Adult deformity surgery is challenging with many associated complications. A high complication rate of 80% and a revision rate of 58% have been reported for adult spinal deformity surgery. This degenerative condition usually occurs in older adults with multiple comorbidities such as cardiopulmonary disease, osteoporosis, and malnutrition. These complications should be properly managed preoperatively to minimize perioperative risks. Any of these complications may affect the duration of surgery as well as the surgical orthopedic outcome. Correction of the deformity can be achieved indirectly by de-rotation of the rods, repositioning manipulation of the cantilever, and anterior vertebral fusion to increase the height of the intervertebral space. Excessive separation of the concave side may result in loss of anterior convexity of the lumbar spine. To reduce scoliosis stiffness, posterior multisegmental osteotomies are required to loosen the spinal vertebral segments. Fusion fixation of the end vertebrae on a rotationally subluxated vertebra should be avoided because it will aggravate the subluxation. After short-segment internal fixation and fusion, degeneration of the residual scoliosis may be accelerated by the development of adjacent spondylolisthesis. Spinal fusion segments confined to the malformed segment may cause adjacent spondylosis. Fusion segments terminating in the thoracolumbar region can also lead to proximal neighboring spondylosis. Fusion to T10 or higher may avoid this. However, some believe that adjacent segment degeneration cannot be prevented during fusion surgery because it may result from age-related progression of degeneration plus spinal stiffness due to fusion fixation after spinal surgery. Proximal adjacent segment degeneration is characterized by a progressive decrease in disc height, progressive decrease in lordosis or progressive increase in kyphosis, formation of bony encumbrances, sclerosis of the adjacent endplates, as well as coronal or sagittal facet translation and proximal junctional disorders, such as adjacent segment degeneration, compression fracture, or screw failure.