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Study Design: Retrospective analysis of prospectively-collected, multicenter adult spinal deformity (ASD) databases.Objective: To predict the likelihood of reaching minimum clinically important differences in patient-reported outcomes after ASD surgery.Summary Of Background Data: ASD surgeries are costly procedures that do not always provide the desired benefit. In some series only 50% of patients achieve minimum clinically important differences in patient-reported outcomes (PROs). Predictive modeling may be useful in shared-decision making and surgical planning processes. The goal of this study was to model the probability of achieving minimum clinically important differences change in PROs at 1 and 2 years after surgery.Methods: Two prospective observational ASD cohorts were queried. Patients with Scoliosis Research Society-22, Oswestry Disability Index , and Short Form-36 data at preoperative baseline and at 1 and 2 years after surgery were included. Seventy-five variables were used in the training of the models including demographics, baseline PROs, and modifiable surgical parameters. Eight predictive algorithms were trained at four-time horizons: preoperative or postoperative baseline to 1 year and preoperative or postoperative baseline to 2 years. External validation was accomplished via an 80%/20% random split. Five-fold cross validation within the training sample was performed. Precision was measured as the mean average error (MAE) and R values.Results: Five hundred seventy patients were included in the analysis. Models with the lowest MAE were selected; R values ranged from 20% to 45% and MAE ranged from 8% to 15% depending upon the predicted outcome. Patients with worse preoperative baseline PROs achieved the greatest mean improvements. Surgeon and site were not important components of the models, explaining little variance in the predicted 1- and 2-year PROs.Conclusion: We present an accurate and consistent way of predicting the probability for achieving clinically relevant improvement after ASD surgery in the largest-to-date prospective operative multicenter cohort with 2-year follow-up. This study has significant clinical implications for shared decision making, surgical planning, and postoperative counseling.Level Of Evidence: 4. [ABSTRACT FROM AUTHOR]

Study Design: Retrospective review of prospectively-collected, multicenter adult spinal deformity (ASD) databases.Objective: To apply artificial intelligence (AI)-based hierarchical clustering as a step toward a classification scheme that optimizes overall quality, value, and safety for ASD surgery.Summary Of Background Data: Prior ASD classifications have focused on radiographic parameters associated with patient reported outcomes. Recent work suggests there are many other impactful preoperative data points. However, the ability to segregate patient patterns manually based on hundreds of data points is beyond practical application for surgeons. Unsupervised machine-based clustering of patient types alongside surgical options may simplify analysis of ASD patient types, procedures, and outcomes.Methods: Two prospective cohorts were queried for surgical ASD patients with baseline, 1-year, and 2-year SRS-22/Oswestry Disability Index/SF-36v2 data. Two dendrograms were fitted, one with surgical features and one with patient characteristics. Both were built with Ward distances and optimized with the gap method. For each possible n patient cluster by m surgery, normalized 2-year improvement and major complication rates were computed.Results: Five hundred-seventy patients were included. Three optimal patient types were identified: young with coronal plane deformity (YC, n = 195), older with prior spine surgeries (ORev, n = 157), and older without prior spine surgeries (OPrim, n = 218). Osteotomy type, instrumentation and interbody fusion were combined to define four surgical clusters. The intersection of patient-based and surgery-based clusters yielded 12 subgroups, with major complication rates ranging from 0% to 51.8% and 2-year normalized improvement ranging from -0.1% for SF36v2 MCS in cluster [1,3] to 100.2% for SRS self-image score in cluster [2,1].Conclusion: Unsupervised hierarchical clustering can identify data patterns that may augment preoperative decision-making through construction of a 2-year risk-benefit grid. In addition to creating a novel AI-based ASD classification, pattern identification may facilitate treatment optimization by educating surgeons on which treatment patterns yield optimal improvement with lowest risk.Level Of Evidence: 4. [ABSTRACT FROM AUTHOR]

