An in vivo comparison study in goats for a novel motion-preserving cervical joint system

Abstract

Cervical degenerative disease is one of the most common spinal disorders worldwide, especially in older people. Anterior cervical corpectomy and fusion (ACCF) is a useful method for the surgical treatment of multi-level cervical degenerative disease. Anterior cervical disc replacement (ACDR) is considered as an alternative surgical method. However, both methods have drawbacks, particularly the neck motion decrease observed after arthrodesis, and arthroplasty should only be performed on patients presenting with cervical disc disease but without any vertebral body disease. Therefore, we designed a non-fusion cervical joint system, namely an artificial cervical vertebra and intervertebral complex (ACVC), to provide a novel treatment for multi-level cervical degenerative disease. To enhance the long-term stability of ACVC, we applied a hydroxyapatite (HA) biocoating on the surface of the artificial joint. Thirty-two goats were randomly divided into four groups: a sham control group, an ACVC group, an ACVC-HA group, and an ACCF group (titanium and plate fixation group). We performed the prosthesis implantation in our previously established goat model. We compared the clinical, radiological, biomechanical, and histological outcomes among these four different groups for 24 weeks post surgery. The goats successfully tolerated the entire experimental procedure. The kinematics data for the ACVC and ACVC-HA groups were similar. The range of motion (ROM) in adjacent level increased after ACCF but was not altered after ACVC or ACVC-HA implantation. Compared with the control group, no significant difference was found in ROM and neutral zone (NZ) in flexion-extension or lateral bending for the ACVC and ACVC-HA groups, whereas the ROM and NZ in rotation were significantly greater. Compared with the ACCF group, the ROM and NZ significantly increased in all directions. Overall, stiffness was significantly decreased in the ACVC and ACVC-HA groups compared with the control group and the ACCF group. Similar results were found after a fatigue test of 5,000 repetitions of axial rotation. The histological results showed more new bone formation and better bone implant contact in the ACVC-HA group than the ACVC group. Goat is an excellent animal model for cervical spine biomechanical study. Compared with the intact state and the ACCF group, ACVC could provide immediate stability and preserve segmental movement after discectomy and corpectomy. Besides, HA biocoating provide a better bone ingrowth, which is essential for long-term stability. In conclusion, ACVC-HA brings new insight to treat cervical degenerative disease.

Biomechanical Comparison of 1-Level Corpectomy and 2-Level Discectomy for Cervical Spondylotic Myelopathy: A Finite Element Analysis

“…Previous studies compared the clinical outcome of ACDF and ACCF in 2-level cervical spondylosis myelopathy and found no difference in adjacent-level ossification and complications [24], suggesting that neither ACDF nor ACCF perform better in the degenerative changes in the adjacent levels, and other techniques, such as use of an anterior non-fusion fixation device, should be considered to address this problem [25].…”

Uncovertebral Joint Fusion Versus End Plate Space Fusion in Anterior Cervical Spine Surgery

“…Micro-CT and bone tissue analysis revealed that osteogenesis in the uncovertebral joint was greater than that in the end-plate space 21 . The goat cervical spine resembles the human cervical spine anatomically, making it suitable for spine-related research [29][30][31] . A large-sample, longterm follow-up study of cervical disc replacement found that high-grade paravertebral ossification mainly occurred in the bilateral uncovertebral joint regions 32 .…”