ObjectiveTo evaluate the effectiveness of the single segmental cervical disc replacement with ProDisc-C, and to explore the location change of the flexion/extension center of rotation (COR) of the target level as well as its clinical significance. MethodsBetween June 2010 and February 2012, 23 patients underwent single segmental cervical disc replacement with ProDisc-C, and the clinical data were retrospectively analyzed. Of 23 patients, 9 were male, and 14 were female with the age range from 27 to 65 years (mean, 45 years), and the disease duration ranged from 10 to 84 months (mean, 25 months). There were 15 patients with radiculopathy, 5 patients with myelopathy, and 3 patients with mixed cervical spondylosis. The involved segments were C4,5 in 5 cases, C5,6 in 14 cases, and C6,7 in 4 cases. Japanese Orthopaedic Association (JOA) score and neck disability index (NDI) were adopted to evaluate the effectiveness. Preoperative and Postoperative radiographic parameters, such as cervical overall range of motion (ROM), target segmental ROM, the adjacent segmental ROM, and intervertebral height were compared. Besides, the location changes of the COR of the target level were further analyzed by the alteration of its coordinates (COR-X,COR-Y), and the relationships between the location changes of the COR and the effectiveness or the radiographic results were analyzed. ResultsAll the operations were completed successfully; 1 case had hoarseness after operation, which disappeared at 3 months after operation. All cases were followed up 18.3 months on average (range, 6-36 months). There was no device migration, loosening, subsidence, or fracture at last follow-up. The JOA score increased significantly and the NDI score decreased significantly at last follow-up when compared with preoperative scores (P<0.05). No difference was found in the cervical overall ROM, target segmental ROM, the adjacent segmental ROM, and the COR-Y of the target level between pre-operation and last follow-up (P>0.05); while the intervertebral height and the COR-X increased significantly (P<0.05). The change of the COR-X had no obvious correlation with the postoperative JOA, NDI, and target segmental ROM (P>0.05). According to whether the difference of the COR-X between pre- and post-operation was less than the average value 1.86 mm or not, the patients were divided into 2 groups; significant difference was shown in the postoperative target segmental ROM between 2 groups (P<0.05), but no significant difference was found in the postoperative JOA、NDI, cervical overall ROM, adjacent segmental ROM, and the intervertebral height between 2 groups (P>0.05). ConclusionSingle segmental cervical disc replacement with ProDisc-C can obtain satisfactory outcomes. The cervical overall ROM, target segmental ROM, and adjacent segmental ROM can be effectively maintained, and the intervertebral height is increased. The location of the flexion/extension COR of the target segment shifts forward after insertion of the ProDisc-C prosthesis, and the postoperative target segmental ROM becomes smaller as the distance of the displacement of the COR becomes greater.
ObjectiveTo investigate the influence of uncovertebral joint foraminal part excision on the motion response, stability and clinical outcomes after single-level cervical disc replacement. MethodsThe clinical data of 57 patients with cervical spondylotic radiculopathy, who underwent single-level Prestige LP cervical disc replacement in West China Hospital of Sichuan University from January 2012 to January 2015, were retrospectively analyzed.According to whether to have the uncovertebral joint foraminal part excision in the process of operation, two groups were divided, named excision group and non-excision group.The Japanese Orthopedic Association score (JOA), neck disability index (NDI) and visual analogue score (VAS) were used to evaluate the clinical outcomes pre-and post-operatively.The stability, overall cervical alignment, range of motion of treated levels in flexion-extension and lateral bending, and the transverse and longitudinal diameter of intervertebral foramen were measured by X-ray and CT-3D examination.The complications and reoperations were also recorded. ResultsThere were statistically significant improvement in the JOA, NDI, neck VAS and arm VAS scores in both of the two groups after the surgery (P < 0.05).The improvement of the NDI and the arm VAS scores were more obvious after the surgery in excision group.The overall cervical alignment, the range of motion of treated levels in flexion-extension and lateral bending were well maintained post-operatively (P > 0.05), and the differences between the two groups were not significant (P > 0.05).The transverse diameter of intervertebral foramen was significantly increased in excision group post-operatively (P < 0.05) while the longitudinal diameter was not (P > 0.05);both of the transverse and longitudinal diameter of intervertebral foramen didn't differ much post-operatively in the non-excision group (P > 0.05).All the prostheses showed a good stability.No prostheses shift, dislocation or unfixed prostheses were found. ConclusionUncovertebral joint foraminal part excision can be used in single-level Prestige LP cervical disc replacement, which is safe and reliable.
