Effect of single-level Discover cervical artificial disc replacement on cervical sagittal alignment

Abstract

Objective To evaluate the effect of single-level Discover cervical artificial disc replacement on cervical sagittal alignment. Methods Retrospective analysis was conducted on patients who underwent single-level Discover cervical artificial disc replacement in our hospital from February 2012 to September 2014. Sixty-two patients (34 males, 28 females) with an average age of 45.2±8.2 (31-61) who were diagnosed with single-level cervical disc herniation were included (C3-4 3 cases, C4-5 12 cases, C5-6 34 cases, C6-7 13 cases). We measured the cervical sagittal alignment parameters: index level disc angle, functional spinal unit (FSU) angle, C2-C7 angle, anterior disc height (ADH), middle disc height (MDH), posterior disc height (PDH), anterior FSU height (AFH), middle FSU height (MFH), posterior FSU height (PFH) on neutral lateral radiographs before surgery and 3 months after surgery. Results All of the patients were followed up for 3 months. The cervical sagittal alignment parameters before surgery and 3 months after surgery were as follows. Index level disc angle increased from 0.0°±4.2° to 7.3°±3.9°, FSU angle increased from 2.3°±5.0° to 6.9°±4.8°, C2-C7 angle increased from 9.5°±10.8° to 13.1°±9.1°, ADH increased from 4.3±1.0 mm to 7.9±1.1 mm, MDH increased from 5.8±0.9 mm to 8.1±0.9 mm, PDH increased from 3.7±0.9 mm to 5.5±0.9 mm, AFH increased from 34.1±3.5 mm to 36.2±3.4 mm, MFH increased from 32.3±3.5 mm to 33.6±3.3 mm, PFH increased from 33.9±3.5 mm to 34.6±3.2 mm. All changes were statistically significant (P<0.05). Conclusion Single-level Discover cervical artificial disc replacement can improve the disk angle, FSU angle, and disk height effectively in early follow-up period, thereby improving the cervical sagittal alignment. Key words: Cervical vertebrae; Total disc replacement; Treatment outcome