BACKGROUND:The biomechanical stability of basal femoral neck fracture is poor,and the treatment plan is different from the traditional femoral neck fracture. At present,there is still no consensus on the surgical plan for the treatment of basal femoral neck fracture in young adults. OBJECTIVE:To compare the biomechanical characteristics of proximal femoral nail antirotation and femoral neck system in the treatment of basal femoral neck fractures by finite element analysis.METHODS:First,Mimics Medical 21.0 software was used to extract the right femur CT data of healthy young female volunteers to establish a preliminary model. Secondly,the model was imported into Geomagic Wrap 2021 software for further smoothing. SOLIDWORKS 2021 software was used to establish and assemble the femoral neck base fracture model,proximal femoral nail antirotation model,and femoral neck system model. Finally,the assembled model was imported into Workbench 2021 R1 software for biomechanical analysis.RESULTS AND CONCLUSION:(1) Stress distribution:the stress distribution of the proximal femoral nail antirotation group was mainly near the fracture line and the medial side of the femur,and the peak stress was 151.90 Mpa. In the femoral neck system group,the stress distribution of the femoral model was mainly near the fracture line,and the peak stress was 290.74 Mpa. The proximal femoral nail antirotation internal fixation stress was mainly distributed at the proximal end of the helical blade and the main nail,and the peak stress was 102.95 Mpa. The stress distribution of internal fixation in femoral neck system mainly extended to both sides of the support rod,and the peak stress was 184.69 Mpa. (2) Total displacement:the maximum displacement of the femoral model in the proximal femoral nail antirotation group was 4.0323 mm,and the maximum displacement of the femoral model in the femoral neck system group was 4.6489 mm. The maximum displacement was located in the femoral head. The peak displacement of internal fixation in the proximal femoral nail antirotation group and the femoral neck system group was 2.7094 mm and 3.1303 mm,respectively. The displacement of internal fixation in the two groups was mainly concentrated in the proximal end of internal fixation,and gradually decreased to the distal end. (3) It is concluded that in the femoral neck base fracture model,whether it is the femoral model or the internal fixation model,the proximal femoral nail antirotation group has more dispersed stress distribution,lower stress peak,smaller femoral head displacement,and better biomechanical stability than the femoral neck system group.

BACKGROUND:Femoral neck fracture is a kind of unsolved fracture.Although cannulated screw,dynamic hip screw,and femoral neck dynamic cross screw have emerged,the best internal fixation scheme for femoral neck fracture with large Pauwels angle and shear force has not been unified.OBJECTIVE:To investigate biomechanical properties of femoral neck dynamic cross screw combined with cannulated screw in the treatment of Pauwels Ⅱ type middle-aged and young femoral neck fractures using finite element analysis.METHODS:According to the extracted CT data of volunteers'femur,the model of femoral neck fracture with Pauwels angle of 50° was established,and the femoral neck was divided into three equal parts.Four groups of models were constructed:In group A,main nail of femoral neck dynamic cross screw was located in the middle 1/3.In group B,main nail of femoral neck dynamic cross screw was located in the lower 1/3.In group C,main nail of femoral neck dynamic cross screw was located at the lower 1/3+cannulated screw at the upper 1/3.In group D,main nail of femoral neck dynamic cross screw was located in the anterior medial part of the middle 1/3+cannulated screw was located in the medial posterior medial part of the middle 1/3.The stress distribution,peak value,maximum deformation,and stress distribution of fracture section of four groups of femur and internal fixation models were measured under 1 200 N load.RESULTS AND CONCLUSION:(1)The finite element analysis showed that the stress distribution and peak value,the maximum deformation and the stress of the fracture section of the femur and internal fixation model in group C were less than those in the other three groups.(2)Compared with group A,group B had smaller stress and displacement of femoral bone,internal fixation,and fracture section,indicating that the placement of head nail of femoral neck dynamic cross screw at the lower 1/3 of the femoral neck was more stable than that of middle 1/3.(3)The results show that the head nail of femoral neck dynamic cross screw located at the lower 1/3 of the femoral neck and 1/3 parallel screws on the femoral neck is more stable for Pauwels Ⅱ femoral neck fracture in young adults,and it is a good choice for the treatment of this type of fracture.

