To explore the relationship between the compression depth and compressive stress of the anterior and posterior cervical spinal cord in different sports positions.

Specimens of ten intact fresh cervical spine (C₁-T₁) from adult cadaver were collected. In order to simulate cervical disc degeneration and abnormal ligamentum flavum, we placed two hemispherical steel balls into the anterior and posterior side of the cervical spinal cord through the bone window of the C_{4, 5}. The measurement was conducted in 10%, 20%, 30%, 40%, 50%, and 60% of the sagittal diameter for the compressive stress of the anterior and posterior cervical spinal cord under different compression depths of flexion, neutral, and posterior extension.

The anterior depth of a certain pressure with the posterior pressure depth was increasing in neutral position, the stress on the anterior of the cervical cord-meningeal complex (CCMC) had no significant change, while the stress on the posterior of the CCMC increased greatly with the increasing of the degree of canal occlusion. The stress on the posterior of the CCMC varied insignificantly between 10% and 20% depth of canal occlusion (P>0.05). However, there was remarkable significance among 30% and 60% (P<0.05). In extension or flexion position, the stress on the anterior of the CCMC had no significant change, while the stress on the posterior of the CCMC increased greatly with the increasing of the degree of canal occlusion. The stress on the posterior of the CCMC varied insignificantly between neighboring depths of canal occlusion from 10% (P>0.05). However, there was remarkable significance among 20% and 60% (P<0.05). The posterior depth of a certain pressure with the anterior pressure depth was increasing in neutral position. The stress on the anterior of the CCMC increased greatly with the increasing of the degree of canal occlusion. The stress on the anterior of the CCMC varied insignificantly between 10% and 20% depth of canal occlusion(P>0.05). However, there was remarkable significance among 30% and 60% (P<0.05). The stress on the posterior of the CCMC had no significant change. In extension or flexion position, the stress on the anterior of the CCMC increased greatly with the increasing of the degree of canal occlusion. The stress on the anterior of the CCMC varied insignificantly between neighboring depths of canal occlusion from 10% (P>0.05). However, there was remarkable significance among 20% and 60% (P<0.05). The stress on the posterior of the CCMC had no significant change. Compared with the neutral position, the anterior flexion position and the posterior extension position had different trends in the compressive stress in the anterior and posterior aspect of the cervical spinal cord.

The stress on the anterior and the posterior of the CCMC has a closely nonlinear relationship with the depth of canal occlusion. With the increase of the depth of canal occlusion, the stress is increasing, especially running over the 30% depress of canal occlusion under neutral position. However, the stress is increased, especially running over the 20% depress of canal occlusion under the flexion and extension position.

Spinal cord; Stress, mechanical; Posture; Biomechanics