Comparison of the Biomechanical Changes After Percutaneous Full-Endoscopic Anterior Cervical Discectomy versus Posterior Cervical Foraminotomy at C5-C6: A Finite Element-Based Study

OBJECTIVE: Percutaneous full-endoscopic anterior cervical discectomy (PEACD) and posterior cervical foraminotomy (PCF) have been reported as effective treatments for the cervical spondylosis radiculopathy (CSR), but the biomechanical effects on the discs and facet joints of PEACD and PCF remain largely unclear. The purpose of this paper is to investigate and compare the biomechanical changes on cervical spine after PECAD and PCF procedures, thus providing evidences for surgeons to select a more appropriate approach. METHODS: An intact cervical C5-C6 digital model was constructed and then modified to obtain the PCF and PEACD models using finite element method. All the models were subjected to a 73.6N preload accompanied by a 1.8 Nm moment during flexion, extension, axial rotation, lateral bending. The range of motion (ROM), intervertebral disc pressure (IDP), facet joint contact area, and contact pressure were calculated under different loading conditions. RESULTS: The ROM of the PCF model changed slightly (0.28%), whereas that of the PEACD model increased significantly (20.49%) compared with intact model. The trend of IDP changes in these 2 surgical models were similar to ROM in the corresponding motion state. The contact pressure on the facet joint of the PEACD model increased by 20.53%, 33.38%, and 17.46% during extension, lateral bending, and axial bending, respectively, compared with the intact model, and the PCF increased by 33.53% and 16.16% during extension and lateral bending, respectively, whereas it decreased 0.97% in axial rotation. The facet joint contact area of the PCF model increased by 85.71%, 1.54%, and 2.17% during extension, lateral bending, and axial rotation, respectively, and the area of the PEACD model increased by 157.14% and 36.96% during extension and axial rotation, whereas it decreased by 13.85% during lateral bending. CONCLUSIONS: This is the first biomechanical finite element study comparing PEACD with PCF for the treatment of CSR. Our results showed that PEACD led to hypermobility with high IDP within the cervical segment undergone surgery, whereas the ROM and IDP changed slightly after PCF. The variations of the contact stress indicated that both procedures changed the transmission path of the force on the facet joint and may accelerate the degeneration of the facet joint. PCF may be a better choice for the treatment of CSR compared with PEACD.