BACKGROUND:Although studies have shown that symmetrical distribution of bone cement can reduce postoperative vertebral refractures and help improve prognosis.However,achieving better bone cement distribution during percutaneous vertebroplasty remains an important issue for surgeons. OBJECTIVE:To explore the effect of cement distribution on the efficacy of unilateral percutaneous vertebroplasty to provide effective preventive and therapeutic measures to prevent postoperative vertebral fracture. METHODS:The 193 patients who underwent unilateral percutaneous vertebroplasty in Sixth Affiliated Hospital of Xinjiang Medical University from January 2018 to December 2022 were selected and divided into group I(bone cement not touching the upper and distal end plates;n=59),group II(bone cement only touching the upper or lower end plate;n=80),and group III(bone cement touching both the upper and distal end plates;n=54).Basic data,operation-related indicators,including operation time,total hospital cost,postoperative hospital time,cement injection,visual analog scale and Oswestry disability index scores of low back pain,postoperative vertebral height recovery rate,local kyphosis angle,incidence of injured vertebral body and adjacent vertebrae were compared among the three groups.Follow-up results of all patients were recorded. RESULTS AND CONCLUSION:(1)In group III,the visual analog scale and Oswestry disability index scores were significantly lower than those in groups I and II,and the difference was statistically significant(P<0.05).(2)The incidence of injured vertebral refracture and incidence of total vertebral fractures in groups I and II were significantly higher than that in group III,and the differences were all statistically significant(P<0.05).(3)There were no significant differences in other indicators of patients of the three groups,such as bone cement leakage,Oswestry disability index,and visual analog scale score at 1 week,1 month after surgery,and during last follow-up,postoperative vertebral height recovery rate,local kyphosis angle,operation time,total hospital cost,and postoperative hospital stay(P>0.05).(4)It is indicated that compared with groups I and II,patients of group III get better long-term prognosis,and bone cement touching both the upper and distal end plates can significantly reduce the incidence of injured vertebral and total vertebral fractures.Surgeons should fully grasp the diffusion of bone cement,and develop targeted prevention and treatment strategies,so as to reduce the risk of further fracture in the future.

BACKGROUND:The treatment of Pauwels type Ⅲ femoral neck fractures in young adults is extremely difficult.When treating Pauwels type Ⅲ femoral neck fractures with internal fixation,it is not only necessary to ensure the mechanical stability of the internal fixation,but also to ensure that it can resist the impact of shear,compression and tension,so as to prevent the internal fixation from breaking or loosening due to fatigue during the fracture healing process.However,existing internal fixation methods do not fully meet our requirements for the treatment of this fracture.OBJECTIVE:To provide a more reasonable and effective choice of internal fixation mode for clinicians in the treatment of young adults with Pauwels type Ⅲfemoral neck fracture,so as to optimize the treatment effect,reduce the occurrence of complications,and improve the recovery speed and quality of life of patients.METHODS:A femoral neck fracture model with Pauwels angle of 70° was constructed using CT data extracted from volunteers,and three placement modes were set up:(1)femoral neck system group:the main nail of femoral neck system was located in the center of the femoral neck axis.(2)Combination group:The main nail of femoral neck system was located in the lower third of the femoral neck axis,and a cannulated compression screw was located in the upper third of the femoral neck axis.