Sagi H C, Jarvis J G, Uhthoff H K
Bone and Joint Research Laboratory, University of Ottawa Health Sciences Center, Ontario, Canada.
Spine (Phila Pa 1976). 1998 Aug 1;23(15):1635-9; discussion 1640. doi: 10.1097/00007632-199808010-00002.
Descriptive study analyzing the histologic development of human fetal lumbar spine pars interarticularis.
To delineate the histologic development of the fetal pars interarticularis and correlate the development of the pars with isthmic spondylolysis.
Isthmic spondylolysis is present in 5% to 6% of the population. The incidence at birth is zero but rises sharply to 5% at age 4 to 5 years. The origin of the lesion is unknown; however, the current theory states that isthmic spondylolysis results from a fatigue fracture through a congenitally weak pars interarticularis. No study exists investigating the histologic development of the pars.
Microscopic examination of lumbar spines of human fetuses aged 8-20 weeks' gestation was performed. Specimens were dissected en bloc, decalcified, embedded in paraffin wax, sectioned and fixed on glass slides, and stained.
The pars begins to ossify at 12 to 13 weeks' gestation by endochondral ossification. The ossification center originates in the region of the pars in lower lumbar vertebrae, resulting in uneven distribution of trabeculation and cortication in this region. The ossification center arises at the end of the pedicle in upper lumbar segments giving rise to uniform trabeculation through the pars.
Uneven distribution of isthmic ossification results in formation of a potential stress riser in the region of the pars in lower lumbar vertebrae, which could be susceptible to fatigue fracture.
分析人类胎儿腰椎峡部组织学发育的描述性研究。
描绘胎儿峡部的组织学发育情况，并将峡部的发育与峡部裂联系起来。
峡部裂在5%至6%的人群中存在。出生时发病率为零，但在4至5岁时急剧上升至5%。该病变的起源尚不清楚；然而，目前的理论认为峡部裂是由先天性薄弱的峡部发生疲劳骨折所致。尚无研究调查峡部的组织学发育情况。
对妊娠8至20周的人类胎儿腰椎进行显微镜检查。标本整块解剖、脱钙、石蜡包埋、切片并固定在载玻片上，然后进行染色。
峡部在妊娠12至13周时通过软骨内成骨开始骨化。骨化中心起源于下腰椎峡部区域，导致该区域小梁和皮质分布不均。骨化中心出现在上腰段椎弓根末端，使峡部形成均匀的小梁。
峡部骨化分布不均导致下腰椎峡部区域形成潜在的应力集中点，可能易发生疲劳骨折。
