Faculty Bibliography

BACKGROUND CONTEXT: Corrective surgery for adult spinal deformity (ADS) provides long-term benefits but often at the cost of significant perioperative morbidity. The use of minimally invasive surgery (MIS) for correction of ADS has been theorized to lower the perioperative morbidity when compared to traditional open surgical approaches. However, there is concern that patients treated with MIS techniques will not achieve the same level of clinical improvement as those treated with traditional open surgery approaches. This study compared patients treated with MIS (MIS lateral or transforaminal interbody fusion (LIF or TLIF) with percutaneous pedicle screw fixation), hybrid techniques (HYB) (MIS LIF or TLIF in combination with open posterior pedicle screw fixation), and open techniques to assess ODI at 1 and 2 years. PURPOSE: To compare disability outcomes between open and MIS deformity surgery. STUDY DESIGN/SETTING: Retrospective review of propensity matched cohorts. PATIENT SAMPLE: 120 patients with adult deformity treated with MIS, hybrid or open surgeries. OUTCOME MEASURES: Radiographic parameters and ODI. METHODS: All cases were reviewed retrospectively. Inclusion criteria included: age>18yr, ASD, min 2-yr follow-up. Patients treated for adult spinal deformity using either less invasive or open surgical approaches were propensity matched by preop SVA, baseline ODI, and by number of fused levels. Patients' results were compared at 1 and 2 years postop. RESULTS: 40 patients were propensity matched into each group for a total number of 120. Mean number of levels fused and SVAwas HYB = 5.9, 37.7mm, MIS = 3.7, 30.7mm, OPEN = 6.0, 47.5 mm. At baseline, ODI was: HYB569.6, MIS549.7, Open549.6. At postop 1 year patients reported significantly improved ODI (P<0.01 when compared to baseline) (HYB537.3, MIS526.8, Open535.6) (between groups P>0.05). At 2 years the patients maintained improvement in disability (HYB537.5, SVA 43.6, MIS 28.0, SVA 34.5, and Open 30.6, SVA 33.5). CONCLUSIONS: Patients treated !

BACKGROUND CONTEXT: The maintenance of horizontal gaze is an essential function of upright posture and global sagittal spinal alignment. Horizontal gaze is classically measured by the Chin Brow Vertical Angle (CBVA), which is not readily measured on most lateral spine radiographs. PURPOSE: This study proposes to evaluate the correlation of CBVA with two more accessible angles: the Slope of the Line of Sight (SLS) (slope of Frankfort line: anterior/inferior margin of orbit to the top of the external auditory meatus) and the slope of McGregor's line (McGS). Furthermore, this study also aims to correlate these 3 angles with HRQOL, specifically the Oswestry Disability Index (ODI). STUDY DESIGN/SETTING: Single-center, retrospective, non-consecutive case series. PATIENT SAMPLE: 531 Patients with spinal pathologies (primary cervical, lumbar, or adult scoliosis) from November 2012 to November 2013. OUTCOME MEASURES: Oswestry Disability Index (ODI). METHODS: Patients were identified from a multicenter database of 531 spine patients who underwent full body EOS X-rays with a variety of presenting complaints (primary cervical, lumbar, or adult scoliosis). Exclusion criteria were age<18y, total hip arthroplasty, total knee arthroplasty, neuropathic scoliosis, fractures, and tumor. Correlations between CBVA, SLS, and McGS and were assessed. Using a quadratic regression with ODI and CBVA, we established a low disability range of values for the CBVA and then, by simple regression, a low disability range of values for SLS and McGS. RESULTS: 435 patients were included (67% females, mean age 57 +; 15yo, mean BMI 27.4 +; 6.4 kg/m²). CBVA strongly correlated with SLS (r=.996, p<.001) and McGS (r=.862, p<.001). A significant negative correlation was observed between ODI and all 3 angles (with CBVA: r= -0.232, p=.022, with SLS: r=-0.228, p=.024, with McGS: r=-0.213, p=.036). By applying a quadratic regression on the ODI and CBVA establishing range of values corresponding to low disability (-4.7degree to 17!

