The Collaborative International Dictionary of English v.0.48:

Rachitome \Ra"chi*tome\ (r[=a]"k[i^]*t[=o]m), n. [F., fr. Gr.
   "ra`chis, -ios, the spine + te`mnein to cut.]
   A dissecting instrument for opening the spinal canal.
   [Written also rachiotome.]
   [1913 Webster]