Congenital kyphosis is a pathological kyphosis that occurs anywhere in the spine and is caused by congenital anomalies of the spine. 1844 saw the first article by Von Rokitansky describing kyphosis postmortem, and in 1932 Van Schrick further divided congenital kyphosis into two types, namely vertebral malsegmentation and formation defects, bringing the study of this condition to a new level. In 1965, Hodgson made an outstanding contribution to the treatment of congenital kyphosis by reporting for the first time a case of congenital kyphosis treated by anterior surgery, and in 1973, Winter, Moe, and Wang conducted the first comprehensive review of 130 patients. Some of the principles presented therein still have application today. The natural progression of congenital kyphosis is sinister and predisposes to paraplegia. Bracing is ineffective and often requires anterior-posterior spinal fusion, and it is advisable to focus on prevention of spinal cord compression during treatment. Yang Cao, Department of Orthopedics, Wuhan Union Medical College Hospital Congenital kyphosis includes two main types, type I: defects in vertebral body formation, mostly in the thoracic and thoracolumbar spine, and rarely in the cervical spine. Type I has a high incidence and is potentially dangerous, and is prone to angular kyphosis and paraplegia. The speed and severity of deformity progression is directly related to the anterior vertebral defects, the more vertebral defects, the faster the progression and the more severe the deformity. Type II: poorly segmented vertebrae, mostly in the thoracolumbar spine, followed by the thoracic and lumbar spine. Patients with type II have a relatively well-developed course, and the degree of progression is related to the length of the malsegmentation (involving vertebral segments) and the growth imbalance (posterior and anterior growth relationships). The vast majority of congenital kyphotic deformities are ineffective for non-surgical treatment, and there are two effective surgical options: simple posterior fusion and combined anterior-posterior fusion. (a) Posterior fusion The indications for posterior fusion include: (i) Type I deformity found at an early age (under 5 years old) with a supine lateral deformity of less than 50o; (ii) Type II deformity under 5 years old that does not require orthopedic treatment and for which surgery is performed only to stop its progression. For type I deformity found early, posterior fusion does not correct the deformity because the growth plate still existing anteriorly will continue to grow during the developmental stage and can automatically relieve the retroconvex deformity. Intraoperatively, the diseased vertebra and one normal vertebra each superiorly and inferiorly. Postoperatively, an orthopedic cast (Risser anti-gravity type) was used for fixation. Walking in a cast after 4 months of bed rest should result in a strong fusion by 6 months. In the second case (type II), anterior fusion is already present and only posterior fusion is needed to prevent progression of the deformity. (B) Combined anterior-posterior fusion 1, treatment of type I vertebral body formation defect deformity Combined anterior-posterior fusion is the main method for treating congenital retroconvex deformity. The deformity is anterior to the presence of bony components (congenitally caused anterior column defect) and soft tissue contracture (especially the anterior longitudinal ligament), the surgical objective is to remove the contracted ligament, fibrous tissue and remaining cartilage, and to implant autologous bone to reconstruct the anterior column. Due to the pre-existing bony defect, vertebral osteotomy is not required unless spinal cord compression is present. The anterior approach is performed using a conventional transthoracic or combined thoracoabdominal approach. The vessels of the posterior convex segment are ligated, the contralateral spine is exposed, and the contracted ligament and fibrous annulus are completely removed, with all discs except the posterior fibrous annulus being removed. Access to the spinal canal is not required except for paraplegic patients who require decompression. After anterior release, the spine becomes more flexible. At this point, the anesthesiologist tracts the head and the assistant pushes and squeezes the parietal vertebrae to obtain good orthosis and embed the supporting bone graft. Although the ribs also have some strength, autogenous fibula is mostly used. The remaining autogenous bone is placed in the intervertebral space and around the supporting bone block, and the incision is closed layer by layer. If the posterior deformity is severe, orthopedic devices such as Santa Casa spacers and Slot spacers are used after releasing the soft tissue. The orthopedic device provides a slow and steady opening force for the pathologic kyphosis, and intraoperative spinal monitoring and arousal tests are performed. If optimal orthosis is obtained, a fibular support implant is placed posterior to the spacer, the spacer is removed and a second support fibula is placed, and the rib and iliac bone strips are filled in the triangle formed by the anterior support bone block and the retroflexion deformity. Anterior placement of internal fixation is not satisfactory and internal fixation should be placed posteriorly. Posterior fusion must include the full length of the deformity and one normal vertebra above and below it, which is slightly longer than anterior fusion, and use autogenous bone graft. Internal fixation is used as an adjunct to implant fusion. For simple kyphosis, the main force is posterior compression and “three-point” correction of the deformity without bracing. If the posterior convexity is combined with lateral convexity, the concave side can be braced after placing a compression device on the convex side of the lateral convexity. In all cases of anterior-posterior fusion without internal fixation, a Risser hyperextension cast (including the neck) is required to maintain the dorsal extension and prevent axial shortening. Bracing alone is not adequate unless a Mil-waukee brace is worn 24 hours a day with absolute bed rest. If the patient has a pediatric-type posterior internal fixator, 24-hour cast or brace fixation is also required. No external fixation is required for youth or adults with CD or other identical devices. 2.Treatment of type II (malunion) deformity Patients with type II deformity (malunion) require anterior osteotomy in the unsegmented area. In patients with progressive deformity, the anterior bone bridge at the unsegmented area only occupies the first 1/2 or 2/3 of the vertebral space, but not the entire vertebral space. Therefore, the surgeon can cut the bone bridge down to the posterior residual disc tissue. At this point, the deformity becomes more flexible and can be orthopedic with a spreader (malsegmentation often does not involve posterior structures). The incision is closed layer by layer after filling the intervertebral space with bone strips. With posterior surgery, the deformity can be corrected by applying the principle of compression and three-point action of internal fixation devices. If the patient is too young for internal fixation, a Risser hyperextension cast can be used to correct the deformity. (C) Surgical treatment of spinal cord compression Spinal cord compression is divided into two degrees: mild and severe. In mild cases, there are hyperreflexia and clonus without lower limb weakness and dysraphism; in severe cases, any symptom or sign is aggravated. For mild spinal cord compression, no decompression is needed. The spinal cord compression can be released after anterior release, orthopedic, anterior-posterior fusion and restoration of spinal canal order. For severe spinal cord compression, anterior spinal cord decompression and anterior-posterior fusion are required. The anterior decompression needs to be adequate, with sufficient length above and below and width on both sides, to avoid compression of the spinal cord by the vertebral osteotomy margins. Adequate decompression and fusion must be performed via a formal open or thoracolumbar approach. Although spinal cord decompression can be performed via transverse rib resection, it is difficult to support bone grafting and is prone to failure. Laminectomy for spinal cord compression due to this condition is an absolute contraindication.