Youthful hunchback (Scheuermann’s disease) is one of the most common disorders causing structural hunchback in adolescents. Its etiology is unknown and the disease, if undiagnosed before skeletal maturity, mostly progresses to mild to moderate deformity, exhibiting a relatively benign course. Occasionally, severe deformities occur and can lead to disabling back pain in adult patients. Surgical treatment is required when the deformity is severe, especially when non-surgical treatments fail to relieve the pain. Seheuermann’s disease often begins around puberty with a hunchback in the thoracic or thoracolumbar segment. It is often delayed in diagnosis and treatment because it is thought to be caused by poor posture. Patients may present with very pronounced pain which often disappears when growth stops. When the deformity is severe, in addition to pain at the site of the lesion, lower back pain may also occur, which may be associated with overcompensation of the anterior convexity of the spine or occasional combined spinal slippage. In addition to thoracic kyphosis, patients also have varying degrees of lumbar lordosis and reduced cervical lordosis, with the head protruding relatively forward for the trunk. In addition to the spinal deformity, Scheuermann’s disease is often associated with anterior muscle tension in the scapular girdle, as well as tension in the carpus and iliopsoas muscles. Severe kyphosis resulting in spinal cord compression and mild paralysis of the lower extremities is rare. Radiographic diagnostic criteria for Scheuermann’s disease include a wedge shape of more than 5o formed by at least 3 or more adjacent vertebrae of the parietal vertebrae of the posterior convexity. Associated imaging features include Schmorl’s nodes, irregular or flattened spinal endplates, narrowing of the intervertebral spaces, and an increased anterior-posterior diameter of the parietal spine. Standing anteroposterior views in nearly one-third of patients show varying degrees of scoliosis, often exceeding the extent of the kyphosis. Supine hyperextension lateral views may show the structural features of the deformity. In adult patients, there is often moderate to severe disc degeneration within the spinal deformity. two types of curvature changes are common in the Scheuennann’s disease spinal deformity curve, the most common type being in the thoracic segment, from thoracic 1 or 2 to thoracic 12 or lumbar 1, with the parietal vertebrae located from thoracic 6 to thoracic 8; the other type is the thoracolumbar segment, often from thoracic 4 or 5 to lumbar 2 or 3, with the parietal vertebrae located near the thoracolumbar junction. The thoracolumbar segment is often more flexible in the hyperextended position and lacks thoracic support, and is more likely to continue to develop in adulthood. This type is more likely to be painful and may be associated with degeneration of the lumbar 3 disc in an oblique orientation. Spondylolisthesis is more common in Seheuennann’s disease and may be associated with excessive anterior lumbar convexity. There are different views on the treatment of this disease; Sorenson believes that patients with this disease have a good prognosis and do not require treatment. Conversely, Brodford advocates aggressive treatment aimed at correcting the deformity, reducing pain, preventing the progression of the deformity, and preventing other complications caused by kyphosis. Most scholars believe that if kyphosis is not treated in children during the growth period, the kyphosis will continue to develop, not only affecting the appearance, but also causing heart and lung dysplasia and dysfunction, leaving the patient with incurable back pain and mental anguish, and serious patients may develop spinal cord compression symptoms. We believe that the disease should be diagnosed and treated at an early stage. Treatment should depend on the patient’s specific situation (such as the patient’s age, gender, strength and toughness of the deformity, etc.). If the deformity has developed stiffness and the kyphosis is greater than 75 degrees, surgical treatment is necessary. Since the growth epiphyseal plate of the vertebral body closes at the age of 25 years, the disease should be followed regularly until the age of 25 years. Although there are quite a few treatment options available, they are generally divided into two main categories: non-surgical and surgical treatments. (i) Non-surgical treatment Bracing can be performed before skeletal maturity (Risser 1 to 2). In thoracic Scheuermann’s disease, the parietal vertebrae are located from thoracic 6 to thoracic 8 and are best treated with Milkwaukee brace, which has a dynamic three-point correction function and can increase the extension of the thoracic vertebrae and make the anterior lumbar convexity shallow. In thoracolumbar Scheuennann’s disease, the top vertebra is thoracic 9 or lower, and a modified axillary thoracolumbosacral brace can be used. After wearing the brace for 16 to 20 hours a day and treating for 12 to 18 months, there can be some degree of recovery of the parietal wedge deformation. During brace treatment, postural stretching and traction exercises of the carpal tunnel muscles should be performed from the beginning to the end. Bracing should be maintained until at least 2 years after skeletal maturity. Skeletal maturity is best marked by the fusion of the iliac bones (Risser5) and the closure of the vertebral epiphyseal rings within the posterior convexity. During the final year of brace therapy, brace therapy is worn at night only. Although the patient’s deformity can be significantly corrected at the beginning of brace treatment, 15% to 