(3)Cannulated compression screw group:The arrangement of three cannulated compression screws was arranged in the classic inverted triangle shape to ensure the maximum fixed effect.Stress distribution and displacement of proximal femoral fracture fragments and internal fixation devices were analyzed under three different internal fixation methods.RESULTS AND CONCLUSION:(1)The stress of the proximal femur models in the three groups was concentrated near the fracture line:combination group(201.10 MPa)＜femoral neck system group(222.25 MPa)＜cannulated compression screw group(271.25 MPa).(2)The peak value of proximal femur displacement was located at the top:combination group(6.33 mm)＜femoral neck system group(9.37 mm)＜cannulated compression screw group(9.92 mm).(3)The internal fixation stress was concentrated on the screw surface at the broken end of the fracture and gradually extended from there to both sides;cannulated compression screw group(136.67 MPa)＜combination group(201.10 MPa)＜femoral neck system group(222.25 MPa).(4)The maximum displacement of the internal fixation device model was located at the very top of the internal fixation.The three groups gradually decreased from the top to the far end.The peak displacement values of combination group(6.21 mm)＜femoral neck system group(9.19 mm)＜cannulated compression screw group(9.51 mm).(5)The stress of proximal bone mass in the three models was mainly concentrated in the fracture end,especially in the lower part of the fracture end.This indicates that these regions were subjected to greater stress and strain during mechanical transfer;combination group(24.96 MPa)＜femoral neck system group(39.69 MPa)＜cannulated compression screw group(44.47 MPa).(6)The results indicate that the internal fixation strategy of femoral neck system combined with cannulated compression screw arranged in parallel coronal surface shows higher biomechanical stability than single femoral neck system fixation or cannulated compression screw in inverted triangle arrangement fixation,and provides a more reliable and effective solution for the treatment of Pauwels type Ⅲ femoral neck fracture in young adults.

BACKGROUND:Unstable femoral neck fracture with anterior medial bone defect is very rare and difficult to manage.The best internal fixation scheme for the treatment of this kind of fracture has been a controversial topic among orthopedic surgeons.OBJECTIVE:To evaluate the biomechanical properties of different internal fixation in the treatment of Pauwels Ⅲ femoral neck fracture with anterior medial defect by finite element analysis in order to provide experimental support for clinical operation decision.METHODS:The models of femoral neck fracture with anterior medial defect and Pauwels angle of 70° were constructed by Mimics 21.0,Geomagic,and Solidworks software.Three internal fixation methods were simulated:group A(3 hollow nails+medial plate),group B(femoral neck dynamic crossover nail+1 hollow nail),and group C(4 hollow nails"diamond fixation").The stress and displacement changes of femur,internal fixation,and femoral head were analyzed under 2 100 N load of 3 times body weight.RESULTS AND CONCLUSION:(1)The overall stress of the femur in group A was the smallest,and the force was more uniform and dispersed.The stress of the internal fixation model in group B was smaller,indicating that it had a better effect of stress dispersion and shear resistance.The stress on the stress side of the femur in group A was significantly lower than that in the other two groups,and there was no stress concentration.(2)The displacement of the whole femoral model,internal fixation or femoral head in group A was less than that in the other two groups,indicating that"hollow nail combined with medial plate"could play a better stabilizing role and could better reduce the occurrence of hip varus.(3)The application of three screws combined with medial supporting plate in vertical,unstable and anteromedial bone defect of femoral neck fracture can significantly improve the stability of fracture and resistance to deformation.It is a good choice for the treatment of this type of fracture.

