I must admit, I was not aware that orthopedic surgeons treated Chiari associated syringomyelia. They do in Japan. They perform extradural decompression (dura not opened). The results of a study published in the Journal of Neurosurgery: Spine are not surprising: foramen magnum decompression with duraplasty was superior to an extradural decompression.
The results of the study:
"A total of 232 patients with syringomyelia caused by Chiari I malformation were included in this study. Two-thirds of patients were treated in a neurosurgery department and the other third in an orthopedics department. Neurosurgeons preferred foramen magnum decompression (FMD) with dural patch grafting, and orthopedists preferred FMD with dural dissection. Foramen magnum decompression with dural patch grafting was associated with better outcomes than was dural dissection with regard to the following: motor impairment (66% vs 39%, p < 0.05), sensory disturbance (60% vs 43%, p = 0.051), pain (67% vs 47%, p < 0.05), and cavity size (74% vs 58%, p < 0.05). Improved motor function was associated more with cavity size reduction than with sensory disturbance and pain."
The authors conclusion:
"Neurosurgeons and orthopedists preferred different surgical procedures for the treatment of syringomyelia. Better outcomes were achieved by FMD with dural patch grafting."