BACKGROUND:Pauwels type Ⅲ femoral neck fractures may be subjected to more shear and bending forces,and may be prone to complications such as internal fixation failure,bone nonunion,or femoral head necrosis. There is no consensus on the optimal selection of internal fixation devices.OBJECTIVE:To compare the biomechanical properties of four types of internal fixation methods for Pauwels type Ⅲ femoral neck fracture by finite element analysisMETHODS:Femur CT data of a healthy young volunteer were imported into Mimics software to construct a three-dimensional model of normal femur. Pauwels type Ⅲ femoral neck fracture was simulated based on 70° fracture line. Four types of fracture internal fixation models were optimized and constructed using Geomagic and UG software:conventional inverted triangle hollow screw,femoral neck fixation system,femoral neck fixation system plus anterior or posterior hollow screw treatment. Finally,Ansys software was used to analyze the stress distribution,peak stress,and peak displacement of proximal femur fracture block in four types of different internal fixation models. The displacement distribution and peak displacement of internal fixation device and femoral neckfracture were observed.RESULTS AND CONCLUSION:(1) The peak stress of proximal fracture fragments in the four groups was concentrated near the fracture line. The peak stress in the femoral neck fixation system group was the largest,and that in the conventional inverted triangle hollow screw group was the smallest. (2) The peak displacement of fracture fragments was located at the top of the femoral head. The peak displacement of the conventional inverted triangle hollow screw group was the largest,and that in the femoral neck fixation system+hollow screw (posterior) group was the smallest. (3) The peak displacement of the internal fixation model was located at the top of the model. The peak displacement was maximum in the conventional inverted triangle hollow screw group and minimum in the femoral neck fixation system+hollow screw (posterior) group. (4) The displacement of the fracture surface in the femoral neck fixation system+hollow screw (posterior) group was at the upper part of the fracture end. The peak displacement was the largest in the conventional inverted triangle hollow screw group and the smallest in the femoral neck fixation system+hollow screw (posterior) group. (5) It is indicated that compared with the other three internal fixation methods,femoral neck fixation system+hollow screw (posterior) group showed good biomechanical stability. When Pauwels type Ⅲ femoral neck fracture occurs in a young person,from the point of view of finite element analysis,it may be a more favorable choice to treat the Pauwels type Ⅲ femoral neck fracture.

BACKGROUND:Pauwels type Ⅲ femoral neck fractures may be subjected to more shear and bending forces,and may be prone to complications such as internal fixation failure,bone nonunion,or femoral head necrosis. There is no consensus on the optimal selection of internal fixation devices.OBJECTIVE:To compare the biomechanical properties of four types of internal fixation methods for Pauwels type Ⅲ femoral neck fracture by finite element analysisMETHODS:Femur CT data of a healthy young volunteer were imported into Mimics software to construct a three-dimensional model of normal femur. Pauwels type Ⅲ femoral neck fracture was simulated based on 70° fracture line. Four types of fracture internal fixation models were optimized and constructed using Geomagic and UG software:conventional inverted triangle hollow screw,femoral neck fixation system,femoral neck fixation system plus anterior or posterior hollow screw treatment. Finally,Ansys software was used to analyze the stress distribution,peak stress,and peak displacement of proximal femur fracture block in four types of different internal fixation models. The displacement distribution and peak displacement of internal fixation device and femoral neckfracture were observed.RESULTS AND CONCLUSION:(1) The peak stress of proximal fracture fragments in the four groups was concentrated near the fracture line. The peak stress in the femoral neck fixation system group was the largest,and that in the conventional inverted triangle hollow screw group was the smallest. (2) The peak displacement of fracture fragments was located at the top of the femoral head. The peak displacement of the conventional inverted triangle hollow screw group was the largest,and that in the femoral neck fixation system+hollow screw (posterior) group was the smallest. (3) The peak displacement of the internal fixation model was located at the top of the model. The peak displacement was maximum in the conventional inverted triangle hollow screw group and minimum in the femoral neck fixation system+hollow screw (posterior) group. (4) The displacement of the fracture surface in the femoral neck fixation system+hollow screw (posterior) group was at the upper part of the fracture end. The peak displacement was the largest in the conventional inverted triangle hollow screw group and the smallest in the femoral neck fixation system+hollow screw (posterior) group. (5) It is indicated that compared with the other three internal fixation methods,femoral neck fixation system+hollow screw (posterior) group showed good biomechanical stability. When Pauwels type Ⅲ femoral neck fracture occurs in a young person,from the point of view of finite element analysis,it may be a more favorable choice to treat the Pauwels type Ⅲ femoral neck fracture.

Objective:To compare the clinical efficacy of femoral distraction and homeopathic double reverse traction reduction assisted internal fixation in the treatment of Schatzker type IV-VI tibial plateau fractures.Methods:A total of 51 patients (28 males and 23 females) with Schatzker IV-VI tibial plateau fractures treated with femoral distraction or homeopathic double reverse traction reduction from January 2017 to June 2021 in the Second Affiliated Hospital of Wenzhou Medical University were retrospectively analyzed. The average age was 49.6±11.9 years (range, 28-71 years). The time from injury to operation was 4.5±3.0 days (range, 1-15 days). There were 5 cases with combined anterior cruciate ligament injuries and 9 cases with posterior cruciate ligament injuries. Twenty-five cases were treated with femoral distraction reduction (distraction reduction group) and 26 cases with homeopathic double reverse traction reduction (traction reduction group). The operation time, intraoperative blood loss, visual analogue scale (VAS) on the first day after operation, hospitalization time, fracture healing time, and incidence of complications were compared between the two groups. Hospital for Special Surgery (HSS) knee function score at 1, 3, 6, 12 months after operation were also compared.Results:All patients were operated successfully. The operation time was 125.9±35.1 min (range, 60-220 min), and the intraoperative blood loss was 138.4±85.4 ml (range, 30-400 ml). 15 patients received autologous iliac bone grafting and 36 patients received allogeneic bone grafting. The VAS score on the first day after operation was 2.4±0.7 (range, 1-4), the hospital stay was 12.6±3.6 days (range, 7-24 days), and the fracture healing time was 14.6±2.2 weeks (range, 12-21 weeks). All patients were followed up for 16.8±2.8 months (range, 13-25 months). The operation time, intraoperative blood loss and hospital stay in the traction reduction group were 106.2±21.7 min, 86.9±42.6 ml and 11.6±3.3 days, respectively, which were less than 146.4±34.9 min, 192.0±86.2 ml and 13.7±3.6 days in the distraction reduction group. The differences were statistically significant ( P<0.05). The HSS scores of traction reduction group at 1 month and 3 months after operation were 83.8±1.7 and 86.7±2.0, which were higher than those of distraction reduction group (81.0±2.6 and 84.9±2.6), and the differences were statistically significant ( P<0.05). There was no significant difference in HSS score between the two groups at 6 and 12 months after operation ( P>0.05). Conclusion:The internal fixation treatment of Schatzker type IV-VI tibial plateau fracture assisted with homeopathic double reverse traction reduction can reduce the amount of intraoperative blood loss, operation time and hospital stay, and improve the knee function in the early postoperative period.