Intervertebral disc degeneration, age, and sex affect the range of motion of the cervical spine.

Influences of intervertebral disc degeneration, age, sex, and segmental level on the range of motion (ROM) of the cervical spine are widely unknown. This in vitro study aimed to evaluate these effects using large sample sizes. 19 fresh frozen human cervical spines (occiput-T1) were loaded with pure moments of 2.5 Nm. Segmental ROMs were measured by optical motion tracking from C2-C3 to C6-C7. Disc degeneration of these levels was assessed using a validated classification system for the cervical spine. ROMs gradually and significantly decreased with increasing disc degeneration (p < 0.05) and showed high negative correlation with age in flexion/extension (rho =  - 0.637) and axial rotation (rho =  - 0.628). In flexion/extension, ROMs were significantly higher in specimens from female donors compared to male (p < 0.05). The level did overall not significantly affect ROMs (p > 0.05), except for C2-C3, which showed significantly lower ROMs compared to C3-C4 (p < 0.05). Increasing disc degeneration and age as well as male sex reduce the ROM of the cervical spine. The relatively continuous decrease of ROM with increasing disc degeneration in all motion directions largely differs from previous findings of our group on the lumbar spine (gradual ROM increase in axial rotation) and the thoracic spine (strong ROM decrease already for mild disc degeneration).