Migration of a Lumbar Spinal Fusion Rod Into the Posterolateral Knee: A Case Report.

STUDY DESIGN: Case report (level V evidence). OBJECTIVE: We report a case of a 33-year-old man with Marfan syndrome that visited our clinic for left knee pain and stiffness. Radiographs of the left knee and lumbar spine demonstrated a spinal rod in the posterolateral left knee and its origin being a broken rod from his previous unilateral spinal fusion 17 years prior. SUMMARY OF BACKGROUND DATA: Spinal arthrodesis is a common treatment modality for a wide range of spinal pathologies including infection, trauma, congenital and developmental deformities, and degenerative conditions. A rare complication that may arise from said procedure is implant migration, most often a result of pseudoarthrosis. METHODS: Description of the case report. RESULTS: Patient was taken to the operating room 2 weeks later for an uneventful removal of the implant and immediate improvement with pain and range of motion. CONCLUSION: Spinal implant migration is a rare complication most often due to implant failure from pseudoarthrosis. In the case presented, this phenomenon was likely attributed to the use of unilateral instrumentation coupled with Marfan syndrome, shown to lead to insufficient implant stability and poorer fusion rates, respectively.Level of Evidence: 5.

Compression of the S1 Nerve Root by an Extradural Vascular Malformation: A Case Report and Discussion of Atypical Causes of Lumbar Radiculopathy.

We present a case of lumbar radiculopathy due to a vascular malformation in the lumbar spine and discuss various causes of atypical lumbar radiculopathy. Lumbar radiculopathy is a condition of neurologic deficits and painful symptoms of the lower extremities due to nerve root compression, most commonly at the L5 and S1 levels. Several factors contribute to lumbar radiculopathy, including intervertebral disc herniation, foraminal stenosis, and spinal instability. There are also a number of atypical causes, including medication side effects or metabolic disorders, which produce symptoms of radiculopathy but do not involve compression of the nerve root. Anatomic variations in the nerve roots or vascular supply surrounding the nerve root may also increase the risk of developing radiculopathy and serve as an obstacle to interpreting imaging during a preoperative workup. A 38-year-old woman presented with sudden onset radicular symptoms in her right lower extremity. Lumbar magnetic resonance imaging demonstrated a right-sided L5-S1 extruded nucleus pulposus. Her symptoms failed to improve after conservative management so she underwent surgical decompression of L4-S1. Intraoperatively, we discovered an extensive, extradural vascular malformation present at the L5-S1 level and believed this to be the true cause of her radiculopathy. This case represents an atypical cause of lumbar radiculopathy and demonstrates the importance of considering atypical causes during diagnostic workup and preoperative planning.

Progressive double major scoliotic curve with concurrent lumbosacral spondylolisthesis in a skeletally immature patient with Marfan syndrome treated with anterior scoliosis correction.

STUDY DESIGN: Case report (review of patient records, imaging, and pulmonary function tests) and literature review. OBJECTIVES: To describe the case of a skeletally immature patient with Marfan syndrome who underwent anterior scoliosis correction (ASC) and muscle-sparing posterior far lateral interbody fusion (FLIF) in a two-stage procedure to correct progressive severe double major scoliosis and spondylolisthesis. Patients with Marfan syndrome suffer from rapidly progressive scoliosis and spondylolisthesis. Operative treatment has typically been limited to PSF, but newer techniques may be less invasive and provide more spine motion. METHODS: A 12-year-old girl with Marfan syndrome, spondylolisthesis, and severe progressive scoliosis underwent a two-stage procedure to achieve correction. Muscle-sparing posterior FLIF of the spondylolisthesis from L4-S1 was initially performed, followed 1 week later by ASC from right T4-T11 and left T11-L3 using an anterior screw/cord construct. RESULTS: Follow-up from the index procedures for the spondylolisthesis and scoliosis is 35 months. No significant complications occurred in perioperative and postoperative follow-up periods. At the 13-month follow-up, the double major scoliosis showed continued curve correction via growth modulation and overcorrection of the lumbar to - 13°. A revision lengthening procedure of the anterior cord from T11-L3 was performed. An asymptomatic elevated hemidiaphragm was discovered at 6 weeks postoperation, which was believed to be secondary to retraction neuropraxia and subsequently improved. At 21 months postlengthening and 35 months postindex procedure, she is skeletally mature and the curves have maintained correction in both the coronal and sagittal planes without any further complications. CONCLUSIONS: Anterior scoliosis correction of both a thoracic and lumbar curve combined with an L4-S1 PSF was effective for this patient and may be promising for patients with Marfan syndrome, progressive scoliosis, and spondylolisthesis. Overcorrection can be planned for and easily corrected by inserting a new cord of a different length.

