[The antero-posterior diameter of the cervical spinal canal in cervical spondylosis (author's transl)].

1. The antero-posterior diameter (APD) of the cervical spinal canals in 96 healthy adults, 108 cases of radiological cervical spondylosis (asymptomatic) and 96 cases of cervical spondylosis with radiculopathy or radiculomyelopathy was measured for each vertebra by the method of Burrows. (Filmfocus distance was 1.2m). 2. The APD in patients with symptomatic spondylosis was found to be significantly narrower than those of without. 3. Since the upper limit of APD at C4 to C6 vertebrae in symptomatic spondylosis was 16 mm, while the lower limit of APD in asymtomatic spondylosis was 14 mm, the following conclusion appears justified. 1) When the APD is narrower than 16 mm, the osteophytes along the posterior border of the spinal bodies or degenerative disc protrusions may produce cervical radiculomyelopathy, although the cord and the roots may escape from compression by the spondylotic changes even when the APD is wider than 14 mm. 2) When the APD is narrower than 13 mm, it is almost always certain that the osteophytes or herniated discs compress the cervical cord and roots.