Objective To analyze the distribution of stress in the upper and lower plates of the prosthesis-bone interface, and the effect of interface pressure on osseointegration. Methods CT scanning was performed on goats at 1 week after artificial cervical disc replacement to establish the finite element model of C3, 4. The stress distribution of the upper and lower plates of the interface was observed. At 6 and 12 months after replacement, Micro-CT scan and three dimensional reconstruction were performed to measure the bone volume fraction (BVF), trabecular number (Tb. N), trabecular thickness (Tb. Th), trabecular separation (Tb. Sp), bone mineral density (BMD), bone surface/bone volume (BS/BV), and trabecular pattern factor (Tb. Pf). The C3 lower plate and C4 upper plate of 4 normal goat were chosen to made the cylinder of the diameter of 2 mm. The gene expressions of receptor activator for nuclear factor κB ligand (RANKL), osteoprotegerin (OPG), transforming growth factor β (TGF-β), and macrophage colony-stimulating factor (M-CSF) were detected by real time fluorescent quantitative PCR at immediate after cutting and at 24 and 48 hours after culture. The samples of appropriate culture time were selected to made mechanical loading, and the gene expressions of RANKL, OPG, M-CSF, and TGF-β were detected by real time fluorescent quantitative PCR; no mechanical loading samples were used as normal controls. Results Under 25 N axial loading, the stress of the upper plate of C3, 4 was concentrated to post median region, and the stress of the lower plate to middle-front region and two orbits. According to stress, the plate was divided into 5 regions. The Micro-CT scan showed that BMD, Tb.Th, BVF, and Tb.N significantly increased, and BS/BV, Tb.Sp, and Tb.Pf significantly decreased at 12 months after replacement when compared with ones at 6 months (P<0.05). At 24 and 48 hours after culture, the gene expressions of RANKL, OPG, and TGF-β were signifi-cantly higher than those at immediate (P<0.05), but no significant difference was found between at 24 and 48 hours after culture (P>0.05). The mechanical loading test results at 24 hours after culture showed that the RANKL and OPG gene expressions and OPG/RANKL ratio in C3 lower plate and C4 upper plate were significantly up-regulated when compared with controls (P<0.05), but no significant difference was shown in TGF-β and M-CSF gene expressions (P>0.05). Conclusion Domestic artificial cervical disc endplate has different pressure distribution, the stress of lower plate is higher than that of upper plate. Pressure has important effect on local osseointegration; the higher pressure area is, the osseointegration is better. Under the maximum pressure in interface, the osteoblast proliferation will increase, which is advantageous to the local osseointegration.
Objective To observe the early effectiveness of cervical disc replacement with Pretic-I, a new type artificial disc. Methods A retrospective analysis was made on the clinical data of 10 patients who underwent single segmental cervical disc replacement with Pretic-I from June to December 2014. Among 10 patients, 4 were male and 6 were female, with an average age of 40 years (range, 27-51 years). The mean disease duration was 15.4 months (range, 4-36 months). Affected segments located at C4, 5 level in 1 case, at C5, 6 level in 8 cases, and at C6, 7 level in 1 case. The visual analogue scale (VAS), Japanese Orthopaedic Association (JOA) score, and neck disability index (NDI) were used to evaluate the clinical outcomes. Besides, the disc height and the range of motion (ROM) at operated level, and ROM of upper and lower adjacent level were measured to assess the function. Results The operation was successfully completed in all patients who were followed up for 12 months. No complications of aggravated nerve symptoms, vertebral artery injury, esophagotracheal fistula, cerebrospinal fluid leakage, incision infection, hematoma and prosthetic loosening were observed during follow-up. The VAS score, JOA score, and NDI significantly improved at each time point after operation when compared with preoperative scores (P<0.05). The height of intervertebral disc at operated level was significantly increased at immediate and 3 months after operation when compared with preoperative one (P<0.05), but no significant difference was found between at 6 months or 12 months after operation and at pre-operation (P>0.05). No significant difference was shown in the ROM at operated level, and ROM of upper and lower adjacent level between at pre-operation and at each time point after operation (P>0.05). Conclusion The early effctiveness of cervical disc replacement using Pretic-I is satisfactory. The symptoms can be relieved significantly and the dynamic features of the operated level, as well as the upper and lower adjacent levels, are well preserved.
