Impact of Fat Infiltration in Cervical Extensor Muscles on Cervical Lordosis and Neck Pain: A Cross-Sectional Study

Background: Weakness of cervical extensor muscles causes loss of cervical lordosis, which could also cause neck pain. The aim of this study was to investigate the impact of fat infiltration in cervical extensor muscles on cervical lordosis and neck pain. Methods: Fifty-six patients who suffered from neck pain were included in this study. Fat infiltration in cervical extensor muscles was measured at each level of C2-3 and C6-7 using axial magnetic resonance imaging. The visual analogue scale (VAS), 12-Item Short Form Health Survey (SF-12), and Neck Disability Index (NDI) were used for clinical assessment. Results: The mean fat infiltration was 206.3 mm(2) (20.3%) at C2-3 and 240.6 mm(2) (19.5%) at C6-7. Fat infiltration in cervical extensor muscles was associated with high VAS scores at both levels (p = 0.047 at C2-3; p = 0.009 at C6-7). At C2-3, there was a negative correlation between fat infiltration of the cervical extensor muscles and cervical lordosis (r = -0.216; p = 0.020). At C6-7, fat infiltration in the cervical extensor muscles was closely related to NDI (p = 0.003) and SF-12 (p > 0.05). However, there was no significant correlation between cervical lordosis and clinical outcomes (VAS, p = 0.112; NDI, p = 0.087; and SF-12, p > 0.05). Conclusions: These results suggest that fat infiltration in the upper cervical extensor muscles has relevance to the loss of cervical lordosis, whereas fat infiltration in the lower cervical extensor muscles is associated with cervical functional disability.