Faculty Bibliography

OBJECTIVE:The aim of this study was to determine if there are any specific procedural, demographic, and/or radiographic factors that are associated with an improved postoperative lower extremity (LE) motor score (LEMS) among patients with adult spinal deformity (ASD) and abnormal baseline LEMS undergoing surgical correction. METHODS:Patients with ASD enrolled in an observational prospective study from 2018 to 2023 at 13 spinal deformity centers in North America were queried. Eligible participants met at least one of the following radiographic and/or procedural inclusion criteria: pelvic incidence minus lumbar lordosis mismatch ≥ 25°, T1 pelvic angle ≥ 30°, SVA ≥ 15 cm, thoracic scoliosis ≥ 70°, thoracolumbar scoliosis ≥ 50°, global coronal malalignment ≥ 7 cm, underwent 3-column osteotomy (3CO), spinal fusion ≥ 12 levels, and/or age ≥ 65 years with ≥ 7 levels of instrumentation. Patients with a baseline abnormal LEMS were dichotomized based on whether the LEMS improved or deteriorated from baseline by the 6-week postoperative visit. Patients with a maintained LEMS by 6 weeks compared with baseline were excluded. Patient and operative characteristics were compared through bivariate analyses to assess differences in treatment. A multivariable logistic regression model was built to discern independent factors associated with improved LEMS while controlling for potential confounders. RESULTS:Of 121 patients (77 female, mean age 62.9 years) included in the study, 109 (90.1%) improved and 12 (9.9%) experienced further deterioration from baseline to 6 weeks. Both groups had similar baseline LEMS by laterality and per nerve root. The groups were similar in age, sex, comorbidities, baseline LEMS, BMI, surgical indication, number of instrumented levels, estimated blood loss, operating room time, and hospital length of stay (p > 0.05). No differences in radiographic parameters at baseline and 6 weeks were observed aside from patients whose score had deteriorated experiencing greater change in the L1 pelvic angle (∆L1PA) (-8.0° ± 8.3° vs -1.6° ± 7.6°, p = 0.0413). Despite having similar frequencies of lumbar decompressions performed across a similar number of levels, patients whose conditions had deteriorated at 6 weeks had fewer lumbar posterior column osteotomies (PCOs) performed (50% vs 82.6%, p = 0.0169). No differences in in the frequency and number of 3COs performed were observed. Patients whose score had deteriorated experienced greater intraoperative neurophysiological monitoring (IONM) changes (41.7% vs 8.3%, p = 0.0050), all of which were motor deficits. Controlling for ∆L1PA and IONM changes revealed lumbar PCOs to be an independent driver of improved LEMS (OR 4.99 [95% CI 1.05-23.70]), with excellent model performance (p = 0.0031, area under the receiver operating characteristic curve of 0.77, Hosmer-Lemeshow goodness-of-fit test p = 0.3017). CONCLUSIONS:Performing lumbar decompressions alone might not be enough to improve LE weakness in patients with ASD and preoperative motor impairment, while the use of PCO was beneficial for improvement. Thus, more aggressive and thorough decompressions afforded by a combined approach of lumbar PCOs and decompression should be considered in this patient population to optimize postoperative motor strength.

