Degenerative spondylolisthesis is one of the most common clinical conditions. Junghanns first described spondylolisthesis without isthmic discontinuity in 1930 and called it pseudolisthesis. This was followed by Newman’s more in-depth discussion of the disease in 1955. I. Etiology Degenerative spondylolisthesis is common in people over 50 years of age. The etiology is multifactorial, with pregnancy, generalized joint laxity, and oophorectomy being the main factors in the development of the disease in women. In addition, the sagittal orientation of the articular surface of the synovial process and the increased angle between the pedicle and the synovial process are also important factors in its development. In a recent study by Iguchi (2002), degenerative spondylolisthesis accounted for 8.7% of 3259 outpatients with lower back pain; of these, 70% had anterior spondylolisthesis, predominantly in L4-L5, and 30% had posterior spondylolisthesis, predominantly in L2-L3, with no difference in gender. 66% of the spondylolisthesis were single-segment and 34% were multisegmental, with two-segmental spondylolisthesis predominating. The majority of multi-segmental slippage is in two segments. The initial degeneration begins with degeneration of the intervertebral disc, followed by a series of degenerative changes including narrowing of the intervertebral space, hypertrophy of the ligamentum flavum, formation of vertebral redundum, subchondral sclerosis, synovial joint hyperplasia and “microinstability”. In addition to segmental instability and degenerative slippage in the sagittal plane, lateral slippage in the frontal plane can also occur, i.e., degenerative scoliosis. Degenerative slippage and degenerative scoliosis often coexist. The occurrence of degenerative scoliosis is mainly due to the asymmetry of the degeneration of the synovial joints on both sides, and the unevenness of the vertebral body on both sides. The source of pain in degenerative spondylolisthesis Degenerative spondylolisthesis can produce three different types of pain through three different mechanisms: 1. Neurogenic claudication: secondary to spinal stenosis caused by slippage, hypertrophic ligamentum flavum and protrusion of the synovial process into the spinal canal. The pain can radiate distally along the buttocks and lower extremities, and is mostly accompanied by numbness and weakness of the lower extremities, which occurs when standing or walking, but the above symptoms can be relieved when resting and forward flexing the spine, such as adopting the posture of pushing a shopping cart, which is called the “pushing cart sign” (Shopping cart sign). In the clinic, it must be distinguished from vascular claudication. 2. Radicular pain: Sensory and motor dysfunction along the innervated area due to nerve root compression caused by lateral saphenous fossa or intervertebral foraminal stenosis. The pain is the result of mechanical compression of the nerve root or stimulation by inflammatory chemical mediators. 3. Mechanical lower back pain: Lower back pain and involvement pain in the buttocks and posterior thighs may originate from degenerated discs and synovial joints. The typical manifestation is a sudden “catching pain” in the lower back when the patient straightens his back from a bent position. It has been shown that mechanical low back pain is mainly due to abnormal distribution of the endplate of the vertebral body after disc degeneration and nucleus pulposus dehydration. There are many ways to classify the degree of slippage, but the Meyerding classification is still the easiest and most practical. The Meyerding classification method is to determine the degree of slippage by calculating the percentage of slippage of the upper vertebral body in relation to the lower vertebral body with the help of lateral radiographs; specifically: slippage <25% is degree 1, slippage 25%-49% is degree 2, slippage 50%-74% is degree 3, slippage 75%-9% is degree 4, and slippage >100% is degree 5. V. Diagnosis Based on the principle of combining symptoms, signs and imaging, the clinical diagnosis of degenerative spondylolisthesis is not difficult. The diagnosis of degenerative spondylolisthesis is relatively easy to determine and requires differentiation in the following two aspects: on the one hand, we must carefully study the radiographic data, especially the observation of the X-ray oblique plain film, except for true spondylolisthesis with discontinuity of the isthmus; on the other hand, for patients with neurogenic claudication, we must further differentiate it from vascular claudication, as long as the possibility of peripheral vascular disorders is considered. It is not difficult to distinguish between the two. The main points of differentiation are: check whether the dorsalis pedis artery of the affected limb is weakened; ask the patient to ride an exercise bicycle, and if there is no discomfort in the lower limb, it is neurogenic claudication, and vice versa, it is vascular claudication. In 2000, Matsunaga reported the results of non-surgical treatment of 145 cases of degenerative spondylolisthesis over a period of 10 to 18 years. The results found that only 30% of the slippages worsened, and 76% of the patients in the group without neurological symptoms had no worsening of symptoms during follow-up and could continue non-operative treatment, whereas 83% of the patients in the group with neurological symptoms had further worsening of symptoms during follow-up and required surgical treatment. The recommended indications for surgical treatment are: 1. persistent or recurrent low back and leg pain or neurogenic claudication after more than 3 months of conservative treatment, which seriously affects the quality of life. 2.Progressive aggravation of nerve damage. 3. Those who have symptoms of cauda equina damage. Although the main goal of surgical treatment is decompression, there is no consensus on the indications for fusion, and the need for instrumentation is more controversial; however, it is generally accepted that the purpose of decompression is to relieve neurological symptoms, and the purpose of fusion is to reduce low back pain by eliminating instability, and the application of instrumentation can help improve the fusion rate and correct slippage and deformity. However, the benefits of device fixation come at the cost of increased surgical complications. The use of BMP can improve fusion rates without the risk of increased surgical complications. More recently, there have been attempts to develop a powered fixation approach without fusion. The surgical treatment of degenerative spondylolisthesis includes: 1. Simple decompression: Lombardi (1985) and Johnsson (1986) reported the results of their respective treatments using a simple decompression procedure. The results were similarly unsatisfactory, and it was suggested that fusion should be applied to improve the efficacy. 2. Decompression plus posterior posterolateral fusion: A prospective study by Herkowitz and Kurz (1991) showed that the decompression plus fusion group was more effective than the decompression group alone, with a lower rate of pseudarthrosis. 3. Decompression, posterior posterolateral fusion with instrumentation: In the past decade, many scholars have conducted detailed studies on the question of whether the application of instrumentation in conjunction with fixation can actually increase the fusion rate and improve clinical outcomes. (1997) and Booth (1999) reported the results of their respective studies, all of which suggest that the fusion rate of this combined procedure is higher and faster than that of the control group and is currently the main treatment for degenerative spondylolisthesis. 4. Anterior lumbar interbody fusion (ALIF): Inou (1988) and Satomi (1992) reported good results in the treatment of degenerative spondylolisthesis using the ALIF procedure, respectively, and concluded that decompression and repositioning of the spondylolisthesis can be achieved indirectly by restoring the intervertebral height, which is more suitable for early degenerative cases. For patients with more severe degeneration, a posterior approach is still recommended. In addition, the need for slippage repositioning and sagittal balance reconstruction is still very controversial, but there is a growing tendency to believe that repositioning and sagittal balance reconstruction for slippage will help improve the outcome.