The postoperative adjacent segment degeneration between the microscopically anterior cervical discectomy with fusion and anterior cervical corpectomy with fusion in the treatment of cervical spondylotic myelopathy and the influencing factors analysis of / 中国医师进修杂志

Objective:To compare the postoperative adjacent segment degeneration (ASD) between the microscopically anterior cervical discectomy with fusion (ACDF) and anterior cervical corpectomy with fusion (ACCF) in the treatment of cervical spondylotic myelopathy and its influencing factors.Methods:Fifty patients with cervical spondylotic myelopathy treatment in the Qinzhou Second People′s Hospital from July 2018 to July 2020 were selected, they were divided into two groups, 25 patients performed ACDF (ACDF group), and 25 patients performed ACCF (ACCF group). The perioperative period, efficacy and incidence of ASD were compared between the two groups, and the influencing factors of ASD were analyzed.Results:The intraoperative blood loss, operation time, length of hospital stay and postoperative drainage in ACCF group were higher than those in ACDF group: (58.34 ± 8.61) ml vs. (46.77 ± 7.24) ml, (99.57 ± 10.72) min vs. (86.14 ± 9.64) min, (8.97 ± 1.43) d vs. (7.56 ± 1.24) d, (17.92 ± 2.95) ml vs. (14.28 ± 2.66) ml, there were statistical differences ( P<0.05). The postoperative Japanese Orthopaedic Association (JOA) scores and Neck Disability Index (NDI) scores in the two groups were improved significantly ( P<0.05), but the scores of JOA and NDI in the two groups had no significant differences ( P>0.05). The incidence of ASD in the two groups had no significant differences ( P>0.05). The Cox univariate analysis showed that age >59 years, intervertebral disc degeneration, number of fusion segments >2, osteoporosis and postoperative ASD were risk factors for ASD( P<0.05). Conclusions:The effect of microscopically ACDF is similar to that of ACCF in the treatment of cervical spondylotic myelopathy, but ACDF has the advantages of less trauma and quick recovery. The risk of postoperative ASD should be vigilant for patients with age >59 years old, intervertebral disc degeneration, number of fusion segments >2 or osteoporosis.

Three-dimensional finite element analysis of the biomechanical changes of the lumbar spine after the combination of intervertebral fusion with dynamic internal fixation of the interspinous process in the lumbosacral region / 中国组织工程研究

BACKGROUND: The Topping-off technique, which combines lumbar fusion with the dynamic internal fixation system (Coflex), can not only reduce the pressure, but also protect the adjacent segments. There is no relevant mechanical analysis performed on the rationality of the application of Topping-off technique to young patients with the need for fusion on the lumbosacral region and adjacent degenerated segments. OBJECTIVE: To establish a finite element model of Topping-off surgery on the lumbosacral junction and to analyze the biomechanical changes of the adjacent segments and the range of motion trend of the lumbar spine. METHODS: A healthy young male volunteer with no previous history of low back pain or congenital malformations was randomly selected for thin-slice CT scanning after signed the informed consent. The image information was imported into the computer and the whole lumbar spine model as the healthy group model was established by analyzing the image information through Mimics, Geomagic Studio 12.0, HyperMesh and Abaqus successively. After verifying the effectiveness of the model, the moderate degeneration model of intervertebral disc was established by changing the material properties of L4-s1 discs on the basis of the healthy model, and the fusion model and Topping-off model were respectively established on the basis of the degeneration model. After applying 400 N compressive load and 10 N-m momentum to the four groups of models, the variation trends of range of motion from L2 to L5 and the stress changes of L4/L5 intervertebral disc, nucleus pulposus and facet joints were calculated respectively. RESULTS AND CONCLUSION: (1) Compared with the degeneration model, the lumbar range of motion of Topping-off model and fusion model decreased, and the Topping-off model decreased more significantly than the fusion model. (2) The range of motion of fusion model L4-L5 increased significantly and the range of motion of L2/L3 and L3/L4 segments did not change significantly. Compared with the degeneration model, the L4-L5 range of motion of Topping-off model decreased, and range of motion of the L2/L3 and L3/L4 levels increased to some extent in the flexion and extension positions. (3) Compared with the degeneration model, the stress on the disc, nucleus pulposus and facet joint of the fusion model L4-L5 increased in four positions of flexion, extension, rotation and bending, while the fiber stress on the Topping-off model decreased significantly in all four positions. (4) These results suggest that Topping-off technology can not only reduce the stress on the upper adjacent degenerative intervertebral disc, nucleus pulposus and facet joints, but also reduce the hyperactivity of the adjacent segments and increase the range of motion of other upper segments, thereby compensating the lumbar spine mobility and delaying the degeneration of upper adjacent segments.

