Influence of cervical spine sagittal alignment on range of motion after corpectomy: a finite element study

• Published in: Acta neurochirurgica Vol. 163; no. 1; pp. 251 - 257
• Main Authors: John, Jobin D., Kumar, Gurunathan Saravana, Yoganandan, Narayan, Rajshekhar, Vedantam
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01-01-2021; Springer Nature B.V
• Subjects: Adult; Cervical Vertebrae - diagnostic imaging; Cervical Vertebrae - surgery; Female; Finite Element Analysis; Humans; Interventional Radiology; Kyphosis; Kyphosis - diagnostic imaging; Lordosis - diagnostic imaging; Male; Mathematical models; Medicine; Medicine & Public Health; Minimally Invasive Surgery; Neurology; Neuroradiology; Neurosurgery; Original Article - Spine - Other; Postoperative Complications - diagnostic imaging; Radiography - methods; Range of motion; Range of Motion, Articular; Spine (cervical); Spine - Other; Surgical Orthopedics; Sagittal alignment; Finite element model; Mesh morphing; Cervical spine; Adjacent segment pathology
• ISSN: 0001-6268; 0942-0940
• DOI: 10.1007/s00701-020-04619-9

Background
Sagittal alignment of the cervical spine might influence the development of radiological adjacent segment pathology (RASP) after central corpectomy (CC). Range of motion (ROM) of the adjacent segments is closely linked to the development of RASP.
Methods
To investigate the ROM of the adjacent segments after CC, we developed a C2-T1 finite element (FE) model. The model with a lordotic sagittal alignment served as the baseline model. Models with straight and kyphotic alignment were generated using mesh morphing methods. Single-level corpectomy at C5 was done on these models. Segmental ROMs of intact and corpectomized spines were compared for physiologic flexion-extension loads.
Results
The flexion ROM decreased by an average of 13% with the change in sagittal alignment from lordosis to kyphosis; however, a consistent decrease was not observed in extension. After CC, the ROM increased by an average of 95% and 31% in the superior and inferior adjacent segments. With kyphotic change in the sagittal alignment, the postoperative increase in flexion ROM exhibited a decreasing trend, while this was not seen in extension.
Conclusions
Kyphotic changes of the intact spine resulted in segmental stiffening, and after corpectomy, it resulted in inconsistent variations of segmental extension ROMs.