Analysis of the causes of cage subsidence after oblique lateral lumbar interbody fusion / 中国骨伤

OBJECTIVE@#To observe the cage subsidence after oblique lateral interbody fusion (OLIF) for lumbar spondylosis, summarize the characteristics of the cage subsidence, analyze causes, and propose preventive measures.@*METHODS@#The data of 144 patients of lumbar spine lesions admitted to our hospital from October 2015 to December 2018 were retrospectively analyzed. There were 43 males and 101 females, and the age ranged from 20 to 81 years old, with an average of (60.90±10.06) years old. Disease types:17 patients of lumbar intervertebral disc degenerative disease, 12 patients of giant lumbar disc herniation, 5 patients of discogenic low back pain, 33 patients of lumbar spinal stenosis, 26 patients of lumbar degenerative spondylolisthesis, 28 patients of lumbar spondylolisthesis with spondylolisthesis, 11 patients of adjacent vertebral disease after lumbar internal fixation, 7 patients of primary spondylitis in the inflammatory outcome stage, and 5 patients of lumbar degenerative scoliosis. Preoperative dual-energy X-ray bone mineral density examination showed 57 patients of osteopenia or osteoporosis, and 87 patients of normal bone density. The number of fusion segments:124 patients of single-segment, 11 patients of two-segment, 8 patients of three-segment, four-segment 1 patient. There were 40 patients treated by stand-alone OLIF, and 104 patients by OLIF combined with posterior pedicle screw. Observed the occurrence of fusion cage settlement after operation, conducted monofactor analysis on possible risk factors, and observed the influence of fusion cage settlement on clinical results.@*RESULTS@#All operations were successfully completed, the median operation time was 99 min, and the median intraoperative blood loss was 106 ml. Intraoperative endplate injury occurred in 30 patients and vertebral fracture occurred in 5 patients. The mean follow-up was (14.57±7.14) months from 6 to 30 months. During the follow-up, except for the patients of primary lumbar interstitial inflammation and some patients of lumbar spondylolisthesis with spondylolisthesis, the others all had different degrees of cage subsidence. Cage subsidence classification:119 patients were normal subsidence, and 25 patients were abnormal subsidence (23 patients were gradeⅠ, and 2 patients were gradeⅡ). There was no loosening or rupture of the pedicle screw system. The height of the intervertebral space recovered from the preoperative average (9.48±1.84) mm to the postoperative average (12.65±2.03) mm, and the average (10.51±1.81) mm at the last follow-up. There were statistical differences between postoperative and preoperative, and between the last follow-up and postoperative. The interbody fusion rate was 94.4%. The low back pain VAS decreased from the preoperative average (6.55±2.2 9) to the last follow-up (1.40±0.82), and there was statistically significant different. The leg pain VAS decreased from the preoperative average (4.72±1.49) to the final follow-up (0.60±0.03), and the difference was statistically significant (t=9.13, P<0.000 1). The ODI index recovered from the preoperative average (38.50±6.98)% to the latest follow-up (11.30±3.27)%, and there was statistically significant different. The complication rate was 31.3%(45/144), and the reoperation rate was 9.72%(14/144). Among them, 8 patients were reoperated due to fusion cage subsidence or displacement, accounting for 57.14%(8/14) of reoperation. The fusion cage subsidence in this group had obvious characteristics. The monofactor analysis showed that the number of abnormal subsidence patients in the osteopenia or osteoporosis group, Stand-alone OLIF group, 2 or more segments fusion group, and endplate injury group was higher than that in the normal bone mass group, OLIF combined with pedicle screw fixation group, single segment fusion group, and no endplate injury group, and the comparison had statistical differences.@*CONCLUSION@#Cage subsidence is a common phenomenon after OLIF surgery. Preoperative osteopenia or osteoporosis, Stand-alone OLIF, 2 or more segments of fusion and intraoperative endplate injury may be important factors for postoperative fusion cage subsidence. Although there is no significant correlation between the degree of cage subsidence and clinical symptoms, there is a risk of cage migration, and prevention needs to be strengthened to reduce serious complications caused by fusion of cage subsidence, including reoperation.

