BACKGROUND:Plate fixation is the mainstream method for the surgical treatment of distal femoral fractures.The intramedullary nailing has the advantages of minimally invasive,such as less soft tissue injury and bone blood supply destruction.At the same time,it is a central fixation and has better biomechanical effect.Therefore,retrograde intramedullary nailing has become another option for the internal fixation of distal femoral fractures.OBJECTIVE:The biomechanical characteristics of new retrograde intramedullary nail on lateral femur condyle,common femoral retrograde intramedullary nail,and lateral femur condyle anatomical locking plate for the treatment of A2-type distal femoral fractures were compared using finite element analysis,and the advantages of new retrograde intramedullary nail on lateral femur condyle was studied.METHODS:A new retrograde intramedullary nail on lateral femur condyle was designed,which was inserted into the bone cortex in front of the insertion point of the lateral collateral ligament of the lateral femoral condyle.A CT scan was performed on the lower limb bone of a male volunteer,and a three-dimensional model of the femur was established.The model was then segmented to create a three-dimensional model of a femoral distal A2-type fracture,The three-dimensional models of small(small group),standard type retrograde intramedullary nail on the lateral femoral condyle(standard group),common retrograde intramedullary needle(common group),and lateral femur condyle anatomical locking plate(plate group)were established respectively.The axial stresses of 600,1 800 N and the torsional load of 4 000,8 000 N·mm were applied to the models,and the displacement and stress of femur and the displacement,stress and shear force of internal fixators were observed in each group.RESULTS AND CONCLUSION:(1)When subjected to axial load of 600 and 1 800 N,the femoral peak displacement,the femoral peak stress,and the peak stress of interal fixation in the standard group were the lowest among the four groups.(2)When subjected to torsional load of 4 000 and 8 000 N·mm,the femoral peak displacement and peak displacement of the internal fixation in the standard group were the lowest among the four groups.(3)Compared with femoral lateral condylar locking plate and common retrograde intramedullary needle,the new retrograde intramedullary needle on lateral femur condyle has mechanical advantages of reducing stress concentration and decreasing the risk of internal fixation failure.

BACKGROUND:Plate fixation is the mainstream method for the surgical treatment of distal femoral fractures.The intramedullary nailing has the advantages of minimally invasive,such as less soft tissue injury and bone blood supply destruction.At the same time,it is a central fixation and has better biomechanical effect.Therefore,retrograde intramedullary nailing has become another option for the internal fixation of distal femoral fractures.OBJECTIVE:The biomechanical characteristics of new retrograde intramedullary nail on lateral femur condyle,common femoral retrograde intramedullary nail,and lateral femur condyle anatomical locking plate for the treatment of A2-type distal femoral fractures were compared using finite element analysis,and the advantages of new retrograde intramedullary nail on lateral femur condyle was studied.METHODS:A new retrograde intramedullary nail on lateral femur condyle was designed,which was inserted into the bone cortex in front of the insertion point of the lateral collateral ligament of the lateral femoral condyle.A CT scan was performed on the lower limb bone of a male volunteer,and a three-dimensional model of the femur was established.The model was then segmented to create a three-dimensional model of a femoral distal A2-type fracture,The three-dimensional models of small(small group),standard type retrograde intramedullary nail on the lateral femoral condyle(standard group),common retrograde intramedullary needle(common group),and lateral femur condyle anatomical locking plate(plate group)were established respectively.The axial stresses of 600,1 800 N and the torsional load of 4 000,8 000 N·mm were applied to the models,and the displacement and stress of femur and the displacement,stress and shear force of internal fixators were observed in each group.RESULTS AND CONCLUSION:(1)When subjected to axial load of 600 and 1 800 N,the femoral peak displacement,the femoral peak stress,and the peak stress of interal fixation in the standard group were the lowest among the four groups.(2)When subjected to torsional load of 4 000 and 8 000 N·mm,the femoral peak displacement and peak displacement of the internal fixation in the standard group were the lowest among the four groups.(3)Compared with femoral lateral condylar locking plate and common retrograde intramedullary needle,the new retrograde intramedullary needle on lateral femur condyle has mechanical advantages of reducing stress concentration and decreasing the risk of internal fixation failure.

Objective To compare the biomechanical characteristics of novel retrograde intramedullary nail,common femoral retrograde intramedullary nail,and medial femoral condyle locking plate for treating distal femur type A fractures by finite element analysis,and study the advantages of retrograde intramedullary nail on medial femoral condyle.Methods A novel retrograde intramedullary nail on medial femur condyle was designed.CT scan was performed on lower limb bones of a male volunteer,and a three-dimensional(3D)model of the femur was established.The model was then segmented to create models of distal femur type A2 and A3 fractures.The 3D models of internal fixator were established.The small and standard retrograde intramedullary nail on medial femoral condyle,common femoral retrograde intramedullary nail,locking plate on medial femoral condyle were used for internal fixation on A2 type fracture.A3 type fracture was fixed with one of the above internal fixators combined with lateral condylar plate respectively.The 600 N axial load and 4 N·m torsional load were applied to the models.The displacement and stress of femurs,the displacement and stress of internal fixators,the micro-momentum between the internal fixator and the bone,the relative displacement of the two fracture broken ends were observed in each group.Results Among the A2 and A3 type fractures under axial loads,the correponding standard group and corresponding standard combined group had the smallest peak displacement and peak stress of internal fixation.Among the A2 and A3 type fractures under torsional loads,the correponding standard group and corresponding standard combined group had the smallest peak displacement of the femur and internal fixation.The relative displacement of the two broken ends in the standard combined group was the smallest.Conclusions Compared with femoral medial condylar locking plate and common retrograde intramedullary nail,this novel retrograde intramedullary nail on medial femur condyle has a mechanical advantage of reducing stress concentration and reducing the risk of internal fixation failure,and it can be used alone for distal femur type A2 fracture,or in combination with the lateral condylar plate to fix distal femur type A3 fracture.

