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.

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.

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.

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.

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.

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.

Frailty Index as a Predictor of Adverse Postoperative Outcomes in Patients Undergoing Cervical Spinal Fusion.

STUDY DESIGN: Retrospective study of prospectively collected data. OBJECTIVE: To investigate the applicability of the modified frailty index (mFI) as a predictor of adverse postoperative events in patients undergoing anterior cervical discectomy and fusion (ACDF) or posterior cervical fusion (PCF). SUMMARY OF BACKGROUND DATA: Prior studies have investigated the mFI and shown it as an independent predictor of adverse postoperative outcomes across multiple surgical specialties. However, this topic has not still been studied in patients undergoing cervical fusion or in spinal surgery. METHODS: The National Surgical Quality Improvement Program is a multicenter clinical registry that prospectively collects preoperative risk factors, intraoperative variables, and 30-day postoperative morbidity and mortality outcomes from about 400 hospitals nationwide. Current Procedural Terminology codes were used to query the database for adults who underwent elective ACDF and PCF between 2005 and 2012. The mFI was calculated for each patient. Univariate analysis and multivariate logistic regression were used to analyze the mFI as a predictor for postoperative complications. RESULTS: For ACDF group, Clavien-Dindo grade IV complications rate increased from 0.8% to 9.0% as mFI increased from 0 to ≥0.27, and mFI = 0.27 was found to be an independent predictor of Clavien-Dindo grade IV complications (odds ratio, OR, = 4.67, 95% confidence interval, CI, = 2.27-9.62, P < 0.001). For PCF groups, Clavien-Dindo grade IV complications rate increased from 0.7% to 20.0% as mFI increased from 0 to ≥0.36, and mFI ≥ 0.36 was identified as an independent predictor of Clavien-Dindo grade IV complications (OR = 41.26, 95% CI = 6.62-257.15, P < 0.001). CONCLUSION: The mFI was shown to be an independent predictor of Clavien-Dindo grade IV complications in patients undergoing ACDF or PCF. The mFI itself may be used to stratify risks in patients undergoing cervical fusion, or, the mFI scheme could be used as a platform upon which more efficient risk stratification could be done with addition of other variables. LEVEL OF EVIDENCE: 4.

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.

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.

Hospital-Acquired Conditions in Adult Spinal Deformity Surgery: Predictors for Hospital-Acquired Conditions and Other 30-Day Postoperative Outcomes.

STUDY DESIGN: A retrospective study of prospectively collected data. OBJECTIVE: The aim of this study was to identify risk factors in developing hospital-acquired conditions (HACs) and association of HACs with other 30-day complications in the adult spinal deformity (ASD) population. SUMMARY OF BACKGROUND DATA: HACs are subject to a nonpayment policy by the Center for Medicare and Medicaid Services and provide an incentive for medical institutions to improve patient safety. HACs in the ASD population may further exacerbate the already high rates of postoperative morbidity and mortality. METHODS: The 2010 to 2014 ACS-NSQIP database was queried using Current Procedural Terminology (CPT) codes for adults who had fusion for spinal deformity. Patients were divided into two cohorts on the basis of the development of an HAC, as defined as a case of surgical site infection, urinary tract infection, or venous thromboembolism. Univariate and multivariate logistic regression analyses were employed to determine predictors for HACs and association of HACs with other 30-day postoperative outcomes. RESULTS: Five thousand eight hundred nineteen patients met the inclusion criteria for the study of whom 313 (5.4%) had an HAC. Multivariate logistic regression analysis revealed that age 61 to 70 versus ≤50 years [odds ratio (OR) = 1.58, 1.10-2.27, P = 0.013], 71 to 80 versus ≤50 years (OR = 1.94, 1.31-2.87, P = 0.001), and >80 versus ≤50 years (OR = 2.30, 1.21-4.37, P = 0.011), dependent/partially dependent versus independent functional status (OR = 1.74, 1.13-2.68, P = 0.011), combined versus anterior surgical approach (OR = 2.46, 1.43-4.24, P = 0.001), and posterior versus anterior surgical approach (OR = 1.64, 1.19-2.25, P = 0.002), osteotomies (OR = 1.61, 1.22-2.13, P = 0.001), steroid use (OR = 2.19, 1.39-3.45, P = 0.001), obesity (OR = 1.38, 1.09-1.74, P = 0.007), and operation time ≥4 hours (OR = 2.42, 1.82-3.21, P < 0.001) were predictive factors in developing an HAC. CONCLUSION: Several modifiable and nonmodifiable factors (age, functional status, surgical approach, utilization of osteotomies, steroid use, obesity, and operation time ≥4 hours) were associated with developing an HAC. HACs were also risk factors for other postoperative complications. LEVEL OF EVIDENCE: 3.