30% of the effect will be lost over time. (B) Surgery Surgery can be considered for adolescents whose deformity development cannot be controlled by brace treatment. Indications for surgery include: (1) very rigid kyphosis of more than 80o with immature skeleton (less than Risser3); (2) adults with kyphosis of more than 75o causing persistent dysfunctional pain that has failed after at least 6 months of non-surgical treatment; and (3) those who require an aesthetic appearance. surgical treatment of Scheuermann’s disease often includes correction of the kyphosis and spinal fusion. The latter requires an anterior-posterior spinal fusion with instrumentation. The primary goal of surgical treatment of kyphosis is to stabilize and balance the spine without causing neurological damage. Correction of the deformity is also important, but the correction of the deformity is related to the degree of deformity and the flexibility of the kyphosis in each patient. The length of correction depends on whether there is a combination of structural scoliosis within the segment of the spinal deformity to be operated on, and where the scoliosis is located. Pain is the main problem in elderly patients, and deformity correction is not as demanding. Posterior instrumented internal fixation fusion alone has a high success rate and is less risky than combined anterior and posterior surgery. This is because there is no need to perform anterior open-heart surgery. Biomechanical principles for correction of kyphosis include: (1) lengthening the anterior spinal column; (2) providing anterior column support; and (3) shortening the posterior spinal column. Anterior discectomy and release of the anterior longitudinal ligament facilitate lengthening of the anterior spinal column. Anterior column support can be achieved by anterior vertebral growth in skeletally immature individuals (less than Risser3) and by intervertebral fusion or brace implantation after skeletal development has matured. Shortening of the posterior column can be achieved by posterior spinal compression instrumentation, and installation of a posterior internal fixator along the length of the deformity can increase the stability of the correction. Posterior fusion with instrumentation alone is unsatisfactory because this approach does not follow the principles outlined above. This treatment often results in orthotic loss, failure of instrumentation, and a high rate of prosthetic joint formation. This orthopedic failure is due to the inability of the anterior column to share the load during fusion and fixation of the posterior column along the tension side. This bending activity at the fusion site and separation stresses can result in fusion site flexion, device fixation failure, and prosthetic joint formation. The selection of the fusion segment is important for orthopaedic and spinal balance restoration. Preoperative radiographs should be taken in the standing anterior-posterior position, lateral views and supine hyperextension lateral radiographs centered on the posteriorly convex parietal vertebra. If scoliosis is present, supine scoliosis anteroposterior views should also be taken. These films will help determine the segment to be fused anteriorly and posteriorly. The question to be considered is whether to perform a purely posterior procedure or a combined anterior and posterior procedure. If the patient’s skeleton is not yet mature, the anterior spine can still grow, and the posterior convexity can be corrected to less than 50o on the hyperextension lateral radiograph, a purely posterior instrumented fusion can be considered. In the elderly where pain relief is the primary goal and orthopedics is secondary, simple posterior surgery is sufficient. However, for optimal long-term results, simultaneous anterior and posterior surgery is required to share the load between the anterior and posterior columns, and if combined anterior and posterior surgery is performed, anterior release and fusion are often performed first. Some advocate simultaneous anterior and posterior surgery, believing that it is better from a nutritional point of view and that the hospital stay is shorter. Other surgeons prefer to perform the surgery in stages, with 7 to 10 days between the two periods, during which the patient is allowed to move around to improve lung function. 1. anterior release and fusion When there is an indication for anterior fusion, the anterior approach is often performed first. The right-sided approach is usually chosen because the abdominal aorta crosses the left side of the spine, and the right-sided approach can avoid the large vessels. If the kyphosis is quite severe and stiff and requires an anterior approach to support the bone graft, the surgery should be performed on the concave side in order to support the bone graft. Anterior release and discectomy should include the central few segments of the deformity, the stiff portion of the segment, and all discs without anterior convexity. With transthoracic surgery, the incision is often based on the position of the rib on the nearest cephalad side of the discectomy and fusion. Assuming that the upper part of the fusion is T6, the open position should be the 6th rib. If exposure to below T12 is required, a combined thoracoabdominal incision is required. First, the rib nearest to the fusion site is removed, separated anteriorly to the costochondral joint and posteriorly two finger widths from the transverse rib joint, and the rib is cut into segments to be used as the graft for intervertebral fusion. The pleura is incised along the rib bed. A retractor is inserted and the mural pleura is incised longitudinally along the median