Radiation Exposure in Minimally Invasive Transforaminal Lumbar Interbody Fusion: The Effect of the Learning Curve.

BACKGROUND: Minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) has comparable fusion rates and outcomes to the open approach, though many surgeons avoid the technique due to an initial learning curve. No current studies have examined the learning curve of MI-TLIF with respect to fluoroscopy time and exposure. Our objective with this retrospective review was to therefore use a repeatable mathematical model to evaluate the learning curve of MI-TLIF with a focus on fluoroscopy time and exposure. METHODS: We conducted a retrospective review of single level, primary fusions performed by a single surgeon during his initial experience with minimally invasive spine surgery. Chronologic case number was plotted against variables of interest, and learning was identified as the point at which the instantaneous rate of change of a curve fit to the data set equaled the average rate of change of the data set. RESULTS: One hundred nine cases were reviewed. Proficiency in operative time was achieved at 38 cases with the first 38 requiring a median of 137 minutes compared to 104 minutes for the latter 71 cases (P < .0001). Mastery of fluoroscopy use occurred at case 51. The median fluoroscopy time for the first 51 cases was 2.8 minutes, which dropped to 2.1 minutes for cases 52 to 109 (P < .0001). The complication rate plateaued after 43 cases, with 3 of 11 total complications occurring in the latter 76 cases. CONCLUSIONS: Our results demonstrate the most gradual learning occurred with respect to fluoroscopy time and exposure, and operative time improved the quickest. LEVEL OF EVIDENCE: IV. CLINICAL RELEVANCE: These findings may guide spine surgeon education and training in minimally invasive techniques, and help determine safe case loads for radiation exposure during the initial learning phase of the technique. The model used to identify the learning curve can also be applied to several fields and surgical techniques.

Anatomical Modifications during the Lateral Transpsoas Approach to the Lumbar Spine. The Impact of Vertebral Rotation.

BACKGROUND: We investigated impact of vertebral axial rotation on neurovascular anatomy in adult spinal deformity (ASD) patients and provided recommendations on the approach based on degree of axial rotation. In order to isolate vertebral rotation (VR) impact from the superimposed degenerative cascade observed in adulthood, adolescent idiopathic scoliosis (AIS) patients were analyzed. METHODS: Magnetic resonance imaging (MRI) scans (L1-S1) from 50 right-convex thoracic (left-convex lumbar) AIS patients were analyzed. At each intervertebral level, VR, lumbar plexus depth (LPD), and vascular structure depth (VSD) were evaluated. Paired t test analyses were used to describe anatomic differences between the concave and convex aspect of our patients' curves. Correlation analysis was used to investigate relationships with soft tissue modifications and VR. RESULTS: Fifty AIS patients (17M, 33F) with mean thoracic Cobb of 50.6° ± 17.0° and mean lumbar Cobb of 41.9° ± 13.0° were included. Mean VR at each level was L1-2 = -6.6°, L2-3 = -7.7°, L3-4 = -6.5°, L4-5 = -4.7°, L5-S1 = -2.6° (negative value denotes clockwise rotation). We found significant differences (P < .05) between concave-convex (right-left) LPD at each level (L1-2 = 3.7 mm, L2-3 = 5.1 mm, L3-4 = 4.2 mm, L4-5 = 2.2 mm, L5-S1 = 2.2 mm). Vascular structure depth was significantly different at L1-L2 (3.2 mm) and L5-S1 (3 mm). Significant correlation was found between increasing VR and concave-convex LPD difference (r = 0.68, P < .001). CONCLUSIONS: This study demonstrates that displacement of the lumbar plexus is tied to the magnitude of VR in patients with AIS. When approaching the lumbar spine, this displacement widens the safe surgical corridor on the convex side and narrows the corridor on the concave side. LEVEL OF EVIDENCE: IV. CLINICAL RELEVANCE: Preoperative review of MRI scans should occur to assess the patient's safe surgical corridor for lateral lumbar interbody fusion (LLIF). Adult spinal deformity surgeons who approach a degenerated spine in patients with progressive AIS in adulthood must carefully plan for patient positioning, neurovascular anatomy, and realignment objectives prior to the day of surgical intervention.

Motion analysis in the axial plane after realignment surgery for adolescent idiopathic scoliosis.

