Faculty Bibliography

BACKGROUND:Changing from standing to sitting positions requires rotation of the femur from an almost vertical plane to the horizontal plane. Osteoarthritis of the hip limits hip extension, resulting in less ability to recruit spinopelvic tilt (SPT) while standing and requiring increased SPT while sitting to compensate for the loss of hip range of motion. To date, the effect of total hip arthroplasty (THA) on spinopelvic sitting and standing mechanics has not been reported, particularly in the setting of patients with coexistent sagittal plane spinal deformity. METHODS:A retrospective review was performed of patients ≥18 years of age undergoing unilateral THA for hip osteoarthritis with sitting and standing radiographs made before and after THA. Alignment was analyzed at baseline and follow-up after THA in both standing and sitting positions in a relaxed posture with the fingers resting on top of the clavicles. Patients were grouped according to the presence or absence of sagittal plane deformity preoperatively into 3 groups: no sagittal plane deformity (normal), thoracolumbar (TL) deformity (pelvic incidence-lumbar lordosis [PI-LL] mismatch > 10° and/or T1-pelvic angle [TPA] > 20°), or apparent deformity (PI-LL ≤ 10° and TPA ≤ 20°, but sagittal vertical axis [SVA] > 50 mm). RESULTS:In this study, 192 patients were assessed: 64 had TL deformity, 39 had apparent deformity, and 89 had normal alignment. Overall, patients demonstrated a reduction in standing SVA (45 to 34.1 mm; p < 0.001) and an increase in SPT (14.6° to 15.7°; p = 0.03) after THA. There was a greater change in standing SVA (p < 0.001) among patients with apparent deformity (-29.0 mm) compared with patients with normal alignment (0.9 mm) and patients with TL deformity (-16.3 mm). Those with apparent deformity also experienced the greatest difference (p = 0.03) in postural SPT change (moving from standing to sitting) (-10.1°) from before to after THA when compared with those with normal alignment (-3.6°) and TL deformity (-1.2°). The difference in postural SVA change from before to after THA was also greatest (p < 0.001) in those with apparent deformity (32.1 mm) compared with those with normal alignment (6.5 mm) and TL deformity (17.3 mm). CONCLUSIONS:Postural changes in spinopelvic alignment vary after THA depending on the presence of TL deformity or apparent deformity due to hip flexion contracture. Patients with apparent deformity had larger changes in standing and sitting alignment than patients with TL deformity or patients with normal alignment. The assessment of global sagittal alignment findings can be used to predict the likelihood of improvement in sagittal alignment after THA. LEVEL OF EVIDENCE/METHODS:Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

STUDY DESIGN/METHODS:Single-center retrospective cohort study. OBJECTIVE:To compare the correction of fractional curve and L5 tilt in 2RVBT versus PSF with LIV in the lumbar spine. SUMMARY OF BACKGROUND DATA/BACKGROUND:Vertebral body tethering, an AIS fusion-alternative, avoids rigid constructs, allowing for lower instrumented vertebra (LIV) selection. Single-tether constructs break, but mini-open thoracoscopic assistant double-row vertebral body tethering (2RVBT) reduces this. Limited comparative studies exist with posterior spinal fusion (PSF). METHODS:Retrospective analysis of AIS correction surgeries with lumbar LIV using preoperative and minimum 2-year postoperative imaging. Patients were divided into 2RVBT or PSF groups. Data included age, Riser, UIV, LIV, instrumented levels, and revision rates. Radiographic analyses included preoperative and postoperative main curve Cobb (MCC), secondary curve Cobb (SCC), fractional curve Cobb (FCC), and L5 tilt. RESULTS:Ninety-nine patients participated (49 in 2RVBT, 50 in PSF). Preoperatively, secondary CC differed significantly (2RVBT: 44.6±10.4 degrees vs. PSF: 39.5±11.8 degrees, P=0.026), but not L5 tilt, MCC, or FCC. Postoperatively, MCC (2RVBT: 25.7±12.3 degrees vs. PSF: 19.5±7.4 degrees, P=0.003) and SCC (2RVBT: 18.0±8.4 degrees vs. PSF: 14.5±6.6 degrees, P=0.012) varied. Preoperative to postoperative changes in MCC (2RVBT: -32.0±11.3 degrees vs. PSF: -37.2±13.3 degrees, P=0.044) and L5 tilt (-13.8±9.0 degrees vs. PSF: -8.1±6.8 degrees, P=0.001) differed. Revision rates were similar (2RVBT: 2.0%, PSF: 4.0%, P=0.57). In 2RVBT, 3 tethers broke, 1 revision occurred for a broken tether, and 1 pleural effusion needed thoracocentesis. In PSF, 1 superficial infection needed surgery, and 1 revision was for add-on phenomenon. After PSM for Lenke classification, 54 patients remained (27 in each group). At 2 years, 2RVBT showed less MCC correction (-30.8±11.8 degrees vs. -38.9±11.9 degrees, P=0.017), but greater L5 tilt correction (-14.6±10.0 degrees vs. -7.5±6.0 degrees, P=0.003). CONCLUSIONS:This study with a minimum 2-year radiographic follow-up demonstrates that 2RVBT results in greater L5 tilt correction when compared with posterior spinal fusion after PSM for Lenke classification and similar rates of revision surgery. LEVEL OF EVIDENCE/METHODS:Level III.

