<h3>BACKGROUND CONTEXT</h3> Adult spinal deformity (ASD) refers to multiple types of spinal deformity. This study used a prospective multicenter database of patients with "complex" surgical ASD to derive a data-driven classification of different deformity patterns, and assessed if such patterns have distinct clinical outcomes. <h3>PURPOSE</h3> Use an AI-based unsupervised approach to identify patterns of ASD. <h3>STUDY DESIGN/SETTING</h3> Retrospective analysis of a multi-center prospective database. <h3>PATIENT SAMPLE</h3> A total of 286 patients with complex ASD who underwent surgical correction. <h3>OUTCOME MEASURES</h3> Operative decision-making and 30-day adverse events. <h3>METHODS</h3> Complex surgical ASD included severe deformity, surgical complexity or advanced age with a multilevel fusion. An unsupervised cluster analysis that allowed for 10% outliers was used to identify different patterns of deformity. Perioperative outcomes of these clusters were then compared using ANOVA, Kustal-Wallis, and Chi-Squared analyses as indicated, with p-value < 0.05 considered significant. <h3>RESULTS</h3> The Hyper-Kyphosis (Hyper TK, n = 31) group had a mean thoracic kyphosis of 82.6±17.6°, lumbar hyperextension (PI-LL: -20.4±14.7°) and relatively straight coronal curvatures. Hyper-Kyphosis patients were the youngest (mean age 48±20 years) and had the lowest disability (mean ODI 32.9±17.1) and pain scores (median NRS back 6 IQR 3 to 8, median NRS leg 1 IQR 0 to 4). The Severe Coronal (Coronal, n = 91) group had a mean thoracic Cobb of 44.7±17.8° and a mean thoraco-lumbar Cobb of 57.9±16.5° with preserved global sagittal alignment. Coronal patients had moderate disability (mean ODI 33.5±18.8), functional impairment (PCD: 34.4±12.3) and pain scores (median NRS back 7 IQR 5 to 8, median NRS leg 4 IQR 0 to 7). The Severe Sagittal (Sev. Sag. n=79) group had a severe spino-pelvic mismatch (42.9±12.9°) and global sagittal deformity (24.3±7.9°). Sev Sag had higher BMIs (28.9±5.9), high levels of disability (mean ODI 49.3±15.6) and low appearance scores (2.3±0.7). Finally, the Moderate Sagittal (Mod. Sag. n=85) group had moderate deformities without distinctive radiographic characteristics, a mean age of 68.8±7.8°, the highest PROMIS pain interference sub-scores (65.2±5.8), high levels of disability (mean ODI 47.6±15.3) and back pain (NRS back 7 IQR 6 to 9), and poor overall quality of life (mean SRS total 2.8±0.6). Thirty-day adverse events were equivalent. Hyper TK and Coronal patients had the longest constructs, but fusion to the pelvis was most common in Mod Sag (89.4%) and Sev Sag (97.5%) deformities. Coronal patients had more osteotomies per case (median 11 IQR 6.5 to 14), longer OR times, and more 30-day implant-related complications (5.5%). Sev Sag and Hyper TK patients were more likely to require a 3-column osteotomy (43% and 32.3%, respectively). Sev Sag deformities were more likely to require interbody implants (29.1%) and operative wound debridement (7.6%). Hyper TK patients had shorter hospital stays. <h3>CONCLUSIONS</h3> AI methodologies identified 4 distinct patient clusters within a large population of surgically treated ASD patients. Each ASD cluster presented with 1) a unique spinal deformity pattern, 2) reported distinct pathognomonic health deficits, 3) received consistent surgical treatment across 11 centers, and 4) had characteristic perioperative complications and hospital stays. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.
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