The odontoid-CSVL distance in a global population of asymptomatic volunteers: normative values and implications for spinal coronal alignment.

PURPOSE: In a population of asymptomatic volunteers across 5 countries, we sought to: (a) establish normative values of the Odontoid-Central Sacral Vertical Line (OD-CSVL) across patient factors, and (b) assess correlations of OD-CSVL with other radiographic parameters. METHODS: A prospective, cross-sectional study of asymptomatic adult volunteers, ages 18-80 years, were enrolled across 5 countries (France, Japan, Singapore, Tunisia, United States) forming the Multi-Ethnic Alignment Normative Study (MEANS) cohort. Included volunteers had no known spinal disorder(s), no significant neck/back pain (VAS ≤ 2; ODI ≤ 20), and no significant scoliosis (Cobb ≤ 20°). Radiographic measurements included commonly used coronal alignment parameters (mm) and angles (°). OD-CSVL was defined as the difference between the odontoid plumb line (line from the tip of the odontoid vertically down) and the CSVL (vertical line from the center of the sacrum). Chi-square, student's t tests, Kruskal-Wallis, Wilcoxon rank-sum, linear regression, and Pearson's correlation were used with significance at p < 0.05. RESULTS: 467 volunteers were included with normative OD-CSVL values by age decade, gender, BMI, and country. Mean ± SD OD-CSVL was 8.3 mm ± 6.5 mm and 31 (6.6%) volunteers were almost perfectly aligned (OD-CSVL < 1 mm). A linear relationship was seen between OD-CSVL with both age (p < 0.001) and BMI (p = 0.015). Significant variation was seen between OD-CSVL and 5 different ethnicities (p = 0.004). OD-CSVL correlated best with other coronal radiographic parameters, C7-CSVL (r = 0.743, p < 0.001), OD-knee (r = 0.230, p < 0.001), CAM-knee (r = 0.612, p < 0.001), and regional TL cobb angle (r = 0.4214, p = 0.005). CONCLUSION: Among asymptomatic volunteers, increased OD-CSVL was significantly associated with increased age, increased BMI, and ethnicity, but not gender. OD-CSVL correlated strongest with C7-CSVL, TL cobb angle, OD-knee, and CAM-knee. OD-CSVL. These results support further study of OD-CSVL in symptomatic adult spine deformity patients.

Fracturing the Lateral Hinge Improves Radiographic Alignment and Does Not Affect Clinical Outcomes of the Minimally Invasive Akin Osteotomy.

BACKGROUND: Intraoperative fracture of the lateral cortex is common during Akin osteotomy. In a recent study, lateral cortex fracture did not impede healing or result in loss of correction in a combined cohort of open and percutaneous osteotomies stabilized by K-wire fixation. We hypothesize that undesired lateral cortex fracture will not affect radiographic correction and patient-reported outcomes in a percutaneous cohort stabilized by permanent, rigid screw fixation. METHODS: Consecutive patients with hallux valgus who underwent first metatarsal osteotomy and percutaneous Akin osteotomy stabilized by permanent, rigid screw fixation between May 2020 and January 2022 were retrospectively reviewed. Patients were stratified based on fractured lateral cortex (FC) or its absence (nonfractured cortex [NFC]). Visual analog scale (VAS) and Foot Function Index (FFI) were used to assess pain and patient-reported outcomes at 1-year follow-up. Patients were polled for satisfaction at 1-year follow-up by yes/no survey. RESULTS: Ninety-eight patients (89% female) were reviewed (98 feet; 43 NFC, 55 FC). Mean age was 48.3 years (range, 18-83 years). Mean preoperative VAS score was 7.5 and 7.7 in NFC and FC groups, which significantly decreased to 0.6 (P < .01) and 0.6 (P < .01), respectively. Mean total FFI was 53.9 and 54.2 and decreased to 17.9 (P < .01) and 17.2 (P < .01) in the NFC group and FC group, respectively. Overall, 97.8% of the NFC group and 96.4% of the FC group reported satisfaction.Mean HVA improved from 27.2 (16-42) degrees to 10.7 degrees (4-12) postoperatively in the NFC group. And in the FC group, HVA improved from 29.3 (19-39) degrees to 7.1 (4-12) degrees postoperatively. Postoperative HVA was significantly lower in the FC group (P < .05). CONCLUSION: In an exclusively percutaneous surgical cohort with correction maintained by rigid screw fixation, fracture of the lateral cortex is associated with improved postoperative radiologic alignment without detriment to patient-reported outcomes. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

Practical Methods of Assessing Coronal Alignment and Outcomes in Adult Spinal Deformity Surgery: A Comparative Analysis.