BACKGROUND CONTEXT: Previous force plate studies analyzing the impact of sagittal spinal deformity (SSD) on pelvic parameters have demonstrated compensatory mechanisms of translation in addition to rotation. However, compensatory changes in the hip, knee and ankle joints have not been assessed in patients with sagittal malalignment. PURPOSE: This study aims to 1) analyze the relationship between sagittal spinopelvic (SPP) and lower limb (LLP) parameters, 2) to clarify the role of pelvic translation (pelvic shift) and 3) to correlate Oswestry Disability Index with spinopelvic parameters and compensatory mechanisms. STUDY DESIGN/SETTING: Retrospective single center study. PATIENT SAMPLE: From November 2012 to November 2013, 409 patients with spinal deformity and full-body EOS images (EOS system) were included, without age or gender restriction. Patients with only a diagnosis of stenosis or low back pain were excluded. Subjects were grouped by T1 Spino Pelvic inclination (T1SPi): sagittal forward (FW, > 0.6degree), neutral (NE, -6.6degree to 0.6degree) and backward (BW,<-6.6degree). OUTCOME MEASURES: T1SPi, Pelvic Shift (P.Shift), sagittal vertical axis (SVA), pelvic tilt (PT), lumbar lordosis (LL), "pelvic incidence minus lumbar lordosis" (PI-LL), TK (T1T12 kyphosis), T9SPi (T9 spinopelvic inclination), Sacro Femoral Angle (SFA), Knee Angle, Ankle Angle, chin brow vertical angle, and ODI (Oswestry Disability Index). METHODS: Pelvic translation was quantified by Pelvic Shift (the sagittal offset between the postero-superior corner of the sacrum and the anterior cortex of distal tibia). SPP were measured such as: SVA, PT, PI-LL, TK, T9SPi. Hip extension was measured using the SFA (angle between a line from middle of sacral endplate to bicoxo femoral axis and the femoral mechanical axis), Knee Angle (KA, angle of knee flexion), and Ankle Angle (AA, between tibial axis and vertical reference line) were positive in case of flexion. CBVA (chin brow vertical angle, between the chin-brow line and the ver!

BACKGROUND CONTEXT: 3-column osteotomy (3CO) is an effective technique to correct sagittal malalignment, but is associated with high complication rates. However the distribution of correction of global truncal alignment versus pelvic retroversion remains unclear, with a belief that more caudal osteotomy leads to larger correction. PURPOSE: This study sought to investigate the impacts of osteotomy site and postoperative apex of lumbar lordosis 1) on sagittal correction and 2) on postoperative complications and revisions rates. STUDY DESIGN/SETTING: Radiographic retrospective study of a multicenter database. PATIENT SAMPLE: 347 adult spinal deformity patients with 2-year follow-up, upper instrumented vertebra above L1, and lumbar 3CO were included. OUTCOME MEASURES: 3CO resection angle, sagittal vertical axis (SVA), pelvic tilt (PT), lumbar lordosis (LL), LL apex, pelvic incidence minus lumbar lordosis (PI-LL). METHODS: Radiographic, demographic, and OR data, revisions and complications, were analyzed at baseline, 6m, 1Y, 2Y FU to quantify spinopelvic alignment, apex of lordosis, resection angle and complications or revisions rates. Uni- and multivariate analyses were performed and correlations were tested using Pearson for continuous variables and Spearman for apex or osteotomy level. RESULTS: 347 patients were included (mean age 60 yrs, BMI 28kg/m², 69% female). Preoperative parameters demonstrated a severe deformity (PT: 32.6degree +; 10.9, SVA: 145.6 +; 78.6mm, PI-LL: 36.8degree +; 19.3). Average resection angle was 25.3degree without significant difference across 3CO levels. Postoperatively, all these parameters were significantly improved (at 1 year, PT: 23.9degree +; 11.5, SVA: 45.7degree +; 63.4, PI-LL: 5.2degree +; 18.0, p<0.001). There were no significant correlations between 3CO level and amount of SVA or PT correction (postoperative change in SVA: -106.8degree +; 76.8, in PT: -8.7degree +; 9.2). Postop apex location, which was more caudal than 3CO level, significantly corre!

