Characteristics of head and neck alignment and function of deep cervical flexor muscles in patients with nonspecific neck pain

Objective To compare forward head posture (FHP) in natural and corrected head postures between patients with nonspecific neck pain (NSNP) and controls, and to clarify the relationship between natural- and corrected-head posture angle differences and deep cervical flexor function. Design Survey study Setting Patients with NSNP were outpatients at an orthopedic clinic; the controls were community volunteers. Participants Thirty-eight patients were divided into the NSNP and control groups (n=19 each), including patients reporting a numerical rating pain score of 3-7 for at least 3 months and those with no neck pain within 12 months previously, respectively. Interventions To evaluate FHP, the cranial rotation and vertical angles were measured using lateral photographs of the head and neck. The craniocervical flexion test was used to evaluate deep cervical flexor activation and endurance. Main outcome measures We evaluated the head and neck alignment in natural and corrected head postures and the relationship between the degree of change and deep cervical flexor function. Results The FHP in the natural head posture did not differ significantly between the groups. For corrected head posture, the FHP was significantly smaller in the NSNP group than in the control group. In the NSNP group, the cranial rotation and vertical angles were significantly different between natural and corrected head postures, and the angle difference between these postures was significantly correlated with deep cervical flexor function. Conclusions In patients with NSNP, hypercorrection in the corrected head posture was shown and may be correlated with dysfunction of the deep cervical flexors. Further investigation into the causal relationship between hypercorrection, deep neck flexor dysfunction, and neck pain is required.