Finite element analysis and in vitro biomechanical experiment of new domestic lumbar interspinous process distraction device / 中国组织工程研究

BACKGROUND: The non-fusion system of lumbar interspinous process distraction device provides a new treatment option for lumbar degenerative diseases. However, at present, the clinical application and research of lumbar interspinous process distraction device are reported insufficiently in China, especially for the domestic lumbar interspinous process distraction device. OBJECTIVE: To verify the scientific nature and effectiveness of the new domestic lumbar interspinous process distraction device through finite element analysis and in vitro biomechanical experiment of goat lumbar spine. METHODS: (1) Finite element analysis of new domestic lumbar interspinous process distraction device: L2-L5 three-dimensional model of vertebral body was established based on normal adult lumbar CT data. From then on, new domestic lumbar interspinous process distraction device model, new lumbar interspinous process distraction device model of lumbar non fusion system were successively built. The mechanical conditions were given under the physiological conditions of lumbar spine. Biomechanical analysis was carried out before and after the new domestic lumbar interspinous process distraction device was implanted. (2) In vitro biomechanical analysis of new domestic lumbar interspinous process distraction device: the lumbar vertebrae (L1-L5) of 24 adult male goats were obtained, and the new domestic lumbar interspinous process distraction device was implanted between the L3-4 spinous process. Before and after the placement of the lumbar interspinous process distraction device, the lumbar motion range and the pressure of the intervertebral disc under the flexion, extension, lateral bending and rotation of the lumbar specimens were detected. RESULTS AND CONCLUSION: (1) After the new lumbar interspinous process distraction device was implanted, the motion range and the pressure of the intervertebral disc of responsible segment were reduced, while the adjacent segments' mobility and the pressure of the intervertebral disc were almost unaffected. It was theoretically verified that the new domestic lumbar interspinous process distraction device could provide the biomechanical basis for the treatment of the lumbar degenerative diseases, and contribute to the theoretical reference for the prevention of the clinical diseases. (2) In the state of extension, the motion range of L3-4 vertebral body after implanting the new lumbar interspinous process distraction device was significantly lower than that before implantation (P 0. 05). In the state of flexion, lateral bending and rotation, there was no significant difference between L2-3, L3-4 and L4-5 vertebral body after implanting the lumbar interspinous process distraction device and that before implantation (P > 0. 05). In the state of extension, the pressure of intervertebral disc after L3-4 vertebral body implantation was significantly lower than that before implantation (P 0. 05). In the state of flexion, lateral bending and rotation, there was no significant difference between L2-3, L3-4 and L4-5 vertebral body implantation and that before implantation (P > 0. 05). (3) The results showed that the scientific nature and validity of the new domestic lumbar interspinous process distraction device was verified by three-dimensional finite element analysis and in vitro animal lumbar specimens experiment, which provided a strong basis for the animal experiment, clinical experiment, clinical application and clinical production of the new domestic lumbar interspinous process distraction device.

Biomechanical characteristics of transforaminal lumbar interbody fusion combined with different pedicle screw fixation methods in single-segment lumbar spine and adjacent segments / 中国组织工程研究

BACKGROUND: Decompression-fixation-fusion is the key to spinal surgery since early effective fixation to achieve intervertebral fusion can restore spinal stability in lumbar degenerative disease. OBJECTIVE: To compare biomechanical stability of fusion segment and adjacent segments of bilateral pedicle screw fixation, unilateral pedicle screw fixation and unilateral pedicle screw combined with contralateral translaminar facet screw fixation under transforaminal lumbar interbody fusion. METHODS: Eighteen fresh calf L3-5 specimens were selected. Different forms of fixation were conducted under transforaminal lumbar interbody fusion. The specimens were divided into group A (complete specimens) and group B (bilateral pedicle screws), group C (unilateral pedicle screws), and group D (unilateral pedicle screw combined with contralateral translaminar facet screw). The range of motion of adjacent segment L3-4 and fusion segment L4-5 in six directions of backward extension, forward bending, left bending, right bending, left rotation and right rotation and the stiffness of fusion segment L4-5 were tested. RESULTS AND CONCLUSION: (1) For the range of motion of fusion segment L4-5, the stability was highest in the group B in six directions, followed by group D, which showed similar results in rotation in the group B (P > 0.05). The stability of right curvature and left rotation in group C was insufficient, and there was no significant difference in range of motion between group A and group C (P > 0.05). The range of motion in group A was largest and the stability was worst in the six motion directions. (2) For the stiffness value of fusion segment L4-5, the stiffness value of group B was largest in six directions, which was significantly different from other groups (P 0.05). There was no significant difference between group C and group A in the range of motion of six directions (P > 0.05). (4) The results showed that the motion ramge of unilateral pedicle screw fixation in the right and left rotation directions was large in the early stage, which was close to that of the complete specimen group. There is a shortage of stability, so we need to use it carefully and grasp the indications strictly. Unilateral pedicle screw fixation combined with contralateral translaminar facet screw fixation improves the disadvantages of asymmetric fixation of unilateral pedicle screw, increases the stability of rotation and lateral bending, and avoids the influence of bilateral pedicle screw fixation on adjacent segments, thus becoming an effective clinical surgical treatment.

