BACKGROUND Leg length discrepancy(LLD)following total hip arthroplasty(THA)is a common complaint,leading to decreased patient satisfaction.However,the effect of LLD before THA on outcomes and complications is not well...BACKGROUND Leg length discrepancy(LLD)following total hip arthroplasty(THA)is a common complaint,leading to decreased patient satisfaction.However,the effect of LLD before THA on outcomes and complications is not well defined.AIM To assess the effect of prior LLD on rates of falls,implant-related complications,stay length,readmissions,and implant survival following THA.METHODS A retrospective review of a nationwide insurance database was conducted from 2010 to 2021.All cases of THA and those with a prior diagnosis of LLD were identified.THA patients with LLD were matched to control patients 1:5 based on demographic and comorbidity profiles.Two-year fall rates and implant complications,lengths of stay,90-day readmissions,and time to revision were compared between cohorts.RESULTS A total of 2038 patients with LLD were matched to 10165 control patients.The LLD group showed significantly greater rates of falls[odds ratio(OR)=1.58;95%confidence interval(95%CI):1.24-2.01],dislocation(OR=2.61;95%CI:2.10-3.24),mechanical loosening(OR=4.58;95%CI:3.28-6.29),and periprosthetic fracture(OR=2.70;95%CI:1.96-3.72)compared to the control group(all P<0.001).Mean length of stay(LOS)was also significantly higher in the LLD group(3.1 days vs 2.8 days,P=0.034).No significant difference in 90-day readmission rates(7.75%vs 7.02%,P=0.244)was observed between the groups(P=0.244).Time to revision was significantly less in the LLD group(225 days vs 544 days,P<0.001).CONCLUSION LLD in patients having THA is related with significantly higher fall risk,rates of implant-related complications,LOS,and quicker time to revision.Identifying patients with LLD before their THA may help in identifying risks,better patient counselling,and more effective preoperative planning.However,the study have important limitations:Its design lacks information on the degree and cause of LLD,the time between diagnosis and surgery,and which leg with the discrepancy underwent the operation.Future well-designed studies should confirm the findings of this study.展开更多
Objective To examine the relationship between upper leg length （ULL） and metabolic syndrome （MetS） in older adults.Methods Data was collected from National Health and Nutritional Examination Survey （NHANES, 2009-...Objective To examine the relationship between upper leg length （ULL） and metabolic syndrome （MetS） in older adults.Methods Data was collected from National Health and Nutritional Examination Survey （NHANES, 2009-2010）. 786 individuals （385 males and 401 females） who were 60 years of age or older were included in this analysis. MetS was defined as having at least three of following conditions, i.e., cen-tral obesity, dyslipidemia, insulin resistance, and hypertension based on National Cholesterol Education Program guidelines. ULL was grouped into gender-specific tertiles.Results328 （41.7%） of participants were categorized as having MetS （38.7% in men and 49.1% in women,P = 0.002）. Compared to individuals in the 1st tertile （T1） of ULL, those in the 3rd tertile （T3） had lower levels of triglycerides （120.8 vs. 153.1 mg/dL,P = 0.045）, waist circumference （100.7vs. 104.2 cm,P = 0.049）, and systolic blood pressure （126.7vs. 131.4 mmHg, P = 0.005）, but higher levels of high-density-lipoprotein cholesterol （58.1vs. 52.4 mg/dL,P = 0.024）. The odds ratios （95% CI） of MetS from multivariate logistic regression were 0.57 （0.32-1.03） for individuals in the T2 of ULL and 0.39 （0.24-0.64） for individuals in the T3 of ULL, respectively （P-value for the trend 0.022）.Conclusions ULL was negatively associated with MetS in older adults. Further research is needed to identify potential mechanisms.展开更多
