Biomechanical comparison of suspensory traction and axial traction in preoperative correction of cervical kyphosis: a finite element study

Hongyu Chen^1*Tianchi Wu²Shengfa Pan¹Li Zhang¹Yanbin Zhao¹Xin Chen¹YU SUN¹William W Lu²Feifei Zhou¹

• ¹Peking University Third Hospital, Haidian, China
• ²The University of Hong Kong, Pokfulam, Hong Kong, SAR China

Preoperative traction plays an important role in the treatment of cervical kyphosis, but the conventional axial traction has some problems such as nerve damage and iatrogenic fracture during traction. A new type of preoperative traction, suspensory traction, has been found to have potential advantages in clinical observation. However, there is a paucity of supportive evidence from biomechanical data. The purpose of this study was to biomechanically evaluate and compare the effects of axial and suspensory traction on the preoperative correction of cervical kyphosis, aiming to provide clinical guidance on a traction method that potentially reduces the risk of nerve damage and iatrogenic fractures. A three-dimensional finite element model of C2-T2 with cervical kyphosis was developed. Simulations of both axial and suspensory traction were applied, and the changes in cervical kyphotic angle, cervical spinal canal length, and vertebral stress distribution were analyzed. Both traction methods reduced the kyphotic angle, with suspensory traction showing a greater reduction. Axial traction slightly increased the cervical spinal canal length, while suspensory traction decreased it. The stress distribution patterns were similar for both methods, but suspensory traction resulted in lower maximum von Mises stress on the vertebral bodies. Suspensory traction demonstrated a superior corrective effect on cervical kyphosis with reduced stress on the cervical vertebrae and a decrease in spinal canal length, which may decrease the likelihood of traction-related complications, suggesting its potential as a safer preoperative traction method for clinical use.