Prevention of Mechanical Complications in Adult Spinal Deformity Surgery

Mechanical complications (MCs), including proximal junctional kyphosis (PJK), proximal junctional failure (PJF), rod fractures, and distal junctional pathologies, represent significant challenges in adult spinal deformity (ASD) surgery. These complications adversely impact patient outcomes, increase revision surgery rates, and reduce quality of life. This chapter outlines a comprehensive, stage-specific strategy for preventing MCs, integrating risk stratification, biomechanical planning, and individualized surgical techniques. In the preoperative phase, assessment of modifiable risk factors is essential, alongside evaluation of radiographic parameters including PI–LL mismatch, sagittal vertical axis (SVA), and thoracic kyphosis (TK). Age-adjusted alignment goals and full-extension lateral views (FELV) aid in personalized surgical planning. Intraoperatively, optimal selection of instrumented levels, soft tissue preservation, and techniques such as cement augmentation and kyphotic rod contouring reduce mechanical stress. The use of anterior approaches such as oblique lumbar interbody fusion (OLIF) or anterior column realignment (ACR) can improve alignment restoration with minimal invasiveness. Postoperatively, pharmacologic bone management, muscle strengthening, and bracing further support construct integrity. Emerging tools including the Global Alignment and Proportion (GAP) score, Sagittal Age-Adjusted Score (SAAS), and vertebral pelvic angles (VPA) can enhance prediction and support personalized treatment planning. Successful prevention of mechanical complications in adult spinal deformity surgery depends on a patient-centered, biomechanically informed approach that applies evidence-based strategies throughout all phases of care.