Mid-long-term effect of only placed expandable Interbody fusion cage in the treatment of lumbar spinal Stenosis with vertebral instability using micro-endoscopic Discectomy system / 中国组织工程研究

BACKGROUND: The incidence of lumbar spinal stenosis with vertebral instability is increasing year by year, which can cause symptoms such as waist and leg pain, lower limbs feeling numbness and intermittent claudication. In recent years, scholars have tried various minimally invasive treatment methods to further reduce the trauma and complications of surgery. The improvement of the clinical effect of minimally invasive surgery for lumbar spinal stenosis with vertebral instability is an important issue to be solved. OBJECTIVE: To evaluate the mid-long-term effect of only placed expandable interbody fusion cage in the treatment of lumbar spinal stenosis with vertebral instability using micro-endoscopic discectomy system. METHODS: A retrospective, self-control clinical trial was conducted in the First Affiliated Hospital of Zhengzhou University from 2012 to 2014. Totally 35 patients with lumbar spinal stenosis combined with vertebral instability were treated by only placed expandable interbody fusion cage using micro-endoscopic discectomy system. This study was approved by the Ethics Committee of the First Affiliated Hospital of Zhengzhou University. RESULTS AND CONCLUSION: (1) All 35 patients were followed-up for 60-85 months, mean (70.17±5.40) months. Among these patients, lumbar interbody fusion in 1 segment, 2 segments and 3 segments was performed in 6, 20 and 9 cases, respectively. A total of 73 intervertebral spaces were fused. (2) The mean operation time was 53.49±9.13 minutes (range, 35-75 minutes). The mean blood loss was 114.86±54.23 mL (range, 50-250 mL). (3) Dural rupture occurred in one case during operation and then hypotensive cranial pressure headache occurred after operation. Headache gradually eased after the patient received rehydration and analgesic treatment for 3 days. Poor incision healing occurred in one case after operation and then healed well after one-week vacuum sealing drainage technique. (4) The Visual Analogue Scale scores, Oswestry Disability Index, and height of intervertebral space were significantly decreased at 1 week, 6 months, 1 year, 2 years after surgery and the final follow-up compared to the preoperative ones. At 6 months after the operation, 31(42.5%) intervertebral spaces reached a strong fusion, 25(34.2%) possible fusion, and 17(23.3%) did not reach fusion. At 1 year after surgery, 51(69.9%) intervertebral spaces achieved a strong fusion and 22(30.1%) achieved possible fusion. At 2 years after surgery, 57(78.1%) intervertebral spaces achieved a strong fusion and 16(21.9%) achieved possible fusion. During final follow-up, 62(84.9%) intervertebral spaces achieved a strong fusion and 11(15.1%) achieved possible fusion. (5) At the last follow-up, cage migration was found in one case. The patient was not treated because of symptomless. (6) Unilateral approach only placed expandable interbody fusion cage by using micro-endoscopic discectomy system is a safe and reliable minimally surgical method, which has a good mid-long-term effect on lumbar spinal stenosis with vertebral instability.

Imaging evaluation of short-segment fixation and fusion for degenerative lumbar scoliosis assisted by highly selective nerve root block / 中国组织工程研究

BACKGROUND: Short-or long-segment fixation is still controversial in the treatment of adult degenerative lumbar scoliosis. OBJECTIVE: To investigate the effectiveness and feasibility of accurate treatment of short-segment fixation in adult degenerative lumbar scoliosis patients assisted by highly selective nerve root block. METHODS: Thirty-five patients with adult degenerative lumbar scoliosis treated in Chinese PLA General Hospital and People’s Hospital of Peking University from May 2014 to September 2017 were analyzed retrospectively, including 14 males and 21 females aged (64.2±8.1) years. The fixation segments were determined by a highly selective nerve root block. All patients were subjected to transforaminal lumbar interbody fusion. During the follow-up, visual analogue scale score and Oswestry disability index were evaluated. Parameters including lumbar curvature Cobb angle, lumbar lordosis angle, sacral slope, and pelvic tilt and interbody fusion condition were obtained by imaging; and complications were recorded. This study was approved by the Ethics Committee of Chinese PLA General Hospital and People’s Hospital of Peking University. RESULTS AND CONCLUSION: (1) Of the 35 patients, 27 underwent single-segment minimally invasive transforaminal lumbar fusion, 5 underwent double-segment minimally invasive transforaminal lumbar fusion, and 3 underwent three-segment minimally invasive transforaminal lumbar fusion. (2) The follow-up time of 35 patients was (25.6±1.5) months. All patients achieved the grade I fusion. Within 3 months, there were 3 cases of dural tear and cerebrospinal fluid leakage, 1 case of lower-extremity muscular venous thrombosis, 1 case of pneumonia and 1 case of wound fat liquefaction. Three months later, there was 1 case of adjacent segment degeneration; no nerve injury or nonunion, no screw or titanium rod breakage. (3) Visual analogue scale score, Oswestry disability index, Cobb angle, lumbar lordosis angle, sacral slope, and pelvic tilt at the last follow-up were significantly improved in 35 patients compared with those before surgery (P < 0.01). (4) Short-segment precision treatment of adult degenerative lumbar scoliosis with highly selective nerve root block can achieve good clinical effect.

