Application of a modified surgical position in anterior approach for total cervical artificial disc replacement

BACKGROUND Total cervical artificial disc replacement(TDR)has been considered a safe and effective alternative surgical treatment for cervical spondylosis and degenerative disc disease that have failed to improve with conservative methods.Positioning the surgical patient is a critical part of the procedure.Appropriate patient positioning is crucial not only for the safety of the patient but also for optimizing surgical exposure,ensuring adequate and safe anesthesia,and allowing the surgeon to operate comfortably during lengthy procedures.The surgical posture is the traditional position used in anterior cervical approach;in general,patients are in a supine position with a pad under their shoulders and a ring-shaped pillow under their head.AIM To investigate the clinical outcomes of the use of a modified surgical position versus the traditional surgical position in anterior approach for TDR.METHODS In the modified position group,the patients had a soft pillow under their neck,and their jaw and both shoulders were fixed with wide tape.The analyzed data included intraoperative blood loss,position setting time,total operation time,and perioperative blood pressure and heart rate.RESULTS Blood pressure and heart rate were not significantly different before and after body positioning in both groups(P>0.05).Compared with the traditional position group,the modified position group showed a statistically significantly longer position setting time(P<0.05).However,the total operation time and intraoperative blood loss were significantly reduced in the modified position group compared with the traditional position group(P<0.05).CONCLUSION The clinical outcomes indicated that total operation time and intraoperative blood loss were relatively lower in the modified position group than in the traditional position group,thus reducing the risks of surgery while increasing the position setting time.The modified surgical position is a safe and effective method to be used in anterior approach for TDR surgery.

Lumbar and cervical viscoelastic disc replacement:Concepts and current experience

The ideal lumbar and cervical discs should provide six degrees of freedom andtri-planar (three-dimensional) motion. Although all artificial discs are intended toachieve the same goals, there is considerable heterogeneity in the design oflumbar and cervical implants. The “second generation total disc replacements”are non-articulating viscoelastic implants aiming at the reconstruction ofphysiologic levels of shock absorption and flexural stiffness. This review aims togive an overview of the available implants detailing the concepts and thefunctional results experimentally and clinically. These monobloc prostheses raisenew challenges concerning the choice of materials for the constitution of theviscoelastic cushion, the connection between the components of the internalstructure and the metal endplates and even the bone anchoring mode. Newobjectives concerning the quality of movement and mobility control must bedefined.

Effect of total lumbar disc replacement on the treatment of discogenic low lumbar pain： preliminary outcomes

Background Lumbar pedicle screw fixation and fusion are major procedures for treating discogenic low back pain （DLBP）. However, due to its advantages of preserving the segmental motion and biomechanical simulation, artificial total lumbar disc replacement （TDR） is increasingly popular. Methods From 2007 to 2010, 68 DLBP patients were enrolled. TDR were performed on 34 patients and the other 34 controls underwent the traditional fixation procedure. Qualitative and quantitative evaluations were followed including the changes in range of motion （ROM） and interpedicle height （IPH） at the posterior intervertebral body of operated level, in 6 and 12 months, and 3 years, postoperatively. Results Qualitative results showed satisfying improvement in the two groups after 6 and 12 months, respectively, and the inter-group differences were significant （P 〉0.05）. The results of ROM and IPH have shown significant differences between the TDR and spinal fusion groups （P 〈0.05）. Conclusion With similar clinical improvements as the traditional spinal fusion method, TDR offered significantly better ROM and intervertebral foramen hei.qht.

Footprint Mismatch of Cervical Disc Prostheses with Chinese Cervical Anatomic Dimensions

Background：The footprint of most prostheses is designed according to Caucasian data.Total disc replacement （TDR） has been performed widely for cervical degenerative diseases in China.It is essential to analyze the match sizes of prostheses footprints and Chinese cervical anatomic dimensions in our study.Methods：The anatomic dimensions of the C4-C7 segments of 138 patients （age range 16-77 years） in a Chinese population were measured by computed tomography scans.We compared the footprints of the most commonly used cervical disc prostheses （Bryan：Medtronic,Minneapolis,MN,USA; Prestige LP：Medtronic,Fridley,Minnesota,USA; Discover：DePuy,Raynham,MA,USA; Prodisc-C：Synthes,West Chester,PA,USA） in China with Chinese cervical anatomic dimensions and assessed the match of their size.Results：The mismatch of available dimensions of prostheses and anatomic data of cervical endplates ranged from 17.03% （C4/C5,Prestige LP,Prodisc-C） to 57.61% （C6/C7,Discover） in the anterior-posterior （AP） diameter,and 35.51% （C4/C5,Prodisc-C,Prestige LP） to 94.93% （C6/C7,Bryan） in the center mediolateral （CML） diameter.About 21.01% of endplates were larger than the largest prostheses in the AP diameter and 57.25% in the CML diameter.All available footprints of prostheses expect the Bryan with an unfixed height,can accommodate the disc height （DH）,however,36.23% of the middle DH was less than the smallest height of the prostheses.The average disc sagittal angles （DSAs） of C4-C7 junctions were 5.04＆#176;,5.15＆#176;,and 4.13＆#176; respectively.Only the Discover brand had a built-in 7＆#176; lordotic angle,roughly matching with the DSA.Conclusions：There is a large discrepancy between footprints of prostheses and Chinese cervical anatomic data.In recent years,possible complications of TDR related with mismatch sizes are increasing,such as subsidence,displacement,and heterotopic ossification.Manufacturers of prostheses should introduce or produce additional footprints of prostheses for Chinese TDR.