BACKGROUND: This study aimed to define changes occurring in axial plane motion after scoliosis surgery in patients with adolescent idiopathic scoliosis (AIS) using gait analysis. Pre- and postoperative axial plane motion was compared to healthy/control subjects. This may potentially improve our understanding of how motion is impacted by deformity and subsequent surgical realignment. METHODS: 15 subjects with AIS underwent pre- and postoperative radiographic and gait analysis, with focus on axial plane motion (clockwise [CW] and counterclockwise [CCW]). Age, weight, and gender-matched controls (n = 13) were identified for gait analysis. Control, preoperative and postoperative groups were compared with paired student's t-tests. RESULTS: Surgical realignment resulted in significantly decreased in upper thoracic, thoracic, thoracolumbar and lumbar Cobb angles pre-to-postoperatively (36.7° vs. 15.2°, 60.1° vs. 25.6°, 47.7° vs. 17.7° and 27.2° vs. 4.8°, respectively) (all p < 0.05), with no significant change in thoracic kyphosis, lumbar lordosis, central sacral vertical line, pelvic incidence, and sagittal vertical axis. However, pelvic tilt significantly increased from 4.9° to 8.1° (p = 0.035). Using gait analysis: preoperative thoracic axial rotation differed (mean CW and CCW rotation was 1.9° and 3.1° [p = 0.01]), whereas mean CW & CCW pelvic rotation remained symmetric (2.0° and 3.0°; p = 0.44). Postoperatively, CCW thoracic rotation range of motion decreased (CW: 0.6° and CCW: 1.4°; p = 0.31). No significant difference in postoperative pelvic rotation occurred (1.1° and 3.4°; p = 0.10). Compared to controls, AIS patients demonstrated no significant difference in total CW & CCW thoracic motion relative to the pelvis both pre- (14.9° and 12.3°, respectively; p = 0.45) and postoperatively (12.9° and 12.3°, respectively; p = 0.82). SIGNIFICANCE: AIS patients demonstrated abnormal gait patterns in the axial plane compared to normal controls. After surgical realignment and de-rotation, marked improvement in axial plane motion was observed, highlighting how motion analysis can afford surgeons three-dimensional perspective into the patient's functional status.

Short-Term Complications of Anterior Fixation of Odontoid Fractures.

STUDY DESIGN: Retrospective study. OBJECTIVE: Anterior fixation of odontoid fracture has been associated with high morbidity and mortality in small, single institution series. Identifying risk factors may improve risk stratification and highlight factors that could be optimized preoperatively. The objective of this study was to determine the 30-day complication rate following anterior fixation of odontoid fractures and to identify associated risk factors among patients in a large national database. METHODS: Patients who underwent anterior fixation were identified in the American College of Surgeons National Quality Improvement Program database (ACS NSQIP) from 2007 to 2012. Patient demographics, medical comorbidities, perioperative complications, and postoperative complications up to 30 days were analyzed by univariate and multivariate analysis. RESULTS: Overall, 103 patients met criteria for the study. The average age was 73.9 years and patients were predominantly white (85.4%). Cardiac comorbidity was common (66.0%), as were dependent functional status (14.6%) and bleeding disorders (13.6%). Complications occurred in 37.9% of patients, and mortality was high (6.8%). Age, white race, and history of bleeding disorders were independently predictive of complications in the multivariate analysis. The postoperative hospital stay was >5 days for 45.6% of patients. CONCLUSION: In a large, multicenter database study, anterior fixation of odontoid fracture was associated with high morbidity and mortality. Although advanced age was associated with increased risk of complications, patients undergoing anterior fixation were older, on average, than in prior studies. Bleeding disorder was a potentially modifiable risk factor for complications that could be optimized prior to surgery.

The Impact of Resident Involvement in Elective Posterior Cervical Fusion.