Long-term effectiveness of posterior lumbar interbody fusion of retaining posterior ligamentous complex / 中国修复重建外科杂志

Objective: To compare the long-term effectiveness of wheather posterior ligamentous complex (PLC) preserved between posterior fenestration decompression interbody fusion and posterior total laminectomy interbody fusion. Methods: The clinical data of 89 patients who suffered from single segmental degenerative diseases of lower lumbar spine and followed up more than 10 years after receiving lumbar spinal fusion between January 2000 and January 2005 were retrospectively analysed. The patients were divided into two groups according to the different surgical methods, the 33 patients in group A were treated with posterior lumbar fenestration decompression, interbody fusion, and internal fixation, while 56 patients in group B were treated with posterior total laminectomy resection decompression, interbody fusion, and internal fixation. There was no significant difference in gender, age, body mass index, type of lesion, disease duration, lesion segment, and preoperative Japanese Orthopedic Association (JOA) score, visual analogue scale (VAS) score, and Cobb angle of lumbar lordosis between the two groups ( P>0.05). The effectiveness was evaluated by JOA score, and the improvement of pain was evaluated by VAS score. The incidence of adjacent segment degeneration (ASD) at last follow-up was recorded. Results: Both groups were followed up 10-17 years (mean, 12.6 years). There were 3 cases (9.1%) in group A and 5 cases (8.9%) in group B complicated with cerebrospinal fluid leakage, showing no significant difference ( χ2=0.001, P=0.979). There was no complication such as infection, nerve root injury, internal plant loosening or transposition in both groups. Intervertebral fusion was satisfactory in both groups. The fusion time in groups A and B was (3.4±1.2) months and (3.7±1.6) months respectively, and there was no significant difference between the two groups ( t=0.420, P=0.676). At last follow-up, the JOA score and VAS score of the two groups were significantly improved when compared with preoperative ones ( P<0.05); there was no significant difference in Cobb angle of lumbar lordosis before and after operation in group A ( t=0.293, P=0.772), but the Cobb angle of lumbar lordosis in group B was significantly lost at last follow-up ( t=14.920, P=0.000). At last follow-up, the VAS score and Cobb angle of lumbar lordosis in group A were significantly superior to those in group B ( P<0.05); there was no significant difference in JOA score between the two groups ( t=0.217, P=0.828). There were 3 cases (9.1%) in group A and 21 cases (37.5%) in group B complicated with ASD, showing significant difference between the two groups ( χ2=8.509, P=0.004). Conclusion: Long-term effectiveness of both groups was satisfactory, but in terms of maintaining lumbar lordosis and reducing the incidence of ASD, the lumbar fusion retaining PLC is superior to total laminectomy and lumbar fusion removing PLC.

Effect of pre-existing adjacent segment degeneration on short-term effectiveness after lumbar fusion surgery / 中国修复重建外科杂志

Objective: To analyze the prospective effect of pre-existing spinal stenosis of adjacent segment on the short-term effectiveness after lumbar fusion surgery. Methods: A prospective comparative study was conducted to divide 183 patients with L 4-S 1 lumbar spinal stenosis who met the selection criteria between July 2015 and December 2017 into two groups according to the status of adjacent segment degeneration (ASD) judged by preoperative disc degeneration and spinal stenosis. There were 98 patients in group A (no degeneration of adjacent segments before operation) and 85 patients in group B (adjacent segments degenerated before operation). There was no significant difference in gender, American Society of Anesthesiologists (ASA) grade, body mass index (BMI), combined spondylolisthesis, and preoperative visual analogue scale (VAS) score of low back pain and leg pain, Japanese Orthopaedic Association (JOA) score, and Oswestry disability index (ODI) score between the two groups ( P>0.05); the age of group A was significantly younger than that of group B ( t=-3.560, P=0.000). The operation time, intraoperative blood loss, hospitalization stay, and perioperative complications were recorded and compared. The VAS score of low back pain and leg pain, JOA score, and ODI score at last follow-up were used to evaluate the effectiveness. The incidence of ASD after operation was compared between the two groups, and logistic regression was used to analyze the independent risk factors affecting the occurrence of ASD after operation. Results: There was no significant difference in operation time, intraoperative blood loss, and hospitalization stay between the two groups ( P>0.05). The incidence of perioperative complications in groups A and B was 13.3% and 20.0%, respectively, with no significant difference ( χ2=1.506, P=0.220). Two groups of patients were followed up, the follow-up time of groups A and B was (24.9±8.8) months and (24.8±7.8) months, respectively, there was no significant difference ( t=0.050, P=0.960). At last follow-up, no adjacent segment disease was found in either group. There was no significant difference in Pfirrmann grade between the two groups at last follow-up ( P>0.05), and there was significant difference in Pfirrmann grade between the two groups before operation and at last follow-up ( P<0.001). At last follow-up, 21 cases (21.4%) in group A and 53 cases (62.4%) in group B had ASD, with significant difference ( χ2=31.652, P=0.000). The main cause of ASD was the severity of adjacent spinal canal stenosis. The clinical scores of the two groups at last follow-up were significantly improved when compared with those before operation ( P<0.05). The JOA score of group A was significantly higher than that of group B at last follow-up ( P<0.05). In group B, the VAS score of low back pain and ODI score in patients with ASD after operation at last follow-up were significantly higher than those in patients without ASD ( P<0.05). logistic regression analysis showed that preoperative pre-existing degeneration and BMI were independent risk factors for ASD after operation ( P<0.05). Conclusion: Pre-existing mild spinal stenosis in adjacent segment can significantly affect the effectiveness, and can significantly increase the risk of ASD early after operation. The main pathological type of ASD was the severity of adjacent segment spinal stenosis. For preoperative assessment of pre-existing degeneration, we should evaluate the overall degeneration of the adjacent segment of the spinal canal, rather than simply evaluating the degeneration of the adjacent disc and facet joints.

