Most patients with degenerative scoliosis are older than 50 years old, and with the aging of our population, adult scoliosis will become more common. The main focus is on symptom relief, and on the premise of being able to ensure a certain quality of life for the patient, simple, convenient and less invasive treatment methods are chosen as much as possible. Degenerative scoliosis refers to the loss of anterior lumbar convexity and segmental kyphosis in the sagittal plane due to severe degeneration of the intervertebral discs and small bilateral intervertebral joints after skeletal maturation, except for organic spinal pathology. Epidemiology Degenerative scoliosis is a slow process that occurs mainly in people after the age of 50 and less frequently before the age of 40. The prevalence ratio is 1:2 for men and women, with a group prevalence of about 6%. Mostly caused by intervertebral disc or small synovial degeneration, osteoporosis, etc. caused by the bending deformity of the spine, lesions of the spine to the lumbar segment is most common, a small number of thoracolumbar segment can also be involved, the top vertebrae are located between the two adjacent vertebral bodies, most likely in the L2-3, L3-4 intervertebral space, often involving 2-5 segments, the lumbar spine appears to the left or right bending probability is comparable. Most lateral bends with a Cobb angle <60° are often accompanied by lesions such as reduced anterior lumbar convexity, lateral slippage of the vertebral body and narrowing of the spinal canal or nerve root canal. It leads to intractable low back pain and nerve root symptoms in the lower extremities, which can seriously affect the quality of life of the elderly. Mechanism of occurrence It is generally believed that DS occurs gradually on the basis of spinal degeneration and instability, including degeneration of intervertebral discs and synovial joints, and degeneration of muscles and ligaments, but its specific pathogenesis is unclear. From an anatomical point of view, the activity of each motor segment of the spine is accomplished by a triple joint complex consisting of two small joints in the posterior and intervertebral discs in the anterior. Asymmetric degeneration of the discs and bilateral intervertebral small joints in this composite region structure eventually causes scoliosis, rotational deformity, narrowing of the spinal canal or nerve root canal, irritation or compression of nerve roots, and a series of corresponding neurological symptoms. Asymmetric degeneration of the intervertebral discs, especially the "vacuum phenomenon", may increase rotational instability, and degeneration of the synovial joints causes intervertebral tilting, slipping, and rotational displacement. This vicious circle leads to the progressive development of scoliosis. Paravertebral muscle degeneration and fatty fibrosis in the elderly also contribute to pain, deformity, and imbalance. In addition, menopausal women are prone to osteoporosis, which, combined with asymmetric loading of the vertebral body, is highly susceptible to wedge-shaped changes and compression fractures, further aggravating the development of scoliosis. Osteoporosis does not directly cause scoliosis, but plays an active role in accelerating the progression of scoliosis. Typing 1. Schwab typing system Schwab classifies adult spinal deformities into 5 subtypes and 2 modified types based on imaging data such as Cobb angle, parietal vertebral position, lumbar anterior convexity angle, and intervertebral subluxation combined with sagittal balance in patients with adult spinal deformities. Because this typing is based on the patient's imaging data and quality-of-life assessment, it has good credibility, and the authors' study showed good correlation between the imaging measurements in the typing and clinical symptoms and the decision to operate or not, which is of great value in guiding the surgical strategy. All patients must meet one of the following criteria: (1) Cobb angle >30°; (2) sagittal or coronal imbalance >5 cm; (3) thoracic kyphosis (T3 or T5-T12) >60°; (4) lumbar anterior kyphosis <30° and ≥15° of lateral kyphosis; (5) thoracolumbar kyphosis (T12 or T10-L2) >20°; (6) lumbar kyphosis (spanning at least (6) lumbar lordosis (spanning at least 3 segments) >10°. Table 1 Schwab typing 2. SRS typing system Lowe et al. borrowed from the King/Moe and Lenke typing of adolescent idiopathic scoliosis and divided adult scoliosis into 7 subtypes and 3 modified types by considering 3 modified factors, namely sagittal balance, lumbar degeneration and overall trunk balance, in addition to the main bending type. The typing is based mainly on the analysis of imaging measurements and has a high degree of confidence. Deformity definition Thoracic curvature: parietal vertebrae located in the T2-T12 intervertebral disc was defined as thoracic curvature; thoracolumbar curvature: parietal vertebrae located in T12-L1 was defined as thoracolumbar curvature; lumbar curvature: parietal vertebrae located in the L1-2 intervertebral disc to L4 was defined as lumbar curvature; main thoracic curvature: Cobb angle >40° and parietal vertebrae not on the C7 plumb line was defined as main thoracic curvature; main thoracolumbar curvature: if thoracolumbar curvature Cobb angle >30° and parietal vertebrae not on the sacral mid plumb line If the thoracic bend, thoracolumbar bend and lumbar bend do not meet the criteria of the main bend and the posterior convexity Cobb angle of any one or several segments is greater than the modified type of sagittal plane, it is defined as type VII sagittal plane deformity. According to the coronal balance of degenerative scoliosis not only closely related to the patient’s appearance, but also closely related to the progression of scoliosis and the occurrence and development of nerve root pain and claudication gait, the coronal imbalance of standing spine orthopantomographs is used for typing. With reference to the classification criteria for coronal balance in adult scoliosis proposed by Lowe et al, the distance between the C7 plumb line and the mid-sacral plumb line on the coronal plane >3 cm was considered to be out of balance. DS typing: C7 plumb line deviation <3 cm from the sacral midline was defined as type A; C7 plumb line deviation >3 cm to the concave side of the main lumbar curve was defined as type B; C7 plumb line deviation >3 cm to the convex side of the main lumbar curve was defined as type C. These three types of typing were used to treat degenerative scoliosis by total vertebral osteotomy at different sites, and this typing method has certain guiding significance for cases requiring osteotomy for degenerative scoliosis.