STUDY DESIGN: Retrospective study of prospectively collected data OBJECTIVE.: The aim of this study was to assess the impact of resident surgeon involvement on patient outcomes following posterior cervical fusion (PCF) surgery. SUMMARY OF BACKGROUND DATA: Recently, there has been a significant uptrend in the number of PCF performed in the United States. Prior studies have investigated patient outcomes after cervical arthrodesis. Despite the heightened concern for patient safety and quality improvement, the data on the safety of resident participation in PCF is sparse. METHODS: The American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) was examined from 2005 to 2012. Current Procedural Terminology codes were used to query the database for adults (≥18 years) who underwent PCF. Multivariate logistic regression models were employed on data adjusted by propensity scores to determine whether resident involvement was an independent predictor for the outcomes of interest. RESULTS: A total of 448 cases were assessed in NSQIP. Less than half of these cases involved residents (224, 43.1%). Resident involvement was found to be a significant predictor for blood transfusions [odds ratio (OR) = 1.7, confidence interval (CI) = 1.1-2.6, P = 0.010], length of stay of more than 5 days (OR = 1.6, CI = 1.0-2.6, P = 0.040), and operative time more than 4 hours (OR = 3.6, CI = 1.7-7.4, P = 0.0007). Other independent risk factors for prolonged length of stay included age 81 years or older versus 50 years or younger (OR = 4.7, CI = 1.7-12.6, P = 0.016) and diabetes (OR = 2.3, CI = 1.3-4.1, P = 0.006). In addition, multifusion was identified as a significant risk factor for extended operative time (OR = 1.8, CI = 1.1-2.9, P = 0.023). CONCLUSION: The present study used a large, nationwide sample to assess the impact of resident involvement in PCF. Resident participation was not associated with mortality, but had a minimal association with morbidity. LEVEL OF EVIDENCE: 3.

Incidence and Risk Factors for 30-Day Unplanned Readmissions After Elective Posterior Lumbar Fusion.

STUDY DESIGN: Retrospective study of prospectively collected data. OBJECTIVE: To perform a multiinstitutional assessment on the incidence and risk factors for unplanned readmissions following elective posterior lumbar fusion (PLF) surgery. SUMMARY OF BACKGROUND DATA: Understanding what may drive rehospitalizations is a necessary step toward higher quality care. Identifying risk factors for unplanned readmission is especially important for elective PLF, which is a common procedure that is known to be associated with significant adverse events. METHODS: Adult patients undergoing PLF were identified using current procedure terminology (CPT) from the American College of Surgeons National Surgical Quality Improvement Program. Both descriptive and comparative statistics were performed for patient characteristics, clinical factors, and postoperative complications. Subsequently, a step-wise multivariate logistic regression was employed. RESULTS: Of the 2301 patients who met inclusion criteria for this study, 117 were unplanned readmissions (5.1%). These occurred at a mean of 15.9 days (range: 3-30 days) after surgery. The risk-adjusted analysis revealed that bleeding disorder (odds ratio, OR = 2.8, confidence intervals, CI = 1.0-7.6, P = 0.043), insulin dependent diabetes (OR = 2.5, CI = 1.4-4.4, P = 0.004), and total length of stay > 5 days (OR = 1.8, CI = 1.2-2.8, P = 0.009) were independent predictors for unplanned readmission. Significant postoperative complications included wound complications (OR = 27.6, CI = 13.9-54.8, P < 0.0001), pulmonary embolism and/or deep vein thrombosis/thrombophlebitis (OR = 11.9, CI = 5.0-28.5, P < 0.0001), sepsis (OR = 8.5, CI = 2.3-32.1, P = 0.002), and urinary tract infections (OR = 2.4, CI = 0.9-6.9, P = 0.094). CONCLUSION: The unplanned readmission rate for patients undergoing PLF was low, but this study's findings of potentially modifiable risk factors suggest that substantial improvement with this quality metric is possible. LEVEL OF EVIDENCE: N/A.

Differences in Fundamental Sagittal Pelvic Parameters Based on Age, Sex, and Race.

STUDY DESIGN: This is a retrospective cohort study. OBJECTIVE: To determine whether age, sex, and race have independent effects on sagittal pelvic parameters. SUMMARY OF BACKGROUND DATA: Pelvic parameters and sagittal balance correlate with health-related quality of life and are important for patient assessment and surgical planning. Age, sex, and race are 3 unalterable patient factors that may influence pelvic morphology. METHODS: We conducted a retrospective review of consecutive adult patients who presented to our radiology practice between 2010 and 2015 and had a standing, lateral lumbosacral radiograph. Any patients without both femoral heads and L1-S1 visible on the radiograph, and any patients presenting with traumatic injury, coronal deformity, prior instrumentation, spondylolisthesis, or neoplasm of the spine were excluded. Univariate analysis determined differences in measurements among African American, white, and Hispanic races, as well as between male and female sexes. Correlation analysis between age and different measurements was also conducted. Multivariable regression was then used to determine the independent effect of age, sex, and race on pelvic parameters. RESULTS: We investigated 1801 adults (older than 18 y) and 1246 had a recorded race. There were 1165 women, 636 men, 525 whites, 404 African Americans, and 317 Hispanics. Multivariable regression demonstrated a statistically significant increase in pelvic tilt (PT), pelvic incidence (PI), and pelvic incidence-lumbar lordosis (PI-LL) with aging, and statistically significant decrease in sacral slope (SS) and LL with aging. Women had a statistically greater LL than men. African Americans had a statistically smaller PT and greater SS and PI-LL relative to whites, while Hispanics had a statistically smaller PT and PI-LL, and a statistically greater SS and LL relative to whites. CONCLUSIONS: Pelvic parameters were different between sexes, among races, and changed with age. These findings are important for patient assessment and preoperative planning to obtain optimal sagittal balance. LEVEL OF EVIDENCE: Level 3.

