PMC8995112_01
Images before the first operation. (A) An X-ray of the global sagittal alignment of the whole body in standing position. (B) (C) X-rays (lateral view) of cervical flexion and extension. The X-rays show atlantoaxial subluxation, vertical subluxation, subaxial subluxation, and kyphotic alignment. (D) T2-weighted MRI.
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In the dynamic radiographs, the anterior slips of C1 and C3 were 5 and 1 mm, respectively (Fig. 1), and the instability causing the pain seemed to be due to C1-C2.
Images after the first operation. (A) (B) X-ray and CT after atlantoaxial fusion using a C1 lateral mass screw and C2 pedicle screw. (C) CT showing bone graft on laminas of C1-C2.
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Based on the assessment that her symptom was caused from atlantoaxial instability, posterior atlantoaxial fixation was performed using C1 lateral mass and C2 pedicle screws with bone grafting from iliac bone to C1-C2 lamina (Fig. 2).
Postoperative X-rays showing the progression of subaxial kyphosis and an increase in the O-C2 angle. C1 screw breakage was recognized at 3 years and 4 months after the first operation.. O-C2, occipitoaxial angle; C2-C7, C2-C7 angle
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Radiography and computed tomography of the cervical spine demonstrated bilateral broken C1 screws, the progression of subaxial kyphosis with C3-C4 instability, an increased occipitoaxial angle, and occipital bone erosion induced by the protruding rods (Fig. 3, 4A-C).
(A) (B) X-rays (lateral view) of cervical flexion and extension before the second operation. (C) CT before the second operation showing the erosion of the occipital bone. (D) T2-weighted MRI before the second operation showing C3 subluxation and canal stenosis. (E) X-ray after the second operation.
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Radiography and computed tomography of the cervical spine demonstrated bilateral broken C1 screws, the progression of subaxial kyphosis with C3-C4 instability, an increased occipitoaxial angle, and occipital bone erosion induced by the protruding rods (Fig. 3, 4A-C). MRI demonstrated multiple levels of cervical canal stenosis (Fig. 4D). Occipitothoracic fusion surgery was considered, but we decided to perform only C2-C6 decompression and fusion surgery with removal of the rods and C1 screwhead because of her several comorbidities (Fig. 4E).