DDD. RESULTS: : C0-2 improved from a mean of 1.59+/-17.3 degrees preoperatively to a mean of 15+/-9.8 degrees postoperatively (P<0.001). C2-7 changed from a mean of 25.55+/-19.6 degrees to a mean of 14.2+/-14.4 degrees postoperatively (P<0.001). The OA and subaxial alignment were negatively correlated in this population both before (r=-0.84; P<0.001) and after (r=-0.64; P<0.001) surgical treatment. There was an increased incidence of DDD postoperatively (P<0.01), which was positively correlated with the postoperative C0-2 angle (r=0.54; P<0.001), but negatively correlated with the postoperative C2-7 angle (r=-0.79; P<0.001). CONCLUSIONS: : Changes in OA alignment before and after surgery are associated with changes in the subaxial spine. There is a high incidence of postoperative DDD in the subaxial spine that seems to be related to sagittal alignment after surgery.

STUDY DESIGN/METHODS:Controlled experimental study. OBJECTIVE:To evaluate the kinematical effects of X-Stop device on the spinal process at the operated and the adjacent segments before and after X-Stop surgeries during various weight-bearing postures in elderly patients with lumbar spine stenosis. SUMMARY OF BACKGROUND DATA/BACKGROUND:The mechanism of interspinous process (ISP) devices is to directly distract the ISP of the implanted level to indirectly decompress the intervertebra foramen and spinal canal. Few studies have investigated the changes of ISP gap caused by X-Stop implantation using magnetic resonance imaging or radiography, but the effect of X-Stop surgery on the kinematics of spinous processes during functional activities is still unclear. METHODS:Eight patients were tested before and, on average, 7 months after surgical implantation of the X-Stop devices using a combined computed tomography/magnetic resonance imaging and dual fluoroscopic imaging system during weight-bearing standing, flexion-extension, left-right bending, and left-right twisting positions of the torso. The shortest distances of the ISPs at the operated and the adjacent levels were measured using iterative closest point method and was dissected into vertical (gap) and horizontal (lateral translation) components. RESULTS:At the operated levels, the shortest vertical ISP distances (gap) significantly (P<0.05) increased by 1.5 mm during standing, 1.2 mm during left twist, 1.3 mm during extension, and 1.1 mm during flexion, whereas they also increased yet not significantly (P>0.05) in right twist, left bend, and right bend after the X-Stop implantation. The lateral translations were not significantly affected. At both cephalad and caudad adjacent levels, the ISP distances (vertical and horizontal) were not significantly affected during all postures after X-Stop implantation. CONCLUSION/CONCLUSIONS:The findings of this study indicate that implantation of the X-Stop devices can effectively distract the ISP space at the diseased level without causing apparent kinematic changes at the adjacent segments during the studied postures.

BACKGROUND:The ideal surgical treatment for adult low-grade isthmic spondylolisthesis (ALIS) remains unknown. Isolated anterior and posterior procedures are popular but have resulted in equivocal outcomes, whereas combined anterior and posterior procedures are associated with higher complication rates despite improved outcome. OBJECTIVE:To evaluate the clinical and radiographic outcomes following the treatment of ALIS using a 1-stage posterior approach with posterior decompression and posterolateral arthrodesis combined with an interbody fibular allograft strut. METHODS:Fifteen patients underwent fusion by a single surgeon using our modified technique. Seven patients were female and 8 were male, with a mean age of 48 years. All patients were classified as Meyerding grade II slips and underwent a posterior approach only, a decompressive laminectomy, and a circumferential fusion with the use of a transsacral fibular allograft and a posterolateral instrumented fusion. Postoperative clinical and radiographic evaluations were performed at 3, 6, and 12 months, and then on an annual basis. RESULTS:The average follow-up interval was 61 months. Three complications were seen: a single dural tear, an L5 radiculopathy secondary to a malpositioned pedicle screw, and one patient with urinary retention. The spines of all patients were determined to be fused by the 6-month postoperative visit. All patients returned to their normal activities of daily living. Significant improvements in the visual analog score were seen at all follow-up intervals. CONCLUSION/CONCLUSIONS:Transsacral interbody fibular allograft can be used successfully to supplement a posterolateral instrumented fusion in selected patients with low-grade ALIS.

STUDY DESIGN/METHODS:Analysis of population-based national hospital discharge data collected for the Nationwide Inpatient Sample. OBJECTIVE:To study perioperative outcomes of circumferential spine surgery performed on either the same or different days of the same hospitalization. SUMMARY OF BACKGROUND DATA/BACKGROUND:Circumferential spine fusion surgery has been linked to an increased adjusted risk in perioperative morbidity and mortality compared with procedures involving only 1 site. To minimize these risks, some surgeons elect to perform the 2 components of this procedure in separate sessions during the same hospitalization. The value of this approach is uncertain. METHODS:Data collected between 1998 and 2006 for the Nationwide Inpatient Sample were analyzed. Hospitalizations during which a circumferential noncervical spine fusion was performed were identified. Patients were divided into those who had their anterior and posterior portion performed on the same and those performed on different days of the same hospitalization. The prevalence of patient and health care system-related demographics was evaluated. Frequencies of procedure-related complications and mortality were determined. Multivariate regression models were created to identify whether timing of procedures was associated with an independent increase in risk for adverse events. RESULTS:We identified a total of 11,265 entries for circumferential spine fusion. Of those, 71.2% (8022) were operated in 1 session. Complications were more frequent among staged- versus same-day surgery patients (28.4% vs. 21.7%, P < 0.0001). The incidence of venous thrombosis and adult respiratory distress syndrome also increased among staged candidates, while the trend toward higher mortality (0.5% vs. 0.4%) did not reach significance. In the regression model, staged circumferential spine fusions were associated with a 29% increase in the odds morbidity and mortality compared with same-day procedures. CONCLUSION/CONCLUSIONS:Staging circumferential spine surgery procedures during the same hospitalization offers no mortality benefit and may even expose patients to increased morbidity.