Multi-Rod Constructs Can Prevent Rod Breakage and Pseudarthrosis at the Lumbosacral Junction in Adult Spinal Deformity.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To determine if patients fused with multi-rod constructs to the pelvis have a lower incidence of lumbosacral rod failure and pseudarthrosis than those fused with dual-rod constructs. METHODS: We performed a retrospective review of consecutive adult spinal deformity patients who underwent long fusion to the pelvis. Inclusion criteria were >5 levels, primary fusion or revision for L5-S1 pseudarthrosis, and minimum 1-year follow-up. Revision patients with indications other than L5-S1 pseudarthrosis were excluded. One-year follow-up plain radiographs were reviewed for rod integrity, and computed tomography scan (CT) was obtained whenever rod breakage was observed. Dual-rod and multi-rod (3 or 4 rods) cohorts were statistically compared. RESULTS: There were 31 patients with 15 in the dual-rod group and 16 in the multi-rod group, with average ages of 68 ± 9 and 63 ± 12 years, respectively. No patients in the multi-rod group experienced rod fracture, whereas 6 in the dual-rod group fractured a rod (P = .007), with 4 occurring at the lumbosacral junction (P = .04). CT scan in the 4 lumbosacral rod fracture cases, and surgical exploration in 3, confirmed pseudarthrosis and hypertrophic nonunion at the L5-S1 junction. CONCLUSION: Patients with dual-rod constructs had a statistically greater incidence of lumbosacral pseudarthrosis with implant failure than those with multi-rod constructs. CT and surgical exploration showed hypertrophic nonunion as opposed to oligo- or atrophic nonunion. This suggests that mechanical instability, not biology, is the main reason for failure, and could be addressed with the use of multi-rods.

Frailty Is Predictive of Adverse Postoperative Events in Patients Undergoing Lumbar Fusion.

STUDY DESIGN: Retrospective study of prospectively collected data. OBJECTIVE: To analyze the modified frailty index (mFI) as a predictor of adverse postoperative events following posterior lumbar fusion. METHODS: The American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database including all adult patients undergoing posterior lumbar interbody fusion or transforaminal lumbar interbody fusion between 2005 and 2012. Outcomes measured included mortality, postoperative complications, length of stay, reoperations, and readmissions. The previously described mFI was calculated, and univariate and multivariate logistic regression analysis were used to analyze risk factors associated with morbidity, mortality, and adverse postoperative events. This study was qualified as exempt by the Mount Sinai Hospital Institutional Review Board. RESULTS: A total of 6094 patients met inclusion criteria. The mean mFI was 0.087(0-0.545). Increasing mFI score was associated with increased complications, reoperations, prolonged length of stay (LOS), and morbidity (P < .05). As the mFI score increased from 0.27 (3/11 variables present) to ≥0.36 (4/11), the rate of any complication increased from 26.8% to 35% (P < .0001), sepsis 2.4% to 5.2% (P < .0001), wound complications 4.4% to 6.5% (P < .0001), unplanned readmissions 4.7% to 20% (P = .02), and urinary tract infection 4.1% to 10.4% (P < .0001). An mFI of ≥0.36 was an independent predictor of any complication (odds ratio [OR]= 2.2, 95% confidence interval [CI] = 1.3-3.7), sepsis (OR = 6.3, 95%, CI = 1.8-21), wound complications (OR = 2.9, 95% CI = 1.1-8.2), prolonged LOS (OR = 2.3, 95% CI = 1.4-3.7), and readmission (OR = 4.3, 95% CI = 1.5-12.7). CONCLUSION: Patients with higher mFI scores (≥ 4/11 variables) are at a significantly higher risk of major complications, readmissions, and prolonged LOS following lumbar fusion.

Beyond Pelvic Incidence-Lumbar Lordosis Mismatch: The Importance of Assessing the Entire Spine to Achieve Global Sagittal Alignment.