STUDY DESIGN: Asymptomatic cohort: prospective, cross-sectional, multicenter. Symptomatic: retrospective, multisurgeon, single-center. OBJECTIVE: To assess the association between cranial coronal alignment and adult spinal deformity (ASD) surgical risk and outcomes. SUMMARY OF BACKGROUND DATA: ASD leads to decreased quality of life. Studies have shown that coronal malignment (CM) is associated with worse surgical outcomes. MATERIALS AND METHODS: A total of 468 adult participants were prospectively enrolled in the asymptomatic cohort. Totally, 172 symptomatic ASD patients with 2-year follow-ups were retrospectively enrolled in the symptomatic cohort. Three cranial plumb line parameters: the positions of the plumb lines from the midpoint between the medial orbital rims (ORB-L5), the odontoid (OD-L5), and the C7 centroid (C7-L5) relative to the L5 pedicle, were measured. Each subject had plumb line medial (M), touching (T), or lateral (L) to either pedicle. The association between each group of patients and radiographic parameters, intraoperative variables, patient-reported outcomes, and clinical outcomes were analyzed. RESULTS: In the asymptomatic cohort, OD-L5 was medial to or touching the L5 pedicle in 98.3% of volunteers. In the symptomatic patients, preoperative OD-L5-L exhibited higher mean age (56.2±14.0), odontoid-coronal vertical axis (OD-CVA) (5.5±3.3 cm), Oswestry disability index (ODI) score (40.6±18.4), pelvic fixation rate (56/62, 90.3%), OR time (528.4±144.6 min), median estimated blood loss (1300 ml), and durotomy rate (24/62, 38.7%). A similar pattern of higher CVA, preoperative ODI, intraoperative pelvic fixation rate, OR time, estimated blood loss, and durotomy rate was observed in ORB-L5-L and C7-L5-L patients. Final follow-up postoperative OD-L5-L was associated with higher rates of proximal junctional kyphosis (13.0%) and pseudarthrosis (17.4%). CONCLUSION: Preoperative OD-L5, ORB-L5, and C7-L5 lateral to pedicles were associated with worse preoperative ODI and higher intraoperative complexity. Postoperative OD-L5-L was associated with higher rates of proximal junctional kyphosis and pseudarthrosis. Postoperative CM, approximated by the cranial plumb line lateral to the L5 pedicles, was associated with sagittal plane complications.

The Importance of Pelvic Obliquity in Assessing Spinal Coronal Alignment: Normative Values, Demographic, and Radiographic Correlations.

STUDY DESIGN: Prospective, cross-sectional study. OBJECTIVE: In a geographically diverse population of asymptomatic volunteers, we sought to report the incidence of pelvic obliquity (PO), establish normative values of PO across patient factors, and assess the correlation of PO with radiographic parameters. SUMMARY OF BACKGROUND DATA: PO is defined as the misalignment of the pelvis and can be assessed through several anatomic landmarks. Significant PO, whether caused by leg-length discrepancy or not, can lead to coronal malalignment which causes severe pain and disability. Significant emphasis has been placed on achieving appropriate sagittal alignment in recent decades; however, a greater understanding of coronal alignment is needed, and PO is a crucial aspect of evaluating the coronal plane in adult spinal deformity patients. METHODS: Asymptomatic adult volunteers, ages 18-80 years, enrolled patients from 5 countries (France, Japan, Singapore, Tunisia, and the United States) in the "multiethnic alignment normative study" cohort (IRB 201812144). The included volunteers had no known spinal disorder(s), no significant neck or back pain (Visual Analog Scale: ≤2; Oswestry Disability Index: ≤20), and no abnormal alignment (Cobb ≤20°). PO was measured in the frontal plane as the distance between the highest points of each acetabulum, calculated along the vertical axis in millimeters (mm). The incidence of PO was defined as PO ≥10 mm. Kruskal-Wallis, Wilcoxon rank-sum, Pearson correlation, and linear regression were used. RESULTS: A total of 467 patients were included, and PO values by age, sex, body mass index, and country were provided. The overall incidence of PO ≥10 mm was 4.3%, and a nonsignificant trend toward increased PO with age was seen ( P = 0.077). No significant differences were seen in PO between sex, ethnicity, or body mass index groups. No significant correlation existed between PO and other commonly used coronal radiographic measurements. CONCLUSION: PO ≥10 mm occurred in 4.3% of asymptomatic volunteers. Despite the importance of recognizing PO in preventing coronal malalignment, PO did not seem to be associated with other radiographic and demographic information, which underscores the importance of intentionally assessing for any PO before surgery. These results in an asymptomatic population provide a foundation for studying PO in patients with spinal pathology.

Improvement in axial rotation with bracing reduces the risk of curve progression in patients with adolescent idiopathic scoliosis.

