Topographic anatomical study of the sciatic nerve relationship to the posterior portal in hip arthroscopy

Objective: To evaluate the anatomic topographic relation between the sciatic nerve in relation to the piriform muscle and the posterior portal for the establishment of hip arthroscopy.Methods: We dissected 40 hips of 20 corpses of adult Brazilians, 17 male and three female, six black, six brown and eight white. We studied the anatomical relationship between the sciatic nerve and the piriform muscle with their variations and the distance between the lateral edge of the sciatic nerve and the posterior portal used in hip arthroscopy. We then classified the anatomical alterations found in the path of the sciatic nerve on the piriform muscle.Results: Seventeen corpses had bilateral relationship between the sciatic nerve and the piriform muscle, i.e., type A. We found the following anatomical variations: 12.5% of variant type B; and an average distance between the sciatic nerve and the portal for arthroscopy of 2.98cm. One body had type B anatomical variation on the left hip and type A on the right.Conclusion: the making of the posterior arthroscopic portal to the hip joint must be done with careful marking of the trochanter massive; should there be difficult to find it, a small surgical access is recommended. The access point to the portal should not exceed two centimeters towards the posterior superior aspect of the greater trochanter, and must be made with the limb in internal rotation of 15 degrees.

研究目的：评估坐骨神经（sciatic nerve）与梨状肌（piriform muscle）、髋关节镜（hip arthroscopy）手术后侧入路（posterior portal）之间的解剖位置关系。
方法：本研究对20具成年巴西籍尸体的40侧髋关节进行解剖，其中男性17具、女性3具，黑人6具、棕种人6具、白人8具。我们分析了坐骨神经与梨状肌的解剖关系及其变异类型，测量了坐骨神经外侧缘与髋关节镜后侧入路之间的距离，并对坐骨神经在梨状肌走行路径上的解剖变异进行分类。
结果：17具尸体的双侧坐骨神经与梨状肌均呈A型关系。本次研究发现的解剖变异中，B型变异占比为12.5%；坐骨神经与关节镜入路之间的平均距离为2.98cm。其中1具尸体的左侧髋关节为B型解剖变异，右侧为A型。
结论：建立髋关节后侧关节镜入路时，需精准标记股骨大转子（greater trochanter）；若难以准确定位，建议采用小型手术切口。入路位点距离股骨大转子后上方的距离不应超过2cm，且操作时需将患肢内旋15度。