Objective To compare the biomechanical characteristics of novel retrograde intramedullary nail,common femoral retrograde intramedullary nail,and medial femoral condyle locking plate for treating distal femur type A fractures by finite element analysis,and study the advantages of retrograde intramedullary nail on medial femoral condyle.Methods A novel retrograde intramedullary nail on medial femur condyle was designed.CT scan was performed on lower limb bones of a male volunteer,and a three-dimensional(3D)model of the femur was established.The model was then segmented to create models of distal femur type A2 and A3 fractures.The 3D models of internal fixator were established.The small and standard retrograde intramedullary nail on medial femoral condyle,common femoral retrograde intramedullary nail,locking plate on medial femoral condyle were used for internal fixation on A2 type fracture.A3 type fracture was fixed with one of the above internal fixators combined with lateral condylar plate respectively.The 600 N axial load and 4 N·m torsional load were applied to the models.The displacement and stress of femurs,the displacement and stress of internal fixators,the micro-momentum between the internal fixator and the bone,the relative displacement of the two fracture broken ends were observed in each group.Results Among the A2 and A3 type fractures under axial loads,the correponding standard group and corresponding standard combined group had the smallest peak displacement and peak stress of internal fixation.Among the A2 and A3 type fractures under torsional loads,the correponding standard group and corresponding standard combined group had the smallest peak displacement of the femur and internal fixation.The relative displacement of the two broken ends in the standard combined group was the smallest.Conclusions Compared with femoral medial condylar locking plate and common retrograde intramedullary nail,this novel retrograde intramedullary nail on medial femur condyle has a mechanical advantage of reducing stress concentration and reducing the risk of internal fixation failure,and it can be used alone for distal femur type A2 fracture,or in combination with the lateral condylar plate to fix distal femur type A3 fracture.

Objective:To explore the clinical efficacy of internal fixation with a reduction plate assisted by our self-designed lower extremity fracture traction reduction device for tibial plateau fractures of Schatzker type Ⅵ.Methods:A retrospective study was conducted of the 32 patients with tibial plateau fracture of Schatzker type Ⅵ who had been treated at Orthopaedic Department, Mindong Hospital Affiliated to Fujian Medical University from April 2018 to July 2021. Depending on their treatments, they were divided into 2 groups. In the control group of 16 cases subjected to open reduction and internal fixation with manual traction, there were 9 males and 7 females with an age of 50.0±11.7 years; in the observation group of 16 cases subjected to internal fixation with a reduction plate assisted by our self-designed lower extremity fracture traction reduction device, there were 8 males and 8 females with an age of 54.6±11.1 years. The operation time, fracture reduction time, total incision length, intraoperative blood loss, Rasmussen knee function score and maximum active range of knee motion were compared between the 2 groups.Results:There was no significant difference in the preoperative general data between the 2 groups, showing comparability between the groups ( P>0.05). The operation time [(158.6±26.0) min], fracture reduction time [(61.6±9.6) min], and total incision length [16.0 (13.3, 17.0) cm] in the observation group were significantly shorter than those in the control group [(199.9±60.9) min, (73.8±17.2) min, and 20.0 (17.0, 21.8) cm]; the intraoperative blood loss [175.0 (100.0, 200.0) mL] in the observation group was significantly less than that in the control group [200.0 (162.5, 387.5) mL]; the maximum active ranges of knee motion at one week and one month in the observation group were 94.9°±12.0° and 113.8°±14.1°, significantly larger than those in the control group (78.3°±14.6° and 96.8°±11.4°) (all P<0.05). Fractures achieved bony union at one year after operation in both groups. At 12 months after operation, there was no significant difference in the maximum active range of knee motion or the Rasmussen knee function score between the 2 groups ( P>0.05). Conclusion:In the treatment of Schatzker type Ⅵ tibial plateau fractures, compared with manual traction and open reduction, internal fixation with a reduction plate assisted by our self-designed lower extremity fracture traction reduction device can shorten operation time and total incision length, reduce intraoperative blood loss, and facilitate postoperative functional recovery of the knee for the patients.

Objective To evaluate mivacurium-induced release of histamine in the patients undergoing general anesthesia.Methods Eighty patients of both sexes,aged 19-58 yr,weighing 42-75 kg,of ASA physical status Ⅰ or Ⅱ,undergoing ureteroscopy under general anesthesia,were randomly divided into 2 groups (n =40 each) using a random number table:rocuronium group (group R) and mivacurium group (group M).Anesthesia was induced with iv midazolam 0.04 mg/kg,fentanyl 3 μg/kg,etomidate 0.3 mg/kg,and mivacurium 0.20 mg/kg (group M) or rocuronium 0.75 mg/kg (group R).Streamlined liner of the pharynx airway (SLIPA) was inserted for mechanical ventilation.PET CO2 was maintained at 35-40 mmHg.Anesthesia was maintained with fentanyl and propofol.Before muscle relaxant administration,at 3 min after muscle relaxant administration and at 5 min after insertion of SLIPA,venous blood samples were collected for determination of plasma histamine concentrations (by HPLC) and the histamine release was classified.Results Compared with group R,the plasma histamine concentration and histamine release were increased at 3 min after muscle relaxant administration in group M.No fatal responses caused by histamine release were found in the two groups.Conclusion Although mivacurium induces release of histamine,it can still be safely used for the patients undergoing ureteroscopy under general anesthesia.