PURPOSE: New evidence highlights the significance of 3D in-brace correction for Adolescent Idiopathic Scoliosis (AIS) patients. This study explores how axial parameters relate to treatment failure in braced AIS patients. METHODS: AIS patients (Sanders 1-5) undergoing Rigo-Chêneau bracing at a single institution were included. Axial vertebral rotation (AVR) was determined by utilizing pre-brace and in-brace 3D reconstructions from EOS® radiographs. The primary outcome was treatment failure: surgery or coronal curve progression > 5°. Minimum follow-up was two years. RESULTS: 75 patients (81% female) were included. Mean age at bracing initiation was 12.8 ± 1.3 years and patients had a pre-brace major curve of 31.0° ± 6.5°. 25 patients (76% female) experienced curve progression > 5°, and 18/25 required surgical intervention. The treatment failure group had larger in-brace AVR than the success group (5.8° ± 4.1° vs. 9.9° ± 7.6°, p = 0.003), but also larger initial coronal curve measures. In-brace AVR did not appear to be associated with treatment failure after adjusting for the pre-brace major curve (Hazard Ratio (HR):0.99, 95% Confidence Interval (CI):0.94-1.05, p = 0.833). Adjusting for pre-brace major curve, patients with AVR improvement with bracing had an 85% risk reduction in treatment failure versus those without (HR:0.15, 95% CI:0.02-1.13, p = 0.066). At the final follow-up, 42/50 (84%) patients without progression had Sanders ≥ 7. CONCLUSIONS: While in-brace rotation was not an independent predictor of curve progression (due to its correlation with curve magnitude), improved AVR with bracing was a significant predictor of curve progression. This study is the first step toward investigating the interplay between 3D parameters, skeletal maturity, compliance, and brace efficacy, allowing a future prospective multicenter study. LEVEL OF EVIDENCE: Retrospective study; Level III.

Strategies to Avoid Distal Junctional Pathology.

Distal junctional pathology remains an unsolved issue in spine surgery. Distal junctional pathology can occur on a spectrum from asymptomatic radiographic finding to catastrophic distal construct failure. It is significant to address as postoperative sagittal balance has been shown to be correlated with patient-reported outcomes. Current literature and clinical experience suggest there are techniques that can be implemented regardless of setting to avoid distal junctional pathology. Much of the avoidant strategy relies on understanding the deformity pathology, selection of the lowest instrumented vertebra (LIV), health of the segments caudal to the LIV, and methods of fixation.

Clinical Outcomes Following Percutaneous Ankle Fusion With Bone Graft Substitute.

Background: Percutaneous ankle fusion is an emerging technique with minimal published outcome data. The goal of the present study is to retrospectively review clinical and radiographic outcomes following percutaneous ankle fusion and provide technique tips to perform percutaneous ankle fusion. Methods: Patients >18 years of age, treated by a single surgeon, from February 2018 to June 2021, who underwent primary isolated percutaneous ankle fusion supplemented with platelet-derived growth factor B (rhPDGF-BB) and beta-tricalcium phosphate, with at least 1-year follow-up were included. Surgical technique consisted of percutaneous ankle preparation followed by fixation with 3 headless compression screws. Pre- and postoperative visual analog scale (VAS) and Foot Function Index (FFI) were compared using paired t tests. Fusion was assessed radiographically by the surgeon on postoperative radiographs and computed tomography (CT) at 3 months postoperatively. Results: Twenty-seven consecutive adult patients were included in the study. Mean follow-up was 21 months. Mean age was 59.8 years. Mean preoperative and postoperative VAS scores were 7.4 and 0.2, respectively (P < .01). Mean preoperative FFI pain domain, disability domain, activity restriction domain, and total score were 20.9, 16.7, 18.5, and 56.4, respectively. Mean postoperative FFI pain domain, disability domain, activity restriction domain, and total score were 4.3, 4.7, 6.7, and 15.8, respectively (P < .01). Fusion was achieved in 26 of 27 patients (96.3%) at 3 months. Four patients (14.8%) had complications. Conclusion: We found in this cohort with surgery performed by a surgeon highly experienced in minimally invasive surgery that percutaneous ankle fusion augmented with a bone graft supplement achieved a high rate of fusion (96.3%) and a significant improvement in pain and function postoperatively while associated with minimal complications. Level of Evidence: Level IV, case series.

Is There a Difference in Screw Accuracy, Robot Time Per Screw, Robot Abandonment, and Radiation Exposure Between the Mazor X and the Renaissance? A Propensity-Matched Analysis of 1179 Robot-Assisted Screws.

STUDY DESIGN: Prospective single-cohort analysis. OBJECTIVES: To compare the outcomes/complications of 2 robotic systems for spine surgery. METHODS: Adult patients (≥18-years-old) who underwent robot-assisted spine surgery from 2016-2019 were assessed. A propensity score matching (PSM) algorithm was used to match Mazor X to Renaissance cases. Preoperative CT scan for planning and an intraoperative O-arm for screw evaluation were preformed. Outcomes included screw accuracy, robot time/screw, robot abandonment, and radiation. Screw accuracy was measured using Vitrea Core software by 2 orthopedic surgeons. Screw breach was measured according to the Gertzbein/Robbins classification. RESULTS: After PSA, a total of 65 patients (Renaissance: 22 vs. X: 43) were included. Patient/operative factors were similar between robot systems (P > .05). The pedicle screw accuracy was similar between robots (Renaissance: 1.1%% vs. X: 1.3%, P = .786); however, the S2AI screw breach rate was significantly lower for the X (Renaissance: 9.5% vs. X: 1.2%, P = .025). Robot time per screw was not statistically different (Renaissance: 4.6 minutes vs. X: 3.9 minutes, P = .246). The X was more reliable with an abandonment rate of 2.3% vs. Renaissance:22.7%, P = .007. Radiation exposure were not different between robot systems. Non-robot related complications including dural tear, loss of motor/sensory function, and blood transfusion were similar between robot systems. CONCLUSION: This is the first comparative analyses of screw accuracy, robot time/screw, robot abandonment, and radiation exposure between the Mazor X and Renaissance systems. There are substantial improvements in the X robot, particularly in the perioperative planning processes, which likely contribute to the X's superiority in S2AI screw accuracy by nearly 8-fold and robot reliability by nearly 10-fold.

