[Establishment of finite element model of anterior cervical transpedicular system for reconstruction of cervical stability after subtotal resection of two segments of lower cervical spine].

OBJECTIVE: To establish the fixation model of anterior cervical transpedicular system (ACTPS) after subtotal resection of two segments of lower cervical spine(C3-C7) in order to provide a finite element modeling method for anterior cervical reconstruction. METHODS: The CT data of the cervical segment (C1-T1) of a 30-year-old adult healthy male volunteer was collected. Used Mimics 10.0, Rapidform XOR3, HyperMesh 10.0, CATIA5V19 and ANSYS 14.0 to establish the three-dimensional nonlinear complete model of lower cervical spine(C3-C7) as the intact group. The number of units and nodes of the complete model were recorded. After the effectiveness of the complete model was verified, the C5 and C6 vertebral subtotal resection was performed, and the ACTPS model was established as the ACTPS group. The axial force of 75 N and moment couple of 1N·m was loaded on the upper surface of C3 in intact group and ACTPS group, the range of motion(ROM)and stress distribution in states of flexion extension, lateral flexion, rotation was compared between two groups. RESULTS: There were 85 832 elements and 23 612 nodes in the complete model of lower cervical spine(C3-C7) which was established in this experiment. The stress distribution of ACTPS internal fixation model was relatively uniform. Comparing with the intact group, the overall range of motion in ACTPS group was decreased in flexion extension, lateral flexion and rotation directions, and the corresponding compensation of adjacent C3,4 segment was increased slightly. CONCLUSION: The stress distribution of ACTPS fixation system is uniform, there is no stress concentration area at the joint of screw and titanium plate, and the fracture risk of internal fixation is low. It is suitable for stability reconstruction after anterior decompression of two or more cervical segments.

[Imaging study of soft tissue swelling after anterior cervical corpectomy].

OBJECTIVE: To study the changes of anterior soft tissue swelling after anterior cervical subtotal corpectomy, titanium mesh fusion and internal fixation. METHODS: From November 2015 to July 2018, 151 patients with cervical spondylotic myelopathy were treated with anterior single corpectomy, titanium mesh fusion and internal fixation, including 109 males and 42 females, aged 44 to 81 (59.77±8.34) years. Through postoperative follow up observation, the C2-C7 level of anterior intervertebral space distance was measured to evaluate the changes of anterior soft tissue swelling. RESULTS: All patients were followed up for 15 to 40(28.00±3.52) months. One week after the operation, the swelling of anterior soft tissue reached the peak, and then decreased. At 8 months after the operation, the swelling of anterior soft tissue on C5, C6 and C7 plane returned to normal. At 12 months after the operation, the swelling of anterior soft tissue on C2, C3 and C4 plane returned to normal. CONCLUSION: Anterior subtotal cervical corpectomy, titanium mesh bone graft fusion and internal fixation can cause swelling of the anterior soft tissue. One week after operation, we should pay more attention to the aggravation of the swelling of the anterior soft tissue to avoid the occurrence of dysphagia, respiratory obstruction, asphyxia and other complications.

[Application of posterior arch of the atlasrch resection for high-level cervical dumbbell schwannoma surgery].

OBJECTIVE: To investigate the feasibility and clinical effect of hemi-resection of posterior arch of atlas in the upper cervical spinal dumbbell-shaped schwannomas. METHODS: A retrospective analysis was performed on 13 patients with high level cervical dumbbell schwannomas from January 2005 to December 2018, including 10 males and 3 females, aged 19 to 67 years old. The occipital foramen to the C1 were 4 cases and 9 cases of C1,2. Tumors were removed by posterior arch of the atlas resection without internal fixation. The clinical efficacy was evaluated by visual analogue pain scale (VAS), Japanese Orthopaedic Association (JOA) scores, and American Spinal Injury Association(ASIA) ratings. RESULTS: The operation was successfully completed in 13 cases of this group. No vertebral artery injury or spinal cord injury occurred during the operation. All 13 patients were followed up for more than 12 months. No local recurrence was found. Both the VAS and the JOA score were significantly improved compared with those before surgery. The ASIA classification before operation was:1 case of grade C, 6 cases of grade D, 6 cases of grade E;the latest follow up was 3 cases of ASIA grade D and 10 cases of E. CONCLUSION: The posterior arch of the atlas hemisection can remove the upper cervical dumbbell schwannoma in one stage. The short-term clinical effect is good, and there are no complications such as cervical instability.