vertebral body. As much of the segmental vessels as possible should be preserved, especially in the lower thoracic and upper lumbar regions. If segmental vessels need to be ligated and separated, they should be cut and ligated from as far away from the intervertebral foramen as possible to avoid affecting the blood supply to the spinal cord, especially in the T5 to T9 watershed region, the posterior vessels should not be dissected free, and the intervertebral foramen region should not be electrocautery to avoid damaging the spinal artery traffic branches. Discectomy and fusion are performed in each segment. Anterior release and fusion below T11 is required for thoracic and retroperitoneal surgery in cases of thoracolumbar kyphosis. The level of ribs to be removed is determined by the upper segment to be fused, and the distal end of the incision ends in the epigastrium according to the direction of the segmental nerves. The deep abdominal tissues, the internal oblique and transversus abdominis muscles, are separated and the peritoneum is pulled away from the abdominal wall towards the midline, and the peritoneum is peeled away from the subdiaphragmatic surface. The corresponding ribs (usually T9 or T10) are then removed, and the thoracic cavity is entered along the ribbed bed. Under direct vision, the diaphragm is transected 2 to 3 cm from the rib attachment, and a thoracic dilator is placed to sever the lower part of the diaphragm, while the visceral nerves, lumbar ascending veins and sympathetic nerve trunks must be carefully protected, and the psoas muscle is stripped from the beginning of the disc. Before discectomy, the head of each rib is completely removed so that the posterior 1/3 of the disc is completely exposed, and after partial discectomy, a small spreader is placed between each disc to completely remove the disc to the posterior longitudinal ligament and the upper and lower endplates of the vertebral body. Each gap is filled with gelatin sponge until each disc is removed, and then small fragments of rib bone are filled into each intervertebral space, and the intervertebral fusion is complete. The severely posteriorly convex vertebra with angular deformity can be supported by bone graft. 2.Posterior surgery After anterior surgery, posterior and instrumented fusion is usually performed immediately. A standard posterior median incision is made, with the epiphyseal membrane exposed to the transverse process on both sides, and the spinous process is usually removed and minced for use as bone graft material. The screw and hook implant sites are identified and prepared, and the tuberosity of each segment is resected. In severe kyphosis, the lower part of the vertebral plate adjacent to the parietal segment is removed to correct the deformity. The iliac bone is taken as the graft bone. The entire fusion area from the spinous process to the transverse process is removed, and each articular surface is filled with small strips of iliac cancellous bone to ensure that the graft is placed over the entire fusion area. The extent of instrumentation and fusion of the retroflexion deformity can be determined from standing lateral views. The extent of instrumentation and fusion is dependent on the extent of the lateral projection and supine flexion radiographs, which need to exceed the proximal or distal extent of the posterior projection, when combined with significant structural scoliosis on anteroposterior radiographs. When evaluating standing lateral views, the upper limit of reconstruction must include the proximal end vertebrae of the measured (Cobb technique) kyphotic deformity. In the case of the thoracic type of Scheuerman disease, usually T1 or T2, the upper end of the fused vertebrae may be prevented from developing into a kyphotic deformity. In the thoracolumbar type, fixation fusion should include the first anteriorly convex segment of the proximal end vertebra, usually one or two segments above the end vertebra, to avoid the development of a retroflexion deformity at the junction of proximal fusion fixation. The distal end of the internal fixation instrumentation should include not only the measured distal end of the posterior convexity, but also the first anteriorly convex vertebral body, which is just below the first anteriorly convex disc at the lower end of the posterior deformity, and if the fused segment does not reach this level, the posterior deformity below the fused segment is likely to occur. 3. Posterior internal fixation devices used for posterior internal fixation in Scheuerman’s disease include the Harrington compression device, the Luque device, and the posterior double rod multi-segment hook system (CD, TSRH, and Isola). For more than 20 years, Harrington compression devices have been used to correct kyphosis. They consist of two Harrington compression rods with six to seven hooks each, three to four hooks placed at the transverse processes on each side of the thoracic spine and three hooks placed near the inferior lamina on each side of the lumbar spine, and compression is applied by tightening the screw caps on the threaded rods. Although the Harrington compression device is easy to place, it is fixed by compression only and is difficult to maintain the sagittal curve contour and balance. Although some follow-up studies have shown better results with this instrumentation, other instrumentation systems provide better control of the sagittal curve and excellent internal fixation. The Luque device provides better balance and sagittal curve through the shape of the bar and better fixation through the sublaminar wire, often without postoperative braking. However, there are two major