The lumbar spine is responsible for weight bearing, motion and nerve protection. All disorders that cause loss of stability of the lumbar spine, such as bulging and herniated discs, hyperplasia, and spinal stenosis, lead to low back pain, leg pain, numbness in the lower extremities, and difficulty in walking. Spinal fusion has gained wide acceptance as a treatment for chronic lower back pain caused by degenerative disc disease. In most spinal surgeries, fusion has become one of the main criteria for determining the success of the surgery. However, some studies have concluded that although spinal fusion has achieved a radiographic improvement in fusion rates, patients’ clinical symptoms have not improved to a corresponding degree; furthermore, there are potential complications associated with ankylosing fixation and spinal fusion, such as an increased incidence of secondary degeneration of neighboring segments, which can lead to instability and spinal stenosis; and there are also risks of screw fracture, pseudoarthrosis formation, and so on. Therefore, it is controversial to perform lumbar fusion for degenerative lumbar spine pathologies such as spinal stenosis, lumbar spine slippage, disc herniation, and lumbar scoliosis. Nowadays, there is a new technique to overcome the above disadvantages, which preserves the spinal segmental motion function, called non-fusion spinal functional reconstruction technique, also called dynamic fixation technique. Ideally, internal spinal fixation surgery should restore and maintain postoperative stability of the operated segment and reduce or mitigate increased degeneration of adjacent segments while relieving or eliminating clinical symptoms. Based on this principle, Mulholland et al. proposed the concept of non-fusion fixation to preserve the motor function of the operated segment, control its abnormal activity, change the way of pressure transmission of the disc in the diseased segment, and maintain spinal stability, and the Dynamic Internal Fixation System came into being as a result. The concept of non-fusion technology contains three elements: (1) to provide the necessary stability; (2) to retain part of the motor function of the operated segment; (3) to reduce the occurrence of degenerative diseases in neighboring segments. Currently, there are a wide variety of dynamic internal fixation systems, which are divided into interspinous implants, disc replacements, and dynamic internal fixation devices based on pedicle screw placement, depending on the site where the built-in implants are placed. Among them, the Dynesys dynamic stabilization system has been used for the longest time in the clinic, has the most stable effect, and has been reported in the literature the most, and is one of the most widely used dynamic stabilization systems in the clinic at present. It is capable of relieving nerve compression while adopting dynamic immobilization, which not only restores the stability of the lumbar spine, but also preserves the motor function of the lumbar spine at the surgical site. Indications for the Dynesys system: The Dynesys system has been in clinical use since 1994, and has been widely used in European clinics. Although the Dynesys system has been in clinical use for more than 10 years, the indications for its use are still unclear. It is still necessary to deduce what kind of indications are applicable to the Dynesys system, which is able to maintain the height of the intervertebral discs and limit the hypermobility of the motion segments. Dynamic balanced immobilization is best suited for the treatment of lumbar degenerative diseases with herniated discs and the resulting increased or decreased mobility, functional instability, and stenosis of one or more segments, and is therefore indicated for self-recovery of unstable discs as well as for loss of disc height with small intersegmental displacements, or for normal disc height with significant slippage in the diseased discs. These disc instability disorders culminate in clinically dynamic spinal stenosis. Contraindications to the Dynesys system are: (1) degenerative scoliosis greater than 10°; (2) slip greater than I degree; (3) obesity; (4) previously fused segments; and (5) others: intervertebral disc space narrowing, osteoporosis. Compared with lumbar fusion surgery, Dynesys dynamic internal fixation surgery has shorter operation time, less bleeding and fewer postoperative complications. The surgical incision for a segmental lesion is 5-6 centimeters and the procedure takes more than an hour with no blood transfusion. Patients undergoing this type of surgery recover quickly and can get out of bed within 3-5 days after surgery and can basically resume their daily lives in about 1 month. Severe lumbar disc herniation, lumbar spine instability, and lumbar spinal stenosis are all indications for this technique. This technique is less traumatic, more effective, faster recovery, and suitable for patients of all ages. Typical cases: I. Lumbar spine fusion surgery: Case 1: 46-year-old male patient, lumbar pain and leg pain, walking not far, intermittent claudication for 5 years. x-ray film and CT, MRI shows lumbar spine multi-segment degeneration instability, which lumbar 4/5 and lumbar 5/sacral 1 intervertebral disc degeneration instability of the most serious. The patient was selected for lumbar 4/5 and lumbar 5/sacral 1 decompression of the spinal canal, disc removal, internal fixation with a pedicle nailing system, and lumbar fusion due to lack of funding. Case 2: 42-year-old female patient with back pain and leg pain, walking not far, intermittent claudication for 4 years. x-ray and CT, MRI showed lumbar 4/5 disc herniation spinal canal stenosis. The patient opted for lumbar 4/5 spinal canal decompression, disc removal, internal fixation with pedicle nail system and lumbar fusion surgery due to lack of funds. Dynesys Dynamic Internal Fixation Surgery Case 3: A 53-year-old male patient with lumbar pain and leg pain, walking not far, intermittent claudication for 6 years. x-ray film and CT, MRI showed lumbar 3/4 and lumbar 4/5 intervertebral disc degeneration and herniation, among which lumbar 4/5 intervertebral disc degeneration, herniation, and stenosis were the most serious. The patient was selected for lumbar 4/5 decompression, disc removal, and Dynesys dynamic internal fixation. The operation time was short, with less bleeding and fewer postoperative complications. Case 4: 76 years old male patient with back pain and leg pain, walking not far, intermittent claudication for 10 years. x-ray film and CT, MRI showed that the lumbar spine was unstable with degeneration of multiple segments, among which the lumbar 3/4 and lumbar 4/5 discs were the most serious degeneration, herniation and spinal canal stenosis. The patient was selected to undergo lumbar 3/4 and lumbar 4/5 spinal canal decompression, disc removal, and Dynesys dynamic internal fixation. Surgical time was short, bleeding was low, and postoperative complications were few.