[Diagnosis and surgical treatment of symptomatic lumbar spinal epidural liposis].

OBJECTIVE: To explore diagnosis and surgical treatment of symptomatic lumbar spinal epidural lipoplasia. METHODS: A retrospective analysis of 19 patients with symptomatic lumbar spinal epidural hyperplasia treated with hemilaminectomy and interbody fusion and internal fixation from February 2012 to November 2018 were performed, including 7 males and 12 females, aged from 48 to 72 years old with an average of (57.6±1.2) years old;the course of disease ranged from 6 to 60 months with an average of (18.6±5.1) months;plane requiring decompression:L2, 3-L5S1 on 4 cases, L2, 3-L4, 5 on 5 cases, L3, 4-L4, 5 on 2 cases, L3, 4-L5S1 on 6 cases, L4, 5-L5S1 on 2 cases. Visual analogue scale (VAS) before operation and 6 months after opertaionwere used to evaluate relief of leg pain and back pain, Oswestry Disability Index (ODI) was used to evaluate recovery of functiona, and Fischgrund was used to assess overall efficacy. RESULTS: All patients were followed up from 12 to 37 months with an average of (16.3±3.8) months. Ninteen patients were successfully completed operation, and all adipose tissues in the compressed segment of the spinal canal were removed. Operation time was from 125 to 260 min with an average of (186± 15) min, and blood bleeding was from 150 to 500 ml with an average of (280±46) ml. Two patients occurred partial incision fat liquefaction and exudate did not heal, the incision was opened to remove effusion, the dressing was changed and anti-inflammatory treatments were performed. No complications such as cauda equina injury, cerebrospinal fluid leakage, and broken nails occurred. Preopertaive VAS of back pain and leg pain were 5.3±0.7 and 6.8±0.8, respectively, while 2.1±0.4 and 2.3±0.5 respectively at 6 months after opertaion, there were statisticalsignificant difference between 6 months after operation and before operation (P<0.05). Postoperative ODI score at 6 months was 12.1±2.3, and significantly improved than that of before operation 45.5±2.8 (P<0.05). According to Fischgrund criteria, 13 patients got excellent result, 4 good, and 2 fair. CONCLUSION: Patients with symptomatic lumbar spinal epidural lipoplasia undergo hemilaminectomy and internal fixation of compression segment could relieve compression of dura mater and cauda equina, and achieve good clinical results.

[Diagnosis, treatment and etiology analysis of nerve compression by bone fragment after lumbar spine surgery].

OBJECTIVE: To explore the diagnosis, treatment, cause and prevention of nerve compression by bone fragment after lumbar spine surgery. METHODS: The clinical data of 23 patients with nerve compression by bone fragment after lumbar spine surgery from February 2012 to March 2019 were collected retrospectively, including 9 males and 14 females, aged 42 to 81 years with an average of (62.60±5.70) years. The surgical methods included lumbar interbody fusion in 20 cases and spinal endoscopy in 3 cases. All 23 patients experienced radiating pain on the decompression side or the contralateral limb after operation. The time of occurrence was from immediately after operation to 2 weeks after operation, with an average of (3.2±1.7) days. All patients underwent postoperative examination of lumbar spine CT or MRI to confirm residual ectopic bone fragments, and at the same time, bilateral lower extremity color Doppler ultrasound excluded thrombosis. Sources of ectopic bone fragments:14 cases of residual bone fragments caused by intervertebral fusion bone graft loss or fenestration fusion, 6 cases of fractured upper articular process head, and 3 cases of upper articular process bone remaining during spinal endoscopic surgery. RESULTS: The patient's hospital stay was 10 to 37 (23.4±6.2) days. All patients were followed up for 6 to 25 (13.6±3.4) months. Three patients underwent posterior open nerve root exploration for removing bone fragments on the same day or the second day after surgery, and the symptoms were relieved. Twenty patients underwent conservative treatment firstly, and 13 patients were discharged after pain relieved by conservative treatment, 7 patients failed conservative treatment, the 2 cases of failed 7 cases had undergone nerve root block surgery during conservative treatment. Two patients underwent spinal endoscopy nerve root exploration and bone mass removal, and five patients underwent posterior open nerve root exploration and bone fragmentation removal. All postoperative pain symptoms were relieved. Preoperative CT, MRI and intraoperative bone fragment removal confirmed the shape and location of the bone fragments. The most likely source of bone fragments was the loss of intervertebral fusion bone grafts or residual bone fragments resulting from fenestration fusion (14 cases), fractured upper articular process head (6 cases), and upper articular process bones remaining in endoscopic surgery (3 cases). According to the Macnab criteria in evaluating clinical outcome, 20 cases got excellent results and 3 good. CONCLUSION: After the lumbar spine surgery, the nerve compression by bone fragments is treated with appropriate treatments, and good clinical results can be obtained. Timely removal of residual bone fragments during operation and careful exploration of nerve roots before closing incision can avoid such complications.

