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Objective:To analyze the fail mode of neoadjuvant therapy combined with surgery for locally advanced esophageal squamous cell carcinoma (ESCC) after long-term follow-up.Methods:Clinical data of consecutive 238 patients with locally advanced resectable ESCC who underwent neoadjuvant therapy combined with surgery in Zhejiang Cancer Hospital from September 2012 to October 2019 were retrospectively analyzed. The failure mode in the whole cohort was analyzed after long-term follow-up. The overall survival (OS) and disease free survival (DFS) rates were analyzed by Kaplan-Meier method. Survival differences were determined by log-rank test.Results:The pathological complete response (pCR) rate was 42.0% in 238 patients. After a median follow-up of 46.1 months, tumor progression occurred in 96 patients (40.3%), including 25 patients (10.5%) with local recurrence, 61 patients (25.6%) with distant metastases, and 10 patients (4.2%) with simultaneous local recurrence and distant metastases. The median OS and DFS were 64.7 months and 49.9 months. And the 3-, 5-, and 7-year OS and DFS rates were 70.0%, 52.8%, 36.4% and 63.5%, 42.5%, and 30.0%, respectively. The 3-, 5-, and 7-year locoregional recurrence-free survival rates and distant metastasis-free survival rates were 86.0%, 71.4%, 61.2% and 70.6%, 55.9%, 43.0%. Compared with non-pCR patients, the overall progression rate and distant metastasis rate of pCR patients were lower (26.0% vs. 50.7%, 16.0% vs. 32.6%, both P<0.05). And the 3-, 5-, and 7-year OS (83.0% vs. 60.2%, 69.7% vs. 41.7%, 50.4% vs. 27.7%, all P<0.001) and DFS rates (80.4% vs. 51.4%, 63.9% vs. 31.2%, 45.9% vs. 20.3%, all P<0.001) were significantly better in pCR patients. Conclusions:Distant metastasis is the main failure mode of patients with locally advanced ESCC after neoadjuvant therapy. Patients with postoperative pCR can achieve better long-term survival.
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Objective:To explore the clinical efficacy of open-door laminoplasty in treatment of cervical spinal hyperextension injury accompanied with or without spinal cord-canal mismatch.Methods:A retrospective case-control study was performed to analyze the clinical data of 42 patients with cervical spine hyperextension in Shanghai Ninth People’s Hospital,Shanghai Jiaotong University School of Medicine from January 2016 to June 2019. There were 31 males and 11 females at age range of 40-78 years[(59.7 ± 9.9)years]. All patients underwent open-door laminoplasty.Preoperative Japanese Orthopaedic Association score(JOA)was(10.2 ± 3.8)points,and American Spinal Injury Association(ASIA)spinal cord injury score was(260.4 ± 47.5)points. Those with spinal cord occupation rate(SCOR)equal to or more than 70% were classified as spinal cord-canal mismatched group(n=21),and those with SCOR less than 70% were classified as spinal cord-canal matched group(n=21). ASIA total score,ASIA upper and lower limb motor scores,ASIA sensory score,JOA score,surgical improvement rates and complications were compared between the two groups before operation,at postoperative one week and at the latest follow-up.Results:All patients were followed up for 12-26 months[(19.1 ± 2.3)months]. Both groups had significantly improved ASIA total score at postoperative one week and at the latest follow-up,compared with that before operation( P < 0.05). The two groups showed no significant difference in ASIA total score at postoperative one week( P > 0.05). ASIA total score in unmatched group was(307.6 ± 9.9)points at the latest follow-up,significantly lower than that in matched group[(315.4 ± 8.7)points]( P < 0.01). ASIA upper limb motor score in mismatched group was(29.1 ± 7.0)points and(36.6 ± 6.5)points at postoperative one week and at the latest follow-up,significantly lower than that in matched group[(42.0 ± 5.7)points,(47.4 ± 2.5)points]( P < 0.01),while there was no significant difference in ASIA lower limb motor score and sensory score between the two groups( P > 0.05). Both groups showed significantly improved JOA score at postoperative one week and at the latest follow-up,compared with that before operation( P < 0.05). JOA score in mismatched group was(11.5 ± 3.0)points and(12.5 ± 3.0)points at postoperative one week and at the latest follow-up,significantly lower than that in matched group[(13.5 ± 2.4)points,(15.0 ± 2.0)points]( P < 0.01). Postoperative improvement rate in matched group was 95%(20/21),and was 85%(18/21)in mismatched group( P < 0.05). Cervical axial pain occurred in 3 patients in each group and C 5 nerve root palsy in 2 patients in matched group,all of which were relieved after conservative treatment. No implant loosening or breakage occurred during follow-up. Conclusions:Open-door laminoplasty can improve part of the nerve function of patients with cervical hyperextension injury. However,the overall improvement degree of nerve function especially recovery of upper limb motor function in patients with spinal cord-canal mismatch is inferior to those in spinal cord-canal matched patients.