Comparing National Inpatient Sample and National Surgical Quality Improvement Program: An Independent Risk Factor Analysis for Risk Stratification in Anterior Cervical Discectomy and Fusion.

STUDY DESIGN: Retrospective study of prospectively collected data. OBJECTIVE: To explore interdatabase reliability between National Inpatient Sample (NIS) and National Surgical Quality Improvement Program (NSQIP) for anterior cervical discectomy and fusion (ACDF) in data collection and its impact on subsequent statistical analyses. SUMMARY OF BACKGROUND DATA: Clinical studies in orthopedics using national databases are ubiquitous, but analytical differences across databases are largely unexplored. METHODS: A retrospective cohort study of patients undergoing ACDF surgery was performed in NIS and NSQIP. Key demographic variables, comorbidities, intraoperative characteristics, and postoperative complications were analyzed via bivariate and multivariate analyses. RESULTS: A total of 112,162 patients were identified from NIS and 10,617 from NSQIP. Bivariate analysis revealed small, but significant, differences between patient demographics, whereas patient comorbidities and ACDF intraoperative variables were largely much more distinct across the two databases. Multivariate analysis identified independent risk factors between NIS and NSQIP for mortality, cardiac complications, and postoperative sepsis, some of which were identified in both but most of which were unique to one database. Identification of independent risk factors from both databases specifically highlights their greater validity and importance in stratifying patient risks. In addition, NSQIP was found to be a more accurate predictor for complications based on the average areas under the receiver-operating curve (CNSQIP = 0.83 vs. CNIS = 0.81) across the multivariate models. Complication rate analysis between inpatient and outpatient settings in NSQIP showed the importance of at least 30-day patient follow up, which was devoid in NIS data tabulation and further marked its weakness compared with NSQIP. CONCLUSION: Despite having largely similar patient demographics, this study highlights critical risk factors for ACDF and demonstrates how different patient profiles can be across NIS and NSQIP, the impact of such differences on identification of independent risk factors, and how NSQIP is ultimately better suited for adverse-event studies. LEVEL OF EVIDENCE: 3.

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.

Frailty is associated with morbidity in adults undergoing elective anterior lumbar interbody fusion (ALIF) surgery.

BACKGROUND CONTEXT: Prior studies have suggested no significant differences in functional status and postoperative complications of elderly versus nonelderly patients undergoing posterior lumbar interbody fusion; however, similar studies have not been comprehensively investigated in the setting of anterior lumbar interbody fusion (ALIF). PURPOSE: The objective was to quantify the ability of the modified Frailty Index (mFI) to predict postoperative events in patients undergoing ALIF. STUDY DESIGN: Secondary analysis of prospectively collected data. PATIENT SAMPLE: Patients undergoing ALIF in the National Surgical Quality Improvement Program (NSQIP) participant files for the period 2010 through 2014. OUTCOMES MEASURES: Outcome measures included any postoperative complication, return to operating room (OR), and length of stay >5 days. METHODS: NSQIP participant files from 2010 to 2014 were used to identify patients undergoing ALIF. The mFI used in the present study is an 11-variable assessment that maps 16 NSQIP variables to 11 variables in the Canadian Study of Health and Ageing Frailty Index. Univariate analysis and multivariable logistic regression models were used to compare the relative strength of association between mFI with outcome variables of interest. RESULTS: In total, 3,920 ALIF cases were identified and grouped according to their mFI score: 0 (n=2,025), 0.09 (n=1,382), 0.18 (n=464), or ≥0.27 (n=49). As the mFI increased from 0 (no frailty-associated variables) to 0.27 (4 of 11) or higher, there was a significant stepwise increase in any complication from 10.8% to 32.7%. After multivariable regression analysis, no significant association was found between higher mFI scores with urinary tract infections and venous thromboembolism. High frailty scores were significant predictors of any complication (mFI of ≥0.27 [reference: 0]; OR 2.4; p=.040) and pulmonary complications (mFI score ≥0.27; OR 7.5; p=.001). CONCLUSIONS: In summary, high mFI scores were found to be independently associated with any complication and pulmonary complications in patients who underwent ALIF. The use of mFI together with traditional risk factors may help better identify high-surgical risk patients, which may be useful for preoperative and postoperative care optimization.