BACKGROUND:The biomechanical stability of basal femoral neck fracture is poor,and the treatment plan is different from the traditional femoral neck fracture. At present,there is still no consensus on the surgical plan for the treatment of basal femoral neck fracture in young adults. OBJECTIVE:To compare the biomechanical characteristics of proximal femoral nail antirotation and femoral neck system in the treatment of basal femoral neck fractures by finite element analysis.METHODS:First,Mimics Medical 21.0 software was used to extract the right femur CT data of healthy young female volunteers to establish a preliminary model. Secondly,the model was imported into Geomagic Wrap 2021 software for further smoothing. SOLIDWORKS 2021 software was used to establish and assemble the femoral neck base fracture model,proximal femoral nail antirotation model,and femoral neck system model. Finally,the assembled model was imported into Workbench 2021 R1 software for biomechanical analysis.RESULTS AND CONCLUSION:(1) Stress distribution:the stress distribution of the proximal femoral nail antirotation group was mainly near the fracture line and the medial side of the femur,and the peak stress was 151.90 Mpa. In the femoral neck system group,the stress distribution of the femoral model was mainly near the fracture line,and the peak stress was 290.74 Mpa. The proximal femoral nail antirotation internal fixation stress was mainly distributed at the proximal end of the helical blade and the main nail,and the peak stress was 102.95 Mpa. The stress distribution of internal fixation in femoral neck system mainly extended to both sides of the support rod,and the peak stress was 184.69 Mpa. (2) Total displacement:the maximum displacement of the femoral model in the proximal femoral nail antirotation group was 4.0323 mm,and the maximum displacement of the femoral model in the femoral neck system group was 4.6489 mm. The maximum displacement was located in the femoral head. The peak displacement of internal fixation in the proximal femoral nail antirotation group and the femoral neck system group was 2.7094 mm and 3.1303 mm,respectively. The displacement of internal fixation in the two groups was mainly concentrated in the proximal end of internal fixation,and gradually decreased to the distal end. (3) It is concluded that in the femoral neck base fracture model,whether it is the femoral model or the internal fixation model,the proximal femoral nail antirotation group has more dispersed stress distribution,lower stress peak,smaller femoral head displacement,and better biomechanical stability than the femoral neck system group.

BACKGROUND:Unstable femoral neck fracture with anterior medial bone defect is very rare and difficult to manage.The best internal fixation scheme for the treatment of this kind of fracture has been a controversial topic among orthopedic surgeons.OBJECTIVE:To evaluate the biomechanical properties of different internal fixation in the treatment of Pauwels Ⅲ femoral neck fracture with anterior medial defect by finite element analysis in order to provide experimental support for clinical operation decision.METHODS:The models of femoral neck fracture with anterior medial defect and Pauwels angle of 70° were constructed by Mimics 21.0,Geomagic,and Solidworks software.Three internal fixation methods were simulated:group A(3 hollow nails+medial plate),group B(femoral neck dynamic crossover nail+1 hollow nail),and group C(4 hollow nails"diamond fixation").The stress and displacement changes of femur,internal fixation,and femoral head were analyzed under 2 100 N load of 3 times body weight.RESULTS AND CONCLUSION:(1)The overall stress of the femur in group A was the smallest,and the force was more uniform and dispersed.The stress of the internal fixation model in group B was smaller,indicating that it had a better effect of stress dispersion and shear resistance.The stress on the stress side of the femur in group A was significantly lower than that in the other two groups,and there was no stress concentration.(2)The displacement of the whole femoral model,internal fixation or femoral head in group A was less than that in the other two groups,indicating that"hollow nail combined with medial plate"could play a better stabilizing role and could better reduce the occurrence of hip varus.(3)The application of three screws combined with medial supporting plate in vertical,unstable and anteromedial bone defect of femoral neck fracture can significantly improve the stability of fracture and resistance to deformation.It is a good choice for the treatment of this type of fracture.