Background: This is a rare case of piriformis syndrome. We discuss the patient’s symptoms, imaging study results, laboratory examination findings, and prescribed treatment in an attempt to determine the possible mech...Background: This is a rare case of piriformis syndrome. We discuss the patient’s symptoms, imaging study results, laboratory examination findings, and prescribed treatment in an attempt to determine the possible mechanisms or reasons for this patient’s development of piriformis syndrome. Methods: The patient is a 22-year-old female soldier who was admitted for lower back pain with soreness radiating to her right buttock and right lower extremity. We found that she had leg length discrepancy under X-ray finding. She was diagnosed piriformis syndrome by physical examination and Magenetic Resonance Image. Results: We performed scanography for lower extremities revealed a left femur length of 42.7 cm, a right femur length of 43.3 cm, a left tibia length of 33.2 cm, and a right tibia length of 33.6 cm;her left lower extremity was 1 cm shorter than her right. The MRI of sacrum also reveals hypertrophy of right piriformis muscle. Conclusions: Piriformis syndrome might be caused by short-term compensation in congenital leg length discrepancy. The patient with leg length discrepancy changed posture when standing, walking, and running. These compensation postures could lead to abnormality position of bones where there is insertion of the muscle.展开更多
The use of cementless total hip arthroplasty (THA) is on the increase. In order to achieve rotational and axial stability larger implants may be required than originally templated for. This could potentially result in...The use of cementless total hip arthroplasty (THA) is on the increase. In order to achieve rotational and axial stability larger implants may be required than originally templated for. This could potentially result in a lar-ger leg length inequality. Our objective was to determine whether there is greater inequality in leg length post-operatively in cementless THA as compared to cemented implants. 136 consecutive patients undergoing elective THA between June 2007 and May 2008 were included. Post-operative digital radiographs were ex-amined to determine leg length. Twenty seven patients (20%) underwent a cemented procedure and 109 (80%) a cementless procedure. In the cemented group the mean leg length discrepancy was 7.3 mm (range 19 mm short to 21 mm long). In the cementless group the mean measured leg length discrepancy was 6.3 mm (range 18 mm short to 23 mm long). There was no significant difference between the two groups (P = 0.443). This study shows that with accurate pre-operative templating, both cemented and cementless proce-dures produce comparable and acceptable leg length discrepancies.展开更多