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Objective:To establish a radiomics-based biomarker for predicting pathological response after preoperative neoadjuvant chemoradiotherapy (nCRT) in locally advanced esophageal cancer.Methods:From 2008 to 2018, 112 patients with locally advanced esophageal cancer who received nCRT were enrolled. All patients were treated with preoperative nCRT combined with surgery. Enhanced CT images and clinical information before nCRT were collected. A lesion volume of interest was manually delineated. In total, 670 radiomics features (including tumor intensity, shape and size, texture and wavelet characteristics) were extracted using the pyradiomics package in PYTHON. The stepwise regression combined with the best subset were employed to select the features, and finally the Logistic regression model was adopted to establish the prediction model. The performance of the classifier was evaluated by the area under the ROC curve (AUC). Results:The pathological complete remission (pCR) rate was 58.0%(65/112). 10 radiomics features were included in the final model, The most relevant radiomics feature was the gray feature (the texture information of the image), followed by the shape and voxel intensity-related features. In the training set, the AUC was 0.750 with a sensitivity of 0.711 and a specificity of 0.778, the corresponding values in the testing set were 0.870, 0.757 and 0.900, respectively.Conclusions:Models based on radiomics features from CT images can be utilized to predict the pathological response to nCRT in esophageal cancer. As it is efficient, non-invasive and economic model, it could serve as a promising tool for individualized treatment when validated by further prospective trials in the future.
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Objective:To explore the changes in activity of indoleamine 2, 3-dioxygenase(IDO)before and after stereotactic body radiation therapy (SBRT) in early stage non-small cell lung cancer(NSCLC) and its relationship with survival.Methods:The retrospective study was to assess IDO activity by serum kynurenine (Kyn) and Kyn to tryptophan (Trp) ratio before and after SBRT of early stage NSCLC.Thirty early stage NSCLC patients who received SBRT in the Cancer Hospital of the University of Chinese Academy of Sciences were enrolled, from December 2014 to July 2017. High-performance liquid chromatography and mass spectrometry were used to detect serum Kyn and Trp before and after SBRT. The ratios of Kyn after SBRT to Kyn before SBRT were divided into high and low group according to the median value. Similarly, the ratios of Kyn to Trp after SBRT were divided into high and low group.The correlation between overall survival (OS), progression-free survival (PFS) and IDO activity was evaluated. The factors influencing prognosis were analyzed.Results:In all patients, lower ratio of Kyn after SBRT to Kyn before SBRT significantly was correlated with better PFS (median PFS: not reached vs. 26.8 months, HR=0.31, 95% CI =0.11-0.90, P<0.05). The lower Kyn∶Trp ratio after SBRT had longer OS (median OS: not reached vs. 36.5 months, HR=0.27, 95% CI =0.079-0.95, P<0.05). In multivariate analysis, smoking <30 packs/year, higher BED, and lower ratio of Kyn after SBRT to Kyn before SBRT were associated with longer PFS. Lower Kyn∶Trp ratio after SBRT and higher BED were associated with longer OS. Conclusions:SBRT could alter IDO-mediated antitumor immune activity. IDO is a potentially valuable biomarker for monitoring immune status and predicting survival in early NSCLC patients after SBRT.