[Treatment of migrated lumbar disc herniation with percutaneous endoscopic lumbar discectomy and target foraminoplasty].

OBJECTIVE: To evaluate the clinical outcome of percutaneous endoscopic lumbar discectomy with target foraminoplasty in treating migrated lumbar disc herniation. METHODS: From June 2015 to January 2016, 25 patients with migrated lumbar disc herniation were treated with percutaneous endoscopic lumbar discectomy with target foraminoplasty. A total of 14 males and 11 females, aging from 23 to 52 years old (average: 37.6) were enrolled in this study. Discectomy occurred in L2,3 of 1 case, L3,4 of 3 cases, L4,5 of 12 cases, L5S1 of 9 cases. Preoperative, 1-week and 1-year postoperative visual analogue scale (VAS) scores were collected to evaluate lower back and leg pain; Oswestry Disability Index(ODI) was used to assess the lumbar function. RESULTS: All the patients were followed up for 12 to 19 months with an average of 15.2 months. The mean operation time was 108.6 min. No injury of dura, nerve root, or wound infection were found. Preoperative, 1-week and 1-year postoperative visual analogue scale(VAS) scores of lower back pain were 5.8±0.5, 2.5±0.4, 0.9±0.2, respectively, with significant differences among each other(P<0.05);VAS scores of leg pain were 7.1±0.6, 1.5±0.4, 0.7±0.6, respectively, with significant differences among each other(P<0.05). Lumbar ODI scores were 69.2±1.8, 22.5±4.7, 10.2±2.4 at the above time points and showed significant differences among each other(P<0.05). CONCLUSIONS: Percutaneous endoscopic lumbar discectomy with target foraminoplasty for migrated lumbar disc herniation showed advantages of less injuries, bleeding and complication. It also promotes rapid recovery, being curative safely and effectively.

[Radiological study on the n-HA/PA66 cage used in the transforaminal lumbar interbody fusion].

OBJECTIVE: To explore the effects of nano-hydroxyapatite/polyamide 66 (n-HA/PA66) cage on recovering and maintaining lumbar curvature, lumbar heights and fusion rate when used in the transforaminal lumbar interbody fusion. METHODS: From February to July 2012, 50 patients with degenerative lumbar disease(lumbar disc herniation in 32 cases and lumbar spondylolisthesis in 18 cases) were treated with transforaminal lumbar interbody fusion using the n-HA/PA66 cage, and their preoperative and postoperative clinical outcomes were analyzed. The patients were followed up for 2, 4, 6 and 8 months after operation, during which the CR and CT film of lumbar vertebra were checked to get relative height of vertebral space, Taillard index,index of lumbar spinal curvature,angle of segmental and full lumbar lordosis. The data were analyzed respectively with pair t-test, analysis of variance or LSD-t-test. RESULTS: All the patients were followed up, and the duraion ranged from 8 to 13 months, with a mean of 11.32 months. There were significant differences in relative height of vertebral space, Taillard index, index of lumbar spinal curvature, angle of segmental and full lumbar lordosis after surgery, but there were no significant differences in different periods after operation. The fusion time of lumbar ranged from 4 to 8 months. CONCLUSION: The n-HA/PA66 cage can recover and maintain lumbar normal stability with higher rate of fusion and less complications.