Effects of Preserving Posterior Ligament Complex on Biomechanical Properties of the Adjacent Segments after Lumbar Decompression and Fusion / 医用生物力学

Objective To compare the effects of preserving the posterior ligament complex (PLC) with torque loading and displacement loading on the biomechanical properties of the adjacent segments after lumbar decompression and fusion. Methods Six fresh male cadaver lumbar specimens of T12-S2 were tested in the sequence of intact, L4-5 laminotomy (preserving the PLC) with fixation and L4-5 laminectomy (destructing the PLC) with fixation, by applying both displacement loading and torque loading, respectively. Ranges-of-motions (ROMs) of the adjacent segments were measured under a noncontact photographic recording system. Results In displacement-loading mode, the flexion ROM in laminectomy group was significantly higher than that in laminotomy group, and no obvious ROM differences were found in the laminectomy and laminotomy groups under extension, lateral bending, and rotation movement. Conclusions Torque loading and displacement loading have different biomechanical effects on the adjacent segments after lumbar decompression and fusion. Compared with the laminotomy method, in which the PLC is preserved, the laminectomy method in which PLC structures are damaged can obviously lead to an increment of flexion ROMs at the adjacent segments, and also increase the ROMs of the adjacent segments under extension, lateral bending, and rotation movements, which might increase the risk of further instability of the fused adjacent segments.

Postoperative Radiographic Early-Onset Adjacent Segment Degeneration after Single-Level L4–L5 Posterior Lumbar Interbody Fusion in Patients without Preoperative Severe Sagittal Spinal Imbalance

STUDY DESIGN: Retrospective study. PURPOSE: To investigate the relationship between preoperative total spinal sagittal alignment and the early onset of adjacent segment degeneration (ASD) after single-level posterior lumbar interbody fusion (PLIF) in patients with normal sagittal spinal alignment. OVERVIEW OF LITERATURE: Postoperative early-onset ASD is one of the complications after L4–L5 PLIF, a common surgical procedure for lumbar degenerative disease in patents without severe sagittal imbalance. A better understanding of the preoperative characteristics of total spinal sagittal alignment associated with early-onset ASD could help prevent the condition. METHODS: The study included 70 consecutive patients diagnosed with lumbar degenerative disease who underwent single-level L4–L5 PLIF between 2011 and 2015. They were divided into two groups based on the radiographic progression of L3–L4 degeneration after 1-year follow-up: the ASD and the non-ASD (NASD) group. The following radiographic parameters were preoperatively and postoperatively measured: sagittal vertebral axis (SVA), thoracic kyphosis (TK), lumbar lordosis, pelvic tilt, and pelvic incidence (PI). RESULTS: Eight of the 70 patients (11%) experienced ASD after PLIF (three males and five females; age, 64.4±7.7 years). The NASD group comprised 20 males and 42 females (age, 67.7±9.3 years). Six patients of the ASD group showed decreased L3–L4 disc height, one had L3–L4 local kyphosis, and one showed both changes. Preoperative SVA, PI, and TK were significantly smaller in the ASD group than in the NASD group (p <0.05). CONCLUSIONS: A preoperative small SVA and TK with small PI were the characteristic alignments for the risk of early-onset ASD in patients without preoperative severe sagittal spinal imbalance undergoing L4–L5 single-level PLIF.

Radiographic and Clinical Outcomes of Robot-Assisted Posterior Pedicle Screw Fixation: Two-Year Results from a Randomized Controlled Trial

PURPOSE: We prospectively assessed the early radiographic and clinical outcomes (minimum follow-up of 2 years) of robot-assisted pedicle screw fixation (Robot-PSF) and conventional freehand pedicle screw fixation (Conv-PSF). MATERIALS AND METHODS: Patients were randomly assigned to Robot-PSF (37 patients) or Conv-PSF (41 patients) for posterior interbody fusion surgery. The Robot-PSF group underwent minimally invasive pedicle screw fixation using a pre-planned robot-guided screw trajectory. The Conv-PSF underwent screw fixation using the freehand technique. Radiographic adjacent segment degeneration (ASD) was measured on plain radiographs, and clinical outcomes were measured using visual analogue scale (VAS) and Oswestry disability index (ODI) scores regularly after surgery. RESULTS: The two groups had similar values for radiographic ASD, including University California at Los Angeles grade, vertebral translation, angular motion, and loss of disc height (p=0.320). At final follow-up, both groups had experienced significant improvements in back VAS, leg VAS, and ODI scores after surgery (p < 0.001), although inter-group differences were not significant for back VAS (p=0.876), leg VAS (p=0.429), and ODI scores (p=0.952). In the Conv-PSF group, revision surgery was required for two of the 25 patients (8%), compared to no patients in the Robot-PSF group. CONCLUSION: There were no significant differences in radiographic ASD and clinical outcomes between Robot-PSF and Conv-PSF. Thus, the advantages of robot-assisted surgery (accurate pedicle screw insertion and minimal facet joint violation) do not appear to be clinically significant.