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Objective To compare the efficacy of trimodality therapy and chemoradiation therapy (CRT) alone in patients with locally advanced resectable esophageal squamous cell carcinoma (SCC).Methods A total of 124 cases with locally advanced resectable esophageal SCC were retrospectively analyzed and classified into 2 groups.Fifty-four cases in trimodality group were treated with surgery and preoperative chemoradiation,while 70 cases in CRT alone group only received radiation and chemotherapy.Local tumor control,3-year survival and treatment-related mortality were assessed.Results The local recurrent rate of the resected patients was 18.5% in trimodality group and 35.7% in CRT alone group,respectively(x2 =4.445,P < 0.05).The 3-year progression-free survival (PFS) was 65.3% (95% CI 50.7-80.5) in trimodality group and31.9% (95%CI 19.6-44.2) in CRT alone group (P<0.05),while the overall survival (OS) 66.3% (95% CI43.0-89.6) and 34.4% (95% CI 21.1-47.7),respectively(P < 0.05).Treatment-related mortality was 1.9% in trimodality group and 2.9% in CRT alone group (P > 0.05).For CRT alone group,the sub-group analysis showed that there was no statistically significant difference in the 3-year OS between patients who received 50-50.4 Gy and those who received the dose over 50.4 Gy (39.9% 95% CI 18.5-61.3 vs.31.5% 95% CI 14.8-48.2,P >0.05).Conclusions Compared with CRT alone,trimodality therapy showed the superior local control,PFS and OS,with similar treatment-related mortality in the treatment of patients with SCC of esophagus.The role of surgery could not be replaced by CRT alone even with the augment of radiation dose.
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Objective To investigate the biomechanical properties and clinical effects of the unilateral/bilateral percutaneous vertebroplasty (PVP) on the treatment of osteoporotic vertebral compression fractures in elderly patients. Methods The finite element models of the unilateral/bilateral percutaneous vertebroplasty (PVP) in osteoporotic vertebral compression fractures were established to evaluate changes in strain and stress of the fractured vertebra after surgery. Eighty patients with osteoporotic vertebral compression fractures underwent unilateral or bilateral PVP were collected for retrospective analysis. The operation time,intraoperative fluoroscopy times,injected bone cement volume, bone cement leakage rate and visual analogue scales (VAS) score between the two groups were analyzed. Results The maximum strain and stress in unilateral PVP group were 1.18 times and 1.15 times of those in bilateral PVP group,respectively.The operation time and intraoperative fluoroscopy times in unilateral PVP group were obviously smaller than those in bilateral PVP group (P0.05).Conclusions The biomechanical effect of unilateral PVP was similar to that of bilateral PVP. The puncture needle localization of unilateral PVP for treating elderly patients with osteoporotic vertebral compression fractures had the advantage of less operation time and limited X-ray exposure.