BACKGROUND CONTEXT/BACKGROUND:Correcting sagittal malalignment in adult spinal deformity (ASD) is a challenging task, often requiring complex surgical interventions like pedicle subtraction osteotomies (PSOs). Different types of three-column osteotomies (3COs), including Schwab 3, Schwab 4, Schwab 4 with interbody cages, and the "sandwich" technique, aim to optimize alignment and fusion outcomes. The role of interbody cages in enhancing fusion and segmental correction remains unclear. PURPOSE/OBJECTIVE:This study aimed to compare outcomes among these 4 3CO techniques, evaluating the impact of cage use at the osteotomy site on postoperative radiographic imaging and clinical outcomes. STUDY DESIGN/SETTING/METHODS:This is a multicenter retrospective study utilizing data from a prospective multicenter database of patients undergoing complex ASD surgery. PATIENT SAMPLE/METHODS:Ninety-seven patients who underwent 1 of 4 3CO techniques for thoracolumbar ASD correction with at least 2 years of follow-up were included. The sample consisted of 29 patients who underwent Schwab 3 osteotomy, 20 Schwab 4, 28 Schwab 4 with interbody cages, and 20 who underwent "sandwich" osteotomy. OUTCOME MEASURES/METHODS:The Scoliosis Research Society-22 revised (SRS22r) questionnaire evaluating pain, activity, appearance, mental health, and satisfaction was used to evaluate patient reported outcomes and radiographic measures including segmental lordosis and fusion rates determined by 3 blinded reviewers were used to evaluate physiologic outcomes. METHODS:This study analyzed demographic data, radiographic outcomes, patient-reported outcomes, complications, and fusion rates over a 2-year follow-up period. Fusion status was determined via serial radiographs and evaluated independently by 3 blinded reviewers. Univariate and multivariate statistical analyses were performed to assess differences among the groups and the impact of interbody cage use on outcomes. RESULTS:Patients undergoing "sandwich" osteotomy exhibited worse preoperative leg pain scores and lower SRS22r activity (p=.015), appearance (p=.007), and mental health domain scores (p=.0015). No differences in complications were found among groups (p>.05). Patients who underwent osteotomy with a cage were more likely to have had previous spine fusion (91.7% vs. 71.4%, p=.010). Additionally, these patients had lower preoperative SRS22r mental domain (2.9±1 vs. 3.5±1, p=.009), satisfaction (2.3±1 vs. 2.7±1.2, p=.034), and SRS22r total scores (2.3±0.6 vs. 2.6±0.6, p=.0026) but demonstrated the greatest improvement in the mental health domain (0.9±0.7 vs. 0.3±0.9, p=.002). Cage use was associated with a larger mean change in segmental lordosis at the osteotomy site (32.9±9.6 vs. 28.7±9.5, p=.038). Fusion rates were significantly higher in the cage group (79.2% vs. 55.1%, p=.0012). Regression analysis identified cage use as an independent predictor for fusion (odds ratio, 3.338; 95% confidence interval, 1.108-10.054, p=.032). CONCLUSIONS:Interbody cage use at the osteotomy site during 3COs for ASD correction was associated with improved fusion rates and greater segmental lordosis without increasing complication rates. Incorporating cages may provide enhanced alignment and fusion outcomes in complex ASD surgeries.

BACKGROUND AND OBJECTIVES/OBJECTIVE:The concept of upper cervical (C0-C2) extension reserve (ER) capacity, ER relaxation, and their impact on outcomes following surgical correction of adult cervical deformity (ACD) has not been extensively studied. We aimed to evaluate the impact of upper cervical ER on postoperative disability and outcomes. METHODS:Patients with ACD, from a retrospective cohort study of a prospectively collected multicenter database, undergoing subaxial cervical fusion with 2-year (2Y) follow-up data were included. ER was defined as: ΔC0-C2 sagittal Cobb angle between neutral and extension. Relaxation of ER was defined as the ER mean in those that met all ideal thresholds in radiographic parameters for Passias et al CD modifiers. We used multivariable logistic regression to adjust for confounding, with conditional inference tree approaches used to determine thresholds that affect postoperative ER resolution on patient-reported outcomes. RESULTS:A total of 108 patients with ACD met inclusion. Preoperative C0-C2 ER was 8.7° ± 9.0°, and at last follow-up was 10.3° ± 11.1°. Preoperatively 29% of the cohort had adequate ER, whereas 60% had improved ER postoperatively, with 50% achieving adequate ER by 2Y. Lower ER correlated with greater CD (P < .05). Preoperatively, greater ER had lower Neck Disability Index (P < .001). Controlled analysis found improved ER to have a greater likelihood of achieving Neck Disability Index minimum clinically important difference (odds ratio 6.94, [1.378-34.961], P = .019). In those with inadequate ER at baseline, the preoperative C2-C7 of < -18° and T1 slope-cervical Lordosis mismatch of >59° for T1 slope-cervical Lordosis mismatch was predictive of ER resolution. In those with preoperative C2-C7 >-18°, a T1PA of >13° was predictive of postoperative return of ER (all P < .05). Surgical correction of C2-C7 by > 16° from baseline was found to be predictive of ER return. CONCLUSION/CONCLUSIONS:Increased preoperative use of the C0-C2 ER in CD was associated with worse baseline regional and global alignment and adversely affected health-related measures. Most of the patients had ER relaxation postoperatively. In those who didn't, however, there was a decreased likelihood of achieving satisfactory outcomes.