PURPOSE/OBJECTIVE:To determine if iatrogenic posterior translation (UIV SPi) at the upper instrumented vertebrae (UIV) is associated with increased mechanical complications and secondarily to generate and validate a UIV SPi threshold for increased complications. METHODS:Two patient databases were utilized: one for generating a UIV SPi threshold and another for validation. Patients with a UIV between T8-L1 and a LIV at ilium were included. A receiver operating curve (ROC) curve analyses was performed to generate a threshold that predicted proximal junctional complications. This UIV SPi angle (-16.0°) was rounded to -15.0° for practical clinical use and validated in a separate cohort. Patients were stratified as above (most translated, MT) or below (least translated, LT) the threshold for comparative demographic and outcomes analyses. RESULTS:Generation of the threshold on 192 patients (122 LT, 70 MT) revealed that the MT group had higher absolute postoperative UIV SVA (MT=-56.1 ± 23.1 mm vs. LT=-10.4 ± 31.8 mm, p < 0.001), higher PT (25.7° vs. 19.3°, p < 0.001), and 2.8-5.8 times greater odds of postoperative proximal junctional complications at 2-years (p < 0.05). Validation on 135 patients (95 LT, 40 MT) revealed that the MT group had 11.7 times greater odds of radiographic PJK and had 4.5 times greater odds of all-cause reoperations (p < 0.05). CONCLUSION/CONCLUSIONS:Patients with UIV posterior translation, despite similar PI-LL and T1PA, exhibit a high PT and experience higher odds of proximal junctional complications. Our findings support limiting the UIV SPi to < 15° of posterior translation to mitigate postoperative mechanical complications. LEVEL OF EVIDENCE/METHODS:IV.

STUDY DESIGN/METHODS:Retrospective analysis of retrospectively collected data. OBJECTIVE:To determine the effects of preoperative nonsteroidal anti-inflammatory drug (NSAID) use on estimated blood loss (EBL) and postoperative drain output in TLIF procedures. SUMMARY OF BACKGROUND DATA/BACKGROUND:Current standards of care recommend patients prescribed NSAIDs for chronic lower back pain discontinue NSAIDs at least 1 week before spine fusion surgery. The literature surrounding the effects of preoperative NSAID use is unclear, however, with dissonant findings regarding postoperative blood loss and complications. METHODS:A retrospective case review was performed on 429 cases of 1-level or 2-level TLIF, with patient NSAID use recorded within 3 days of surgery, at a single institution. Linear and logistic regressions were used to assess associations between NSAID use, patient and surgical characteristics, EBL, and drain output. RESULTS:NSAID use was significantly positively associated with drain output (P=0.03), with an approximate increase of 21±9.7 mL/day but no significant association with any postoperative complications (P=0.77). Drain output also had significant, independent positive associations with patient age (P=0.007), male sex (P<0.001), and a number of levels fused (P<0.001), and significant negative associations with robot-assisted (P<0.001) and minimally invasive (P=0.04) procedures. No significant association was detected between NSAID use and EBL (P=0.21), though EBL had significant positive associations with operative time (P<0.001) and levels fused (P<0.001), and multiple NSAIDs had a significant positive association with EBL (P<0.001). CONCLUSIONS:NSAID use had a statistically significant, but small, effect on drain output and no detectable effect on postoperative complications within 3 days of TLIF procedures, suggesting most patients can safely continue NSAID use up until their date of surgery. Future studies should further delineate the effects of preoperative NSAID use, such that a more refined risk profile could be developed from patient and surgical characteristics and NSAID use information.

