Biomechanical effect of Chinese manual therapy for cervical spondylotic radiculopathy after percutaneous endoscopic cervical foraminotomy and diskectomy: A finite element study

Abstract With the recurrence of symptoms and emergence of accompanying disorders for intractable cervical spondylotic radiculopathy (CSR) after cervical spine surgery, Chinese manual therapy (CMT) may be an alternative. Therefore, this study aimed to assess and compare the biomechanical impact of CMT on the cervical spine before and after percutaneous endoscopic cervical foraminotomy and diskectomy (PECFD) with resection at three different extents by the finite element analysis. A three-dimensional finite element digital model of C0-C7, representing a normal and intact cervical spine, was created and validated. Subsequently, the finite element model of PECFD was derived by modifying the validated model. Four different models were subjected to load conditions simulating CMT. Various biomechanical parameters, including range of motion (ROM), intervertebral disc pressure (IDP), and stress on facet ligaments, were calculated for both the operated segment and the adjacent segment under different motion conditions. The maximum displacement (MD) of the cervical spine induced by load 1 was higher than that of the other load. The rotation angle (RA) of M3 was lower in right bending and right rotation and higher in extension. The maximum stress of the annulus fibrosus matrix of the intervertebral disc was calculated during the whole movement of the cervical spine. The more tissue that was removed from the intervertebral disc, the higher was the maximum stress of the annulus fibrosus matrix under the two CMTs. For most cervical segments, the intact model and three PECFD models had little effect on the intervertebral disc pressure (IDP) during physiological activity and the two CMTs. However, the IDP in the operated C5-6 segment of the PECFD models was mostly higher than that of the intact segment. The stress of the right FLs of C5-6 in the PECFD models exceeded that of the intact model during left and right lateral bending; significantly, the stress on M3 was found to be 1.5 times higher than that observed in the intact model. Conversely, in comparison to the intact model, the stress experienced by the left facet ligaments (FLs) of the C5-6 segment in M3 was reduced by 60% and 65% respectively. Although the removal of the annulus fibrosus had minimal impact on cervical spinal stability in the model, it should be noted that the nucleus pulposus was not considered. Considering this limitation, follow-up CMT could potentially offer benefits. With the increase in resection, CMT is more likely to cause reprotrusion and instability with regard to the short-term curative effect.