complications that can occur when Luque devices are used for correction of kyphosis. One is nerve damage, related to sublaminar steel wire penetration. The other is that a high percentage of patients develop a retrobulbar deformity at the fusion junction fixation, mainly due to the severance of the intervertebral ligament and ligamentum flavum by the wire passing under the lamina. Correcting kyphosis secondary to Scheuermann’s disease with the posterior double rod multi-segment hook system (CD, TSRH, and Isola) allows coronal and sagittal balance to be obtained and stability to be maintained with proper rod construction. The posterior double-rod multisegmental hook system was developed based on the CD system, and the sequence of hook placement and rod insertion is basically similar. The only difference is the rod-to-hook and screw attachments. In the generally more flexible patient, the basic built-up should consist of at least 8 hooks in the superior parietal spine and 6 hooks or 2 hooks plus 4 pedicle screws below the parietal spine. In larger patients with rigid kyphosis, 12 hooks are required in the superior parietal spine and three sets of single-segment transverse pedicle claw hooks on each side. The normal configuration of hooks above the parietal spine should include two sets of two-segment pedicle transverse process hooks, and generally do not use pedicle hooks in the thoracic spine because of the potential for nerve injury. In elderly patients with significant bone loss and poor strength of the transverse process, two sets of double-segment pedicle-vertebral plate hooks or vertebral plate-vertebral plate hooks may be used, and it is best to alternate the placement of each segment to avoid fracture of the vertebral plate and hook dislodgement. One or two segments below the deformed parietal vertebrae are placed with an open pedicle hook on each side. When placing the hooks in the lower segment of the posterior convex vertebrae, it is important to ensure that the upper rod and its hooks are connected when the posterior convexity is corrected by manipulation, and that the rod acts as a lever rather than a hook in the vertebral plate of the parietal vertebrae, so as to prevent neurological damage caused by the prolapse of the hooks into the spinal canal. The placement of the distal end of the insert can be chosen from 2 claw hooks of the vertebral plate because the plate is strong enough and there is often enough space in the foramen. An open claw hook is used at the upper end and a closed hook is used at the distal end. The two distal hooks are held in place with hook compression to provide maximum stability and maintain anterior spinal convexity distal to the insert. In larger patients, 1 additional upward hook may be added to the lamina. In adults with reduced bone mass who require stronger fixation, two distal hooks are replaced with pedicle screws on each side. The TSRH variable angle screws are available in a variety of coupling sizes and require minimal bending of the rods, making them easier to use. For patients with good bone quality and small size, a single pedicle nail with an inferior plate hook is generally used distal to the internal fixation. In patients with combined structural scoliosis, the type of hook needs to be modified to allow for the application of the braced segment on the concave side of the scoliosis. A rod with a normal hook is inserted first into the convex side to ensure correction of the posterior convexity deformity, and then a concave side rod is inserted to correct any residual segmental scoliosis without interfering with the correction of the posterior convexity. The degree of posterior convexity of the pre-curved rod is referenced to the over-extended lateral radiograph, and the correction of the posterior convexity must never exceed 50% of the pre- and postoperative convexity, as this may result in postoperative posterior convexity at the proximal fusion junction. The rods are first inserted into the transverse pedicle hooks at the most inferior end of the deformed parietal vertebrae, then the rods are rotated cephalad and advanced into each hook, and then each hook is held with a hook holder, which is adjusted closer to the rod. Bending the proximal end of the rod facilitates rod insertion of the uppermost hook, especially when the hook is located at T1. After the bar is inserted into the uppermost hook use the bar presser and apply pressure to each claw hook to ensure each hook is in place. Tighten each hook screw slightly to secure the hook until the rest of the placement system is installed. Next, using a spreader and rod holder, pressure is applied to each segment starting with the uppermost claw hook and advancing all the way to the deformed parietal spine to create lumbar lordosis. When distal pedicle screws are used, the distal ends of the rods are temporarily moved toward the spine, the appropriate pedicle screw couplers are inserted into each rod, the distal ends of the rods and couplers are moved to the pedicle screws with the rod holder, and the coupler nuts are tightened. Finally, before tightening, slight pressure is again applied to the screw to anteriorly project the distal segment of the insert. The added sublaminar hook is placed under the screw at the most inferior end of each rod and positioned below the screw fixation to act as a protection for the screw. Finally, the hooks on each segment are brought closer to the rods from near to far with hook-holders and braces, and then the hook fixation screws and the screw caps of the hook plugs are tightened with a T-wrench. Place 2 to 3 transverse drawers or transverse couplers (DTTs) between the two bars.