STUDY DESIGN: Retrospective case series. OBJECTIVE: To investigate which sagittal parameters contribute to a normal sagittal vertical axis (SVA) when there is a pelvic incidence-lumbar lordosis (PI-LL) mismatch >10° following adult spinal deformity (ASD) correction. METHODS: We performed a retrospective review of ASD patients with >5 levels fused. Sagittal measurements between cohorts of postoperative PI-LL >10° and PI-LL<10° were compared. We correlated SVA to pelvic tilt (PT), thoracic kyphosis (TK), PI-LL, cervical lordosis (CL), and correlated the pre- to postoperative change in SVA to change in PT, change in TK, change in PI-LL, and change in CL. We also correlated SVA and the change in SVA to combined parameters of ((PI-LL) - PT + TK). RESULTS: We analyzed 52 patients with a mean age of 59 ± 16 years. In patients with a postoperative SVA <5cm, a smaller TK was seen when PI-LL >10° than when PI-LL<10° (15.45° vs 33.04°, P = .0004). Additionally, PT was larger when PI-LL >10° than when PI-LL <10° (25.73° vs 19.07°, P = .006). SVA correlated better with ((PI-LL) - PT + TK) (R2 = 0.51) than with PI-LL alone (R2 = 0.33). Lastly, there was no significant correlation between change in pre- to postoperative SVA with change in TK for all cases (P = .73), but in cases where change in PI-LL was <10°, there was a significant correlation between change in TK and change in SVA (P = .009). CONCLUSION: Our results demonstrate that PT and TK, and not just PI-LL, play an important role in maintaining sagittal balance when there is a PI-LL mismatch >10°.

A Preliminary Algorithm Using Spine Measurement Software to Predict Sagittal Alignment Following Pedicle Subtraction Osteotomy.

STUDY DESIGN: Retrospective case series. OBJECTIVE: To evaluate if spine measurement software can simulate sagittal alignment following pedicle subtraction osteotomy (PSO). METHODS: We retrospectively reviewed consecutive adult spinal deformity patients who underwent lumbar PSO. Sagittal measurements were performed on preoperative lateral, standing radiographs. Sagittal measurements after simulated PSO were compared to actual postoperative measurements. A regression equation was developed using cases 1-7 to determine the amount of manual rotation required of each film to match the simulated sagittal vertical axis (SVA) to the actual postoperative SVA. The equation was then applied to cases 8-13. RESULTS: For all 13 cases, the spine software accurately simulated lumbar lordosis, pelvic incidence lumbar lordosis mismatch, and T1 pelvic angle, with no significant differences between actual and simulated measurements. The pelvic tilt (PT), sacral slope (SS), thoracolumbar alignment (TL), thoracic kyphosis (TK), T9 spino-pelvic inclination (T9SPi), T1 spino-pelvic inclination (T1SPi), and SVA were inaccurately simulated. The PT, SS, T9SPi, T1SPi, and SVA all change with manual rotation of the film, and by using the regression equation developed with cases 1-7, we were able to improve the accuracy and decrease the variability of the simulated PT, SS, T9SPi, T1SPi, and SVA for cases 8-13. CONCLUSIONS: Dedicated spine measurement software can accurately simulate certain sagittal measurements, such as LL, PI-LL, and TPA, following PSO. A number of measurements, including PT, SS, TL, TK, T9SPi, T1SPi, and SVA were inaccurately simulated. Our preliminary algorithm improved the accuracy and decreased the variability of certain measurements, but requires future prospective studies for further validation.

A Matched Cohort Analysis Comparing Stand-Alone Cages and Anterior Cervical Plates Used for Anterior Cervical Discectomy and Fusion.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To compare perioperative characteristics of stand-alone cages and anterior cervical plates used for anterior cervical discectomy and fusion (ACDF). METHODS: We reviewed 40 adult patients who received a stand-alone cage for elective ACDF and matched them with 40 patients who received an anterior cervical plate. We statistically compared operative time, length of stay, proportion of ambulatory cases, overall complications necessitating a trip to the ED, readmission, or reoperation related to index procedure. RESULTS: There were 21 women and 19 men in the plate cohort with average ages of 53 years ± 12 and 20 women and 20 men in the stand-alone group with an average age of 52 years ± 11. With no statistical difference in total number, the plate group experienced 4 short-term (within 90 days of discharge) complications, including 3 patients who visited the emergency department for dysphagia and 1 who visited the emergency department for severe back pain, while the stand-alone group experienced 0 complications. There was no significant difference in operative time between the stand-alone group (75.35 min) and the plate group (81.35 min; P = .37). There was a significant difference between the proportion of ambulatory cases in the stand-alone group (25) and the plate group (6; P < .0001). CONCLUSION: Our results demonstrate that stand-alone cages have fewer complications compared to anterior plating, with a lower trend of incidence of postoperative dysphagia. Stand-alone cages may offer the advantage of sending patients home ambulatory after ACDF surgery.