BACKGROUND Certain implant combinations change leg length and offset in primary total hip arthroplasty(THA).Poor restoration of leg biomechanics is a frequently cited reason for patient dissatisfaction following prima...BACKGROUND Certain implant combinations change leg length and offset in primary total hip arthroplasty(THA).Poor restoration of leg biomechanics is a frequently cited reason for patient dissatisfaction following primary THA.A pure high-offset stem should provide direct lateralization without affecting femoral length when compared to a standard stem.However,clinical experience with preoperative planning software based on computed tomography-based three-dimensionalmodels reveals that using pure high-offset stems in THA may cause a difference between expected(no change in femoral length)and actual(small increase)in postoperative femoral length.AIM To elucidate the causes of these femoral length discrepancies using preoperative planning software.METHODS Preoperative templating for 43 robotic-assisted THAs,optimizing acetabular size and orientation,center of rotation,stem size and offset,and prosthetic head diameter were obtained.The preoperative planning software was used to calculate differences between preoperative and postoperative femoral length for standard and pure high-offset stems,unique to each patient.RESULTS Whilst the increase in femoral length between standard and high-offset stems was not significant(P=0.93),35 femurs(81.4%)experienced a 1-mm increase,and 3(7.0%)experienced a 2-mm increase in femoral length while using high-offset stem compared to the standard stem.The incidence of femoral length increase was lower for patients with shorter femurs(18/22;81.8%)compared to patients with longer femurs(20/21;95.2%).CONCLUSION When pure high-offset stems were used in preoperative planning software,we demonstrated an unexpected increase in leg length between 1-2-mm in 88.4%of patients.This unexpected increase in femoral length is due to a function of the preoperative planning software’s planned stem alignment with the anatomical axis,and not an inherent fault in the stem design.With expanding accessibility of robotic-assisted THA platforms,all potential sources of postoperative leg length discrepancy should be identified during preoperative templating and necessary alterations to the surgical plan should be made to accommodate this unexpected difference when using a pure high-offset stem.展开更多
Background：Total hip arthroplasty （THA） is one of the most effective treatments for phase Ⅲ and Ⅳ hip arthrosis.Lower limb length balancing is one of the determining factors of a successful surgery,particularly i...Background：Total hip arthroplasty （THA） is one of the most effective treatments for phase Ⅲ and Ⅳ hip arthrosis.Lower limb length balancing is one of the determining factors of a successful surgery,particularly in patients with developmental dysplasia of the hip （DDH）.The purpose of this study was to evaluate the postoperative change in intra-pelvic obliquity （intra-PO） angle in the coronal plane and its effects on leg length discrepancy （LLD） within 2 years.Methods：A total of 78 patients （70 females,8 males） were enrolled in this study.All patients were suffering from DDH with varying degrees of LLD.Pelvic plain radiographs were collected before and after the operation.The intra-PO angles were measured 0,0.5,1 and 2 years after THA.At the same time,postoperative LLD was measured with blocking test.Results：PO changed significantly in the first year after THA surgery （0 year vs.0.5 year,P 〈 0.01;0.5 year vs.1 year,P 〈 0.01）,and the changing value of intra-PO angle （△PO） slowed down substantially during the first 2 years after THA （0.5 year vs.0.5-1 year,P 〈 0.01;0.5-1 year vs.1-2 years,P 〈 0.01）.With the change in intra-PO angle,LLD also got narrow within the 1st year （0 year vs.0.5 year,P 〈 0.01;0.5 year vs.1 year,P 〈 0.01）.Elderly patients had a smaller intra-PO angle reduction （Group A vs.Group B,P =0.01;Group B vs.Group C,P〈 0.01）.Conclusions：Intra-PO angle and LLD gap narrowed with time after THA surgery.In particular,elderly patients had smaller change in intra-PO angle.展开更多