OBJECTIVE:Malalignment following cervical spine deformity (CSD) surgery can negatively impact outcomes and increase complications. Despite the growing ability to plan alignment, it remains unclear whether preoperative goals are achieved with surgery. The objective of this study was to assess how good surgeons are at achieving their preoperative goal alignment following CSD surgery. METHODS:Adult patients with CSD were prospectively enrolled into a multicenter registry. Surgeons documented alignment goals prior to surgery, including C2-7 sagittal vertical axis (SVA), C2-7 sagittal Cobb angle, T1 slope minus cervical lordosis (TS-CL), and C7-S1 SVA. Goals were compared with achieved alignment, and the offsets (achieved goal) were calculated. General linear models were created for offset magnitude for each alignment parameter, controlling for baseline deformity and surgical factors. RESULTS:The 88 enrolled patients had a mean age of 63.6 ± 13.0 years. The mean number of anterior and posterior instrumented levels was 3.5 ± 1.0 and 10.6 ± 4.5, respectively. Surgeons failed to achieve their preoperative alignment goals by an average of 17.2 (range 0.1-75.4) mm for C2-7 SVA, 10.3° (range 0.1°-45.5°) for C2-7 sagittal Cobb angle, 15.6° (range 0.0°-42.9°) for TS-CL, and 34.2 (range 0.3-113.7) mm for C7-S1 SVA. The sagittal alignment parameters with the highest rate of extreme outliers were TS-CL and C7-S1 SVA, with 32.2% exceeding 20° and 60.8% exceeding 20 mm from goal alignment, respectively. After controlling for baseline deformity and operative parameters, the only factor associated with achieving targeted alignment for C2-7 sagittal Cobb angle was greater baseline thoracic kyphosis (TK; B = -0.148, 95% CI -0.288 to -0.007, p = 0.040), and for TS-CL, the only associated factor was lower baseline TS-CL (B = 0.187, 95% CI 0.027-0.347, p = 0.022). Both lower TK and greater TS-CL may reflect increased baseline deformity through greater thoracic compensation and increased TS-CL mismatch, respectively. No significant associations were identified for C2-7 SVA and C7-S1 SVA. CONCLUSIONS:Surgeons failed to achieve their preoperative alignment goals by an average of 17.2 mm for C2-7 SVA, 10.3° for C2-7 sagittal Cobb angle, 15.6° for TS-CL, and 34.2 mm for C7-S1 SVA. The few factors identified that were associated with offset between goal and achieved alignment suggest that achievement of goal alignment was most challenging for more severe deformities. Further advancements are needed to enable more consistent translation of preoperative alignment goals into the operating room for adult CSD correction. Clinical trial registration no.: NCT01588054 (ClinicalTrials.gov).