Long-Term Outcome of Dynesys Dynamic Stabilization for Lumbar Spinal Stenosis / 中华医学杂志(英文版)

<p><b>Background</b>Many clinical studies over the past decade have indicated positive outcomes for patients treated with Dynesys dynamic stabilization for lumbar degenerative disease. However, long-term outcomes of Dynesys for lumbar spinal stenosis are rarely reported. The aim of this study was to analyze the long-term clinical and radiologic outcomes for patients with lumbar spinal stenosis treated with Dynesys stabilization.</p><p><b>Methods</b>Thirty-eight patients with lumbar spinal stenosis were treated with Dynesys stabilization from July 2008 to March 2010. The minimal duration of follow-up was 72 months. The patients were divided into stenosis and spondylolisthesis groups according to degenerative spondylolisthesis. Clinical outcomes were evaluated using the Oswestry Disability Index (ODI) and visual analog scale (VAS). Radiographic evaluations included range of motion (ROM) and the disc heights of stabilized segments and the upper adjacent segments. We also evaluated the occurrence of radiographic and symptomatic adjacent segment degeneration (ASD).</p><p><b>Results</b>There were 23 patients in stenosis group and 15 patients in spondylolisthesis group. The ODI scores were significantly improved at the final follow-up evaluation, as compared to the baseline values (16.1 ± 5.7 vs. 57. 2 ± 14.2, t = 61.41, P < 0.01). The VAS scores for back and leg pain were significantly improved from 4.82 ± 0.89 and 4.04 ± 0.82 preoperatively to 0.93 ± 0.61 and 0.54 ± 0.51 postoperatively (t = 6.59, P < 0.01, and t = 5.91, P < 0.01, respectively). There were no differences between the two groups with respect to VAS and ODI scores. The ROM of stabilized segments decreased significantly from 7.8° ± 2.4° to 4.5° ± 1.5° (t = 7.18, P < 0.05), while the upper adjacent segments increased significantly from 8.3° ± 2.4° to 10.4° ± 2.4° (t = 2.87, P = 0.01). The change in disc height of stabilized segments was not significant (11.9 ± 2.1 preoperatively vs. 12.5 ± 1.5 postoperatively, t = 1.43, P = 0.15), whereas the decrease in disc height of the upper adjacent segments was significant (12.5 ± 2.0 preoperatively vs. 11.0 ± 1.7 postoperatively, t = 2.94, P = 0.01). The occurrence of radiographic and symptomatic ASD was 16% (6/38) and 3% (1/38), respectively.</p><p><b>Conclusions</b>Decompression and Dynesys stabilization for lumbar stenosis with or without spondylolisthesis showed good long-term clinical and radiographic results. Lumbar stenosis with or without Grade I spondylolisthesis, particularly in patients <60 years of age with mild-to-moderate lumbar disc degeneration, would be one of the main indications for the Dynesys system.</p>

Analysis of clinical effects in the treatment of single-segment lumbar degenerative disease by lamina osteotomy and former vertebral plates regraft / 中国骨伤

<p><b>OBJECTIVE</b>To compare the clinical effect between the lamina osteotomy and former vertebral plates regraft method and total laminectomy and interbody fusion method in treating single-segment lumbar degenerative disease.</p><p><b>METHODS</b>The clinical data of 167 patients with single-segment lumbar degenerative disease underwent surgical treatment from January 2010 to December 2014 were retrospectively analyzed. There were 92 males and 75 females, aged from 45 to 75 years old with an average of (59.6±12.4) years. The patients were divided into lamina osteotomy and former vertebral plates regraft group(82 cases) and total laminectomy and interbody fusion group(85 cases) according to the different surgical methods used. The general conditions and clinical effects were compared between two groups. General conditions included the operation time, intraoperative blood loss, postoperative drainage, hospitalization time and the clinical effects included the visual analogue scale (VAS), Japanese Orthopaedic Association(JOA), Oswestry Dability Index(ODI), MacNab results, epidural fibrosis (EF), the incidence of adjacent segment degeneration (ASD).</p><p><b>RESULTS</b>All the patients were followed for 18 to 36 months with an average of (24.8±5.7) months, furthermore, there was no significant difference in the follow-up time between two groups. There was no significant difference in general conditions such as operation time, intraoperative blood loss, postoperative drainage, or hospitalization time between two groups. At final follow-up, the VAS, ODI, JOA, of all patients were significantly improved (<0.05);and the three factors above in the lamina osteotomy and former vertebral plates regraft group respectively were(2.0±1.1) points, (24.0±1.8) %, (19.8±8.2) point, while the results of total laminectomy and interbody fusion group were(2.5±1.6) points, (23.3±2.0)%, and(22.5±8.5) point;there was statistical difference between two groups(<0.05). According to the standard of MacNab, 59 cases obtained excellent results, 20 good, 3 fair results in the lamina osteotomy and former vertebral plates regraft group;while 47 cases got excellent results, 26 good, and 12 fair results in the total laminectomy and interbody fusion group;there was significant difference between two groups(<0.05). Sixteen patients(19.51%) with EF and 20 patients(24.39%) with ASD were found in lamina osteotomy and former vertebral plates regraft group;and 30 patients(35.29%) with EF and 37 patients(43.53%) with ASD were found in total laminectomy and interbody fusion group; there was significant difference between two groups(<0.05).</p><p><b>CONCLUSIONS</b>Both two methods can achieve the ideal effects for the treatment of single-segment lumbar degenerative disease, but the lamina osteotomy and former vertebral plates regraft method can reserve the integrity of posterior ligamentous complex, reducing the incidence of EF and ASD, and is a better surgical method.</p>

