Reciprocal change of occipitocervical parameters after anterior cervical discectomy and fusion

Abstract

To evaluate the reciprocal changes in occipitocervical parameters according to the recovery of cervical lordosis (CL) after anterior cervical discectomy and fusion (ACDF) in patients with sagittal imbalance. Sixty-five cases that underwent ACDF were followed. They were divided according to the recovery of the CL: Group 1 (ΔCL > 5°, 30 cases) and Group 2 (ΔCL < 5°, 35 cases). The following parameters were measured: occiput-cervical inclination (OCI), CL, occiput-C2 angle (OC2A), distance between external occipital protuberance and spinous process of C2 (OC2D), distance between spinous processes of C2 and C7 (C27D), and shortest distance between the plumb line of C2 body and posterosuperior corner of C7 (C27SVA). Overall, all parameters changed significantly after ACDF. Preoperative CL and preoperative C27D showed a correlation with ΔCL. ΔCL was negatively correlated with ΔC27D and ΔC27SVA. In Group 1, CL increased from − 2.60 ± 1.88° to 11.57 ± 1.83°, OC2A decreased from 23.96 ± 2.05° to 19.87 ± 1.36°, OC2D increased from 82.96 ± 1.48 mm to 86.50 ± 1.81 mm, C27D decreased from 95.61 ± 2.66 mm to 87.01 ± 2.50 mm, and C27SVA decreased from 24.14 ± 2.20 mm to 17.06 ± 2.14 mm. In Group 2, only OCI decreased significantly after ACDF. ACDF can increase CL postoperatively in patients with cervical sagittal imbalance. Patients with significant CL recovery after ACDF showed a reciprocal change in occipitocervical parameters. (OC2A, OC2D).

Reciprocal Changes Following Cervical Realignment Surgery

“…41 After a patient recovers optimal cervical lordosis (CL), C0-2 angle reciprocally decreases. 22 Concurrently, Lafage et al 23 reported that correction of sagittal cervical deformity (CD) led to reciprocal relaxation of the established CD compensatory mechanisms such as C0-2 hyperlordosis and thoracic hypokyphosis. 23 Furthermore, the preoperative Neck Disability Index (NDI) had a significant correlation with preoperative C0-2 range of motion (ROM) and reserve of extension (ROE).…”

“…Hyperlordotic positioning of the upper cervical spine leads to a kyphotic alignment of the subaxial spine to maintain balanced cervical alignment [ 41 ]. After a patient recovers optimal cervical lordosis (CL), C0–2 angle reciprocally decreases [ 22 ]. Concurrently, Lafage et al [ 23 ] reported that correction of sagittal cervical deformity (CD) led to reciprocal relaxation of the established CD compensatory mechanisms such as C0–2 hyperlordosis and thoracic hypokyphosis [ 23 ].…”

“…4,[13][14][15][16][17][18] Likewise, recent studies report that cervical kyphotic deformity showed compensatory changes in the thoracolumbar spine, analogous to the changes that occur in thoracolumbar deformity. [19][20][21][22][23] At the regional level, the upper cervical spine compensates for C2-7 angle through the extension of C0-2, thereby maintaining the patient's horizontal gaze. [22][23][24][25][26][27] Understanding the compensatory status of a patient is vital because the compensatory mechanisms may resolve reciprocally following cervical realignment surgery which correlates with improved patient outcome.…”

“…[19][20][21][22][23] At the regional level, the upper cervical spine compensates for C2-7 angle through the extension of C0-2, thereby maintaining the patient's horizontal gaze. [22][23][24][25][26][27] Understanding the compensatory status of a patient is vital because the compensatory mechanisms may resolve reciprocally following cervical realignment surgery which correlates with improved patient outcome. 19,23 Despite the efforts, understanding and anticipating the reciprocal changes that occur following realignment surgery is perplexing.…”

“…Likewise, recent studies report that cervical kyphotic deformity showed compensatory changes in the thoracolumbar spine, analogous to the changes that occur in thoracolumbar deformity [ 19 - 23 ]. At the regional level, the upper cervical spine compensates for C2–7 angle through the extension of C0–2, thereby maintaining the patient’s horizontal gaze [ 22 - 27 ].…”