[目的]比较“肩-肩”新型解剖标记定位法与人工智能辅助规划系统(AIHIP系统)规划的全髋关节置换(total hip arthroplasty, THA)中假体置入定位及预防双下肢不等长的准确性。[方法] 2020年8月-2022年12月就诊于本院行初次THA的94例患者,...[目的]比较“肩-肩”新型解剖标记定位法与人工智能辅助规划系统(AIHIP系统)规划的全髋关节置换(total hip arthroplasty, THA)中假体置入定位及预防双下肢不等长的准确性。[方法] 2020年8月-2022年12月就诊于本院行初次THA的94例患者,按照随机数字表法分为两组,47例采用“肩-肩”法(肩-肩组),另外47例采用AIHIP系统规划法(智能组),分别于术前进行规划,比较两组临床和影像结果。[结果]两组患者手术时间、总失血量、术后下地时间的差异均无统计学意义(P>0.05)。影像方面,两组髋臼假体匹配、股骨柄假体匹配、双下肢长度差、联合偏心距的差异均无统计学意义(P>0.05),肩-肩组的尖肩距[(15.9±3.0) mm vs(17.7±3.4) mm, P<0.001]、截骨距[(7.8±2.7) mm vs(9.2±4.1) mm, P=0.003]均显著小于智能组。[结论]“肩-肩”新型解剖标记定位法可以在THA术中准确置入股骨侧假体,并可预防术后双下肢不等长。展开更多
The equivalent mechanism of the system is often considered as one specific mechanism in most existing studies of multi-legged robots, however the equivalent mechanism is varying while the robot moves on the ground. Fo...The equivalent mechanism of the system is often considered as one specific mechanism in most existing studies of multi-legged robots, however the equivalent mechanism is varying while the robot moves on the ground. Four typical tripod period gaits of a radial symmetrical six-legged robot are analyzed. Similar to the metamorphic mechanism, the locomotion of multi-legged robot is considered as a series of varying hybrid serial-parallel mechanisms by assuming the constraints of the feet on the ground with hinges. One gait cycle is divided into several periods, and in different walking period there is a specific equivalent mechanism corresponding to it, and the walking process of multi-legged robot is composed by these series of equivalent mechanisms. Walking performance can be got by analyzing these series of equivalent mechanisms. Kinematics model of the equivalent mechanism is established, workspaces of equivalent mechanisms are illustrated by simulation and a concept of static stability workspace is proposed to evaluate the static stability of these four gaits. A new method to calculate the stride length of multi-legged robots is presented by analyzing the relationship between the workspace of two adjacent equivalent parallel mechanisms in one gait cycle. The stride lengths of four gaits are given by simulations. Comparison of stride length and static stability among these four typical tripod gaits are given. It has been proved that mixed gait and insect-wave gait II have better static stability than mammal kick-off gait and insect-wave gait I. Insect-wave gait II displays its advantage on stride length while the height of robot body lower than 87 mm, mammal kick-off gait has superiority on stride length while the height of robot body higher than 115 mm, and insect-wave gait I shows its shortcoming in stride length. The proposed method based on metamorphic theory and combining the footholds and body height of robot provides a new method to comprehensive analyze the performance of multi-legged robot.展开更多
[目的]比较机器人ARTHROBOT辅助全髋置换术(robot-assisted total hip arthroplasty,r THA)与传统手工全髋置换术(manual total hip arthroplasty,mTHA)的早期效果。[方法]回顾性分析2022年4月—2022年11月本院行THA的58例患者的临床资...[目的]比较机器人ARTHROBOT辅助全髋置换术(robot-assisted total hip arthroplasty,r THA)与传统手工全髋置换术(manual total hip arthroplasty,mTHA)的早期效果。[方法]回顾性分析2022年4月—2022年11月本院行THA的58例患者的临床资料。根据术前医患沟通结果,28例采用rTHA,另外30例采用mTHA,对比两组围手术期、随访及影像学资料。[结果]两组患者均手术顺利,未见术中并发症。rTHA组手术时间、切口总长度、治疗费用均显著大于mTHA组(P<0.05)。rTHA组术后无脱位者,而mTHA组1例因假体位置不良,脱位,行翻修术。随时间推移,两组患者VAS评分、Harris评分、髋伸-屈及内-外旋ROM均显著改善(P<0.05)。rTHA组Harris评分术后1个月[(70.8±3.3)vs(68.2±5.1),P=0.043]、末次随访时[(92.0±3.6)vs(89.7±4.2),P=0.025]及术后6个月髋内-外旋ROM[(48.5±5.9)°vs(44.1±6.6)°,P=0.009]均显著优于mTHA组。