[Anterior revision surgery for the treatment of cervical spondylosis after anterior decompression and titanium mesh fusion].

OBJECTIVE: To analyze the reasons why anterior decompression and titanium mesh fusion for cervical spondylosis always show poor therapeutic effects, and to investigate the clinical effects of anterior revision surgery in these patients. METHODS: From January 2004 to December 2011, 16 patients underwent anterior decompression and titanium mesh fusion for cervical myelopathy were treated with anterior revision surgery. There were 7 males and 9 females with an average age of 61 years old (ranged from 46 to 75 years), including 11 cases with cervical spondylotic myelopathy, 2 cases with nerve root cervical spondylosis and 3 cases with mixed type cervical spondylosis. Average duration from the first operation to reoperation was 7 years(ranged from 4 to 12 years). In the first operation, titanium mesh segment located in C3-C5 (2 cases), C4-C6 (8 cases), C4-C7 (2 cases), C5-C7 (4 cases), and one of them, titanium mesh implantation in C4 and C5,6 intervertebral disk removal and cage fusion. After the first operation, symptom of 13 patients recurred after improvement or disappearance, 2 patients did not show obvious improvement, and 1 patient aggravated. Cervical spine radiography, CT scan and MRI were performed in all patients before re-operation. There were 12 patients with compression of the spinal cord or nerve root caused by degenerative changes in adjacent segments of fusion segments, 4 cases in upper segments, and 8 cases in lower segments; 3 patients with compression of the spinal cord or nerve root caused by vertebral posterior osteophyte of decompressed segments; 1 patient with compression of the spinal cord caused by incomplete anterior decompression. JOA, NDI and Odom classification were used to assess the clinical effects. RESULTS: All anterior revision surgery were successful with a mean time of 110 min (80 to 150 min) and mean bleeding of 160 ml (30 to 200 ml). There was 30 ml clear drainage fluid in 1 patient suspected of cerebrospinal fluid leakage. But the 2nd day after operation, the tube was removed and the drainage opening was sutured, and the suture incision healed in grade A after 10 days. Other patients had no complications such as dysdipsia, hoarseness, and laryngeal edema, etc. All patients were followed up for 12 to 28 months with an average of 16 months. Two months after operation and at last follow-up, JOA scores and ODI index had obviously improved than preoperation (P < 0.01), and there was significant difference between postoperative 2 months and last follow-up (P < 0.01). At the final follow-up, improvement rate of JOA was (72.9 +/- 0.2)%. According to the standard of Odom, 12 cases got excellent results, 3 good, 1 fair. CONCLUSION: After surgery of cervical decompression and bone graft fusion with titanium mesh, the patients need re-operation because of incomplete decompression, degenerative changes in adjacent segments or newly formed compression factors, and complications caused by implants. Anterior revision surgery can obtain good clinical effects.

[Treatment of atlantoaxial hemangioma with vertebroplasty through anterior approach].

OBJECTIVE: To investigate the diagnostic and therapeutic experience for the atlantoaxial hemangioma with vertebral plasty through anterior approach. METHODS: From January 2005 to April 2012,6 cases were initially diagnosed as atlantoaxial hemangioma under MRI,and treated with vertebroplasty through anterior approach. There were 2 males and 4 females ranging in age from 35 to 67 years old with an average of 49 years old. Six patients were followed up by out-patient clinic or telephone after operation for 6 months,and WHO standard clinical effects were used to assesse pain degree. RESULTS: All the hemangioma were confirmed by puncture. The mean operative time and injection amount of bone cement were 58 min and 2.6 ml,repectively. Postoperative X-ray or CT scan showed that the bone cement filled focus satisfactorily. All patients were followed up from 6 to 48 months with average of 28 months. According to the pain degree of WHO standard, 2 cases got partly relief and 4 got completely relief and up to final follow-up,the results were still stable. CONCLUSION: Treatment of atlantoaxial hemangioma with vertebroplasty through anterior approach is a safe and effective method. And correct puncture, adequate injection time and volume of bone cement are keys to successful.