The hyaline cartilage and facet joints above the subchondral bone are the only synovial joints in the spine that help carry 16% of the vertical load on the intervertebral discs (1).
Facet joints provide rear mechanical support to protect the discs from excessive rotations in flexion and extension by fixing the movement segment. Although facet tropism means asymmetry of the left and right facet joints, the criteria for defining it are very different. While Noren et al. defined facet asymmetry as an angle difference of > 5 ° bilaterally (14), Huang et al. accepted the tropism at cervical facet level > 7 ° (7). In other biomechanical studies, facet asymmetry was evaluated that facet joint angles greater than 1 ° − 10 ° (8, 9). According to the study results available in the literature, there is no definitive consensus about the angle ofservical facet tropism.
Unlike the lumbar spine, the facet direction of the cervical spine is more complex. While the facet joints are located more vertically in the lumbar spine, they are located more axially and coronal in the cervical region (16). In previous studies, it has been mentioned that facet tropism can cause unbalanced stress distribution in the disc, thus causing disc degeneration, and even disc herniation (10, 12, 17). Literature studies mostly focus on the relationship between facet tropism,low back or neck problems, degeneration of the disc, facet joint, and spondylolysis (3, 5, 13, 18, 19, 21). In most of these studies, cases are older age, patients who do not exercise regularly and have a low back pain. As far as we know, our study will be the first with the control group evaluating the association of cervical facet joint tropism and cervical disc hernia in multısport athletes aged 20–40 in 8 different sports activity. In a study by Xin Rong et al; In patients over 50 years of age, it was evaluated that there was a relationship between disc degeneration and tropism, and it was shown that facet tropism was mostly at C2-3 level (17). In the same study, it has been experimentally demonstrated that the facet joint and intervertebral disc with facet tropism are exposed to higher pressures than the symmetrical model.
Therefore, we aimed to investigate whether abnormal stress on joints and discs with facet tropism would be related to disc herniation. However;In a study conducted by Okada et al on 223 asymptomatic healthy cases with a 10-year retrospective MRI study, no correlation other than age was found in the development of disc degeneration (15). However, anatomical factors related to the patients were not adequately shed lighted on this study. In individuals with asymmetrical facet tropism, an increase of 49.2% by flexion, 57.1% by extension and 30.6% by axial rotation has been shown (17). Based on this study, it can be suggested that facet tropism may be an anatomical risk factor in the development of cervical disc herniation. In our study, when compared the cervical disc hernia group and the normal group, we could not find a statistically significant facet tropism. In the literature, we could not find a study evaluating the correlation between facet tropism and cervical disc hernia in athletes. Another study supporting ours by D. Y. Lee et al. demonstrated that facet tropism has not played a role in the development of lumbar disc herniation in adolescents (11). On the other hand, a retrospective study by Huang X et al. with 96 cases over the age of 50 years, found a correlation between cervical disc hernia and tropism (6). The cases in our study were in the younger (20–40) age range and consisted of athletes with regularly trained. We evaluated the MRI findings with bulding and protrusion. In the mentioned study, it was not stated at which level disc cases were included. As cervical disc degeneration shows only age-related development, the association of facet tropism with cervical disc hernia may be in older ages (21).