Abstract
BackgroundThe decision to treat multilevel cervical spondylotic myelopathy (MCSM) remains controversial. The purpose of this study is to compare the biomechanical characteristics of the intervertebral discs at the adjacent segments and internal fixation, and to provide scientific experimental evidence for surgical treatment of MCSM.MethodsAn intact C2-C7 cervical spine model was developed and validated. Four additional models were developed from the fusion model, including multilevel anterior cervical discectomy and fusion (mACDF), anterior cervical corpectomy and fusion (ACCF), hybrid decompression and fusion (HDF), and mACDF with cage alone (mACDF-CA). Biomechanical characteristics on the plate and the disc of adjacent levels (C2/3, C6/7) were comparatively analyzed.ResultsOf the four models, stress on the upper (C2/3) adjacent intervertebral disc was the lowest in the mACDF-CA group and highest in the ACCF group. Stress on the intervertebral discs at adjacent segments was higher for the upper C2/3 than the lower C6/7 intervertebral disc. In all models, the mACDF-CA group had the lowest stress on the intervertebral disc, while the ACCF group had the highest stress. In the three surgical models with titanium plate fixation (mACDF, ACCF, and HDF), the ACCF group had the highest stress at the titanium plate-screw interface, while the mACDF group had the lowest stress.ConclusionAmong the four anterior cervical reconstructive techniques for MCSM, mACDF-CA makes little effect on the adjacent disc stress, which might reduce the incidence of adjacent segment degeneration (ASD) after fusion. However, the accompanying risk of the increased incidence of cage subsidence should never be neglected.
Highlights
The decision to treat multilevel cervical spondylotic myelopathy (MCSM) remains controversial
The multilevel anterior cervical discectomy and fusion (mACDF)-CA group had the lowest stress on the intervertebral disc, while the ACCF group had the highest stress
Compared with the mACDF-CA group, the maximum von Mises stresses on the lower (C6/7) adjacent intervertebral disc in the mACDF, ACCF, and hybrid decompression and fusion (HDF) groups increased by 17, 71, and 22% during flexion; by 5, 68, and 16% during extension; by 10, 72, and 44% during lateral bending; and by 9, 15, and 10% during rotation, respectively (Figs. 6 and 7)
Summary
The decision to treat multilevel cervical spondylotic myelopathy (MCSM) remains controversial. Multilevel cervical spondylotic myelopathy (MCSM) refers to cervical spondylosis diagnosed by imaging with three or more levels of contiguous or noncontiguous cervical intervertebral disc degeneration and secondary changes, which causes compression on the dural sac and spinal cord, and which results in corresponding clinical manifestations. Posterior, or combined anterior-posterior approach can be employed according to the clinical situation and the experience of surgeons, and each approach has its unique advantages and disadvantages [3,4,5,6,7,8,9,10,11,12] The anterior techniques such as multilevel anterior cervical discectomy and fusion (mACDF), anterior cervical corpectomy and fusion (ACCF), and hybrid decompression and fusion (HDF) have been proved to be reliable and effective in spinal cord decompression, and sagittal alignment restoration and maintenance achieved a good clinical outcome. Some researchers argue that the use of anterior cervical titanium plate increases the incidence of adjacent segment degeneration (ASD) [16,17,18]
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