Zero-profile anterior cervical ROI-C cage versus traditional fusion cage combined with titanium plate in treatment of two-level cervical spondylotic myelopathy / 中国组织工程研究

BACKGROUND: Self-locking self-stabilizing zero-profile cage ROI-C is advanced from the traditional titanium plate fusion cage, but the systematic studies on ROI-C internal fixation system applied in the comprehensive evaluation of two-level cervical spondylotic myelopathy are few. OBJECTIVE: To comprehensively evaluate the clinical efficacy of small-incision anterior cervical self-locking self-stabilizing zero-profile cage ROI-C in the treatment of two-level cervical spondylotic myelopathy. METHODS: Fifty-seven patients with two-level cervical spondylotic myelopathy at the First Affiliated Hospital of Guangdong Pharmaceutical University from September 2016 to March 2018 were selected, including 30 males and 27 females, aged 34-77 years old. Of which, 33 patients underwent small-incision anterior cervical self-locking self-stabilizing zero-profile fusion cage ROI-C implantation (observation group), and another 24 patients received small-incision cervical anterior titanium internal fixation (control group). The JOA score, Neck Disability Index, Odom criteria, Visual Analogue Scale score, dysphagia degree, Cobb angle of cervical lordosis, angle of fusion segment, and disc height and cervical fusion rate were assessed at 2 weeks and 1, 3, 6, and 12 months after surgery. The study was approved by the Ethics Committee of the First Affiliated Hospital of Guangdong Pharmaceutical University. RESULTS AND CONCLUSION: (1) There was no significant difference in the Odoms criteria between two groups (P > 0.05). All 57 patients were followed up for 12 months after surgery. No internal fixation loosening or vertebral structure changes were found. No complications such as loosen and broken of titanium plate occurred. (2) Postoperative JOA score, Neck Disability Index, and Visual Analogue Scale in the two groups were significantly improved compared with those before surgery (P 0.05). (3) The incidence of dysphagia at 2 weeks and 1 month in the observation group was significantly lower than that in the control group (P 0.05). (4) The Cobb angle of cervical lordosis, angle of fusion segment, and disc height were significantly improved in both groups after surgery (P 0.05). (5) The cervical fusion rate at the last follow-up in both groups was > 95%, and the fusion effect was good. There was no significant difference in the fusion rate at different time points between two groups (P > 0.05). (6) These results indicate that the small-incision anterior cervical self-locking self-stabilizing Zero-profile interbody fusion ROI-C and anterior titanium plate internal fixation exert significant effects in the treatment of two-level cervical spondylotic myelopathy. However, ROI-C can reduce the incidence of postoperative dysphagia.

Research advances in biodegradable intervertebral fusion cage for spine / 局解手术学杂志

Objective At present, the mainstream surgical mode and the gold standard for the treatment of spine related diseases are still the intervertebral fusion with the intervertebral implantation of the intervertebral fusion device.The intervertebral fusion device routinely used in clinical practice cannot degrade in vivo after implantation, resulting in lifelong foreign body.High elastic modulus also leads to osteoporosis in adjacent vertebral bodies, which leads to implant sinking, stress shielding and'pseudomorphism'of fusion.The ideal biodegradable synthetic intervertebral fusion cage can be progressively degraded and eventually replaced by new bone, which has the advantages of elastic modulus close to cortical bone, good biocompatibility, X-ray permeability and good initial mechanical strength.In this paper, animal analysis of biodegradable intervertebral fusion cage, clinical effect analysis, current shortcomings and future trends were reviewed.