Incidence, Impact, and Risk Factors for 30-Day Wound Complications Following Elective Adult Spinal Deformity Surgery.

STUDY DESIGN: Case-control study. OBJECTIVE: To determine the incidence, impact, and risk factors for wound complications within 30 days following elective adult spinal deformity surgery. METHODS: Current Procedural Terminology and International Classification of Diseases, Ninth Edition, diagnosis codes were used to query the database for adults who underwent spinal deformity surgery from 2010 to 2014. Patients were separated into groups of those with and without wound complications. Univariate analysis and multivariate logistic regression were used to analyze the influence of patient factors, operative variables, and clinical characteristics on the incidence of postoperative wound complication. This study was qualified as exempt by the Mount Sinai Hospital Institutional Review Board. RESULTS: A total of 5803 patients met the criteria for this study. Wound complications occurred in 140 patients (2.4%) and were significantly associated with other adverse outcomes, including higher rates of unplanned reoperation (P < .0001) and prolonged length of stay (P < .0001). Regardless of fusion length, wound complication rates were higher with a posterior approach (short = 2.7%; long = 3.7%) than an anterior one (short = 2.2%; long = 2.7). According to the multivariate analysis, posterior fusion (odds ratio [OR] = 1.8; P = .010), obese class II (OR = 1.7; P = .046), obese class III (OR = 2.8; P < .0001), preoperative blood transfusion (OR = 6.1; P = .021), American Society of Anesthesiologists class ≥3 (OR = 1.7; P = .009), and operative time >4 hours (OR = 1.8; P = .006) were statistically significant risk factors for wound complications. CONCLUSION: The 30-day incidence of wound complication in adult spinal deformity surgery is 2.4%. The risk factors for wound complication are multifactorial. This data should provide a step toward developing quality improvement measures aimed at reducing complications in high-risk adults.

Early Complications and Outcomes in Adult Spinal Deformity Surgery: An NSQIP Study Based on 5803 Patients.

STUDY DESIGN: Retrospective analysis. OBJECTIVE: The purpose of this study is to determine the incidence, impact, and risk factors for short-term postoperative complications following elective adult spinal deformity (ASD) surgery. METHODS: Current Procedural Terminology codes were used to query the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) for adults who underwent spinal deformity surgery from 2010 to 2014. Patients were separated into groups of those with and without complications. Univariate analysis and multivariate logistic regression were used to assess the impact of patient characteristics and operative features on postoperative outcomes. RESULTS: In total, 5803 patients were identified as having undergone ASD surgery in the NSQIP database. The average patient age was 59.5 (±13.5) years, 59.0% were female, and 81.1% were of Caucasian race. The mean body mass index was 29.5(±6.6), with 41.9% of patients having a body mass index of 30 or higher. The most common comorbidities were hypertension requiring medication (54.5%), chronic obstructive pulmonary disease (4.9%), and bleeding disorders (1.2%). Nearly a half of the ASD patients had an operative time >4 hours. The posterior fusion approach was more common (56.9%) than an anterior one (39.6%). The mean total relative value unit was 73.4 (±28.8). Based on multivariate analyses, several patient and operative characteristics were found to be predictive of morbidity. CONCLUSION: Surgical correction of ASD is associated with substantial risk of intraoperative and postoperative complications. Preoperative and intraoperative variables were associated with increased morbidity and mortality. This data may assist in developing future quality improvement activities and saving costs through measurable improvement in patient safety.

Cervical disc replacement surgery: indications, technique, and technical pearls.

PURPOSE OF REVIEW: Cervical disc replacement (CDR) is a surgical option for appropriately indicated patients, and high success rates have been reported in the literature. Complications and failures are often associated with patient indications or technical variables, and the goal of this review is to assist surgeons in understanding these factors. RECENT FINDINGS: Several investigations have been published in the last 5 years supporting the use of CDR in specific patient populations. CDR has been shown to be comparable or favorable to anterior cervical discectomy and fusion in several meta-analyses and mid-term follow-up studies. CDR was developed as a technique to preserve motion following a decompression procedure while minimizing several of the complications associated with fusion and posterior cervical spine procedures. Though success with cervical fusion and posterior foraminotomy has been well documented in the literature, high rates of mid- and long-term complications have been clearly established. CDR has also been associated with several complications and challenges with regard to surgical technique, though improvements in implant design have lead to an increase in utilization. Several devices currently exist and vary in terms of material, design, and outcomes. This review paper discusses indications, surgical technique, and technical pearls and reviews the CDR devices currently available.