A New Objective Radiographic Criteria for Diagnosis of Adult Idiopathic Scoliosis: Apical Pedicle Diameter Asymmetry.

OBJECTIVE: We sought to test the hypothesis that a difference of ≥1 mm in pedicle diameter between the convex and concave pedicles at the apex of a lumbar curve is a sensitive and/or specific criteria for adult idiopathic scoliosis (AdIS). METHODS: Thirty-nine operative patients with adult deformity and lumbar major curves were identified. A chart review was performed. Radiographic measurements included lumbar Cobb, curve apex, and Cobb levels involved. Apical pedicle diameter at the concavity and convexity of the curve apex were measured. RESULTS: Among these 39 patients, the average Cobb angle was 48.3 degrees. Curve apex averaged at L1/2 (range L1-L3). The curves spanned 4.7 levels (range 3-7). Twenty-five curves had the apex to the left, while 14 had the apex to the right. The average pedicle diameter at the apex was 6.1 mm. Fourteen patients had apical pedicle diameter asymmetry (APDA) >1 mm. Most (7 of 8, or 87.5%) of the patients with a history of adult idiopathic scoliosis had APDA >1 mm. A minority (7 of 31, 22.5%) of patients without known history of adult idiopathic scoliosis had APDA >1 mm (P < 0.01). CONCLUSIONS: Apical pedicle diameter asymmetry is among the sensitive diagnostic criteria for AdIS and may be useful for differentiating lumbar major AdIS from degenerative lumbar scoliosis. The sensitivity of APDA >1 mm is 87.5%, with specificity of 77.4%. We propose a new, sensitive radiographic criterion for adult idiopathic scoliosis. A difference of ≥1 mm in pedicle diameter between the convex and concave pedicles at that apex of a lumbar curve has a sensitivity of 87.5% and specificity of 77.4% for patient-reported history of adolescent scoliosis. It can be a useful tool as exclusion criteria for studies on AdIS.

Living with a C2-Sacrum Spinal Fusion: Surgical Outcomes and Quality of Life in Patients Fused from C2 to the Sacrum.

STUDY DESIGN: Single center, retrospective cohort study. OBJECTIVES: Little is known about the surgical outcomes and quality of life in patients with C2-sacrum posterior spinal fusion (PSF). Though it is thought to be a "final" construct, it remains unknown how patients fare postoperatively. We sought to evaluate the surgical outcomes and quality of life of patients after C2-sacrum PSF. METHODS: Consecutive patients undergoing C2-Sacrum PSF from 2015-2020 by 4 surgeons at a single institution were included. The study time period for each patient began after their index operation that led to the C2-sacrum fusion. Dates of surgery, complications, reoperations, patient reported outcomes (PROs) including EuroQol 5 Dimensions (EQ-5D), Oswestry Disability Index (ODI), Scoliosis Research Society (SRS) questionnaires, and activities of daily living (ADL) questions were collected and analyzed. Descriptive statistics, paired t-tests, student t-tests, and linear regression were used. RESULTS: Of the 23 patients who underwent C2-sacrum PSF, 6 patients (26%) required a total of 10 reoperations after a mean of 1.5 years (range 0-4 years) after C2-sacrum PSF. Five reoperations were for mechanical failure; 3 for wound complications/infection; and 2 for instrumentation and spinous process prominence. PROs were collected on 18 patients with mean follow-up of 2.4 years (range .5-4.5) after their C2-sacrum PSF. At 6-months, both SRS-22 and ODI scores improved significantly after C2-sacrum PSF (SRS: 57.5 to 76.3, P = .0014; ODI: 47.0 to 31.7, P = .013). Similarly, at a mean 2.4 years postoperatively, mean ODI improved significantly (47.0 to 30.4, P = .0032). Six patients (33%) had minimal symptoms (ODI <20). The median postoperative EQ-5D score was .74 (range .19 to 1.0), which compares favorably to patients with hip/knee osteoarthritis (EQ-5D .63) and diabetes mellitus (DM) (EQ-5D .69) and hypertension (HTN). In terms of activities of daily living (ADL), 10 patients (56%) exercised regularly-a mean 4.5 days/week. 11 (61%) could do light aerobic activity (e.g. stationary bike). 10 (55%) were able to play with children/grandchildren as desired. Eight patients (44%) hiked, and 2 (11%) drove independently. 11 (61%) could tolerate short air-travel comfortably. Of the 17 patients who could toilet and perform basic hygiene preoperatively, 16 (94%) were able to do so postoperatively. CONCLUSION: Though C2-sacrum PSF is thought to be a "final" construct, approximately 1 in 4 patients require subsequent operations. However, C2-sacrum PSF patients had a significant improvement in SRS and ODI scores by 6 months postop. Over 60% of patients were regularly performing light aerobic activity 2 years after their C2-sacrum PSF. EQ-5D suggests that this population fares better than those with degenerative hip/knee arthritis and similarly to those with common chronic conditions like DM and HTN.