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Objective To assess the disc injury in neurologically intact thoracolumbar bust fractures and to evaluate the correlation between the severity of disc injury and the parameters of vertebral body damage as as to formulate radiologic index for further MRI examination.Methods A retrospective case series review was made on 22 patients (44 discs) with thoracolumbar burst fractures without neurologic deficit treated from January 2015 to December 2015.Vertebral level involved was from T11-L2.There were 12 males and 10 females,with the mean age of 47.9 years (range,43-60 years).MRI were used to evaluate the severity of disc injury.Among the 44 discs,18 were Grade 0,11 were Grade 1,12 were Grade 2,and three were Grade 3.Then patients with Grade 0 and 1 were taken as disc intact group and other 12 patients disc rupture group.Vertebral wedge angle,local kyphosis angle,anterior and posterior vertebral body height and canal compromise were measured on CT to determine the damage of fracture.Spearman correlation coefficient was used to analyze the correlation between the severity of disc injury and the parameters of vertebral body damage,and receiver operative curve (ROC) was used to assess the effectiveness of these indexes in predicting disc injury.Results Vertebral wedge angle and anterior/posterior vertebral body height ratio were correlated with the severity of superadjacent disc injury (P < 0.05 or 0.01).Canal compromise,vertebral wedge angle and anterior/posterior vertebral body height ratio were significantly different between the two groups (P < 0.05 or 0.01).ROC results showed the area under curve of canal compromise,vertebral wedge angle and anterior/posterior vertebral body height ratio were 0.758,0.762,and 0.867 respectively,indicating no significant difference (P > 0.05).Threshold of canal compromise,vertebral wedge angle and anterior/posterior vertebral body height ratio were 21%,15.4°,and 0.69 respectively.Conclusions Vertebral wedge angle and anterior/posterior vertebral body hight ratio are correlated with the severity of superadjacent disc injury.Canal compromise >21%,VWA > 15°and anterior/posterior vertebral body height ratio > 0.69 may be the practice preferences of indications for ordering a MRI in patients with neurologically intact thoracolumbar bust fractures.
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Objective To evaluate the safety and clinical efficacy of stereotactic body radiation therapy (SBRT) for lung cancer.Methods A retrospective analysis was performed on 200 patients with primary non-small cell lung cancer (NSCLC)(118 patients) or solitary pulmonary metastasis (82 patients) who underwent SBRT in Zhejiang Cancer Hospital from January 2012 to September 2015.The 80% isodose line covered 95% of the planning target volume,and the 100% isodose line covered 100% of the internal gross tumor volume.The fractional dose was 4.0-18.0 Gy daily or every other day,and the biologically equivalent dose ranged from 40.0 to 151.2 Gy (median 100 Gy).Results All patients completed treatment.The follow-up rate was 96.0%.The complete response and partial response rates were 14.8%(17/115) and 65.2%(75/115) for the primary tumor group,versus 25%(19/77) and 38%(29/77) for the metastasis group.The incidence rates of grade Ⅱ and Ⅲ acute radiation pneumonitis were 4.7% and 3.1%,respectively.The median follow-up was 14.9 months.The 1-and 2-year local control rates were 95.7% and 84.3% for the primary tumor group,versus 92% and 73% for the metastasis group.The 1-and 2-year overall survival rates were 94.5% and 92.0% for the primary tumor group,versus 85% and 62% for the metastasis group.Conclusions SBRT is a safe and effective treatment for early primary NSCLC and solitary pulmonary metastasis,resulting in high 1-and 2-year local control and overall survival rates and low rate of complications.
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Objective To investigate cause analysis and treatment strategy of cage migration after lumbar interbody fusion.Methods Retrospective study was performed on 9 cases with cage migration after lumbar interbody fusion from January 2009 to February 2015 in our hospital.There were 4 males and 5 females,and mean age was 61.6 years (rang,38-75 years).The types of cage included Titanium metal cage used in 3 cases,cylindrical thread cage in 1 case and PEEK cage in the other cases.Bilateral instrumented posterior lumbar interbody fusion was found in 7 cases,and unilateral fixation in 2 cases.Analyze the risk factors of cage migration and the strategies of revision surgery,and evaluate the radiological outcomes and clinical efficacy of revision surgery.Results Risk factors of cage backward migration are as follows:nucleus pulposus left too much in 6 cases,poor cartilage endplate resection in 4 cases,small size of cage selection in 5 cases,unsatisfied cage placement in 2 cases,and improper operation in 1 case.Follow-up survey was fulfilled in all patients,the follow-up time was 6 to 32 months,and bony union was detected in all patients.No cage re-migration,non-fusion,or loosen pedicle screw was found during follow-up period.Clinical symptoms were all improved after revision.Conclusion The causes of cage migration after bilateral or unilateral instrumented transforaminal lumbar interbody fusion were complicated.Risk factors of cage migration may be poor intervertebral space preparation,small cage size,and improper cage placement,which may be not associated with unilateral fixation.Excellent or good radiological outcomes and clinical efficacy depend on a reasonable revision surgery.