Thirty-Day Morbidity Associated with Pelvic Fixation in Adult Patients Undergoing Fusion for Spinal Deformity: A Propensity-Matched Analysis.

STUDY DESIGN: Retrospective study of prospectively collected data. OBJECTIVE: To determine if patients undergoing spinal deformity surgery with pelvic fixation are at an increased risk of morbidity. METHODS: The American College of Surgeons National Surgical Quality Improvement Program is a large multicenter clinical registry that prospectively collects preoperative risk factors, intraoperative variables, and 30-day postoperative morbidity and mortality outcomes from ~400 hospitals nationwide. Current Procedural Terminology codes were used to query the database between 2010 and 2014 for adults who underwent fusion for spinal deformity. Patients were separated into groups of those with and without pelvic fixation. Univariate analysis and multivariate logistic regression were used to analyze the effect of pelvic fixation on the incidence of postoperative morbidity and other surgical outcomes. RESULTS: Multivariate analysis showed that pelvic fixation was a significant predictor of overall morbidity (odds ratio [OR] = 2.3, 95% confidence interval [CI]: 1.7 to 3.1, p = 0.0002), intra- or postoperative blood transfusion (OR = 2.3, 95% CI: 1.7 to 3.1 p < 0.0001), extended operative time (OR = 4.7, 95% CI: 3.1 to 7.0 p < 0.0001), and length of stay > 5 days (OR = 2.1, 95% CI 1.5 to 2.8, p < 0.0001) in patients undergoing fusion for spinal deformity. However, fusion to the pelvis did not lead to additional risk for other complications, including wound complications (p = 0.3191). CONCLUSION: Adult patients undergoing spinal deformity surgery with pelvic fixation were not susceptible to increased morbidity beyond increased blood loss, greater operative time, and extended length of stay.

Risk Factors for Reoperation in Patients Treated Surgically for Degenerative Spondylolisthesis: A Subanalysis of the 8-year Data From the SPORT Trial.

STUDY DESIGN: Retrospective analysis of prospective data from the degenerative spondylolisthesis (DS) arm of the Spine Patient Outcomes Research Trial. OBJECTIVE: The aim of this study was to identify risk factors for reoperation in patients treated surgically for DS and compare outcomes between patients who underwent reoperation with nonreoperative patients. SUMMARY OF BACKGROUND DATA: Several studies have examined outcomes following surgery for DS, but few have identified risk factors for reoperation. METHODS: Analysis included patients with neurogenic claudication (>12 weeks), clinical neurological signs, spinal stenosis, and DS on standing lateral x-rays. Univariate and multivariate analyses were used to investigate patient characteristics and risk factors. Treatment effects (TEs) were calculated and compared between study groups. RESULTS: Of 406 patients, 72% underwent instrumented fusion, 21% noninstrumented fusion, and 7% decompression alone. At 8 years, the reoperation rate was 22%, of which 28% occurred within 1 year, 54% within 2 years, 70% within 4 years, and 86% within 6 years. The reasons for reoperation included recurrent stenosis or progressive spondylolisthesis (45%), complications such as hematoma, dehiscence, or infection (36%), or new condition (14%). Reoperative patients were younger (62.2 vs. 65.3, P = 0.008). Significant risk factors were use of antidepressants (P = 0.008, hazard ratio [HR] 2.08) or having no neurogenic claudication upon enrollment (P = 0.02, HR 1.82). Patients who were smokers, diabetics, obese, or on workman's compensation were not at greater risk for reoperation. At 8-year follow-up, scores for SF-36 bodily pain (BP), Oswestry Disability Index, American Academy of Orthopaedic Surgeons/Modems version (ODI), and stenosis frequency index were better in nonreoperative patients. TE favored nonreoperative patients for SF-36 BP, physical function, ODI, Stenosis Bothersomeness Index, and satisfaction with symptoms (P < 0.001). CONCLUSION: The incidence of reoperation for patients with DS was 22% 8 years following surgery. Patients with a history of no neurogenic claudication and patients taking antidepressants were more likely to undergo reoperation. Outcome scores and TE were more favorable in nonreoperative patients. LEVEL OF EVIDENCE: 2.