Incidence, mechanism, and protective strategies for 2-year pelvic fixation failure after adult spinal deformity surgery with a minimum six-level fusion.

OBJECTIVE: The purpose of this study was to determine the incidence, mechanism, and potential protective strategies for pelvic fixation failure (PFF) within 2 years after adult spinal deformity (ASD) surgery. METHODS: Data for ASD patients (age ≥ 18 years, minimum of six instrumented levels) with pelvic fixation (S2-alar-iliac [S2AI] and/or iliac screws) with a minimum 2-year follow-up were consecutively collected (2015-2019). Patients with prior pelvic fixation were excluded. PFF was defined as any revision to pelvic screws, which may include broken rods across the lumbosacral junction requiring revision to pelvic screws, pseudarthrosis across the lumbosacral junction requiring revision to pelvic screws, a broken or loose pelvic screw, or sacral/iliac fracture. Patient information including demographic data and health history (age, sex, BMI, smoking status, American Society of Anesthesiologists score, osteoporosis), operative (total instrumented levels [TIL], three-column osteotomy [3CO], interbody fusion), screw (iliac, S2AI, length, diameter), rod (diameter, kickstand), rod pattern (number crossing lumbopelvic junction, lowest instrumented vertebra [LIV] of accessory rod[s], lateral connectors, dual-headed screws), and pre- and postradiographic (lumbar lordosis, pelvic incidence, pelvic tilt, major Cobb angle, lumbosacral fractional curve, C7 coronal vertical axis [CVA], T1 pelvic angle, C7 sagittal vertical axis) parameters was collected. All rods across the lumbosacral junction were cobalt-chrome. All iliac and S2AI screws were closed-headed tulips. Both univariate and multivariate analyses were performed to determine risk factors for PFF. RESULTS: Of 253 patients (mean age 58.9 years, mean TIL 13.6, 3CO 15.8%, L5-S1 interbody 74.7%, mean pelvic screw diameter/length 8.6/87 mm), the 2-year failure rate was 4.3% (n = 11). The mechanisms of failure included broken rods across the lumbosacral junction (n = 4), pseudarthrosis across the lumbosacral junction requiring revision to pelvic screws (n = 3), broken pelvic screw (n = 1), loose pelvic screw (n = 1), sacral/iliac fracture (n = 1), and painful/prominent pelvic screw (n = 1). A higher number of rods crossing the lumbopelvic junction (mean 3.8 no failure vs 2.9 failure, p = 0.009) and accessory rod LIV to S2/ilium (no failure 54.2% vs failure 18.2%, p = 0.003) were protective for failure. Multivariate analysis demonstrated that accessory rod LIV to S2/ilium versus S1 (OR 0.2, p = 0.004) and number of rods crossing the lumbar to pelvis (OR 0.15, p = 0.002) were protective, while worse postoperative CVA (OR 1.5, p = 0.028) was an independent risk factor for failure. CONCLUSIONS: The 2-year PFF rate was low relative to what is reported in the literature, despite patients undergoing long fusion constructs for ASD. The number of rods crossing the lumbopelvic junction and accessory rod LIV to S2/ilium relative to S1 alone likely increase construct stiffness. Residual postoperative coronal malalignment should be avoided to reduce PFF.

Intraoperative Anaphylaxis to the Bovine Flowable Gelatin Matrix: A Report of 2 Cases.

CASE: We present 2 cases of life-threatening intraoperative anaphylaxis to the bovine flowable gelatin matrix during pediatric spinal deformity surgery for kyphoscoliosis. Both patients had no known bovine or gelatin allergies. Anaphylaxis occurred shortly after pressurized injection into the first cannulated pedicle tract and was successfully treated with epinephrine, diphenhydramine, and methylprednisolone infusion. The allergic reaction was confirmed with tryptase levels and serum-specific immunoglobulin E for beef, pork, bovine collagen, and porcine collagen. CONCLUSION: In patients with beef, pork, or gelatin intolerance, a significant atopic history or childhood vaccine reaction, preoperative allergy consultation, and testing should be performed to prevent this life-threatening complication.

The deformity angular ratio: can three-dimensional computed tomography improve prediction of intraoperative neuromonitoring events?