BACKGROUND CONTEXT/BACKGROUND:While the treatment of adult spinal deformity (ASD) has increasingly favored surgical correction, the incidence of revision surgery remains high. Yet, little has been explored on the association between the etiology of reoperation and patient outcomes. PURPOSE/OBJECTIVE:To assess the impact of the etiology of revision surgery on postoperative outcomes. STUDY DESIGN/SETTING/METHODS:Retrospective cohort analysis. PATIENT SAMPLE/METHODS:891 ASD patients. OUTCOME MEASURES/METHODS:Complications, radiographic parameters, disability metrics. METHODS:Operative ASD patients with at least 1 revision stratified by etiology (mechanical [Mech] -pseudoarthrosis, thoracic decompensation without junctional failure, x-ray malalignment, implant failure, implant malposition, PJK ± major malalignment; infection [Infx]-early vs late onset, major vs minor; wound [Wound]; SI pain [SI Pain]). Excluded multiple etiologies, and intraoperative or medical complications. Data from the immediate visit prior to the final revision was used as baseline (rBL). Follow-up based on visits best aligned to time points after final revision. Radiographic parameters SVA, PI-LL, and PT were used to assess alignment post-revision via ANOVA. Multivariate analysis controlling for relevant covariates assessed outcome differences after final revision surgery. RESULTS:891 MET INCLUSION (AGE: 60.40±14.17, 77% F, BMI: 27.97±5.87 KG/M2, CCI: : 1.80±1.73). Etiology groups were as follows: Mech: 432; Infx: 296; Wound: 65; SI Pain: 98. Surgically, Infx had lower rates of osteotomy, interbody fusion, and decompression (p<.05). Infx and SI Pain demonstrated similar correction in radiographics SVA, PI-LL, and PT (p>.05), whereas Mech had significantly less improvement by 2 years (p<.003) that improved by 5 years. Compared to without revision, the odds of MCID in ODI were 48.6% lower across groups (OR: 0.514 [.280, .945], p=.032). Indications of x-ray malalignment were 93.0% less likely to reach MCID (OR: 0.071, [.006, .866], p=.038). Similarly, implant failure negatively impacted rates of MCID (40% vs. 15.2%, p=.029). Those with PJK had 57% lower odds of MCID (33% vs 54%, OR: .43, [0.2, 0.9] p= 0.023), further negated by major malalignment (OR: 0.05, [.07, .97], p=.02). Indications of pseudarthrosis, thoracic decompensation, implant malposition were not significant. Major sepsis had lower rates of MCID compared to minor (6.4% vs. 21.2%), and early onset infection improved compared to late (OR: 1.43, [1.17, 2.98], p<.001). In the early follow-up period, the Mech group has significantly worse SRS Pain and Mental Health scores compared to other groups (1-year: Mech 1.56 vs Infx 0.83 vs SI Pain 0.72, p<0.001; 2-year: 1.88 vs 0.71 vs 0.76, p=0.034). Complication rates increased with the number of revisions and with mechanical indication (all p<.05). At 5 years, patient satisfaction was significantly more likely to improve compared to early follow-up (OR: 1.22, p=.011), along with improved pain score, in Mech group (0.89 vs 0.49 vs 0.56, p=.081). CONCLUSIONS:This study focused on the impact of revision as it varies with etiology and time of occurrence postoperatively. Compared to other etiologies, revision surgery due to mechanical complications had less radiographic improvement and worsening patient-reported scores in the early postoperative period despite stabilization at 5 years. The depth of impact of mechanical complication, particularly with the addition of malalignment, merits greater focus during surgical planning. LEVEL OF EVIDENCE/METHODS:III.

STUDY DESIGN/METHODS:Retrospective analysis of prospectively-collected data. OBJECTIVE:This study aims to define clinically relevant blood loss in adult spinal deformity (ASD) surgery. BACKGROUND:Current definitions of excessive blood loss following spine surgery are highly variable and may be suboptimal in predicting adverse events (AE). METHODS:Adults undergoing complex ASD surgery were included. Estimated blood loss (EBL) was extracted for investigation, and estimated blood volume loss (EBVL) was calculated by dividing EBL by the preoperative blood volume utilizing Nadler's formula. LASSO regression was performed to identify five variables from demographic and peri-operative parameters. Logistic regression was subsequently performed to generate a receiver operating characteristics (ROC) curve and estimate an optimal threshold for EBL and EBVL. Finally, the proportion of patients with AE plotted against EBL and EBVL to confirm the identified thresholds. RESULTS:In total 552 patients were included with a mean age of 60.7±15.1 years, 68% females, mean CCI was 1.0±1.6, and 22% experienced AEs. LASSO regression identified ASA score, baseline hypertension, preoperative albumin, and use of intra-operative crystalloids as the top predictors of an AE, in addition to EBL/EBVL. Logistic regression resulted in ROC curve which was used to identify a cut-off of 2.3 liters of EBL and 42% for EBVL. Patients exceeding these thresholds had AE rates of 36% (odds-ratio: 2.1, 95% CI [1.2-3.6]) and 31% (odds-ratio: 1.7, 95% CI [1.1-2.8]), compared to 21% for those below the thresholds of EBL and EBVL, respectively. CONCLUSION/CONCLUSIONS:In complex ASD surgery, intraoperative EBL of 2.3 liters and an EBVL of 42% are associated with clinically-significant AEs. These thresholds may be useful in guiding preoperative-patient-counseling, healthcare system quality initiatives, and clinical perioperative bloodloss management strategies in patients undergoing complex spine surgery. Additionally, similar methodology could be performed in other specialties to establish procedure-specific clinically-relevant bloodloss thresholds.