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Objective:To analyze the characteristics of regional lymph node metastasis in patients with resectable non-small cell lung cancer (NSCLC) and assess its clinical significance in surgical mediastinal lymph dissection and the target volume definition of postoperative radiotherapy. Methods:We retrospectively reviewed 810 patients with NSCLC, and analyzed the metastatic frequency of each regional lymph node station as well as the correlation between tumor location and regional lymph node metastases. Results:Re-gional lymph node metastases were significantly associated with the age of patients, histology, tumor size, and tumor location (P=0.013, 0.000, 0.009 and 0.000, respectively). Conclusion:The younger patients with left lung adenocarcinomas and large tumor size tended to regional lymph node metastases. The trend of regional lymphatic drainage in the lobes of lung occurred differently. The prior location of involved regional lymph nodes in different lobes of the NSCLC patients was as follows:The station 2-4 for right upper lobe tumors, the station 2-4 and 7 for right middle lobe tumors and right lower lobe tumors, the station 5-6 for left upper lobe tumors, and the station 5-6 and 7 for left lower lobe tumors. We should pay more attention to the regions regarding the higher frequencies of lymph node metastases, when determining the extent of lymph node dissection or delineating the target volume of postoperative radiotherapy for NSCLC patients.
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Objective To investigate the differences of measurement of gross target volume (GTV)between endoscopic ultrasonography ( EUS )-based ( GTVEUS ) and computed tomography ( CT ) -based (GTVCT) method for thoracic esophageal squamous cell carcinoma. Methods EUS was performed on 36consecutive patients with thoracic squamous cell carcinoma, and the superior and inferior boarders of the tumor defined by EUS were marked with hemoclips. The CT planning scan was then performed with the patient in supine position, and the GTVCT and GTVEUS were contoured respectively. The lengths ( LCT and LEUS) and spatial locations of longitudinal GTVCT and GTVEUS were compared. Results The mean LCT and LEUS were (7. 79 ± 3. 15 ) cm and (7. 42 ± 2. 72) cm, respectively ( t = 0. 82, P > 0. 05 ), with a correlation coefficient of 0. 61 (P <0. 001 ). Locations of longitudinal GTVCT and GTVEUS were compared in 34cases, with 2 excluded for invisualization on CT. The mean conformal index (CI) was (0. 79 ± 0. 18 ), and spatial variations were found in 71% patients, with 8 patients at proximal end and 21 others at distal end.There was no clip placement associated complication. Conclusion Endoscopic hemoclips placement is safe and reliable. EUS can provide additional information to CT in defining longitudinal GTV in thoracic esophageal squamous cell carcinoma, especially in superficial and submucosal carcinomas.
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Overexpression of epidermal growth factor receptor (EGFR) in esophageal cancer has been related to tumor grade, vascular invasion and metastasis. The level of EGFR expression may be a predictive marker of esophageal caneer's sensitivity to chemoradiotherapy. EGFR inhibitors have been indicated as an effective targeted therapy, and promising results have been observed in phase Ⅱ and Ⅲ clinical trials.
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Objective To evaluate the outcome of radiotherapy for recurrent esophageal cancer after surgery and to determine the prognostic factors. Methods From Jan 2004 to Dec 2009, 93 patients of esophageal carcinoma with loco-regional recurrence as the first site of failure after surgery were retrospectively reviewed. Kaplan-Meier method was used to analyze the survival. Logrank test was used to evaluate the difference between the groups. Multivariate survival analysis was conducted using a Cox proportional hazard regression model with a backward stepwise procedure. Results The overall survival rates at 1, 2 and 3 years were 40. 9% , 10. 1% and 6. 7% ,respectively,but with a median survival time of 11.0 months(95% CI 9. 4-12. 6) . In univariate analysis, age,PS, radiation dose and retreatment methods were independent prognostic factors. In multivariate analysis, only radiation dose and retreatment methods were independent prognostic factors for overall survival. Conclusions The prognosis of patients with postoperative loco-regional recurrence of esophageal cancer is poor. However, a long-term survival maybe expected by definitive chemoradiotherapy.