PURPOSE: Assess whether a novel deformity angular ratio (DAR) calculated using preoperative three-dimensional computed tomography (3D CT) is more accurate than total DAR (T-DAR) radiographic measurements at predicting intraoperative neuromonitoring (IONM) events during vertebral column resection (VCR). METHODS: Consecutive, unique patients undergoing thoracic VCR by a single surgeon from 2015 to 2021 were identified. The T-DAR was calculated by dividing the total radiographic Cobb angle by the number of vertebral segments the angle subtends. 3D CT DAR was calculated for each patient from a preoperative CT scan by finding the maximum angle subtended by three contiguous vertebral segments. All patients were assessed for IONM events. A binary threshold of 25 was used for T-DAR and 3D CT DAR measurements for predictive analysis. p < 0.05 indicated significance. RESULTS: In total, 68 patients were identified. Mean age was 28 years. Mean levels fused was 15. Twenty-one patients (31%) had IONM events. In patients, with and without an IONM event, mean T-DAR was 26.6 ± 9.8 and 21.5 ± 8.8 (p = 0.04), respectively. 3D CT DAR mean values were 26.4 ± 10.8 and 18.4 ± 5.6, respectively (p < 0.001). 3D CT DAR accurately classified 81% of patients with a positive predictive value (PPV) of 75%. In comparison, T-DAR accurately classified 60% of patients with a PPV of 39%. CONCLUSION: 3D CT substantially improves preoperative IONM event prediction when compared to traditional radiographic measurements. A 3D CT DAR of 25 or greater was correlated with an increased rate of IONM events. 3D CT reconstructions are a useful adjunct for planning prior to a VCR.

What Radiographic and Clinical Factors Ultimately Necessitate a C2-Sacrum Instrumented Posterior Spinal Fusion?

OBJECTIVE: /Hypothesis: Patients undergoing C2-sacrum PSF have unique medical histories and multiple prior operations over an extended period. DESIGN: Single center, retrospective cohort. METHODS: Consecutive C2-sacrum PSF patients operated on by 4 surgeons at a single-center from 2015-2020 were reviewed. Demographics, comorbidities, indications, surgical history, and radiographic parameters were collected. RESULTS: 23 patients underwent C2-sacrum PSF. 13 (57%) were male, and 21 (91.3%) were adults. Mean age at time of first spine surgery was 44 years (range 5-71) and 53 years (range 14-72) at the time of C2-sacrum PSF. Six patients (26%) had osteoporosis, and 6 patients (26%) had neurologic comorbidities-including Parkinson's disease (4), cerebral palsy (1), and Brown Sequard syndrome (1). Four (17%) had connective tissue disease. Two patients underwent C2-sacrum PSF as an index procedure: (1) 67M with myelomatous fractures and 124° of cervicothoracic kyphosis; (2) 28F with severe Marfan syndrome with 140° thoracic scoliosis and 130° thoracic kyphosis. The remaining 21 (91%) underwent C2-sacrum PSF as a revision following prior spinal surgeries on average, 4 previous surgeries (range 1-13) over 10.5 years (range .3-37.4). Indications for the remaining 21 C2-sacrum PSF revision procedures included 17 (81%) for kyphosis (5 of whom also had significant coronal deformity), 1 (5%) for only coronal malalignment, 2 (10%) for instrumentation failure, and 1 (5%) for myelopathy. CONCLUSIONS: 91% (21/23) of patients requiring C2-sacrum PSF were treated as revisions of prior fusions, with a mean of 4 prior surgeries over 10 years. Over 80% of these patients underwent C2-sacrum PSF to address kyphosis. 26% had neurologic conditions, and 26% had osteoporosis.

Distal adding-on in adolescent idiopathic scoliosis results in diminished health-related quality of life at 10 years following posterior spinal fusion.

PURPOSE: The purpose of this study was to investigate associations between the various definitions of adding-on identified in the literature and HRQoL at 10 years following posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS) to identify a clinically relevant definition. METHODS: In this retrospective cohort study, patients with Lenke type 1 or 2 AIS with 10-year follow-up after PSF were identified in a multicenter registry. Adding-on was identified independently using 5 published definitions and expert spine surgeons' visual confirmation. Worsening of HRQoL was defined as a preoperative to 10-year postoperative decrease in SRS-22 domain score ≥ the minimal clinically important difference (MCID). RESULTS: One hundred fifty patients were included, and 118 had HRQoL data available for the main analysis. Worsening pain was noted in 49 (41.5%) patients, appearance in 1 (0.8%), and activity in 70 (59.3%) from preoperative to postoperative. 4 of the 5 definitions of adding-on demonstrated no evidence of association with worsening HRQoL. By Cho's definition (either 1. ≥ 5° increase in Cobb angle AND increase in number of vertebrae in curve distally, or 2. ≥ 5° increase in angulation of 1st disc below LIV), adding-on (27 patients, 22.9%) was associated with an increased risk of worsening pain (59.3% vs. 36.3%, p = 0.033) and activity (77.8% vs. 53.8%, p = 0.026). There was no evidence of association with changes in appearance. Risk of worsening pain and activity was increased by 1.75 and 1.51 times (p = 0.023 and p = 0.002), respectively. CONCLUSION: Cho's definition of adding-on was associated with worsening HRQoL at 10 years following PSF for Lenke type 1 and 2 AIS. Consistent use of this definition will allow us to compare studies and obtain meaningful information in this population. LEVEL OF EVIDENCE: Level II.

