Abstract: Background　Disc degeneration is the initiating factor for a series of lumbar degenerative diseases.Previous reports mostly have focused on the epidemiologic and imaging characteristics of lumbar disc degeneration.However，the studies investigating lumbar degenerative diseases with refractory lumbocrural pain that necessitate surgical procedures are sparse.The distribution of the degenerative disc is unknown，along with the index segment（operated segment）.Objective　To study the imaging distribution of disc degeneration and characteristics of the index levels in patients with lumbar degenerative diseases undergoing operation.Methods　503 cases of lumbar degenerative diseases who underwent anteroposterior and lateral radiographs，dynamic radiographs，and sagittal MRI in PLA 960 hospital from January 2012 to February 2016 were enrolled.The distribution of lumbar disc degeneration and index segments was analyzed〔including lumbar instability，Modic changes，high intensity zone（HIZ），and Schmorl's nodes（SN）〕.Disc degeneration was evaluated with the Pfirrmann's staging system，with Ⅰ and Ⅱ designating the normal discs，while Ⅲ-Ⅴ indicating degenerative changes（Ⅳ and Ⅴ implying serious degeneration）.Multi-segment（≥2） disc degenerations used a custom W classification.Results　There were 2 515 degenerative discs in 503 patients，demonstrating a degeneration rate of 74.08% （1 863/2 515），and serious degeneration rate was 36.46%（917/2 515）.The degeneration rate of upper lumbar segments was 56.96%（573/1 006，L1-2 and L2-3），with serious disc degeneration accounting for 34.55%（198/573）.In the lower lumbar segments（L3-4，L4-5，L5-S1），the degeneration rate was 85.49%（1 290/1 509），with the serious disc degeneration rate being 55.74%（719/1 290）.Lower lumbar segments were associated with higher disc degeneration rate and serious degeneration rate（P<0.05）.Female patients of ≥40 years had higher disc degeneration rate（P<0.05）.Female cases ≥40 years showed more instability（P<0.05），but demonstrated no significantly different Modic change，HIZ and SN incidence compared with male cases（P>0.05）.Male patients of <40 years had slightly higher instability than female patients of the same age group（P>0.05），but demonstrated significantly different Modic change，HIZ and SN incidence（P<0.05）.The differences in the incidence of Modic changes and HIZ in males <40 years and ≥40 years were significant（P<0.05）.The differences in the incidence of lumbar spine instability，HIZ and SN in females <40 years and ≥40 years were significant（P<0.05）.There was significant difference in distribution of lumbar instability，Modic changes，SN and HIZ in different degenerated segments（P<0.01）.There were 381 cases of single-segment undergoing operation，102 cases of two-gap，14 cases of three-gap，4 of four-gap，and 2 of five-gap.The degeneration rate of the intervertebral disc in the index level was 99.01%（498/503），and the rate of severe degeneration was 62.82%（316/503）.Conclusion　Lumbar degenerative diseases necessitating surgical interventions had a higher disc degeneration rate，with a female predominance.The degeneration rate increased in lower segments.Female patients were prone to have lumbar instability and Modic changes，whereas showing less serious disc degeneration.The age of 40 years is the watershed for the occurrence of Modic changes and HIZ in male cases，similarly in female patients for lumbar instability，HIZ，and SN.There were disc degeneration in most index segments，representing higher serious degeneration rates.

Key words: Lumbar Vertebrae, Intervertebral Disc Degeneration, Magnetic Resonance Imaging, Index Level

摘要： 背景　椎间盘退变是一系列腰椎退行性疾病的始动因素，既往研究多集中于腰椎间盘退变的流行病学及影像学研究方面，而关于严重腰腿痛的腰椎退行性疾病患者需手术干预的研究少见，其椎间盘退变分布规律并不明确，而责任间隙（手术节段）退变分布情况鲜有报道。目的　分析腰椎退行性疾病手术患者椎间盘退变及责任间隙分布规律。方法　选择2012年1月—2016年2月于中国人民解放军第960医院行腰椎正侧位、过伸过屈位X线和腰椎矢状位MRI检查并确诊为腰椎退行性疾病患者503例，分析腰椎间盘退变及责任间隙分布特点〔包括腰椎失稳、Modic改变、高信号区域（HIZ）、许莫结节（SN）〕；椎间盘退变分级采用Pfirrmann分级标准，Ⅰ、Ⅱ级为正常椎间盘，Ⅲ、Ⅳ、Ⅴ级为退变椎间盘（其中Ⅳ级、Ⅴ级为严重退变）；多间隙椎间盘退变采用自定义W分级标准，即两个及以上节段椎间盘退变程度。结果　503例患者共2 515个腰椎间盘，退变率为74.08%（1 863/2 515），严重退变率36.46%（917/2 515）。上腰椎椎间盘（L1~2、L2~3）退变率为56.96%（573/1 006），严重退变率为34.55%（198/573）；下腰椎椎间盘（L3~4、L4~5、L5~S1）退变率为85.49%（1 290/1 509），严重退变率为55.74%（719/1 290）。下腰椎椎间盘退变率、严重退变率均高于上腰椎（P<0.05）。≥40岁女性腰椎间盘退变率高于男性（P<0.05）。<40岁男性腰椎失稳发生率与女性比较，差异无统计学意义（P>0.05）；而Modic改变、HIZ、SN发生率两性别间比较，差异均有统计学意义（P<0.05）。≥40岁女性腰椎失稳发生率高于男性（P<0.05）；而Modic改变、HIZ、SN发生率两性别间比较，差异均无统计学意义（P>0.05）。≥40岁男性Modic改变、HIZ与女性腰椎失稳、HIZ、SN与<40岁者发生率比较，差异均有统计学意义（P<0.05）。腰椎失稳、Modic改变、SN和HIZ腰椎退变节段分布情况比较，差异均有统计学意义（P<0.01）。手术节段单间隙381例，两间隙102例，三间隙14例，四间隙4例，五间隙2例；责任间隙椎间盘退变率为99.01%（498/503），严重退变率为62.82%（316/503）。结论　腰椎退行性疾病手术患者的椎间盘退变率较高，且女性较高，下腰椎椎间盘高于上腰椎椎间盘，女性腰椎失稳、Modic改变发生率均高于男性，SN发生率低于男性，40岁是男性Modic改变及HIZ发生的转折点，也是女性腰椎失稳、HIZ、SN发生的转折点。责任间隙椎间盘大部分发生退变，且严重退变率较高。

关键词:  , 腰椎, 椎间盘退行性变, 磁共振成像, 责任间隙