BACKGROUND AND OBJECTIVES/OBJECTIVE:The spectrum of patients requiring adult spinal deformity (ASD) surgery is highly variable in baseline (BL) risk such as age, frailty, and deformity severity. Although improvements have been realized in ASD surgery over the past decade, it is unknown whether these carry over to high-risk patients. We aim to determine temporal differences in outcomes at 2 years after ASD surgery in patients stratified by BL risk. METHODS:Patients ≥18 years with complete pre- (BL) and 2-year (2Y) postoperative data from 2009 to 2018 were categorized as having undergone surgery from 2009 to 2013 [early] or from 2014 to 2018 [late]. High-risk [HR] patients met ≥2 of the criteria: (1) ++ BL pelvic incidence and lumbar lordosis or SVA by Scoliosis Research Society (SRS)-Schwab criteria, (2) elderly [≥70 years], (3) severe BL frailty, (4) high Charlson comorbidity index, (5) undergoing 3-column osteotomy, and (6) fusion of >12 levels, or >7 levels for elderly patients. Demographics, clinical outcomes, radiographic alignment targets, and complication rates were assessed by time period for high-risk patients. RESULTS:Of the 725 patients included, 52% (n = 377) were identified as HR. 47% (n = 338) had surgery pre-2014 [early], and 53% (n = 387) underwent surgery in 2014 or later [late]. There was a higher proportion of HR patients in Late group (56% vs 48%). Analysis by early/late status showed no significant differences in achieving improved radiographic alignment by SRS-Schwab, age-adjusted alignment goals, or global alignment and proportion proportionality by 2Y (all P > .05). Late/HR patients had significantly less poor clinical outcomes per SRS and Oswestry Disability Index (both P < .01). Late/HR patients had fewer complications (63% vs 74%, P = .025), reoperations (17% vs 30%, P = .002), and surgical infections (0.9% vs 4.3%, P = .031). Late/HR patients had lower rates of early proximal junctional kyphosis (10% vs 17%, P = .041) and proximal junctional failure (11% vs 22%, P = .003). CONCLUSION/CONCLUSIONS:Despite operating on more high-risk patients between 2014 and 2018, surgeons effectively reduced rates of complications, mechanical failures, and reoperations, while simultaneously improving health-related quality of life.

STUDY DESIGN/METHODS:Retrospective cohort study of prospectively enrolled cervical deformity patients. OBJECTIVE:To investigate patients in whom fusion to the thoracic spine was warranted. SUMMARY OF BACKGROUND DATA/BACKGROUND:Thoracolumbar malalignment is often seen in patients presenting with cervical deformities. For cervical deformity (CD) patients, it is not always clear where in the thoracic spine to end the construct. METHODS:Patients were stratified into upper and lower thoracic groups: T1-T4 [Short Fusion], beyond T4 [Long Fusion]. Optimal outcome (OO) at 2 years postop was defined as: (1) did not have DJF and (2) had Virk et al good clinical outcome [≥2 of the following: NDI <20 or meeting MCID, mild myelopathy (mJOA ≥14), NRS-Neck ≤5 or improved by ≥2 points from baseline]. Univariate analysis compared variables between short and long fusion groups. Multivariate analysis analyzed associations between groups and factors related to treatment success and failures. RESULTS:One hundred forty-four cervical deformity patients were included (60.3±9.0 y, 60% F, 29.4±7.6 kg/m2, levels fused: 7.8±3.2). Eighty-two percent of patients had short fusions, whereas 18% had long fusions. 44.4% met the optimal outcome criteria, with no difference by fusion length (P=0.171). Factors associated with achieving OO in long fusions: baseline sacral slope ≤33.5 degrees (OR: 15.0), not undergoing high-grade osteotomy (OR: 12.3) and being Ames descriptor type C (OR: 13.5); all P<0.05. Factors associated with failure to achieve OO in short fusions: levels fused >6 (OR: 4.3), Ames descriptor type CT (OR: 11.5), Ames cSVA modifier grade 1 or 2 at BL (OR: 4.56), and Flatneck sagittal morphotype (OR: 4.5); all P<0.05. CONCLUSION/CONCLUSIONS:The choice of lower instrumented vertebra (LIV) in cervical deformity fusions may be influenced by multiple factors. In patients with global malalignment, severe frailty, flatneck deformity morphotype, and Ames type CT descriptor types, LIVs beyond T4 are associated with treatment success. LEVEL OF EVIDENCE/METHODS:Level III.

