Fig. 7.

Case 4. A 63-year-old woman with rheumatoid arthritis. Preoperative (left), 6 months postoperative (middle), and 4 years postoperative (right) X-rays. Although the occipito–C2 angle did not change postoperatively, T1 slope increased 6 months postoperatively, probably because of the kyphotic changes of thoracic spine. Compensational lordotic change of the subaxial cervical spine maintained the McGregor slope. Four years postoperatively, the T1 slope increased beyond the limit of cervical compensation, and then the McGregor slope changed.