STUDY DESIGN/METHODS:Retrospective analysis of prospectively collected data. OBJECTIVE:Evaluate the impact of prior cervical constructs on upper instrumented vertebrae (UIV) selection and postoperative outcomes among patients undergoing thoracolumbar deformity correction. BACKGROUND:Surgical planning for adult spinal deformity (ASD) patients involves consideration of spinal alignment and existing fusion constructs. METHODS:ASD patients with (ANTERIOR or POSTERIOR) and without (NONE) prior cervical fusion who underwent thoracolumbar fusion were included. Demographics, radiographic alignment, patient-reported outcome measures (PROMs), and complications were compared. Univariate and multivariate analyses were performed on POSTERIOR patients to identify parameters predictive of UIV choice and to evaluate postoperative outcomes impacted by UIV selection. RESULTS:Among 542 patients, with 446 NONE, 72 ANTERIOR, and 24 POSTERIOR patients, mean age was 64.4 years and 432 (80%) were female. Cervical fusion patients had worse preoperative cervical and lumbosacral deformity, and PROMs (P<0.05). In the POSTERIOR cohort, preoperative LIV was frequently below the cervicothoracic junction (54%) and uncommonly (13%) connected to the thoracolumbar UIV. Multivariate analyses revealed that higher preoperative cervical SVA (coeff=-0.22, 95%CI=-0.43--0.01, P=0.038) and C2SPi (coeff=-0.72, 95%CI=-1.36--0.07, P=0.031), and lower preoperative thoracic kyphosis (coeff=0.14, 95%CI=0.01-0.28, P=0.040) and thoracolumbar lordosis (coeff=0.22, 95%CI=0.10-0.33, P=0.001) were predictive of cranial UIV. Two-year postoperatively, cervical patients continued to have worse cervical deformity and PROMs (P<0.05) but had comparable postoperative complications. Choice of thoracolumbar UIV below or above T6, as well as the number of unfused levels between constructs, did not affect patient outcomes. CONCLUSIONS:Among patients who underwent thoracolumbar deformity correction, prior cervical fusion was associated with more severe spinopelvic deformity and PROMs preoperatively. The choice of thoracolumbar UIV was strongly predicted by their baseline cervical and thoracolumbar alignment. Despite their poor preoperative condition, these patients still experienced significant improvements in their thoracolumbar alignment and PROMs after surgery, irrespective of UIV selection. LEVEL OF EVIDENCE/METHODS:IV.

PURPOSE/OBJECTIVE:To evaluate the variability in intraoperative fluid management during adult spinal deformity (ASD) surgery, and analyze the association with complications, intensive care unit (ICU) requirement, and length of hospital stay (LOS). METHODS:Multicenter comparative cohort study. Patients ≥ 18 years old and with ASD were included. Intraoperative intravenous (IV) fluid data were collected including: crystalloids, colloids, crystalloid/colloid ratio (C/C), total IV fluid (tIVF, ml), normalized total IV fluid (nIVF, ml/kg/h), input/output ratio (IOR), input-output difference (IOD), and normalized input-output difference (nIOD, ml/kg/h). Data from different centers were compared for variability analysis, and fluid parameters were analyzed for possible associations with the outcomes. RESULTS:Seven hundred ninety-eight patients with a median age of 65.2 were included. Among different surgical centers, tIVF, nIVF, and C/C showed significant variation (p < 0.001 for each) with differences of 4.8-fold, 3.7-fold, and 4.9-fold, respectively. Two hundred ninety-two (36.6%) patients experienced at least one in-hospital complication, and ninety-two (11.5%) were IV fluid related. Univariate analysis showed significant relations for: LOS and tIVF (ρ = 0.221, p < 0.001), IOD (ρ = 0.115, p = 0.001) and IOR (ρ = -0.138, p < 0.001); IV fluid-related complications and tIVF (p = 0.049); ICU stay and tIVF, nIVF, IOD and nIOD (p < 0.001 each); extended ICU stay and tIVF (p < 0.001), nIVF (p = 0.010) and IOD (p < 0.001). Multivariate analysis controlling for confounders showed significant relations for: LOS and tIVF (p < 0.001) and nIVF (p = 0.003); ICU stay and IOR (p = 0.002), extended ICU stay and tIVF (p = 0.004). CONCLUSION/CONCLUSIONS:Significant variability and lack of standardization in intraoperative IV fluid management exists between different surgical centers. Excessive fluid administration was found to be correlated with negative outcomes. LEVEL OF EVIDENCE/METHODS:III.