Analysis of clinical outcomes of simplified treatment of lumbar spondylolisthesis with adjacent segment degeneration by MAST Quadrant / 中国骨伤

<p><b>OBJECTIVE</b>To explore the method and clinical effect of MAST Quadrant for lumbar spondylolisthesis with adjacent segment degeneration.</p><p><b>METHODS</b>From April 2014 to January 2016, 36 cases of lumbar spondylolisthesis with adjacent segment degeneration were treated by MAST Quadrant(target nerve decompression and transforaminal lumbar interbody fusion or articulationes zygapophysiales fusion by unilateral fixation with MAST Quadrant). Twenty-three cases were degenerative lumbar spondylolisthesis and 13 cases were isthmic lumbar spondylolisthesis. According to Meyerding grade of spondylolisthesis, 16 cases were grade I, 17 cases were grade II, and 3 cases were grade III. Visual analogue score (VAS), Oswesty Disability Index (ODI) and JOA score were used to evaluate the clinical outcome.</p><p><b>RESULTS</b>The amount of intraoperative bleeding was 230 to 480 ml with an average of 340 ml and the amount of postoperative blood loss was 15 to 80 ml with an average of 43 ml. Operative time was 176 to 240 min with an average of 193 min; X-ray exposure time was 2 to 6 s with an average of 3.6 s. Two cases were complicated with dural tear without nerve injury during operation. Thirty cases were followed up from 12 to 17 months with an average of 15.2 months. VAS scores for preoperative, 5 days, 3 months after surgery were 7.6±1.7, 1.9±0.4, 0.8±0.4 respectively, and there was significant difference before and after operation(<0.05). The ODI scores for preoperative and 3 months after surgery were 35.9±1.2 and 3.7±0.7 respectively, and there was significant difference before and after operation(<0.05). JOA scores for preoperative, 5 days, 1 months, 3 months after surgery were 13.2±0.4, 24.4±0.4, 27.4±0.1, 27.9±0.5 respectively, and there was significant difference before and after operation(<0.05).</p><p><b>CONCLUSIONS</b>MAST Quadrant can be applied to treat lumbar spondylolisthesis with adjacent segment degeneration, and the minimally invasive sugical technique is a safe and effective method, with the advantage of simple operation, fast recovery.</p>

Changes in the Adjacent Segment After Thoracolumbar Posterior Instrumentation and Fusion Surgery in Thoracolumbar Junction Fractures

STUDY DESIGN: Retrospective study. OBJECTIVES: To evaluate changes in the adjacent segment after posterior instrumentation and fusion in thoracolumbar spinal fractures. SUMMARY OF LITERATURE REVIEW: The incidence of adjacent-segment disease is increasing as spinal surgery becomes more common. Many studies have been conducted on the risk factors for adjacent-segment changes in the lumbar spine, but few articles have been published on this topic in the thoracolumbar spine. MATERIALS AND METHODS: The records of 50 patients who received treatment from 2000 to 2013 were reviewed retrospectively. They underwent posterior instrumentation and fusion due to thoracolumbar fracture and were followed up for more than 2 years. To evaluate changes in the adjacent segment, immediate postoperative and last follow-up values of the sagittal angle, disc height, and disc angle were compared between groups divided by age (more or less than 50 years), laminectomy, and fusion levels. The Pfirrmann grade of the discs proximal and distal to the fusion level was also measured using preoperative magnetic resonance imaging. RESULTS: Thirty-six patients were male and 14 were female. The average age of the 50 patients was 45.6 years, and the mean follow-up period was 4.3 years. There were no cases of adjacent-segment disease. The mean kyphotic sagittal angle progression was 6.8° (range, −11° to 28.5°, p=0.000). The mean change of disc height of the proximal adjacent segment was 0.3 mm (range, −1.6 to 3.4 mm, p=0.013) and 0.6 mm (range, −4.1 to 5.8 mm, p=0.013) in the distal adjacent segment. Laminectomy did not make a significant difference. In the group below 50 years of age, the angle of the adjacent segment discs increased by 0.8° (range, −3.1° to 5.1°, p=0.004) at the proximal adjacent segment and by 0.5°(range, −4.8° to 2.9°, p=0.016) at the distal adjacent segment. Proximal adjacent disc height decreased as the fusion levels increased. As the preoperative Pfirrmann grade increased, degenerative changes in the proximal adjacent segment disc tended to accelerate. CONCLUSIONS: Adjacent-segment disease after lumbar fusion surgery was not found in adjacent segments of the thoracolumbar spine. This seems to be due to the anatomical characteristics of the lumbar spine, which is more flexible than the thoracolumbar vertebra. The mobile segments of the lumbar spine may account for this difference, rather than the instrumentation and fusion procedure itself.