An age-stratified follow-up of complications and clinical benefit of posterior lumbar intervertebral fusion procedure in middle-aged and older patients / 中国修复重建外科杂志

Objective: To compare the complications and clinical scores of posterior lumbar intervertebral fusion (PLIF) in middle-aged and older patients of different ages, and to assess the risk of complications of PLIF in different ages, providing a reference for clinical treatment. Methods: The clinical data of 1 136 patients, who were more than 55 years old and underwent PLIF between June 2013 and June 2016, were retrospectively analyzed. According to the age of patients undergoing surgery, they were divided into 3 groups as 55-64 years old, 65-74 years old, and ≥75 years old. The general characteristics, comorbidities, and surgical data of the three groups were compared, with comparison the morbidity of complications. According to the minimal clinical important difference (MCID), the improvement of patient's pain visual analogue scale (VAS) score and the Oswestry disability index (ODI) score were compared. Univariate logistic regression analysis was used to analyze the difference of complications and the improvement of VAS and ODI scores. Multivariate logistic regression analysis was performed for the risk factors of complications. Results: There were significant differences in the number of surgical fusion segments and osteoporosis between groups ( P0.05). All patients were followed up 6-62 months with an average of 27.4 months. Among the results of postoperative complications, there were significant differences in the total incidence of intraoperative complications, systemic complications, minor complications, and the percentage of improvement of ODI score to MCID between groups ( P0.05). Univariate logistic regression analysis showed that after adjusting the confounding factors, there were significant differences in intraoperative complications and the percentage of improvement of ODI score to MCID between 55-64 and 65-74 years old groups ( P<0.05); systemic complications, minor complications, complications at the end of long-term follow-up, and the percentage of improvement of ODI score to MCID in ≥75 years old group were significantly different from those in the other two groups ( P<0.05). Multivariate logistic regression analysis showed that age was a risk factor for systemic complications, minor complications, and complications at the end of long-term follow-up. Except for age, long operation time was a risk factor for intraoperative complications, increased number of fusion segments was a risk factor for systemic complications, the number of comorbidities was a risk factor for minor complications, and osteoporosis was a risk factor for complications at the end of long-term follow-up. Conclusion: The risk of surgical complications is higher in the elderly patients (≥75 years) with lumbar degenerative diseases than in the middle-aged and older patients (<75 years), while the improvements of postoperative VAS and ODI scores were similar. Under the premise of fully assessing surgical indications, PLIF has a positive effect on improving the elderly patients' quality of life.

Clinical effects of Zero-P vs.traditional titanium plate for single level cervical spondylosis / 西安交通大学学报(医学版)

ABSTRACT:Objective To compare the clinical effects of Zero-P and traditional titanium plate with cage in treating single level cervical spondylosis.Methods We retrospectively analyzed the clinical data of 28 patients with single level cervical spondylosis who underwent anterior cervical discectomy and fusion (ACDF)by traditional titanium plate with cage (group A,n=16)or Zero-P implant (group B,n=16)in our department between January 2012 and January 2014.The intraoperative blood loss,operation time,postoperative JOA scores,JOA recovery rate,NDI scores,and dysphagia incidence in both groups were measured and compared.The changes of the midpoint interbody height (IBH),the cervical Cobb angle of the surgical segment and the cervical Cobb angle of C2 and C7 vertebral body were measured on the standing lateral cervical spine X-ray.Results The operation time was significantly longer in group A than in group B (P 0 .0 5 ).The incidence of dysphagia was lower in group B than in group A.The two groups did not significantly differ in JOA score or JOA improvement rate during the same period after operation (P>0.05).The NDI score in group B was significantly lower than that in group A (P0 .0 5 ).The midpoint interbody height in group B was significantly greater than that in group A (P0.05).Conclusion Zero-p and traditional titanium plate with cage have similar effects in treating single level cervical spondylotic myelopathy,and Zero-P system has the advantages of lower incidence of dysphagia after operation,shorter operation time and better recovery of postoperative cervical physiological structure.

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.

Effects of Autologous Blood Transfusion and Allogenic Blood Transfusion on the Patients Undergoing Selective Operation of Intervertebral Fusion with Cage / 中国医科大学学报

Objective To compare the effects of autologous blood transfusion and allogenic blood transfusion on the patients undergoing selective operation of intervertebral fusion with cage. Methods Forty patients who underwent selective operation of intervertebral fusion with cage in the De?partment of Orthopedics of our hospital from September 2012 to June 2014 were recruited for the study,including 20 cases that received autologous blood transfusion only(group A)and 20 cases that received allogenic blood transfusion only(group B). Preoperative and postoperative results of blood routine examination,body temperature,postoperative recovery indicators and expense of blood transfusion were compared between the two groups. Results The postoperative erythrocyte and hemoglobin of the patients in group A were significantly higher than those in group B(P<0.05). When the amount of blood used during the operation reaches or exceeds 4 units,the expense of autologous blood transfusion was lower than that of allogenic blood transfusion. Conclusion Autologous blood transfusion contributes to higher levels of postoperative erythrocyte and hemoglo?bin. When a large amount of blood is used during an operation,autotransfusion can help to reduce the expense of blood transfusion.