BACKGROUND:Our understanding of the relationship between sagittal alignment and mechanical complications is evolving. In normal spines, the L1-pelvic angle (L1PA) accounts for the magnitude and distribution of lordosis and is strongly associated with pelvic incidence (PI), and the T4-pelvic angle (T4PA) is within 4° of the L1PA. We aimed to examine the clinical implications of realignment to a normal L1PA and T4-L1PA mismatch. METHODS:A prospective multicenter adult spinal deformity registry was queried for patients who underwent fixation from the T1-T5 region to the sacrum and had 2-year radiographic follow-up. Normal sagittal alignment was defined as previously described for normal spines: L1PA = PI × 0.5 - 21°, and T4-L1PA mismatch = 0°. Mechanical failure was defined as severe proximal junctional kyphosis (PJK), displaced rod fracture, or reoperation for junctional failure, pseudarthrosis, or rod fracture within 2 years. Multivariable nonlinear logistic regression was used to define target ranges for L1PA and T4-L1PA mismatch that minimized the risk of mechanical failure. The relationship between changes in T4PA and changes in global sagittal alignment according to the C2-pelvic angle (C2PA) was determined using linear regression. Lastly, multivariable regression was used to assess associations between initial postoperative C2PA and patient-reported outcomes at 1 year, adjusting for preoperative scores and age. RESULTS:The median age of the 247 included patients was 64 years (interquartile range, 57 to 69 years), and 202 (82%) were female. Deviation from a normal L1PA or T4-L1PA mismatch in either direction was associated with a significantly higher risk of mechanical failure, independent of age. Risk was minimized with an L1PA of PI × 0.5 - (19° ± 2°) and T4-L1PA mismatch between -3° and +1°. Changes in T4PA and in C2PA at the time of final follow-up were strongly associated (r2 = 0.96). Higher postoperative C2PA was independently associated with more disability, more pain, and worse self-image at 1 year. CONCLUSIONS:We defined sagittal alignment targets using L1PA (relative to PI) and the T4-L1PA mismatch, which are both directly modifiable during surgery. In patients undergoing long fusion to the sacrum, realignment based on these targets may lead to fewer mechanical failures. LEVEL OF EVIDENCE/METHODS:Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

PURPOSE/OBJECTIVE:Understanding the mechanism and extent of preoperative deformity in revision procedures may provide data to prevent future failures in lumbar spinal fusion patients. METHODS:ASD patients without prior spine surgery (PRIMARY) and with prior short (SHORT) and long (LONG) fusions were included. SHORT patients were stratified into modes of failure: implant, junctional, malalignment, and neurologic. Baseline demographics, spinopelvic alignment, offset from alignment targets, and patient-reported outcome measures (PROMs) were compared across PRIMARY and SHORT cohorts. Segmental lordosis analyses, assessing under-, match, or over-correction to segmental and global lordosis targets, were performed by SRS-Schwab coronal curve type and construct length. RESULTS:Among 785 patients, 430 (55%) were PRIMARY and 355 (45%) were revisions. Revision procedures included 181 (23%) LONG and 174 (22%) SHORT corrections. SHORT modes of failure included 27% implant, 40% junctional, 73% malalignment, and/or 28% neurologic. SHORT patients were older, frailer, and had worse baseline deformity (PT, PI-LL, SVA) and PROMs (NRS, ODI, VR-12, SRS-22) compared to primary patients (p < 0.001). Segmental lordosis analysis identified 93%, 88%, and 62% undercorrected patients at LL, L1-L4, and L4-S1, respectively. SHORT patients more often underwent 3-column osteotomies (30% vs. 12%, p < 0.001) and had higher ISSG Surgical Invasiveness Score (87.8 vs. 78.3, p = 0.006). CONCLUSIONS:Nearly half of adult spinal deformity surgeries were revision fusions. Revision short fusions were associated with sagittal malalignment, often due to undercorrection of segmental lordosis goals, and frequently required more invasive procedures. Further initiatives to optimize alignment in lumbar fusions are needed to avoid costly and invasive deformity corrections. LEVEL OF EVIDENCE/METHODS:IV: Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.