Abstract
BACKGROUND: Excessive interarticular compressive force (CF) caused by poor posture increases the risk of neck pain. However, existing research on cervical CF is based on healthy individuals, and studies on those with neck pain are lacking. This study aims to address this gap by simultaneously collecting data from individuals with neck pain and asymptomatic individuals, simulating the CF during physiological movements such as flexion-extension, lateral bending, and rotation, to explore the impact of neck pain and movement performance on the interarticular CF. METHODS: A 3D motion capture system and a multicervical unit were utilized to collect kinematic data and maximum voluntary isometric contraction (MVIC), respectively. The kinematic data were processed in OpenSim, using individually scaled cervical spine models. Time and peak angles were obtained via inverse kinematics, and the CF was calculated via joint reaction analysis. Regression analysis was conducted to assess the correlations between neck pain status, movement performance characteristics (time, peak angle, MVIC) and CF normalized by body mass. Variables with p < 0.1 in the univariate regression were included in the multivariate regression model for further adjustment. RESULTS: Sixty participants were enrolled in the study, comprising 30 individuals in the neck pain group and 30 in the asymptomatic group. The mean peak CF in the neck pain group exceeded that in the asymptomatic group during cervical flexion-extension (13.0 -13.4%), lateral bending (10.4 -15.6%), and rotation (7.0 -8.3%) movements. Multivariate regression analysis revealed that the presence of neck pain was correlated with a significant increase in peak CF during the phases of flexion (p = 0.02), right lateral bending (p = 0.04 except for C6-C7), and left rotation (p = 0.02). The peak CF was positively correlated with peak angles in flexion (p < 0.001), extension (p = 0.001), left lateral bending at C3/4 (p = 0.009), C4/5 (p = 0.008), C5/6 and C6/7 (p = 0.007), right lateral bending at C3/4 and C4/5 (p = 0.002), C5/6 and C6/7 (p = 0.001), left rotation (p < 0.001), and right rotation (p = 0.02) movements. Conversely, peak CF was negatively correlated with MVIC in flexion (p = 0.02), extension at C4/5 (p = 0.008) and C5/6 (p = 0.007), left lateral bending (p = 0.001), right lateral bending at C3/4 (p = 0.02), C4/5 and C5/6 (p = 0.01), and C6/7 (p = 0.009) movements. No significant correlation was found between peak CF and the time taken for movement. CONCLUSIONS: This study reveals the differences in CF between individuals with neck pain and asymptomatic individuals during identical movements. The peak CF appears to correlate with the presence of neck pain, MVIC, and peak angle. These findings highlight the importance of muscle strength training. Early identification of reduced neck muscle strength could be crucial for preventing and relieving neck pain.