| At present, the anterior cervical approach surgeries can be divided into fusionsurgeries and non-fusion surgeries according to whether the cervical vertebrae arefused. The fusion surgeries include anterior cervical diskectomy and fusion andanterior cervical corpectomy and fusion. These fusion surgical procedures canachieve complete decompression of the spinal canal and a good reconstruction ofthe cervical spine stability. However, these surgeries are not physiological fixingsurgeries. They have sacrificed the segmental motion of the cervical spine. Andthey can lead to lose of movement of the levels. At the same time, this kind ofsurgery may increase the load of the adjacent levels and accelerate thedegenerative change of the adjacent levels.With the development of non-fusion ideas and technology, there have been many types of artificial cervical discs, many of which are already widely clinicalapplication and achieved good results. The artificial cervical disc replacementsurgery can not only rebuild the cervical spine stability, but also retains its normalactivity. At present, many anterior cervical diskectomy and fusion surgeries havebeen gradually replaced by intervertebral disc replacement surgeries. While thereis not a kind of non-fusion technology can replace the anterior cervicalcorpectomy and fusion surgeries, which can achieve both the stability andmovement of the cervical spine. To solve this problem, our group has developeda new type of artificial cervical joint complex (ACJC). After the optimizationdesign and biomechanical testing of the prosthesis, it confirmed that thisprosthesis can achieve both stability and activity of cervical spine. However, thisprosthesis is still a preliminary products, the transition to clinical application alsoneed further optimize design and in vivo studies.Objective:1. Optimized design of the artificial cervical joint complex.2. Through the in vivo study, further evaluate the safety and effectiveness ofthe artificial cervical joint complex. It will provide experimental basis for clinicaluse of this prosthesis.Methods:1. Analyze the defects of the prosthesis and make optimized designs of it.The corresponding geometric parameters of the joint head and bodycomponent parts of the prosthesis were imported into the Solid Works drawingsoftware. According to a predetermined design, the medical titanium alloymaterial was processed in the casting equipment and high-precision computernumerical controled machine tools. 2. Select12healthy adult male goats. Take X-ray images in normal, neutral,flexing and extending position before surgery. Measure the size of the goatcervical spine and custom prostheses to match the goat cervical spine. Subtotalresection of the C3vertebrae and implant the artificial cervical joint prosthesissystem into the cervical spine.3. The12goats were randomly divided into two groups after operation:3months group and6months group respectively. Before the goats were killed, takeX-ray photos in normal, neutral, flexing and extending position. Measure thevertebral height, the cervical curvature and the range of movement of the cervicalspine. Compare them with the preoperative values. CT scan and thethree-dimensional reconstruction were used for further understanding of theposition of the prosthesis, the position of the screw and spinal canal.4. After the goats were sacrificed, remove the lymph nodes of the axilla andgroin area, spleen tissue, fibrous tissue in front of the prosthesis, spinal cord tissubehind the prostheses. Take them for HE stain to understand whether the systemicand local tissue toxicity. Take the goats cervical specimens for Micro-CT scanand hard tissue section staining to evaluate the prosthesis, screw and bone unionand bone ingrowth.Results:1. A new generation of artificial cervical joint complex has been designedand processed.2. After the operation, one goat appeared transient lower extremity weakness.The remaining goats can eat, drink and walk freely. The neck can also movefreely. Surgical incisions of all goats were healed very well.3. Postoperative lateral X ray showed that the anterior, posterior and middle height of C2~C4vertebral body in both the3months group and6months groupwere decreased when compared with the preoperative values. But the differenceswere not statistically significant (P>0.05). Compared with those preoperativevalues, the cervical curvature in both the3months group and6months groupwere decreased. The difference was statistically significant (P <0.05). Thedynamic cervical radiographs revealed that C4~C5segment flexion-extensionactivity in both the3months group and6months group were decreased whencompared with those before operation. But the differences were not statisticallysignificant (P>0.05). C2~C3and C3~C4segment flexion-extension activity inboth the3months group and6months group were decreased compared withthose before operation. The difference was statistically significant (P <0.05). TheX-ray images also indicated that the position of the prostheses and the screwsfixation were fine in both the two groups. There was no screw pullout or fracture,no plate fracture or shift. The trabecular bone from the vertebral began graduallyingrowthed to the metal in3months group. In6months group, the trabecularbone ingrowth closer to the surface of metal. CT three-dimensional reconstructionimages showed that the position of prostheses and screws were fine. Thelongitudinal and axial images showed the prostheses and screws did not infringethe spinal canal.4. HE staining results showed that there were no metal wear debris particlesand cell apoptosis in the lymph nodes, spleen, the pre-vertebral tissue and spinalcord tissue in both groups. Micro-CT scan showed that there were densetrabecular between the screws and bone and between the dentate protuberances ofthe prostheses and bone. Compared with the3months group, there were denserand more trabecular between the screws and bone and between the dentateprotuberances of the prostheses and bone in the6month group. Hard-tissue sections indicated that there were a large number of fibrous tissue and a smallamount of cartilage cells between the screws and bone and between the dentateprotuberances and bone in the3months group. In the6months group, part offibrous tissue has changed into the cartilage tissue. There also has visible part ofthe trabecular bone and more cartilage cells.Conclusions:Artificial cervical joint complex can maintain the stability of the cervicalspine and retains the activity of the cervical spine in vivo. Preliminary evidenceconfirmed the prosthesis is safe and effective in vivo applications. It provided theexperimental basis for the clinical application of the prostheses. |
PDF Full Text Request