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Objective To investigate the optimal treatment planning of intensity modulated radiotherapy (IMRT) for non-small cell lung cancer (NSCLC) .Methods Two types of treatment plans were designed for 11 patients with inoperable NSCLC disease.In the first plan(PTV60 plan) ,60 Gy was prescribed to the planning target volume(PTV) which was created using CTV(GTV +6-8 mm) plus the margin for organ motion and setup uncertainties.In the second plan(PTV70 plan) ,70 Gy was prescribed to the PTV which was created using GTV plus the margin for organ motion and setup uncertainties.The dose-volume histogram,the planning target volume coverage,and other dosimetric parameters of normal structures were compared between the two plans.Results These two plans were not significantly different in the dose heterogeneity,but commpared with the PTV60 plan,the PTV70 plan significantly improved 60 Gy volume with regard to PTV coverage.The values of V_(20) and V_5 of lung were reduced in average by (1.69 ±0.42) % ,and (1.29 ±1.09) % (t = 0.047,0.264,P = 0.002) ,respectively.Conclusions The planning of 70 Gy to the PTV using GTV plus the margin for organ motion and setup uncertainties might be better than that of 60 Gy to the PTV using CTV(GTV +6-8 mm) plus the margin for organ motion and setup uncertainties.
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Objective To evaluate the prognostic factors of brain metastasis from non-small cell lung cancer and suggest a individualized treatment method proposal with prognostic estimation. Methods From Dec. 2003 to Jan.2007, 183 patients received whole brain radiation therapy (WBRT) were retrospectively analyzed. Kaplan-Meier method was used to analyze the survival. Logrank test was used to evaluate the difference between the groups. Multivariate survival analysis was conducted using a Cox proportional hazard regression model with a backward stepwise procedure. Results The overall l-, 2- and 3-year survival rate was 40.6%, 16.6% and 11.3%, respectively, but with a median survival time of 10.0 months (95% CI 8.6-11.4 months). In multivariate analysis, RAP grouping, weight loss, LDH in blood serum and treatment method were independent prognostic factors. The median survival time of WBRT alone, WBRT with chemotherapy, surgery with chemoradiotherapy and WBRT with Gefitinib was 9.0, 9.0, 22.0 and 13.0 months, respectively, but their difference were statistical significant (X2 = 10.37, P = 0.016). Conclusions The main prognostic factors of brain metastasis from non-small cell lung cancer are RAP grouping, weight loss, LDH in blood serum and treatment method. The survival time is prolonged by proper multidiseiplinary management than WBRT alone. The effect of combined treatment of surgery with chemoradiotherapy is favorable for the patients operated with single region of metastasis.
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OBJECTIVE: To evaluate the safety and efficacy of Wuling Capsule combined with Deanxit in treating post-stroke depression (PSD). METHODS: One hundred and fourteen patients with PSD were randomly divided into Wuling Capsule-treated group (n=39), Deanxit-treated group (n=37) and Wuling Capsule plus Deanxit-treated group (n=38). Patients in Wuling Capsule-treated group were administered with three Wuling Capsules three times a day, and patients in Deanxit-treated group were administered with Deanxit 10.5 mg twice daily, while patients in the Wuling Capsule plus Deanxit-treated group were administered with both Wuling Capsule and Deanxit. Patients in the three groups were all treated for six weeks. Treatment efficacy was evaluated with Hamilton Depression Scale (HAMD) and the side effects were evaluated with Treatment Emergent Symptom Scale (TESS) before treatment and after 2-, 4-, and 6-week treatment. The blood and urine routine examinations were performed, and the hepatorenal functions and electrocardiogram were examined as well. RESULTS: There was no statistical difference in the total efficacy rate between Wuling Capsule-treated group and Deanxit-treated group (64.1% vs 64.9%, P>0.05), but the total efficacy rate of Wuling Capsule plus Deanxit-treated group was higher than that of the monotherapy (89.5% vs 64.1%, 89.5% vs 64.9%, P<0.05). There were no significant side effects in Wuling Capsule-treated group, while the incidence of side effects was 9% in both groups administered with Deanxit. CONCLUSION: The efficacy of Wuling Capsule plus Deanxit is better than that of the monotherapy in treating PSD.