STUDY DESIGN/METHODS:Retrospective analysis of prospectively collected data. OBJECTIVE:This study evaluates the impact of knee osteoarthritis (OA) and knee arthroplasty on alignments and patient-reported outcomes measures (PROMS) of patients undergoing adult spinal deformity (ASD) corrective surgery. BACKGROUND:The relationship between knee OA and spinal alignment in patients with ASD is incompletely understood. It is also unknown how patients with knee arthroplasty and ASD compare to ASD patients with native knees. METHODS:Baseline full-body radiographs were used, and hip and knee OA were graded by two independent reviewers using the KL classification. Spinopelvic parameters and PROMs were compared across the different knee OA groups and compared between patients with knee replacement and native knees. RESULTS:199 patients with bilateral non severe OA (G1), 31 patients with unilateral severe knee OA (G2), and 60 patients with bilateral severe knee OA (G3). Patients with severe knee OA presented with worse spinopelvic parameters. However, after multivariable regression analysis controlling for age, frailty, PI, T1PA, knee OA was an independent predictor of knee flexion (G1:-0.02±7.3, G2: 7.8±9.4, G3: 4.5±8.7, P<0.001), and ankle dorsiflexion (G1: 2.3±4.0, G2: 6.6±4.5, G3: 5.1±4.1, P<0.001). There was no difference in PROMs (P>0.05). Secondary analysis included 96 patients: 48 patients (50%) with non-severe knee OA, and 48 patients (50%) with knee replacement. There was no difference in radiographic parameters or PROMs between the groups. CONCLUSION/CONCLUSIONS:In this study of complex ASD patients, patients with worse spinal deformity were more likely to have concomitant knee OA. Knee OA was shown to be a predictor of knee flexion and ankle dorsiflexion angles, but was not associated with worse PROMs in this study population. Patients with knee arthroplasty, however, had comparable spinal alignment and PROMs relative to those with mild OA.

BACKGROUND AND OBJECTIVES/OBJECTIVE:To investigate the cost-effectiveness and impact of prophylactic techniques on the development of proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) in the context of postoperative alignment. METHODS:Adult spinal deformity patients with fusion to pelvis and 2-year data were included. Patients receiving PJK prophylaxis (hook, tether, cement, minimally-invasive surgery approach) were compared to those who did not. These cohorts were further stratified into "Matched" and "Unmatched" groups based on achievement of age-adjusted alignment criteria. Costs were calculated using the Diagnosis-Related Group costs accounting for PJK prophylaxis, postoperative complications, outpatient health care encounters, revisions, and medical-related readmissions. Quality-adjusted life years were calculated using Short Form-36 converted to Short-Form Six-Dimension (SF-6D) and used an annual 3% discount rate. Multivariate analysis controlling for age, sex, levels fused, and baseline deformity severity assessed outcomes of developing PJK/PJF if matched and/or with use of PJK prophylaxis. RESULTS:A total of 738 adult spinal deformity patients met inclusion criteria (age: 63.9 ± 9.9, body mass index: 28.5 ± 5.7, Charlson comorbidity index: 2.0 ± 1.7). Multivariate analysis revealed patients corrected to age-adjusted criteria postoperatively had lower rates of developing PJK or PJF (odds ratio [OR]: 0.4, [0.2-0.8]; P = .011) with the use of prophylaxis. Among those unmatched in T1 pelvic angle, pelvic incidence lumbar lordosis mismatch, and pelvic tilt, prophylaxis reduced the likelihood of developing PJK (OR: 0.5, [0.3-0.9]; P = .023) and PJF (OR: 0.1, [0.03-0.5]; P = .004). Analysis of covariance analysis revealed patients matched in age-adjusted alignment had better cost-utility at 2 years compared with those without prophylaxis ($361 539.25 vs $419 919.43; P < .001). Patients unmatched in age-adjusted criteria also generated better cost ($88 348.61 vs $101 318.07; P = .005) and cost-utility ($450 190.80 vs $564 108.86; P < .001) with use of prophylaxis. CONCLUSION/CONCLUSIONS:Despite additional surgical cost, the optimization of radiographic realignment in conjunction with prophylaxis of the proximal junction appeared to be a more cost-effective strategy, primarily because of the minimization of reoperations secondary to mechanical failure. Even among those not achieving optimal alignment, junctional prophylactic measures were shown to improve cost efficiency.

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.