Background: The curvature and range of motion
of the cervical spine decrease after laminaplasty. However, to our knowledge
these changes have not been studied prospectively. Also, the effect
of laminaplasty on the mobility of the occipito-atlanto-axial joints
has not been studied in detail. The purpose of our study was to
prospectively evaluate the range of motion and curvature of the
cervical spine, including the occipito-atlanto-axial joints, following laminaplasty.
Methods: We conducted a prospective study of
twenty-six patients who underwent cervical laminaplasty. They were
followed for a mean of 6.7 years (range, five to nine years). Radiographs
were made before the operation and at one, three, and five years
after the operation. The curvature index, the angle of each vertebra
in the neutral position from the occiput to the seventh cervical
vertebra, and the range of motion in the sagittal plane were measured.
Results: The curvature index, the angle of the
axis and the sixth cervical vertebra, and the angle of the axis and
the seventh cervical vertebra in the neutral position were reduced
after the operation. The rate of reduction declined between the
third and fifth postoperative years. On the other hand, the mean distance
between the occiput and the atlas as well as the mean angle of the
axis and the atlas did not change significantly. The range of motion
of the axis and the seventh cervical vertebra was decreased after
the operation, and it continued to decrease slowly over the study
period. The range of motion of the occipito-atlanto-axial complex
increased slightly, which may represent a compensation for the decreased
mobility of the middle and caudad parts of the cervical spine.
Conclusions: Laminaplasty diminishes lordosis
and straightens the cervical spine. The range of motion and lordosis
continued to decrease, though at a diminishing rate, between the
third and fifth postoperative years.