ABSTRACT
Objective To analyze interface stress of cemented tibial prosthesis platform and determine the interface stress damage area, so as to provide references for stress failure of tibial platform in clinical single condylar replacement. Methods The full cycle gait was simulated by human dynamics software to obtain the load-bearing condition of knee joint. A complete model of the knee joint was established by medical imaging and three-dimensional (3D) reconstruction software, and unicompartmental replacement was performed. The distribution of interfacial stress of tibial prosthesis platform after single condylar replacement was analyzed by finite element method. ResultsIn gait, force and angle of the knee joint changed periodically with time, a cycle lasted 1.3 s, and the peak of knee joint resultant force was 760 N. The maximum shear stress of the interface was 11.82 MPa and the maximum tensile stress was 6.849 MPa, both occurred at inner front end of the corner of prosthesis cement interface. The maximum interface stress of titanium alloy prosthesis was lower than that of stainless steel prosthesis. Conclusions The decrease in elastic modulus of prosthesis can reduce the maximum principal stress at the interface. Considering the interface stress, titanium alloy prosthesis is better than stainless steel prosthesis. The area of tibial prosthetic platform interface damage is mainly at the medial anterior and posterior corners and lateral middle ends,so improving the ability of prosthesis cement bonding in this area can prevent the loosening of tibial prosthesis of unicompartmental knee joint.The findings have practical implications for the prevention of tibial prosthetic platform loosening after unicompartmental knee arthroplasty in clinic.
ABSTRACT
A software and hardware platform for gait simulation and system evaluation for lower limb intelligent prosthesis is proposed and designed, in order that the wearable symmetry effect of the intelligent knee prosthesis can be quantitatively analyzed by machine test instead of human wear test. The whole-body three-dimensional gait and motion analysis system instrument, a device to collect gait data such as joint angle and stride of adults, was used for extracting simulated gait characteristic curve. Then, the gait curve was fitted based on the corresponding joint to verify the feasibility of the test platform in the experiment. Finally, the developed artificial knee prosthesis was worn on the prosthetic evaluation system to quantitatively analyze the gait symmetry effect. The results showed that there was no significant difference in gait symmetry between the developed knee joints at different speeds, which could reach more than 88%. The simulation and evaluation of the prosthetic gait have good effects on the functional simulation and evaluation of the lower limb intelligent prosthesis.
Subject(s)
Adult , Humans , Artificial Limbs , Biomechanical Phenomena , Gait , Knee Joint , Knee Prosthesis , Prosthesis DesignABSTRACT
Objective To explore the biomechanical mechanisms of correlation between lumbar disc degeneration and sacroiliac joint disorder though investigating the biomechanical characteristics of lumbar disc degeneration with sacroiliac joint disorders.Methods One normal healthy volunteer and two patients with lumbar disc herniation and sacroiliac joint disorders (one was with sacrum disorders and the other was with ilium disorders) were selected.Their CT data were collected to establish three corresponding lumbar-pelvis finite-element models,and their gait data were also simultaneously collected to drive the AnyBody musculoskeletal model.The muscle force around the lumbar and pelvis as well as the hip joint force were acquired as loading condition for finite element analysis.The stress changes in L4 and L5 intervertebral discs and sacroiliac joints of the patients and normal volunteer were compared.Results There was no significant difference in the stress of the two sides of L4,L5 disc and two sacroiliac joints in normal model,with a bimodal stress curve.However,in the models of sacrum disorders and ilium disorders,the bimodal stress curve peaks changed,even disappeared.The peak stress differences in left and right side of L4 disc were 0.55 MPa and 0.80 MPa,respectively,the peak stress differences in left and right side of L5 disc were 4.05 MPa and 2.08 MPa,respectively,and the peak stress differences in left and right side of sacroiliac joints were 0.96 MPa and 3.32 MPa,respectively.Conclusions The lumbar disc degeneration with sacroiliac joint disorder leads to the tilt of the body loading line,and sacroiliac joint disorder can aggravate the imbalances of stress on the body sides.The impact of sacroiliac joint dysfunction cannot be ignored in the treatment of lumbar disc herniation.