BACKGROUND:The treatment of Pauwels type Ⅲ femoral neck fractures in young adults is extremely difficult.When treating Pauwels type Ⅲ femoral neck fractures with internal fixation,it is not only necessary to ensure the mechanical stability of the internal fixation,but also to ensure that it can resist the impact of shear,compression and tension,so as to prevent the internal fixation from breaking or loosening due to fatigue during the fracture healing process.However,existing internal fixation methods do not fully meet our requirements for the treatment of this fracture.OBJECTIVE:To provide a more reasonable and effective choice of internal fixation mode for clinicians in the treatment of young adults with Pauwels type Ⅲfemoral neck fracture,so as to optimize the treatment effect,reduce the occurrence of complications,and improve the recovery speed and quality of life of patients.METHODS:A femoral neck fracture model with Pauwels angle of 70° was constructed using CT data extracted from volunteers,and three placement modes were set up:(1)femoral neck system group:the main nail of femoral neck system was located in the center of the femoral neck axis.(2)Combination group:The main nail of femoral neck system was located in the lower third of the femoral neck axis,and a cannulated compression screw was located in the upper third of the femoral neck axis.(3)Cannulated compression screw group:The arrangement of three cannulated compression screws was arranged in the classic inverted triangle shape to ensure the maximum fixed effect.Stress distribution and displacement of proximal femoral fracture fragments and internal fixation devices were analyzed under three different internal fixation methods.RESULTS AND CONCLUSION:(1)The stress of the proximal femur models in the three groups was concentrated near the fracture line:combination group(201.10 MPa)＜femoral neck system group(222.25 MPa)＜cannulated compression screw group(271.25 MPa).(2)The peak value of proximal femur displacement was located at the top:combination group(6.33 mm)＜femoral neck system group(9.37 mm)＜cannulated compression screw group(9.92 mm).(3)The internal fixation stress was concentrated on the screw surface at the broken end of the fracture and gradually extended from there to both sides;cannulated compression screw group(136.67 MPa)＜combination group(201.10 MPa)＜femoral neck system group(222.25 MPa).(4)The maximum displacement of the internal fixation device model was located at the very top of the internal fixation.The three groups gradually decreased from the top to the far end.The peak displacement values of combination group(6.21 mm)＜femoral neck system group(9.19 mm)＜cannulated compression screw group(9.51 mm).(5)The stress of proximal bone mass in the three models was mainly concentrated in the fracture end,especially in the lower part of the fracture end.This indicates that these regions were subjected to greater stress and strain during mechanical transfer;combination group(24.96 MPa)＜femoral neck system group(39.69 MPa)＜cannulated compression screw group(44.47 MPa).(6)The results indicate that the internal fixation strategy of femoral neck system combined with cannulated compression screw arranged in parallel coronal surface shows higher biomechanical stability than single femoral neck system fixation or cannulated compression screw in inverted triangle arrangement fixation,and provides a more reliable and effective solution for the treatment of Pauwels type Ⅲ femoral neck fracture in young adults.

BACKGROUND:Femoral neck fracture is a kind of unsolved fracture.Although cannulated screw,dynamic hip screw,and femoral neck dynamic cross screw have emerged,the best internal fixation scheme for femoral neck fracture with large Pauwels angle and shear force has not been unified.OBJECTIVE:To investigate biomechanical properties of femoral neck dynamic cross screw combined with cannulated screw in the treatment of Pauwels Ⅱ type middle-aged and young femoral neck fractures using finite element analysis.METHODS:According to the extracted CT data of volunteers'femur,the model of femoral neck fracture with Pauwels angle of 50° was established,and the femoral neck was divided into three equal parts.Four groups of models were constructed:In group A,main nail of femoral neck dynamic cross screw was located in the middle 1/3.In group B,main nail of femoral neck dynamic cross screw was located in the lower 1/3.In group C,main nail of femoral neck dynamic cross screw was located at the lower 1/3+cannulated screw at the upper 1/3.In group D,main nail of femoral neck dynamic cross screw was located in the anterior medial part of the middle 1/3+cannulated screw was located in the medial posterior medial part of the middle 1/3.The stress distribution,peak value,maximum deformation,and stress distribution of fracture section of four groups of femur and internal fixation models were measured under 1 200 N load.RESULTS AND CONCLUSION:(1)The finite element analysis showed that the stress distribution and peak value,the maximum deformation and the stress of the fracture section of the femur and internal fixation model in group C were less than those in the other three groups.(2)Compared with group A,group B had smaller stress and displacement of femoral bone,internal fixation,and fracture section,indicating that the placement of head nail of femoral neck dynamic cross screw at the lower 1/3 of the femoral neck was more stable than that of middle 1/3.(3)The results show that the head nail of femoral neck dynamic cross screw located at the lower 1/3 of the femoral neck and 1/3 parallel screws on the femoral neck is more stable for Pauwels Ⅱ femoral neck fracture in young adults,and it is a good choice for the treatment of this type of fracture.