Analysis of differences in imaging morphology between asymptomatic cervical kyphosis and cervical kyphosis associated with cervical spondylotic myelopathy

English Keywords:Cervical kyphosis  Asymptomatic  Cervical spondylotic myelopathy  Cervical sagittal parameters  Imaging assessment

English Abstract:

  【Abstract】 Objectives: To compare the differences in cervical sagittal alignment and morphological characteristics between asymptomatic cervical kyphosis and cervical kyphosis in patients with cervical spondylotic myelopathy(CSM), and to explore potential indicators for distinguishing the two types of kyphosis. Methods: A total of 62 patients(40 males, 22 females; aged 34-76 years, mean 51.9±11.3 years) who exhibited radiological cervical kyphosis and underwent surgical treatment for CSM in the Department of Orthopedics, Huashan Hospital, Fudan University from October 2022 to October 2024 were included. Age- and sex-matched asymptomatic individuals recruited from the physical examination center of our hospital served as the control group(40 males, 22 females; aged 36-73 years, mean 51.9±11.2 years). The differences between the two groups were compared in terms of cervical kyphosis-related parameters(kyphotic segment Cobb angle, the difference between C4-C7 and C2-C4 Cobb angles), overall cervical sagittal parameters[C0-C2 Cobb angle, neck tilt(NT), etc.], intervertebral space angles, vertebral body angles, and the tilt angles of the upper and lower endplates of each vertebra(including C0 slope, C4 lower endplate tilt angle). Results: The Cobb angle of the kyphotic segment in the asymptomatic group(-10.08°±6.72°) was significantly smaller than that in the CSM group(-17.81°±5.28°)(P<0.01). The difference between the C4-C7 and C2-C4 Cobb angles in the asymptomatic group(0.36°±7.04°) was significantly greater than that in the CSM group(-7.83°±13.21°)(P<0.01). The C0-C2 Cobb angle and NT in the asymptomatic group were both significantly smaller than those in the CSM group(P<0.01). The kyphotic angles of the C4/5, C5/6, and C6/7 segments in the asymptomatic group were significantly smaller than those in the CSM group(P<0.01, P=0.02, P=0.04), indicating that the kyphosis in the CSM group primarily originated from the loss of anterior intervertebral disc height. The kyphotic angles of C3, C5, and C7 were significantly greater in the asymptomatic group than those in the CSM group(P=0.03, 0.04, and 0.03, respectively), indicating that the kyphosis in the asymptomatic group was mainly attributed to vertebral wedging. In the asymptomatic group, the C0 slope was significantly greater than that in the CSM group(P<0.01), while the NT value(P<0.01) and the C4 lower endplate tilt angle(P=0.03) were significantly smaller than those in the CSM group. Conclusions: The kyphosis in CSM patients is concentrated in the C4-C7 segments and is characterized by a larger local angle. Conversely, asymptomatic cervical kyphosis is more commonly observed in the C2-C4 segments and primarily originates from vertebral wedging. C0 slope, NT, and C4 lower endplate tilt angle can serve as potential differential parameters.