ABSTRACT
Objective To investigate the trabecular stress distributions on the cortical bone and determine whether the cancellous bone can share the load of the acetabulum with a press-fit acetabular cup. Methods The acetabulum was scanned via micro-computed tomography (CT) to build a three-dimensional micro-finite element analysis (μFEA) model of the acetabulum. The trabecular stress and strain of the bony acetabulum were calculated following total hip arthroplasty (THA) to investigate the biomechanical characteristics of their distributions. Results With the implantation of the press-fit acetabular cup into the acetabulum, the high-stress zone of the articular surface was found to be located in the pubic bone area, with a maximum stress of 1.398 MPa. The largest high-stress zone within the articular surface was at the craniomedial part where it was supported by the iliac. For the cancellous bone within the acetabulum, the high stress was relatively widely distributed on the craniomedial part. When a 1.372 kN load was applied, the high stress was found at the craniomedial and anterior-inferior parts of the articular surface where it was supported by the iliac and pubic bone, with a trabecular micro-damage occurring in the anterior-inferior part. The highest tensile stress at the craniomedial part was 0.604 MPa. For the cancellous bone within the acetabulum, the high stress was mainly distributed on the craniomedial and anterior-inferior parts. Conclusions The high stress near the periphery of the articular surface showed a three-point circular distribution, which was mainly distributed on the iliac, ischial, and pubic bone area. The stress was distributed more uniformly owing to the deformation of the cancellous bone in the acetabulum. The cancellous bone in the acetabulum has the function of load-bearing.
ABSTRACT
Objective To investigate the structure and biomechanical property differences in different regions of the femoral head for elderly patients with femoral neck fractures,and to study its influence on internal fixation for fracture.Methods Twenty femoral head specimens were collected from elderly patients with femoral neck fracture after joint replacement.The femoral head was divided into 3 parts (lateral,inferior and medial region) with reference to anatomical markers on surface of the femoral head.After the position and drilling direction of the ring drill were determined,a circular drill was used to obtain the cylindrical cancellous bone columns with 10 mm in diameter and 10 mm in height.The data of cancellous bone columns in different regions were analyzed by Micro-CT scanning system,including bone volume fraction (BVF),trabecular space (Tb.Sp),trabecular thickness (Tb.Th),the number of trabecular number (Tb.N),the bone surface volume ratio (bone surface/bone volume,BS/BV),structural model index (SMI).Mechanical property differences of bone tissues in different regions were calculated by micro-finite element analysis.Results Bone mass in the elderly osteoporotic femoral head decreased,and there were significant differences in bone microstructure and mechanical properties in different regions of the femoral head.Bone microstructure and mechanical properties in medial region were obviously superior to those in lateral and interior region.Conclusions The bone structure and mechanical strength in medial region of the femoral head are obvious superior to those in lateral and inferior regions.The position for internal fixation should be fully considered during treatment of osteoporotic femoral neck fracture in clinic.
ABSTRACT
Objective To investigate the structure and biomechanical property differences in different regions of the femoral head for elderly patients with femoral neck fractures, and to study its influence on internal fixation for fracture. Methods Twenty femoral head specimens were collected from elderly patients with femoral neck fracture after joint replacement. The femoral head was divided into 3 parts (lateral, inferior and medial region) with reference to anatomical markers on surface of the femoral head. After the position and drilling direction of the ring drill were determined, a circular drill was used to obtain the cylindrical cancellous bone columns with 10 mm in diameter and 10 mm in height. The data of cancellous bone columns in different regions were analyzed by Micro-CT scanning system, including bone volume fraction (BVF), trabecular space (Tb.Sp), trabecular thickness (Tb.Th), the number of trabecular number (Tb.N), the bone surface volume ratio (bone surface/bone volume, BS/BV), structural model index (SMI). Mechanical property differences of bone tissues in different regions were calculated by micro-finite element analysis. ResultsBone mass in the elderly osteoporotic femoral head decreased, and there were significant differences in bone microstructure and mechanical properties in different regions of the femoral head. Bone microstructure and mechanical properties in medial region were obviously superior to those in lateral and interior region. Conclusions The bone structure and mechanical strength in medial region of the femoral head are obvious superior to those in lateral and inferior regions. The position for internal fixation should be fully considered during treatment of osteoporotic femoral neck fracture in clinic.
ABSTRACT
Objective To investigate the structure and biomechanical property differences in different regions of the femoral head for elderly patients with femoral neck fractures,and to study its influence on internal fixation for fracture.Methods Twenty femoral head specimens were collected from elderly patients with femoral neck fracture after joint replacement.The femoral head was divided into 3 parts (lateral,inferior and medial region) with reference to anatomical markers on surface of the femoral head.After the position and drilling direction of the ring drill were determined,a circular drill was used to obtain the cylindrical cancellous bone columns with 10 mm in diameter and 10 mm in height.The data of cancellous bone columns in different regions were analyzed by Micro-CT scanning system,including bone volume fraction (BVF),trabecular space (Tb.Sp),trabecular thickness (Tb.Th),the number of trabecular number (Tb.N),the bone surface volume ratio (bone surface/bone volume,BS/BV),structural model index (SMI).Mechanical property differences of bone tissues in different regions were calculated by micro-finite element analysis.Results Bone mass in the elderly osteoporotic femoral head decreased,and there were significant differences in bone microstructure and mechanical properties in different regions of the femoral head.Bone microstructure and mechanical properties in medial region were obviously superior to those in lateral and interior region.Conclusions The bone structure and mechanical strength in medial region of the femoral head are obvious superior to those in lateral and inferior regions.The position for internal fixation should be fully considered during treatment of osteoporotic femoral neck fracture in clinic.
ABSTRACT
Objective To investigate the structure and biomechanical property differences in different regions of the femoral head for elderly patients with femoral neck fractures,and to study its influence on internal fixation for fracture.Methods Twenty femoral head specimens were collected from elderly patients with femoral neck fracture after joint replacement.The femoral head was divided into 3 parts (lateral,inferior and medial region) with reference to anatomical markers on surface of the femoral head.After the position and drilling direction of the ring drill were determined,a circular drill was used to obtain the cylindrical cancellous bone columns with 10 mm in diameter and 10 mm in height.The data of cancellous bone columns in different regions were analyzed by Micro-CT scanning system,including bone volume fraction (BVF),trabecular space (Tb.Sp),trabecular thickness (Tb.Th),the number of trabecular number (Tb.N),the bone surface volume ratio (bone surface/bone volume,BS/BV),structural model index (SMI).Mechanical property differences of bone tissues in different regions were calculated by micro-finite element analysis.Results Bone mass in the elderly osteoporotic femoral head decreased,and there were significant differences in bone microstructure and mechanical properties in different regions of the femoral head.Bone microstructure and mechanical properties in medial region were obviously superior to those in lateral and interior region.Conclusions The bone structure and mechanical strength in medial region of the femoral head are obvious superior to those in lateral and inferior regions.The position for internal fixation should be fully considered during treatment of osteoporotic femoral neck fracture in clinic.