| Research BackgroundLumbar disc herniation is the major cause of low back pain or backleg pain and a common disorder of clinical orthopaedics.It has been a history of 70 years since Mixture and Barr firstly reported lumbar disc herniation and successed in operative treatment.Along with the development of molecular biology,biomechanics,imageology, materials as well as correlated basic science research.the level of lumbar disc herniation diagnosis and treatment has been devoloping uninterrupt.From traditionary nucleus pulposus exsection to spinal fusion,endoscope and minimally invasive techniques,and prosthetic disc nucleus(PDN) and artificial disc replacement(ADR) in recent years, however,they relieved clinical complaint temporary by means of the destruction of structure and function of lumbar intervertebral disc.They all can't prevent and reverse the degeneration of lumbar disc, accordingly gene therapy and tissue engineering become the topical research in disc degeneration diseases.Magnetic resonance imaging(MRI) capable of showing disc anatomic structure and biochemical changes based on a loss of signal intensity and disc height,is the simplest,accurate and noninvansive method.However, Disc degeneration are subjectively assessed according to a few broad categories in previous reports. Relative signal intensity(RSI) quantize the change of signal intensity in disc andassess objectively. The relation to histopathology and matrix metabolism of disc degeneration has not been well documented.The disc height decrease because of lumbar disc herniation, then the stress distribution and load transmition are changed in lumbar spine.The natural progression and operative result of lumbar disc herniation are effected by the change of disc space height and biochemical composition.Disc degeneration is the prerequisite of disc herniation,the mechanism of molecular biology is unclear.It is a natural process related to age, determined by nutrition, heredity and environment and so on.The key features of disc degeneration are the change of structural components and the loss of biomechanical function. When the equilibrium of the extracellar matrix(ECM) metabolism between synthesis and degradation is disrupted , the disc degeneration initiate sequentia. It was reported matrix metalloproteinases(MMPs) contributes to the degradation of articular cartilage in osteoarthritis and rheumatoid arthritis, the composition of disc matrix resemble the articular cartilage contains collagen and proteoglycan,MMPs are assumed to play a pivotal role in disc degradation in recent researches. MMP3 is the key degrading-enzyme during the process of disc degeneration, which contribute to degradation of nucleus pulposus.In recent years numerous studies have shown that disc herniation may decrease and disappear spontaneously,which has been documented in clinical observation and imageoloy follow-up.Pathologic studies shown it is related to neovascularization surrounding the disc tissue and infiltration of CD68-positive inflammatory cells,but their exact physiopathologic course remain unclear.MMP3 was assumed participate in spontaneous resorption,the relation between CD68 expression and MMP3 expression is unknown.In this study we further identify the natural history of lumbar disc herniation by the assessment of MRI and pathology,provide evidences for clinical descision and exploration of new therapy of lumbar disc herniation and degeneration disc disease.Materials and Methods1 Clinical dataThere were 56 patients who underwent discetomy for lumbar disc herniation,they were 31 men and 25 women, with a mean age of 43.6+11.6years(range,22~71years).The level involved was L4-L5 in 26 patients and L5-S1 in 30 patients.During surgery the disc pathology was classified into two groups according to the rupture of posterior longidinal ligament,namely transligmentous extrusion or sequestration 32 patients,subligmentous protrusiong 24 patients.56 patients were divided into two groups according to the pain's severity and straight leg raising te...
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