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Presented is a method to set up a quantification model of bone growing and remodeling adaptation, which integrates animal experiments, parameter identification of mathematical functions and technique of computer simulation. By designing a new animal experiment, we investigate the effects of growing and remodeling of the rat femurs in different stress environments, gather the bone mineral density (BMD) of proximal femur in the same interval for the unknown parameter (B and K) inversion of bone growing and remodeling equation and create the femur three-dimensional geometrical model based on CT images. The model in this paper can not only numerically measure the relation between outer stimulus and the femur BMD variation of rapid growing rats, but also predict the growth trend of rat femur under different stress environments in its whole lifecycle. The thought and method of creating the model in this paper can be used for reference to modeling human bone growth and remodeling.
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Animales , Femenino , Ratas , Adaptación Fisiológica , Fenómenos Biomecánicos , Densidad Ósea , Fémur , Fisiología , Modelos Biológicos , Ratas Sprague-Dawley , Estrés MecánicoRESUMEN
6-week old rats were subjected to sciatic nerve resection and the right hindlimbs were then under a low stress environment. Bone mineral density (BMD) of different regions and geome-morphological parameters of femurs were measured. The results showed that the increase in the diameter, subperiosteal area and bone mineral density of femurs were suppressed obviously under low stress environment. But the sensitivity of BMD of different regions of the femur to the low stress environment was different. The suppression of the increase in femoral BMD was composed of an early impairment in the gain of BMD at the femoral metaphysis, which is rich in trabecular bone, and a sustained reduction in the gain of BMD at the femoral diaphysis, which is rich in cortical bone. The results of geome-morphology suggested that the early reduction in the increase of BMD at the metaphysis was due to an enhancement of bone resorption, whereas the suppression of gain in cortical bone mass and size is the result of a sustained reduction of periosteal bone formation.
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Animales , Femenino , Ratas , Densidad Ósea , Fisiología , Resorción Ósea , Fémur , Patología , Inmovilización , Ratas Sprague-Dawley , Nervio Ciático , Fisiología , Cirugía General , Estrés Mecánico , Soporte de Peso , FisiologíaRESUMEN
The mechanical model of femur mid-diaphysis with a rectangular open section in the exterior cortex was developed and a finite element method was adopted in calculating and analysing the changes of torsional stiffness and the stress distribution when the dimension of the open section altered. It showed that the open section with a length of 1 OD (femur mid-diaphysis diameter) had little influence on the femur torsional stiffness or stress distribution. The torsional stiffness decreased most dramatically as the length increased from 2 to 4 OD. Shear stress peaked at the center of the open section. This conclusion provides an important theoretical ground for the operative methods and the dimension control of an open section in clinical orthopaedics.
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Humanos , Fenómenos Biomecánicos , Fémur , Cirugía General , Modelos TeóricosRESUMEN
By creating two kinds of stress environment in the same animal model, we performed a three-point bending test and a compressing test on the rat femurs growing under different stress conditions to characterize the effect of stress on bone mechanical properties. The right hindlimbs were subjected to sciatic nerve resection to become cripple and were used as unloading group; the left hindlimbs bore excess load and made up the overloading group; the normal rats were used as control group. The animals were encouraged to exercise for half an hour everyday in the morning, noon and evening. The experiment observation finished in four weeks. The biomechanical parameters of femur diaphyses were measured. The experiment results showed that stress environment may change several mechanical parameters of rat femurs. This study indicated that bone tissues can adapt to its stress environment by changing its mechanical properties. The experimental model in this article is practical and reliable.