Clinical outcome of artificial cervical disc arthroplasty combined with anchoring cervical intervertebral fusion cage for the treatment of multilevel cervical disc herniation / 中国医师进修杂志

Objective To evaluate the clinical outcome of artificial cervical disc arthroplasty combined with anchoring cervical intervertebral fusion cage (ACIFC) in the treatment of multilevel cervical disc herniation. Methods From October 2011 to September 2013, 0.26 patients with multilevel cervical disc herniation underwent artificial cervical disc arthroplasty combined with ACIFC, there were 10 male and 16 female with age from 32 to 60 years (mean 46.8 years). Two segment were involved in 15 patients, three segment were involved in 11 patients. Neck disability index (NDI) and Japanese Orthopaedic Association (JOA) score were used to evaluate neurofunctional recovery preoperatively and postoperatively. The postoperative stabilization and the range of motion (ROM) of implanted disc and the fusion of cage were observed on dynamic radiograph. Results The average operation time and amount of bleeding were (95±15) min and (100±20) ml respectively. The average postoperative follow-up was 15 months(range 6-20 months). At the end of follow up,the scores of JOA was increased and the scores of NDI was decreased:(9.08±1.72) scores vs. (14.88±1.37) scores, (40.31±4.97) scores vs. (25.23±4.10) scores,there had significant differences (P0.05). Solid fusion was achieved in all levels brought by cage.There was no cage subsidence or displacement. All artificial cervical disc achieved definite stabilization, no intraoperative and postoperative complication was noted. Conclusions Artificial cervical disc arthroplasty combined with ACIFC provides a feasible way for the treatment of multilevel cervical disc herniation. The definite stabilization and maintained ROM can reduce the fusion segments and avoid the increased stress of adjacent segment which can ensure a good preliminary clinical outcome.

Development and biomechanical evaluation of a model of lumbar interbody fusion device / 重庆医学

objective To introduce the design concept and structure of a new type of lumbar intervertebral fusion cage ,and to e-valuate its biomechanical properties .Method A partially bioasorbable interbody fusion cage(PBIFC) made of nano hydroxyapatite and poly amino acid /calcium sulfate copolymer materials was developed .Range of motion(ROM ) ,compressive load ,and pull-out test on flexion ,extension ,lateral bending ,and torsion moment on fresh calf L3/L4 specimens of functional spinal union were carried out of iliac bone group ,PBIFC group ,and nano hydroxyapatite/polyamide 66(nHA/PA66) group .Result Of each movement ,the ROM value of iliac bone group are higher than the other two groups ,the difference was statistically significant (P0 .05) .The pull-out strength of PB-IFC group are higher than iliac bone group ,and the difference was statistically significant (P0 .05) .The compressive load of iliac bone group was lower than that of two cage group ,the difference was statistically significant (P0 .05) .Conclusion With good implant stability ,pull-out resistance ,and compression resistance performance ,PBIFC can meet the biomechanics requirements of clinical implant .

Preliminary clinical observation of new allograft posterior lumbar fusion cage of anatomical shape / 实用医学杂志

Objective To explore preliminary clinical results of a new anatomical shape allogeneic bone posterior lumbar fusion cage. Methods Follow-up patients used the allogeneic bone posterior lumbar fusion cage and use imaging methods and clinical score (VAS, ODI) to evaluate the patients′ clinical efficacy. Results 14 patients were followed up for 6 months or more , with an average follow-up time of 9.7 months , mean preoperative VAS 6.8 ± 1.1, ODI 32.7 ± 4.5. The mean preoperative disc height was (9.7 ± 2.0) mm and the average intervertebral height of 3 days post operation was (13.2 ± 1.7) mm. All patients got bony fusion in 6 months post operation, pain and function scores improved significantly compared with the pre-operation: VAS 2.4 ± 0.8 (P =0.000), ODI 9.8 ± 2.5 (P = 0.000), the average intervertebral height was (13.1 ± 1.7) mm (P = 0.000). The average was VAS 2.1 ± 0.1 (P = 0.000), average ODI was 8.9 ± 0.9 (P = 0.000) at last follow up. Average of intervertebral height was (13.0 ± 1.8) mm, no significant difference compared to three days after surgery (P=0.831). No serious complications and deep surgical site infection was observed. All implants were found no fragmentation, shift, cutting boards, and obviously sinking. Conclusion The anatomical shape allogeneic bone posterior lumbar fusion device is suitable for posterior lumbar interbody fusion , advantages of high fusion rate , satisfactory clinical results in the initial clinical trials , but its long-term efficacy requires further observation.