影像方面,rTHA组术后双下肢长度差(leg length discrepancy,LLD)[(0.4±0.2)mm vs(0.6±0.3)mm,P=0.003]、双侧股骨偏心距(femoral offset deviation,FOD)差值[(0.3±0.2)mm vs(0.7±0.5)mm,P<0.001]、双侧髋臼偏心距(acetabular offset deviation,AOD)差值[(0.3±0.2)mm vs(0.5±0.3)mm,P=0.004]和联合偏心距(combined offset deviation,COD)差值[(0.4±0.4)mm vs(0.8±0.6)mm,P<0.001]均显著小于mTHA组,而两组髋臼外展角(acetabular abduction angle,AAA)和髋臼前倾角(acetabular anteversion,AA)差异无统计学意义(P>0.05)。以Lewinnek安全区为标准,rTHA组安全区内病例数占比[例(%),26(92.9)vs 21(70.0),P=0.026]显著高于mTHA组(P<0.05)。[结论]机器人ARTHROBOT辅助THA使假体置入更精准,髋臼杯置入安全区的比例更高,能更好恢复患髋偏心距,有利于减少LLD,疗效更佳。展开更多
目的:使用CT联合Mimics软件测量全髋关节置换术(total hip arthroplasty,THA)后股骨偏心距(femoral offset,FO)、旋转中心高度(rotation center height,RCH)与双下肢长度差(lower leg length discrepancy,LLD),并探讨THA后FO、RCH与LLD...目的:使用CT联合Mimics软件测量全髋关节置换术(total hip arthroplasty,THA)后股骨偏心距(femoral offset,FO)、旋转中心高度(rotation center height,RCH)与双下肢长度差(lower leg length discrepancy,LLD),并探讨THA后FO、RCH与LLD的关系。方法:回顾性分析2020年10月至2022年6月符合标准的40例行单侧THA的患者,其中男21例,女19例;年龄30~81(58.90±14.13)岁;身体质量指数(body mass index,BMI)为17.3~31.5(25.3±3.4)kg·m^(-2);左侧18例,右侧22例。诊断为股骨头坏死30例(FicatⅣ期),髋关节骨性关节炎2例(TünnisⅢ期),发育性髋关节脱位合并终末期骨关节炎2例(CroweⅢ期),股骨颈骨折6例(GardenⅣ期)。术前、术后拍摄骨盆CT三维重建,经Mimics软件处理后建立三维重建模型,在模型上对FO、RCH、LLD进行测量。结果:术后双侧FO差值与LLD呈正相关性(r=0.744,P<0.001);将FO重建组与偏心距未重建组进行卡方检验得出:FO重建组下肢等长率高于FO未重建组(χ^(2)=6.320,P=0.012)。术后双侧RCH差值与LLD呈负相关性(r=-0.877,P<0.001);双侧FO差值及双侧RCH差值与术后LLD之间存在线性关系,且满足线性回归方程:术后LLD=0.038x-0.099y+0.257(x为术后双侧FO差值;y为术后双侧RCH差值;单位为cm),F=77.993,R2=0.808,P=0.009。结论:THA术后LLD随着FO的增大而增大,随着RCH增大而减小;重建FO更易获得下肢等长效果。THA术后双侧FO差值及双侧RCH差值与LLD之间存在线性关系,回归方程可为判断LLD提供一种理论参考。展开更多
文摘BACKGROUND Leg length discrepancy(LLD)following total hip arthroplasty(THA)is a common complaint,leading to decreased patient satisfaction.However,the effect of LLD before THA on outcomes and complications is not well defined.AIM To assess the effect of prior LLD on rates of falls,implant-related complications,stay length,readmissions,and implant survival following THA.METHODS A retrospective review of a nationwide insurance database was conducted from 2010 to 2021.All cases of THA and those with a prior diagnosis of LLD were identified.THA patients with LLD were matched to control patients 1:5 based on demographic and comorbidity profiles.Two-year fall rates and implant complications,lengths of stay,90-day readmissions,and time to revision were compared between cohorts.RESULTS A total of 2038 patients with LLD were matched to 10165 control patients.The LLD group showed significantly greater rates of falls[odds ratio(OR)=1.58;95%confidence interval(95%CI):1.24-2.01],dislocation(OR=2.61;95%CI:2.10-3.24),mechanical loosening(OR=4.58;95%CI:3.28-6.29),and periprosthetic fracture(OR=2.70;95%CI:1.96-3.72)compared to the control group(all P<0.001).Mean length of stay(LOS)was also significantly higher in the LLD group(3.1 days vs 2.8 days,P=0.034).No significant difference in 90-day readmission rates(7.75%vs 7.02%,P=0.244)was observed between the groups(P=0.244).Time to revision was significantly less in the LLD group(225 days vs 544 days,P<0.001).CONCLUSION LLD in patients having THA is related with significantly higher fall risk,rates of implant-related complications,LOS,and quicker time to revision.Identifying patients with LLD before their THA may help in identifying risks,better patient counselling,and more effective preoperative planning.However,the study have important limitations:Its design lacks information on the degree and cause of LLD,the time between diagnosis and surgery,and which leg with the discrepancy underwent the operation.Future well-designed studies should confirm the findings of this study.