Development and Validation of a Health-Related Quality-of-Life Measure in Older Children and Adolescents with Early-Onset Scoliosis: Early-Onset Scoliosis Self-Report Questionnaire (EOSQ-SELF).

BACKGROUND: The 24-question Early-Onset Scoliosis Questionnaire (EOSQ-24) is a proxy measure assessing health-related quality of life (HRQoL) among patients with early-onset scoliosis (EOS). There exists an increasing need to assess HRQoL through a child's own perspective, particularly for older children and adolescents with EOS. The purpose of this study was to develop and validate a self-reported questionnaire, the Early-Onset Scoliosis Self-Report Questionnaire (EOSQ-SELF), to assess HRQoL in older children and adolescents with EOS. METHODS: A literature review, an expert focus group, and patient interviews were used to generate a preliminary survey of appropriate domains and question items. This survey was provided to English-speaking patients with EOS who were 8 to 18 years of age and capable of answering survey questions. Content validity was assessed for clarity and relevance of questions. Confirmatory factors analysis was performed to reduce the number of items and determine domains that fit items. Reliability was evaluated by measuring the internal consistency of items and test-retest reliability. Construct validity was evaluated by convergent, discriminant, and known-group validity. RESULTS: The literature review, expert focus group, and patient interviews identified 59 questions in 14 domains. Psychometric analysis reduced these to 30 questions across 12 domains: General Health, Pain/Discomfort, Pulmonary Function, Transfer, Physical Function/Daily Living, Participation, Fatigue/Energy Level, Sleep, Appearance, Relationships, Emotion, and Satisfaction. The final questionnaire was found to have good content and construct validity and adequate reliability. CONCLUSIONS: The EOSQ-SELF is a valid and reliable instrument for measuring self-reported HRQoL among older children and adolescents with EOS (ages 8 to 18 years). This will serve as an important research outcome measure and enhance clinical care by providing a better understanding of HRQoL for these patients. LEVEL OF EVIDENCE: Diagnostic Level II . See Instructions for Authors for a complete description of levels of evidence.

Including the stable sagittal vertebra in the fusion for adolescent idiopathic scoliosis reduces the risk of distal junctional kyphosis in Lenke 1-3 B and C curves.

PURPOSE: The selection of lowest instrumented vertebra (LIV) in adolescent idiopathic scoliosis (AIS) is determined by coronal and sagittal plane indicators. Failure to properly select the LIV can lead to suboptimal outcomes and the need for revision surgery. A subset of patients have discordant coronal last touched vertebra (cLTV) and stable sagittal vertebra (SSV) which complicates the choice of LIV. The purpose of this study is to report the incidence of discordant cLTV and SSV when choosing LIV and investigate the association between length of fusion and patient-reported outcomes (PROs) and distal junctional kyphosis (DJK). METHODS: This retrospective multicenter cohort study included AIS patients with discordant pre-operative cLTV and SSV. Patients fused only to include the proximal cLTV were compared to patients fused to include the distal SSV. Primary outcomes included DJK and PROs measured by SRS-22. RESULTS: Eight hundred and fifty-six patients were identified of which 114 (13.3%) had discordant SSV and cLTV. The DJK incidence was 7.7% and 45.5% in patients fused to include the SSV versus short of the SSV, respectively. Lenke Modifier type B and C patients with fusions short of the SSV had a 9.2 times increased risk of developing DJK at 2 years compared to patients with fusions including the SSV (95% CI 2.8, 29.7; p < 0.001). However, patients with fusions short of the SSV and no evidence of DJK were 9.2 times more likely to have improvement in the SRS-22 pain domain compared to patients with fusions including the distal SSV (95% CI 1.1, 77.4; p = 0.042) CONCLUSION: Patients fused short of the SSV are at significant risk for the development of DJK at 2 years post-operatively. However, patients with shorter fusions were more likely to have an improvement in their pain as measured by patient-reported outcomes than patients with longer fusions.

Comparing hyperlordotic and standard lordotic cages for achieving segmental lumbar lordosis during transforaminal lumbar interbody fusion in adult spinal deformity surgery.