ObjectiveTo evaluate long-term radiographic and clinical effectiveness of total cervical disc replacement (TDR) with Prodisc-C prosthesis at a minimum of 10 years follow-up.MethodsThe clinical data of 118 patients with cervical disc degeneration disease (CDDD) treated with TDR by using Prodisc-C prosthesis between December 2005 and April 2008 were retrospectively analyzed. There were 66 males and 52 females, with the age of 25-62 years (mean, 46.8 years). There were 38 cases of cervical spondylotic radiculopathy, 28 cases of cervical spondylotic myelopathy, and 52 cases of mixed cervical spondylotic myelopathy. The operative segments were C3-7, including 90 cases of single segment, 20 cases of continuous double segments, and 8 cases of continuous three segments. A total of 154 Prodisc-C prostheses were used during the operation. The clinical effectiveness was evaluated by pain visual analogue scale (VAS) score, neck disability index (NDI), Japanese Orthopaedic Association (JOA) score, and Odom grade before and after operation. Imaging evaluation indicators included range of motion (ROM), sagittal lordosis angle, intervertebral disc height (IDH), and prosthesis displacement, subsidence, loosening, locking, and heterotopic ossification (HO), adjacent segment degeneration (ASD), and other complications. Patients were grouped according to whether HO or ASD occurred or not, the ROM of surgical segment was compared.ResultsAll patients were followed up 121-150 months (mean, 135.8 months). No revision operation was performed during the follow-up period. The VAS, NDI, JOA scores and Odom grades were significantly improved at 1 week after operation and last follow-up when compared with preoperative ones (P<0.05); VAS and NDI scores were further improved at last follow-up than those at 1 week after operation (P<0.05); there was no significant difference in JOA scores and improvement rates between at 1 week after operation and at last follow-up (P>0.05). The ROM of the whole cervical spine and the operative segment decreased at 1 week and 10 years after operation when compared with preoperative ones (P<0.05), but there was no significant difference in the other time points (P>0.05); there was no significant difference in the ROM between the upper adjacent segment (UAS) and the lower adjacent segment (LAS) at each time point after operation (P>0.05). There was no significant difference in sagittal lordosis angle of cervical spine before and after operation (P>0.05); the sagittal lordosis angle of operative segment increased significantly at 1 week, 6 months, 1 year, and 2 years after operation (P<0.05). The IDH of operative segment was significantly improved at each time point after operation (P<0.05), but there was no significant difference in IDH between UAS and LAS at each time point after operation (P>0.05). No prosthesis displacement, subsidence, or loosening occurred at each time point after operation. There was no significant difference of the prosthetic displacement and subsidence distance between all time points after 6 months after operation (P>0.05). At last follow-up, the incidence of prosthetic locking/fusion was 10.4%, showing no significant difference when compared with 6 months (1.9%) (P<0.05). The incidence of upper ASD and lower ASD was 1.3% and 2.6% respectively at 1 week after operation. The incidence of upper ASD and lower ASD increased gradually with time prolonging, and there were significant differences between different time points (P<0.05). The ROM of operative segment in ASD group was lower than that in non-ASD group at each time point after operation, but there was no significant difference (P>0.05). HO appeared in 58.4% of the segments at 6 months after operation, and the incidence of HO increased significantly with time, which was significantly different from that at 6 months after operation (P<0.05). The ROM of operative segments in HO group was significantly lower than that in non-HO group at 6 months, 2 years, 5 years, and 10 years after operation (P<0.05).ConclusionTDR has little effect on adjacent segments, although there are some imaging complications, it has no significant effect on the improvement of overall clinical effectiveness. Prodisc-C prosthesis can provide long-term, safe, and definite clinical effectiveness in the treatment of CDDD.