BACKGROUND CONTEXT: While the SRS-Schwab classification offers a framework defining the alignment categories of adult spinal deformity (ASD) patients, one can wonder if a "one-fits all" solution is appropriate as age-related changes in alignment and patient reported outcomes have been established in the literature. The objective of this study was to investigate age specific alignment thresholds based on US norms SF-36 Physical Component Score (PCS). PURPOSE: To investigate postoperative alignment parameters and HRQOL to determine the validity of targets of correction according to patient age. STUDY DESIGN/SETTING: Retrospective review of a multicenter, prospective consecutive database. PATIENT SAMPLE: 773 patients with adult spinal deformity who received operative and nonoperative treatment. OUTCOME MEASURES: Oswestry Disability Index (ODI) and Short- Form (SF)-36 Physical Component Score (PCS). METHODS: Retrospective review of a multicenter consecutive prospective database of ASD patients who received surgical (OP) or nonoperative (NON) treatment. Patients were stratified by age groups in line with the US norm published values of the SF-36 PCS (under 35 yo, 35-44 yo, 45-54 yo, 55-64 yo, 65-74 yo, over 75 yo). At baseline, relationship between radiographic alignment parameters (PI-LL, PT, SVA, and TPA), age and PCS were established using linear regression analysis and subsequently applied with US-norm PCS values to established agespecific thresholds of alignment. Finally a correlation analysis was performed between ODI and PCS to report alignment thresholds by age. This process was repeated at 2-year follow-up to investigate changes in radiographic parameters corresponding to 1 MICD improvement for the different age groups. RESULTS: Baseline analysis included 773 patients (53.7 yo, 54% OP, 83% female). There was a strong correlation between ODI and PCS (r=0.814, p<0.001) permitting an extrapolation of US norm ODI by age groups. Linear regression analysis (all with r > 0.510, p<0.001) combined w!

BACKGROUND CONTEXT: The relationship between pelvic incidence (PI) and lumbar lordosis (LL) has been well established as a key determinant of sagittal alignment and satisfactory surgical outcomes. The goal of matching PI and LL within 10degree works as a general rule, but may not apply to patients with lower or higher PI. PURPOSE: To analyze the relationship between pelvic incidence and lumbar lordosis required for optimal alignment in patients with extreme PI values. STUDY DESIGN/SETTING: Multicenter retrospective study, ASD patients from 2 databases. PATIENT SAMPLE: 88 patients from a PSO database (1-year follow-up), 142 patients from a prospective database (PON) (2 years follow-up). Age >18 years. OUTCOME MEASURES: Radiographic measurements, pelvic incidence and PI-LL METHODS: Subjects with at least 1 year follow-up were identified from a multicenter database of patients who underwent a pedicle subtraction osteotomy (PSO) from 2004-2013. Patients were included if they were well aligned (WA) based on Vialle criteria, with PT<12degreeand T1SPI between -4.05degreeand 1.35degree. The distribution of the PI was analyzed to create the following 3 groups: Low PI (LPI; < Mean - 1 S.D.), Average PI (API; Mean +/- 1 S.D), High PI (HPI; > Mean + 1 S.D.), and an ANOVA test was carried out to compare. The same analysis was performed on a separate group of patients issued from a prospective database with at least a 2-year follow-up (PON) in order to validate these results. RESULTS: The PSO cohort included 88 patients, mean age=56.2 yo. Mean PI was 57.1 +/- 15.2degree. The analysis of the PI-LL for the 3 groups revealed that the HPI required a lordosis smaller than the PI (PILL=17.7 degree), the API required a lordosis similar to the PI (PI-LL=1.75degree), and the LPI required greater LL than the PI (PI-LL=-11.02degree). There were significant differences between the PI-LL parameter of the HPI group (17.69degree) and the two other groups (API group: -1.75degree, and LPI group: -11.02degree, p<.001). The PO!

BACKGROUND CONTEXT: Sagittal spinal deformity (SSD) patients recruit compensatory mechanisms to maintain erect posture and align the head over the pelvis. Spinopelvic mechanisms of compensation involving retroversion of the pelvis have been described. Additionally, knee flexion and pelvic shift have been proposed as limbs mechanisms, but how and when these mechanisms contribute is poorly understood. PURPOSE: To determine the percentage of spinal, pelvic and lower extremity compensatory response based on global spinal deformity. STUDY DESIGN/SETTING: Single-center, retrospective review of fullbody head-to-foot stereoradiographs. PATIENT SAMPLE: 435 patients with spinal sagittal deformity from November 2012 to November 2013. OUTCOME MEASURES: Oswestry Disability Index (ODI), Short Form 36 Health Questionnaire (SF-36; Physical Component Score [PCS] and Mental Component Score [MCS]), sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT), lumbar lordosis (LL), knee angle (KA) and pelvic shift angle (PSh). METHODS: This is a retrospective review of adult SSD patients who underwent stereoradiography (EOS imaging system) between 2012- 2013. Radiographic measurements were performed with Surgimap (Nemaris Inc.). Patients with a PI greater than LL were categorized based on their mismatch and compared in terms of compensatory mechanisms normalized to each patient's PI-LL: PT, Knee flexion and pelvic shift angle (the angle between the lines formed from the posterior-superior corner of S1 to the anterior distal cortex of the tibia and the vertical). RESULTS: 161 Patients were included with a mean age of 62.93+12.8yrs, BMI 27, and 80.6% females. At baseline, patients had a mean SVA 62.3+61.5mm, PT 29.2+8.4 degree , and PI-LL 21.0+14.9 degree . Patients were categorized based on their PI-LL in 4 groups of PI-LL by mismatch 10 degree (Group 1: PI-LL 0-10 degree , Group 2: 10-20 degree , Group 3: 20-30 degree , and Group 4: >40 degree ). There were significant differences between all groups in PT!