文摘Objective To examine the relationship between upper leg length （ULL） and metabolic syndrome （MetS） in older adults.Methods Data was collected from National Health and Nutritional Examination Survey （NHANES, 2009-2010）. 786 individuals （385 males and 401 females） who were 60 years of age or older were included in this analysis. MetS was defined as having at least three of following conditions, i.e., cen-tral obesity, dyslipidemia, insulin resistance, and hypertension based on National Cholesterol Education Program guidelines. ULL was grouped into gender-specific tertiles.Results328 （41.7%） of participants were categorized as having MetS （38.7% in men and 49.1% in women,P = 0.002）. Compared to individuals in the 1st tertile （T1） of ULL, those in the 3rd tertile （T3） had lower levels of triglycerides （120.8 vs. 153.1 mg/dL,P = 0.045）, waist circumference （100.7vs. 104.2 cm,P = 0.049）, and systolic blood pressure （126.7vs. 131.4 mmHg, P = 0.005）, but higher levels of high-density-lipoprotein cholesterol （58.1vs. 52.4 mg/dL,P = 0.024）. The odds ratios （95% CI） of MetS from multivariate logistic regression were 0.57 （0.32-1.03） for individuals in the T2 of ULL and 0.39 （0.24-0.64） for individuals in the T3 of ULL, respectively （P-value for the trend 0.022）.Conclusions ULL was negatively associated with MetS in older adults. Further research is needed to identify potential mechanisms.
文摘Background: This is a rare case of piriformis syndrome. We discuss the patient’s symptoms, imaging study results, laboratory examination findings, and prescribed treatment in an attempt to determine the possible mechanisms or reasons for this patient’s development of piriformis syndrome. Methods: The patient is a 22-year-old female soldier who was admitted for lower back pain with soreness radiating to her right buttock and right lower extremity. We found that she had leg length discrepancy under X-ray finding. She was diagnosed piriformis syndrome by physical examination and Magenetic Resonance Image. Results: We performed scanography for lower extremities revealed a left femur length of 42.7 cm, a right femur length of 43.3 cm, a left tibia length of 33.2 cm, and a right tibia length of 33.6 cm;her left lower extremity was 1 cm shorter than her right. The MRI of sacrum also reveals hypertrophy of right piriformis muscle. Conclusions: Piriformis syndrome might be caused by short-term compensation in congenital leg length discrepancy. The patient with leg length discrepancy changed posture when standing, walking, and running. These compensation postures could lead to abnormality position of bones where there is insertion of the muscle.
文摘The use of cementless total hip arthroplasty (THA) is on the increase. In order to achieve rotational and axial stability larger implants may be required than originally templated for. This could potentially result in a lar-ger leg length inequality. Our objective was to determine whether there is greater inequality in leg length post-operatively in cementless THA as compared to cemented implants. 136 consecutive patients undergoing elective THA between June 2007 and May 2008 were included. Post-operative digital radiographs were ex-amined to determine leg length. Twenty seven patients (20%) underwent a cemented procedure and 109 (80%) a cementless procedure. In the cemented group the mean leg length discrepancy was 7.3 mm (range 19 mm short to 21 mm long). In the cementless group the mean measured leg length discrepancy was 6.3 mm (range 18 mm short to 23 mm long). There was no significant difference between the two groups (P = 0.443). This study shows that with accurate pre-operative templating, both cemented and cementless proce-dures produce comparable and acceptable leg length discrepancies.