ABSTRACT
Objective To explore the biomechanical mechanisms of correlation between lumbar disc degeneration and sacroiliac joint disorder though investigating the biomechanical characteristics of lumbar disc degeneration with sacroiliac joint disorders.Methods One normal healthy volunteer and two patients with lumbar disc herniation and sacroiliac joint disorders (one was with sacrum disorders and the other was with ilium disorders) were selected.Their CT data were collected to establish three corresponding lumbar-pelvis finite-element models,and their gait data were also simultaneously collected to drive the AnyBody musculoskeletal model.The muscle force around the lumbar and pelvis as well as the hip joint force were acquired as loading condition for finite element analysis.The stress changes in L4 and L5 intervertebral discs and sacroiliac joints of the patients and normal volunteer were compared.Results There was no significant difference in the stress of the two sides of L4,L5 disc and two sacroiliac joints in normal model,with a bimodal stress curve.However,in the models of sacrum disorders and ilium disorders,the bimodal stress curve peaks changed,even disappeared.The peak stress differences in left and right side of L4 disc were 0.55 MPa and 0.80 MPa,respectively,the peak stress differences in left and right side of L5 disc were 4.05 MPa and 2.08 MPa,respectively,and the peak stress differences in left and right side of sacroiliac joints were 0.96 MPa and 3.32 MPa,respectively.Conclusions The lumbar disc degeneration with sacroiliac joint disorder leads to the tilt of the body loading line,and sacroiliac joint disorder can aggravate the imbalances of stress on the body sides.The impact of sacroiliac joint dysfunction cannot be ignored in the treatment of lumbar disc herniation.
ABSTRACT
Objective To explore the biomechanical mechanisms of correlation between lumbar disc degeneration and sacroiliac joint disorder though investigating the biomechanical characteristics of lumbar disc degeneration with sacroiliac joint disorders. Methods One normal healthy volunteer and two patients with lumbar disc herniation and sacroiliac joint disorders (one was with sacrum disorders and the other was ilium disorders) were selected. Their CT data were collected to establish three corresponding lumbar-pelvis finite-element models, and their gait data were also simultaneously collected to drive the AnyBody musculoskeletal model. The muscle force around the lumbar and pelvis as well as the hip joint force were acquired as loading condition for finite element analysis. The stress changes in L4 and L5 intervertebral discs and sacroiliac joints of the patients and normal volunteer were compared. Results There was no significant difference in the stress of the two sides of L4, L5 disc and two sacroiliac joints in normal model, with a bimodal stress curve. However, in the models of sacrum disorders and ilium disorders, the bimodal stress curve peaks changed, even disappeared. The peak stress differences in left and right side of L4 disc were 0.55 MPa and 0.80 MPa, respectively, the peak stress differences in left and right side of L5 disc were 4.05 MPa and 2.08 MPa, respectively, and the peak stress differences in left and right side of sacroiliac joints were 0.96 MPa and 3.32 MPa, respectively. Conclusions The lumbar disc degeneration with sacroiliac joint disorder leads to the tilt of the body loading line, and sacroiliac joint disorder can aggravate the imbalances of stress on the body sides. The impact of sacroiliac joint dysfunction cannot be ignored in the treatment of lumbar disc herniation.
ABSTRACT
Objective To explore the biomechanical mechanisms of correlation between lumbar disc degeneration and sacroiliac joint disorder though investigating the biomechanical characteristics of lumbar disc degeneration with sacroiliac joint disorders.Methods One normal healthy volunteer and two patients with lumbar disc herniation and sacroiliac joint disorders (one was with sacrum disorders and the other was with ilium disorders) were selected.Their CT data were collected to establish three corresponding lumbar-pelvis finite-element models,and their gait data were also simultaneously collected to drive the AnyBody musculoskeletal model.The muscle force around the lumbar and pelvis as well as the hip joint force were acquired as loading condition for finite element analysis.The stress changes in L4 and L5 intervertebral discs and sacroiliac joints of the patients and normal volunteer were compared.Results There was no significant difference in the stress of the two sides of L4,L5 disc and two sacroiliac joints in normal model,with a bimodal stress curve.However,in the models of sacrum disorders and ilium disorders,the bimodal stress curve peaks changed,even disappeared.The peak stress differences in left and right side of L4 disc were 0.55 MPa and 0.80 MPa,respectively,the peak stress differences in left and right side of L5 disc were 4.05 MPa and 2.08 MPa,respectively,and the peak stress differences in left and right side of sacroiliac joints were 0.96 MPa and 3.32 MPa,respectively.Conclusions The lumbar disc degeneration with sacroiliac joint disorder leads to the tilt of the body loading line,and sacroiliac joint disorder can aggravate the imbalances of stress on the body sides.The impact of sacroiliac joint dysfunction cannot be ignored in the treatment of lumbar disc herniation.