BACKGROUND CONTEXT: Understanding various components of global alignment is essential in the effective treatment of sagittal spinal deformity patients (SSD). Despite the development of EOS and full body radiographic technology, sagittal plane assessment commonly remains limited to the spinopelvic area. Evaluation of lower limb compensatory mechanisms has been poorly understood to date. PURPOSE: The objective of this study was to investigate the role of the lower limbs in maintaining erect posture and horizontal gaze in the setting of SSD. STUDY DESIGN/SETTING: Single-center, retrospective review of fulllength head to foot stereoradiographs. PATIENT SAMPLE: 435 patients with spinal sagittal deformity from November 2012 to November 2013. OUTCOME MEASURES: Oswestry Disability Index (ODI), Short Form 36 Health Questionnaire (SF-36; Physical Component Score [PCS] and Mental Component Score [MCS]), Chin Brow Vertical Angle (CBVA), pelvic incidence (PI), lumbar lordosis (LL), pelvic tilt (PT), sagittal vertical axis (SVA), T1 pelvic angle (TPA), knee angle flexion (KA), ankle angle flexion (AA) and sacral femoral angle (SFA). METHODS: In this retrospective study, patients with spinal pathology underwent low dose stereoradiography X-rays (EOS imaging systemdegree). The inclusion criteria were SSD with a PI-LL mismatch>15degree and functional horizontal gaze (CBVA between -4 and 17degree). Patients were divided in 2 groups based on their PI-LL mismatch after surgery: over corrected (OC, PI-LL<-15degree) and under corrected (UC, PI-LL>15degree). Groups were compared in terms of sagittal alignment and lower limb compensatory mechanisms (Student T test). Correlations and regression were performed to predict lower extremity compensation. RESULTS: Eighty-six patients (mean age 55.5 years, BMI 26.4kg/m2, 75% female) were included: 29 UC and 57 OC. By definition, UC patients had a significantly more sagittal spinopelvic deformity (PI-LL, SVA, and TPA) as well as a larger PI, SFA (hip hyperextension), KA and AA!

BACKGROUND CONTEXT: A large percentage of patients with adult spinal deformity (ASD), up to 52% in the literature, gain a minimal clinically important difference (MCID) in one or more of the health-related quality of life (HRQOLs) instruments. PURPOSE: This study attempts to identify and describe baseline characteristics of this subset of nonoperative patients who improve, and propose possible predictors of MCID gain in SRS Activity or Pain. STUDY DESIGN/SETTING: Post-hoc analysis of prospective, multicenter database of operative and nonoperative patients with ASD. PATIENT SAMPLE: 215 nonoperative patients with ASD with minimum 2-year follow-up and an MCID deficit in either SRS Activity or Pain. OUTCOME MEASURES: SRS Activity, SRS Pain, MCID, spinopelvic radiographic parameters. METHODS: Post-hoc analysis of prospective, multicenter, case series of 215 nonoperative patients with ASD with minimum 2-year follow-up and an MCID deficit (need for improvement) at baseline in SRS Pain or Activity scores compared to the normative population. Using a multivariate analysis, 2 groups were compared to identify possible predictors: those that reached an MCID in SRS Pain or Activity (n=86) at 2 years and those that missed MCID (n=129). RESULTS: At baseline, 215 nonoperative patients with ASD needed to improve in SRS Activity or Pain, and there were no statistically significant differences in age, BMI or baseline SVA (17.5mm v 20.5mm p 0.70) between the cohorts that improved and did not improve. At 2-year followup, 40% (n = 86) reached MCID and 60% (n = 129) missed MCID. Of the nonoperative patients who reached MCID at 2 years, they had at baseline a significantly lower SRS Pain (3.0 v 3.6, p<0.05), thoracolumbar Cobb (29.6degree v 36.5degree, p<0.05, 87 patients with Schwab classification Lumbar or Double), sacral slope (33.1degree v 36.4degree, p<0.05) and lumbar lordosis (46.5degree v 52.8degree, p<0.05). PI-LL was significant on univariate analysis but not by multivariate (7.5degree v 2.6degree, p 0.14). !