文摘BACKGROUND Certain implant combinations change leg length and offset in primary total hip arthroplasty(THA).Poor restoration of leg biomechanics is a frequently cited reason for patient dissatisfaction following primary THA.A pure high-offset stem should provide direct lateralization without affecting femoral length when compared to a standard stem.However,clinical experience with preoperative planning software based on computed tomography-based three-dimensionalmodels reveals that using pure high-offset stems in THA may cause a difference between expected(no change in femoral length)and actual(small increase)in postoperative femoral length.AIM To elucidate the causes of these femoral length discrepancies using preoperative planning software.METHODS Preoperative templating for 43 robotic-assisted THAs,optimizing acetabular size and orientation,center of rotation,stem size and offset,and prosthetic head diameter were obtained.The preoperative planning software was used to calculate differences between preoperative and postoperative femoral length for standard and pure high-offset stems,unique to each patient.RESULTS Whilst the increase in femoral length between standard and high-offset stems was not significant(P=0.93),35 femurs(81.4%)experienced a 1-mm increase,and 3(7.0%)experienced a 2-mm increase in femoral length while using high-offset stem compared to the standard stem.The incidence of femoral length increase was lower for patients with shorter femurs(18/22;81.8%)compared to patients with longer femurs(20/21;95.2%).CONCLUSION When pure high-offset stems were used in preoperative planning software,we demonstrated an unexpected increase in leg length between 1-2-mm in 88.4%of patients.This unexpected increase in femoral length is due to a function of the preoperative planning software’s planned stem alignment with the anatomical axis,and not an inherent fault in the stem design.With expanding accessibility of robotic-assisted THA platforms,all potential sources of postoperative leg length discrepancy should be identified during preoperative templating and necessary alterations to the surgical plan should be made to accommodate this unexpected difference when using a pure high-offset stem.
文摘Background：Total hip arthroplasty （THA） is one of the most effective treatments for phase Ⅲ and Ⅳ hip arthrosis.Lower limb length balancing is one of the determining factors of a successful surgery,particularly in patients with developmental dysplasia of the hip （DDH）.The purpose of this study was to evaluate the postoperative change in intra-pelvic obliquity （intra-PO） angle in the coronal plane and its effects on leg length discrepancy （LLD） within 2 years.Methods：A total of 78 patients （70 females,8 males） were enrolled in this study.All patients were suffering from DDH with varying degrees of LLD.Pelvic plain radiographs were collected before and after the operation.The intra-PO angles were measured 0,0.5,1 and 2 years after THA.At the same time,postoperative LLD was measured with blocking test.Results：PO changed significantly in the first year after THA surgery （0 year vs.0.5 year,P 〈 0.01;0.5 year vs.1 year,P 〈 0.01）,and the changing value of intra-PO angle （△PO） slowed down substantially during the first 2 years after THA （0.5 year vs.0.5-1 year,P 〈 0.01;0.5-1 year vs.1-2 years,P 〈 0.01）.With the change in intra-PO angle,LLD also got narrow within the 1st year （0 year vs.0.5 year,P 〈 0.01;0.5 year vs.1 year,P 〈 0.01）.Elderly patients had a smaller intra-PO angle reduction （Group A vs.Group B,P =0.01;Group B vs.Group C,P〈 0.01）.Conclusions：Intra-PO angle and LLD gap narrowed with time after THA surgery.In particular,elderly patients had smaller change in intra-PO angle.
