Comparison of biomechanical differences between cervical rotation and rotation-traction manipulations using finite element analysis

Abstract

BACKGROUND: Currently, the biomechanical differences between cervical rotation manipulation and cervical rotation-traction manipulation for the treatment of cervical radiculopathy have not been systematically elucidated. OBJECTIVE: To compare the biomechanical differences between cervical rotation manipulation and cervical rotation-traction manipulation in the treatment of cervical spondylotic radiculopathy caused by cervical disc herniation, and to provide a basis for the rational selection of manipulation in clinical practice. METHODS: A 27-year-old Asian male patient with cervical spondylotic radiculopathy caused by left posterior cervical disc herniation compressing the nerve root was recruited. The CT scan data of the skull and cervical spine were extracted to construct a finite element model of the head and full cervical spine. After model validation, the key parameters of cervical rotation manipulation and rotation-traction manipulation were loaded into the model, and the effects of the two manipulations on the stress of intervertebral disc, facet joints, spinal cord and nerve roots, disc displacement, and intervertebral foramen volume were compared. RESULTS AND CONCLUSION: (1) In terms of Von-Mise stress, the maximum stresses of cervical rotation manipulation on the annulus fibrosus, nucleus pulposus, and facet joints were 0.903, 0.139, and 2.186 MPa, respectively, which were significantly increased by 18%, 13%, and 30% compared with rotation-traction manipulation (0.765, 0.123, 1.682 MPa); while the maximum stress on the spinal cord and nerve roots was 2.547 MPa, which was 7% lower than that of rotation-traction manipulation (2.738 MPa). (2) In terms of displacement, the maximum forward displacement of the herniated side of the intervertebral disc by cervical rotation manipulation was 1.067 mm, which was 11.1% more than that of rotation-traction manipulation (0.960 mm). (3) In terms of intervertebral foramen volume changes, both manipulations increased the volume after implementation compared with before, with rotation manipulation increasing by 15.5% and rotation-traction manipulation increasing by 19.8%, the latter being more effective in expanding the intervertebral foramen volume. (4) It is suggested that cervical rotation manipulation has advantages in promoting the forward displacement of the herniated disc, but it produces higher stress on the intervertebral disc and facet joints, which may easily cause disc damage; rotation-traction manipulation will cause slightly higher stress on the spinal cord and nerve roots, but it can more effectively expand the intervertebral foramen volume and reduce the risk of disc structural damage. In clinical treatment, the advantages and disadvantages of the two manipulations should be carefully weighed and selected based on the patient's specific condition.

1. Introduction

Cervical disc herniation causing direct or indirect mechanical compression of the cervical nerve roots, along with the stimulation of inflammatory mediators, is a key factor in the pathogenesis of cervical spondylotic radiculopathy [1]. Patients with cervical spondylotic radiculopathy mainly present with pain, numbness, and dysfunction in the areas innervated by the affected nerve roots [2-3]. Currently, non-surgical treatment is the mainstay for cervical spondylotic radiculopathy, and it has been reported that most patients can improve their symptoms through non-surgical therapies [2,4].

Cervical rotation manipulation and cervical rotation-traction manipulation are commonly used conservative treatments for cervical spondylotic radiculopathy. Cervical rotation manipulation plays an important role in the treatment of cervical spondylotic radiculopathy by changing the positional relationship between the herniated disc and nerve roots and loosening soft tissue adhesions [5-6]. Cervical rotation-traction manipulation is an innovation by Academician Zhu Liguo's team based on traditional cervical rotation manipulation. This manipulation can promote greater vertical displacement of the annulus fibrosus, which helps in the short-term reduction of the herniated nucleus pulposus and alleviates compression on the nerve roots [7-8]. Previous studies have confirmed that both manipulations have certain efficacy for cervical spondylotic radiculopathy [9-11]. However, in clinical practice, serious complications caused by improper manipulation use occur from time to time [12-15]. Wang Huihao et al. [12-13] statistically analyzed the occurrence of adverse events in the treatment of cervical spondylosis by manipulation before 2012 and after 2012, and found that most adverse events were caused by rotation reduction manipulations. KRANENBURG et al. [14] systematically reviewed adverse events during cervical manipulation therapy.