Proximal junctional kyphosis (PJK) is one of the most common complications following adult spinal deformity (ASD) surgery and has been intensively studied over the last decade. This study aims to investigate the evolution of PJK rate over a 10-year enrollment period within a prospective database of ASD patients. The hypothesis is that the rate of PJK and PJF will decrease across time. Retrospective review of prospective multicenter database. A total of 641 ASD patients with minimum 2-year follow-up. Rate of PJK and PJF. ASD patients with a fusion extended to pelvis and a minimum of 2-year follow-up were included. To investigate a continuous evolution of the PJK/PJF rate, a moving average of 321 patients was calculated across the entire enrollment period, allowing for 95% CI on rate for an incidence of 30% or less. Radiographic PJK was defined as a PJA>10° at 2Y and ΔPJA>10° between preoperative and 2-year follow-up. PJF was defined as either revised for PJK before 2-year visit or Severe radiographic PJK at 2-year follow-up (PJA>28° & ΔPJA>22°). Logistic regression was used to investigate association between date of surgery and PJK and/or PJF. Comparison of PJK rate, demographics and surgical strategies was performed between the first and second half of the cohort. A total of 641 patients met inclusion criteria (age: 64±10yo, 78.4% F, BMI: 28.3±5.7). The overall rate of radiographic PJK at 2-year was 48.2% (N=309/641); 12.9% (N=83/641) of the patients developed a PJF, with 31.3% (N=26/83) being revised within 2-year. The stratification by date of surgery (DOS) yielded 2 timeframes: First= Oct 2008 to Jul 2014 (with a median DOS of Sep 2011), and Second=Jun 2014 to Apr 2018 (with a median DOS of Aug 2016). Between these 2 periods, the rate of radiographic PJK demonstrated a nonsignificant decrease from 50.3% to 45.5% (p=0.22) and PJF from 15.0% to 10.9% (p=0.12). Linear interpolation of the rate of PJK and PJF by enrollment using a moving average suggested a decrease of 1.1% PJK per year and 1.0% PJF per year. Over the study period, patients became continuously older (from 62.6±10.3 to 65.5±8.7 p<0.001) and were more likely be classified as a pure sagittal deformity (SRS Type N from 31.2% to 47.4% p<0.001). Across the enrollment period, there was a shift in surgical strategy, with a significant reduction of 3CO use (35.1% vs 20.8% p<0.001), an increase in ALL release (0% vs 18.4% p<0.001), a decrease in the number of levels fused (12.2±3.5 vs 11.7±3.9 p=0.016), and an increase in the use of PJK prophylaxis (31.3% vs 55.1%). Logistical regression analysis demonstrated no significant association between date of surgery and radiographic PJK (p=0.19) or PJF (p=0.39). Despite extensive research examining risk factors for PJK/PJF and increasing utilization of intraoperative PJK prophylaxis techniques, the rate of radiographic PJK and/or PJF did not significantly decrease across the 10-year enrollment period of this ASD database. The increase in patient risk factors (older) was probably balanced by changes in surgical strategy and preoperative optimization. Continuous enrollment and follow-up will allow ongoing study which may eventually lead to significant decreases in the rate of PJK and PJF. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

The distribution of lumbar lordosis (LL) between L1-4 and L4-S1 is known to vary based on pelvic incidence (PI). However, the extent to which regional changes effect pelvic tilt (PT) is not clearly elucidated. This information can be useful for adult spinal deformity (ASD) surgical planning. To investigate the change in pelvic tilt (PT) imparted by regional changes in LL at 2-year minimum follow-up. Retrospective study of a multicenter ASD database. A total of 103 ASD patients. Radiographic parameters. Operative patients from a multicenter ASD database were included with LIV S1/Ilium, >5 levels of fusion, PJK angle <20 and >5° of change from L4-S1 and L1-4. Patients with PJK angles >20 were excluded due to the compensatory effect this has on PT. Radiographic analysis was performed evaluating thoracic kyphosis (TK), T10-L2 (TL), L1-S1 (LL), L4-S1, L1-4, SVA and PI-LL from pre- to postoperative and change at 2-year follow-up. Paired t-tests were utilized to analyze the change in parameters and HRQOLs at 2-year follow up. Stepwise regression analysis was performed in order to determine the relationship between PT and the above radiographic parameters. HRQOLs (ODI, PCS, MCS, SRS-22r) were also compared between pre- and postoperative timepoints at 2 years. A total 103 patients met inclusion for the study. Paired t-tests demonstrated improvements in all the radiographic parameters (TK 30.1 vs 49.8, SVA 122 vs 28, LL 19.4 vs 51.9, PI-LL 35.2 vs 3.2, p<0.01) and HRQOLs at 2 year follow up respectively (ODI 47.9 vs 28.1, PCS 28.0 vs 39.9, MCS 45.9 vs 51.5, SRS-22r 2.6 vs 3.7, p<0.01). TL was not significantly different at 2 years (11.2 vs 8.6, p=0.14). Stepwise regression model showed an inverse relationship between PT and LL change (r=0.71, p<0.01). Regionally, an increase in 10° from L4-S1 correlated with a 2.4° decrease in PT (p<0.01), while an increase in 10° from L1-4 resulted in a 1.6° decrease in PT (p<0.01). In the surgical planning for ASD, our data demonstrated significant correlational difference between corrections in the upper (L1-4) and lower (L4-S1) lumbar spine and PT changes. These calculations can be useful in planning sagittal plane corrections for ASD and are analogous to prior literature on alignment changes after 3CO in the lumbar spine. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]