文摘[目的]比较“肩-肩”新型解剖标记定位法与人工智能辅助规划系统(AIHIP系统)规划的全髋关节置换(total hip arthroplasty, THA)中假体置入定位及预防双下肢不等长的准确性。[方法] 2020年8月-2022年12月就诊于本院行初次THA的94例患者,按照随机数字表法分为两组,47例采用“肩-肩”法(肩-肩组),另外47例采用AIHIP系统规划法(智能组),分别于术前进行规划,比较两组临床和影像结果。[结果]两组患者手术时间、总失血量、术后下地时间的差异均无统计学意义(P>0.05)。影像方面,两组髋臼假体匹配、股骨柄假体匹配、双下肢长度差、联合偏心距的差异均无统计学意义(P>0.05),肩-肩组的尖肩距[(15.9±3.0) mm vs(17.7±3.4) mm, P<0.001]、截骨距[(7.8±2.7) mm vs(9.2±4.1) mm, P=0.003]均显著小于智能组。[结论]“肩-肩”新型解剖标记定位法可以在THA术中准确置入股骨侧假体,并可预防术后双下肢不等长。
基金supported by National Science Foundation for Distinguished Young Scholoars, China (Grant No. 51125020)Program for New Century Excellent Talents in University, China
文摘The equivalent mechanism of the system is often considered as one specific mechanism in most existing studies of multi-legged robots, however the equivalent mechanism is varying while the robot moves on the ground. Four typical tripod period gaits of a radial symmetrical six-legged robot are analyzed. Similar to the metamorphic mechanism, the locomotion of multi-legged robot is considered as a series of varying hybrid serial-parallel mechanisms by assuming the constraints of the feet on the ground with hinges. One gait cycle is divided into several periods, and in different walking period there is a specific equivalent mechanism corresponding to it, and the walking process of multi-legged robot is composed by these series of equivalent mechanisms. Walking performance can be got by analyzing these series of equivalent mechanisms. Kinematics model of the equivalent mechanism is established, workspaces of equivalent mechanisms are illustrated by simulation and a concept of static stability workspace is proposed to evaluate the static stability of these four gaits. A new method to calculate the stride length of multi-legged robots is presented by analyzing the relationship between the workspace of two adjacent equivalent parallel mechanisms in one gait cycle. The stride lengths of four gaits are given by simulations. Comparison of stride length and static stability among these four typical tripod gaits are given. It has been proved that mixed gait and insect-wave gait II have better static stability than mammal kick-off gait and insect-wave gait I. Insect-wave gait II displays its advantage on stride length while the height of robot body lower than 87 mm, mammal kick-off gait has superiority on stride length while the height of robot body higher than 115 mm, and insect-wave gait I shows its shortcoming in stride length. The proposed method based on metamorphic theory and combining the footholds and body height of robot provides a new method to comprehensive analyze the performance of multi-legged robot.
文摘目的:使用CT联合Mimics软件测量全髋关节置换术(total hip arthroplasty,THA)后股骨偏心距(femoral offset,FO)、旋转中心高度(rotation center height,RCH)与双下肢长度差(lower leg length discrepancy,LLD),并探讨THA后FO、RCH与LLD的关系。方法:回顾性分析2020年10月至2022年6月符合标准的40例行单侧THA的患者,其中男21例,女19例;年龄30~81(58.90±14.13)岁;身体质量指数(body mass index,BMI)为17.3~31.5(25.3±3.4)kg·m^(-2);左侧18例,右侧22例。诊断为股骨头坏死30例(FicatⅣ期),髋关节骨性关节炎2例(TünnisⅢ期),发育性髋关节脱位合并终末期骨关节炎2例(CroweⅢ期),股骨颈骨折6例(GardenⅣ期)。术前、术后拍摄骨盆CT三维重建,经Mimics软件处理后建立三维重建模型,在模型上对FO、RCH、LLD进行测量。结果:术后双侧FO差值与LLD呈正相关性(r=0.744,P<0.001);将FO重建组与偏心距未重建组进行卡方检验得出:FO重建组下肢等长率高于FO未重建组(χ^(2)=6.320,P=0.012)。术后双侧RCH差值与LLD呈负相关性(r=-0.877,P<0.001);双侧FO差值及双侧RCH差值与术后LLD之间存在线性关系,且满足线性回归方程:术后LLD=0.038x-0.099y+0.257(x为术后双侧FO差值;y为术后双侧RCH差值;单位为cm),F=77.993,R2=0.808,P=0.009。结论:THA术后LLD随着FO的增大而增大,随着RCH增大而减小;重建FO更易获得下肢等长效果。THA术后双侧FO差值及双侧RCH差值与LLD之间存在线性关系,回归方程可为判断LLD提供一种理论参考。