BACKGROUND: Few studies directly compare the effect of interbody cages with different degrees of lordosis in producing segmental lumbar lordosis (SLL) in the transforaminal lumbar interbody fusion (TLIF) procedure. Thus, we aimed to investigate changes in SLL in hyperlordotic cages compared to standard lordotic cages in open TLIF procedures. METHODS: Thirty-eight consecutive patients who received open TLIF procedures performed by a single surgeon between 2017 and 2018 were reviewed. Twenty patients had "hyperlordotic cages" (20° lordosis), while 18 patients had "standard lordotic cages" (6° lordosis). Twenty-three patients had one-level TLIF procedures and 15 had two-level TLIF. Standard radiographic measurements, including SLL were assessed preoperatively, postoperatively, and at 1-year follow-up. SLL was measured from the superior endplate of the cephalad vertebra to the inferior endplate of the caudal vertebra. Changes in SLL were compared using Student's and paired t-tests. RESULTS: In one- and two-level open TLIF, both hyperlordotic and standard lordotic cages produced significant improvement in SLL. Among those receiving a one-level TLIF, SLL increased 7.8° (P=0.024) in those with standard lordotic cages; it increased 8.2° (P=0.020) in those with hyperlordotic cages. Among those receiving a two-level TLIF, SLL increased 13.9° (P=0.032) in those with standard lordotic cages; it increased 8.8° (P=0.023) in those with hyperlordotic cages. However, the improvement in SLL was not significantly different between the two cage types in either one or two-level TLIF procedures (P=0.917, P=0.389). At 1-year follow-up, there was no significant change in SLL, among standard lordotic and hyperlordotic cages (P=0.501, P=0.781). CONCLUSIONS: Although it is theorized that hyperlordotic cages would increase SLL during open TLIF procedures more than standard lordotic cages, our data failed to demonstrate that. As our study examined cases performed by a single surgeon immediately before and after adoption of these lordotic cages, it is likely that surgical technique is of equal or greater importance in improving SLL than the amount of lordosis designed into interbody cages.

Surgical site infections in pediatric spinal surgery after implementation of a quality assurance program.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To assess the effectiveness of two infection-reducing programs in mitigating the incidence of post-operative surgical site infections (SSI) in pediatric patients after spinal deformity surgery at our institution. Infections following spinal deformity surgery are associated with higher morbidity as well as significantly increased healthcare costs. SSI in patients with neuromuscular etiologies is especially high, exceeding 8 percent for myelodysplasia patients and 6 percent for cerebral palsy patients. METHODS: Manual chart review was conducted for 1934 pediatric spine procedures in 1200 patients at our institution between 2008 and 2018. Patients between the ages of 0 and 21 having any spinal surgical procedure including lengthening of growing rods were included. RESULTS: Institution of two separate infection-reducing programs reduced risk of SSI in this population by 65.4%, when adjusted for age and number of instrumentation levels (risk ratio [RR] = 0.3, 95% confidence interval [CI] = 0.2; 0.6, p = 0.001). Patients undergoing Initial Instrumentation demonstrated 68.8% less risk of SSI compared to those who had other types of surgical procedures, after adjusting for age and the number of level instrumented (RR = 0.3, 95% CI 0.2; .6, p = 0.002). It was observed that the effect of each of these infection-reducing programs diminished with time. This effect was also observed with prior programs implemented at our institution. CONCLUSION: The incidence of SSI decreased following the implementation of two infection-reducing programs especially in patients undergoing Initial Instrumentation procedures. However, time-series analysis suggests these programs may have maximal effect immediately following institution that diminishes with time. LEVEL OF EVIDENCE: Level III.

Association between health-related quality of life outcomes and pulmonary function testing.

INTRODUCTION: Investigations in associations between subjective health-related quality of life (HRQoL) measures and objective clinical assessments in patients with early-onset scoliosis (EOS) are limited. The purpose of this study is to investigate the association between pulmonary function rated by parents and pulmonary function testing (PFT) in patients with EOS. MATERIALS/METHODS: In this cross-sectional study, patients with EOS at any stage of treatment from 2011 to 2018 were identified in 2 registries including 33 centers. Parents' perception of pulmonary function was evaluated using pulmonary function (PF) domain in the Early-Onset Scoliosis 24 item Questionnaire (EOSQ-24). PFT measures included FVC% predicted, FEV1/FVC, and TLC% predicted. All PFT predicted values utilized arm span. PFT and EOSQ-24 questionnaire were completed within 180 days of each other with an average day difference of 26 days. RESULTS: 176 patients (mean age: 10.4 years old, female: 56%) were identified. 33% of patients were of congenital/structural etiology, 27% neuromuscular, 26% syndromic, and 14% idiopathic. Wide variance and lower scores of PF domain were reported by parents at lower FVC% predicted values (< 50%). As FVC% predicted values increased, PFD scores increased with simultaneous decreases in variance with few exceptions. CONCLUSION: More variability and frequent lower pulmonary function values are reported by parents when percent forced vital capacity (FVC%) is < 50%. This likely reflects the degree to which children adapt to restrictive lung disease and the limits on adaptation that occur increasingly as lung function falls below 50% predicted. As a direct linear association with high correlation was expected, more research into the character of what the PF domain is measuring is necessary. LEVEL OF EVIDENCE: IV.