Radiologic Findings and Risk Factors of Adjacent Segment Degeneration after Anterior Cervical Discectomy and Fusion : A Retrospective Matched Cohort Study with 3-Year Follow-Up Using MRI

OBJECTIVE: The purpose of this study was to figure out the radiologic findings and risk factors related to adjacent segment degeneration (ASD) after anterior cervical discectomy and fusion (ACDF) using 3-year follow-up radiography, computed tomography (CT), and magnetic resonance image (MRI). METHODS: A retrospective matched comparative study was performed for 64 patients who underwent single-level ACDF with a cage and plate. Radiologic parameters, including upper segment range of motion (USROM), lower segment range of motion (LSROM), upper segment disc height (UDH), and lower segment disc height (LDH), clinical outcomes assessed with neck and arm visual analogue scale (VAS), and risk factors were analyzed. RESULTS: Patients were categorized into the ASD (32 patients) and non-ASD (32 patients) group. The decrease of UDH was significantly greater in the ASD group at each follow-up visit. At 36 months postoperatively, the difference for USROM value from the preoperative one significantly increased in the ASD group than non-ASD group. Preoperative other segment degeneration was significantly associated with the increased incidence of ASD at 36 months. However, pain intensity for the neck and arm was not significantly different between groups at any post-operative follow-up visit. CONCLUSION: The main factor affecting ASD is preoperative other segment degeneration out of the adjacent segment. In addition, patients over the age of 50 are at higher risk of developing ASD. Although there was definite radiologic degeneration in the ASD group, no significant difference was observed between the ASD and non-ASD groups in terms of the incidence of symptomatic disease.

In vivo biomechanical study of cervical spine kinematics / 医用生物力学

The traditional method of in vitro biomechanical study cannot simulate the realistic environment in human body due to the limitation of in vitro technology. Using advanced imaging techniques and testing methods, in vivo biomechanical studies of cervical spine kinematics can directly observe the cervical spine motion of living subjects. The data obtain repeats physiological situations and has important implications for improvement in clinical practice. In this paper, the biomechanical research methods of cervical spine kinematics, as well as the development process and current status were reviewed. The postoperative changes in cervical spine kinematics and the effects on adjacent segments following cervical spine fusion and cervical disc arthroplasty surgery were analyzed. The future developments in cervical spine research were also discussed.

Viscoelastic properties of adjacent segments during prolonged flexion after anterior intervertebral fusion / 医用生物力学

Objective To analyze the viscoelastic properties of adjacent segments after anterior fusion under prolonged flexion, and further reveal the mechanism of accelerated adjacent segment degeneration after intervertebral fusion. Methods The same prolonged flexion lasted 30 minutes was applied on the two-level ovine lumbar specimen before and after anterior fusion respectively, and the moment relaxation and viscoelastic deformation of adjacent segments were measured. The moment relaxation curves from two groups were then fitted to obtain the quantitative viscoelastic results. Results After fusion，the initial and final moment in two groups significantly increased by 30.68% and 34.34%, and the viscoelastic deformation of the adjacent segments increased by 28.21%. The Prony model could perfectly fit the moment relaxation curves (R2=99.50%). The integral stiffness significantly increased by 47.82% and 31.14% for two groups, while the viscoelasticity significantly decreased by 27.19% and 28.16%, respectively(P<0.05). Conclusions After intervertebral fusion, to maintain the same posture with the same time, the joints should bear larger loads than before. The viscoelastic deformation of adjacent segments becomes larger, which increases the risk of instability or injury, and further leads to the accelerated degeneration of adjacent segments. The mechanism of quasi-static daily loading on adjacent segment degeneration should be focused in clinical research.

Survival Rates and Risk Factors for Cephalad and L5-S1 Adjacent Segment Degeneration after L5 Floating Lumbar Fusion : A Minimum 2-Year Follow-Up

OBJECTIVE: Although the L5-S1 has distinct structural features in comparison with other lumbar spine segments, not much is known about adjacent segment degeneration (ASD) at the L5-S1 segment. The aim of study was to compare the incidence and character of ASD of the cephalad and L5-S1 segments after L5 floating lumbar fusion. METHODS: From 2005 to 2010, 115 patients who underwent L5 floating lumber fusion were investigated. The mean follow-up period was 46.1 months. The incidence of radiological and clinical ASD of the cephalad and the L5-S1 segments was compared using survival analysis. Risk factors affecting ASD were analyzed using a log rank test and the Cox proportional hazard model. RESULTS: Radiological ASD of the L5-S1 segment had a statistically significant higher survival rate than that of the cephalad segment (p=0.001). However, clinical ASD of the L5-S1 segment was significantly lower survival rates than that of the cephalad segment (p=0.038). Risk factor analysis showed that disc degeneration of the cephalad segment and preoperative spinal stenosis of the L5-S1 segment were risk factors. CONCLUSION: In L5 floating fusion, radiological ASD was more common in the cephalad segment and clinical ASD was more common in the L5-S1 segment. At the L5-S1 segment, the degree of spinal stenosis appears to be the most influential risk factor in ASD incidences, unlike the cephalad segment.

