为方便切除腰椎体后缘软骨结节及骨化的腰椎间盘突出部分 ,我们设计了内螺纹圆凿。现介绍如下 :1　结构　该凿由“T”形柄与管状凿体组成。柄长 15 cm ,Φ 6 mm。凿体长 4cm ,内径 5 m m ,外径 8m m,下段 1.2 cm车出螺距 1mm、螺沟 0 .5 mm的内螺纹 ,下端打磨出 2 m m刃 ,上段 In order to facilitate the removal of cartilaginous nodes at the posterior margin of the lumbar spine and ossification of the lumbar disc herniation, we designed internal thread chisel. Now introduced as follows: 1 Structure The chisel is composed of “T” shaped shank and tubular chisel body. The handle length is 15 cm and Φ 6 mm. Chisel body length 4cm, inner diameter 5m m, outer diameter 8m m, lower section 1.2cm inner thread pitch 1mm, screw groove 0.5mm inner thread, lower end polished out 2m m edge, upper section