Above two-level segment interbody fusion with double-way connection intervertebral fusion device / 中国组织工程研究

10.3969/j.issn.2095-4344.2013.26.007

Mid-term clinical effect of anterior decompression plus intervertebral fusion cage with nanohydroxyapatite and polyamide 66 composite for thoracolumbar burst fractures / 中华创伤杂志

ObjectiveTo evaluate the mid-term clinical effect of nano-hydroxyapatite and polyamide 66 (n-HA/PA66) intervertebral fusion cage in treatment of thoracolumbar burst fractures.Methods A total of 87 patients with thoracolumbar burst fractures were managed by thoracolumbar body resection combined with n-HA/PA66 intervertebral fusion cage from December 2007 to September 2008.The clinical effect, safety and radiographic outcomes were evaluated.Results No nerve damage was deteriorated in all the patients.The neural function was improved for 1-2 grade except for four patients at Frankel grade A.The patients were followed up for mean 21.3 months (17-24 months).The kyphosis was (14.4 ± 12.6)° preoperatively, (3.7 ± 8.7) ° immediately after surgery and (4.0 ± 8.3)° at final follow-up.The distance between the upper and lower vertebral bodies was (96.9 ± 17.2) mm preoperatively, (109.5 ± 17.1) mm immediately after surgery and (108.3 ± 16.4) mm at final follow-up.No cage replacement, internal fixation breakage or neurologic impairment were observed during follow-up period.There were 58 patients with grade E fusion, 22 with grade D fusion and 7 with grade C fusion.ConclusionsAnterior decompression combined with n-HA/PA66 intervertebral fusion cage is an effective method for treatment of thoracolumbar burst fracture.The kyphosis is rectified and the intervertebral distance is corrected, with a high rate of fusion.

Degradation of PDLLA cage in the intervertebral fusion / 中国矫形外科杂志

[Objective]To observe the degradation process of PDLLA in the intervertebral fusion.[Method]Twenty goats were divided into 4 groups as experimental group,and their L_(3~4)intervertebal spaces were implanted with PDLLA cage containing pieces of graft bone.Animals were sacrificed at 4,8,12,16 wks and specimens were taken for observation of the degradation process and bone fusion by gross observation and electronic microscope.Another 12 goats were used as normal fusion control group.Their L_(3~4)space were grafted with bone block for fusion.[Result]The degradation rate was non-lineal.In the early stage of fusion,the main degradation and decrease of molecular weight was shown at the superficial decomposition.With the proceeding of fusion and degradation,as the kydrolyzation speeding-up,internal decomposition by self-catalyse resulted into the collapse and total disassemble of the PDLLA.The PDLLA cage maintained its shape in the early stage and its biomechanical strength decrease in late stage but was still enough to keep the structure from collapse,till the fusion was achieved in the bone implant area.[Conclusion]The velocity of degradation of PDLLA is slower than the speed of bone regeneration of bone fusion,so the PDLLA cage could provide sufficient support during the process of intervertebal fusion and is a suitable choice of degradative material for cage in the intervertebal fusion.

Treatment of thoracolumbar vertebral fracture by limited decompression of neighbouring segment with internal fixation and intervertebral body fusion / 中国矫形外科杂志

[Objective]To study the feasibility and clinical effect of the treatment of thoracolumbar vertebral fracture with limited decompression of neighbouring segments with internal fixation and intervertebral body fusion.[Method]Forty-three patients with thoracolumbar fractures were treated with this technique.The fusion of bone graft,reduction rate of fracture,nerve functional recovery,the loosening of rectification,subsequent low back pain,and the degeneration of adjacent segments were evaluated.[Result]All cases were followed up for 21.4 months and showed the results of strong spine bony fusion,96.1% satisfactory reduction rate without reduction lost,various differences of nerve functional improvement,a rank-sum test P