New Classification for Clinically Symptomatic Adjacent Segment Pathology in Cervical Disc Disease

STUDY DESIGN: Clinical adjacent segment pathology (CASP) is common after cervical disc surgery. A critical examination of 320 patients operated for cervical disc prolapse revealed that CASP can also occur in patients with congenital and degenerative fusion of cervical spine. This has not been studied in depth and there is a need for a practically applicable classification of CASP. PURPOSE: To develop a new classification scheme of CASP. OVERVIEW OF LITERATURE: A review of the literature did not reveal a practically applicable classification incorporating the occurrence of CASP in congenital and degenerative fusion cases. METHODS: This was a retrospective analysis of 320 patients operated (509 disc spaces) on for cervical disc prolapse. Cases (n=316) were followed-up for 3-11 years. Random sampling of 220 patients with postoperative magnetic resonance imaging (MRI) in 165 cases was analyzed. RESULTS: Six symptomatic CASP cases required resurgery (1.9%), eight cases involved MRI proven CASP with axial neck pain only and 13 patients were asymptomatic with radiological adjacent segment pathology (RASP). The frequency rate was 8.5% (27/316). Four cases of congenital or degenerative fusion of vertebra developed CASP requiring surgery. CASP is classified as primary or secondary follows. Primary A1 was congenital fusion of vertebra and primary A2 was degenerative fusion of the vertebra. Secondary, which was after cervical disc surgery, comprised B1 (RASP in asymptomatic patients), B2 (CASP in patients with axial neck pain), and B3 (CASP with myeloradiculopathy). B3 was subdivided into single-level CASP (B3a) and multiple-level CASP (B3b). CONCLUSIONS: Symptomatic CASP requiring resurgery is infrequent. CASP can occur in patients with congenital and degenerative fusion of the cervical spine. A new classification for CASP along with treatment strategy is proposed. Patients in Primary CASP and B3 CASP require resurgery while others require only observation.

Does Preoperative Cervical Sagittal Alignment And Range of Motion Affect Adjacent Segment Degeneration After Anterior Arthrodesis In Degenerative Cervical Spinal Disorders?: Midterm Follow up Study

STUDY DESIGN: Retrospective study. OBJECTIVES: The purpose of this study was to investigate whether preoperative sagittal alignment and range of motion (ROM) affect adjacent segment degeneration (ASD) and disease after anterior arthrodesis in degenerative cervical spinal disorders. Summary of Literature Review:There is no study about the relationship between preoperative ROM and sagittal alignment and the development of ASD yet. MATERIALS AND METHODS: We took a retrospective approach to study 136 patients who underwent an anterior arthodesis for less than 2 segments with PEEK cage and plate construct method for degenerative cervical diseases and who have a minimum of 3 years of follow-up. We analyzed ASD and cervical ROM, such as less than 40degrees(group A) and more than 40degrees(group B) and sagittal alignment, such as lordosis or kyphosis with less than 10degrees(group a), 10degrees~30degrees(group b) and more than 30degrees(group c). Adjacent segment degeneration was graded according to Park's classification and Hillibrand method. RESULTS: There was no statistically significant difference between group A(1.35+/-0.48) and group B (1.44+/-0.50) in the correlation between the cervical ROM and the variation of disc height(p=0.07). Concerning the relationship between the ROM and osteophyte formation on adjacent segment, no statistically significant difference has been found between group A(1.64+/-0.88) and group B(1.43+/-0.67) (p=0.06). The disc height change at the final follow up after cervical sagittal alignment showed no statistically significant difference among the groups: Group A presented with 1.53+/-0.50, group B with 1.30+/-0.46 and group C with 1.40+/-0.50.(p=0.08) Regarding sagittal alignment and osteophyte change, there was no statistically significant difference among the groups as group A showed an average of 1.33+/-0.48, group Ban average of 1.56+/-0.88 and group Can average of 1.60+/-0.82(p=0.07). CONCLUSION: Although the preoperative sagittal alignment and ROM did not significantly affect adjacent segment degeneration and diseases in a mid-term follow-up evaluation after anterior arthrodesis with PEEK cage and plate in degenerative cervical spinal disorders, we think a future study is required with a sufficient number of patients and a long term follow-up because there were borderline statistical significances shown in the present study.

Biomechanical Analysis of Fusion Segment Rigidity Upon Stress at Both the Fusion and Adjacent Segments: A Comparison between Unilateral and Bilateral Pedicle Screw Fixation

PURPOSE: The purpose of this study was to investigate the effects of unilateral pedicle screw fixation on the fusion segment and the superior adjacent segment after one segment lumbar fusion using validated finite element models. MATERIALS AND METHODS: Four L3-4 fusion models were simulated according to the extent of decompression and the method of pedicle screws fixation in L3-4 lumbar fusion. These models included hemi-laminectomy with bilateral pedicle screw fixation in the L3-4 segment (BF-HL model), total laminectomy with bilateral pedicle screw fixation (BF-TL model), hemi-laminectomy with unilateral pedicle screw fixation (UF-HL model), and total laminectomy with unilateral pedicle screw fixation (UF-TL model). In each scenario, intradiscal pressures, annulus stress, and range of motion at the L2-3 and L3-4 segments were analyzed under flexion, extension, lateral bending, and torsional moments. RESULTS: Under four pure moments, the unilateral fixation leads to a reduction in increment of range of motion at the adjacent segment, but larger motions were noted at the fusion segment (L3-4) in the unilateral fixation (UF-HL and UF-TL) models when compared to bilateral fixation. The maximal von Mises stress showed similar patterns to range of motion at both superior adjacent L2-3 segments and fusion segment. CONCLUSION: The current study suggests that unilateral pedicle screw fixation seems to be unable to afford sufficient biomechanical stability in case of bilateral total laminectomy. Conversely, in the case of hemi-laminectomy, unilateral fixation could be an alternative option, which also has potential benefit to reduce the stress of the adjacent segment.