| Part ? Biomechanical Study of Medial Wall Internal Fixation of Proximal FemurObjective: The finite element analysis technique was used to analyze and calculate the stability of six types of intertrochanteric fractures after fixation with proximal femoral medial plate,and to explore the supporting effect of proximal femoral medial plate on the proximal medial wall of the femur.Methods: The finite element analysis method was used to establish the model of six-part classification of intertrochanteric fracture of femur fixed with PFNA,medial plate(double cortex)and PFNA-medial plate(single cortex).According to the reference materials,the boundary conditions and material properties of the model were set,and the hip was loaded at the peak time of hip force when the adults with weight 70 kg walked normally.According to the above conditions,the finite element analysis of the model was carried out,and the stress and deformation displacement diagrams of 21 groups of internal fixation models were obtained.The stress peak values of the important parts of each group of models and the displacement data of each fracture block were analyzed.The stability of each fracture model after fixation with medial plate was analyzed.Results: When PFNA was used to fix 7 kinds of fracture classification,there was no obvious stress of distal femur,proximal end of femur and stress concentration of internal fixation structure.When the two-part fracture was fixed,the fracture block 1 moved 5.51 mm.When the three-part fracture(3A)was fixed,the fracture blocks 1-2 moved 5.51 mm and 6.32 mm respectively.When the three-part fracture(3B)was fixed,the fracture blocks 1 and 3 moved 6.10 mm and 3.98 mm respectively.When the four-part fracture was fixed,the fracture blocks 1-3 moved 6.22 mm,6.63 mm,and 4.08 mm respectively.When the five-part fracture(5A)was fixed,the fracture blocks 1-4 moved 4.80 mm,7.02 mm,4.10 mm and 3.41 mm respectively.When the five-part fracture(5B)was fixed,the fracture blocks1-3 and 5 moved 6.82 mm,7.10 mm,4.03 mm,and 4.96 mm respectively.When the six-part fracture was fixed,the fracture blocks 1-5 moved 7.01 mm,7.83 mm,4.35 mm,4.85 mm and 5.02 mm respectively.When 7 types of fractures were fixed with medial plate(double cortex),the peak stress of medial proximal femur increased by 34% ~ 37%,the peak stress of proximal lateral femur increased by about 15% ~ 16%,and the stress of femur decreased at other observation points.The decrease was about 6% ~ 8%,and the peak stress of internal fixation structure was about 782 MPa ~ 792 MPa.When the two-part fracture was fixed,the fracture block 1 moved 5.51 mm.When the three-part fracture(3A)was fixed,the block 1-2 moved 5.56 mm and 6.73 mm respectively.When the three-part fracture(3B)was fixed,the fracture blocks 1 and 3 moved 5.56 mm and 3.52 mm respectively.When the four-part fracture was fixed,the fracture blocks 1-3 moved 6.31 mm,7.04 mm and 3.52 mm respectively.When the five-part fracture(5A)was fixed,the fracture blocks 1-4 moved 7.54 mm,7.95 mm,3.85 mm and 4.00 mm respectively.When the five-part fracture(5B)was fixed,the fracture blocks 1-3 and 5 moved 8.17 mm,8.02 mm,3.83 mm and 5.12 mm respectively.When the six-part fracture was fixed,the fracture blocks 1-5 moved 8.99 mm,8.72 mm,4.00 mm,4.33 mm and 5.30 mm respectively.When 7 types of fractures were fixed with PFNA and medial plate(single cortex),the peak stress of medial proximal femur increased by 54% ~ 70%,the peak stress of femur decreased by 2% ~13% at other observation points,and the peak stress of internal fixation was about 363 MPa ~370MPa.When the two-part fracture was fixed,the fracture block 1 moved 5.51 mm.When the three-part fracture(3A)was fixed,the fracture blocks 1-2 moved 5.51 mm and 6.32 mm respectively.When the three-part fracture(3B)was fixed,the fracture blocks 1 and 3 moved 5.51 mm and 3.46 mm respectively.When the fourpart fracture was fixed,the fracture blocks 1-3 moved 5.51 mm,6.63 mm and 3.49 mm respectively.When the five-part fracture(5A)was fixed,the fracture blocks 1-4 moved 5.80 mm,6.89 mm,3.57 mm and 3.38 mm respectively.When the five-part fracture(5B)was fixed,the fracture blocks 1-3 and 5 moved 5.82 mm,6.90 mm,3.58 mm and 4.76 mm respectively.When the six-part fracture was fixed,the fracture blocks 1-5 moved 6.08 mm,7.11 mm,3.62 mm,3.66 mm and 4.76 mm respectively.Conclusion: The application of the medial proximal femoral plate can effectively reduce the stress concentration of the proximal femur,reduce the displacement and deformation of the medial fracture block of the proximal femur,and play a better supporting role in the medial wall of the proximal femur.However,it is not suitable to use it alone for fracture types with high degree of comminution,and PFNA assisted medial plate(single cortex)fixation can effectively reduce the stress on the medial proximal femur compared with PFNA fixation alone.It can reduce the degree of displacement and deformation of each fracture block,and the structural stress of the internal fixation itself is not obviously abnormal,which can play a strong role in fixation.Part ? Anatomical Study on the Surgical Approach of Medial Wall Internal Fixation of Proximal FemurObjective: Referring to the existing medial proximal femoral approach and comparing it,the medial structure of proximal femur was dissected deeply,and a surgical approach with small incision,full exposure and high safety was determined.Methods: The anatomical research method was used to make reference to the existing surgical approach for medial femoral lesion.Eight cadaveric cadavers(4 males and 4 females)with intact proximal femoral structure were dissected through the small trochanter region approach between femoral nerve and femoral vessel and the direct anterior approach of hip joint.To observe the shape distribution of blood vessel,nerve and muscle in different medial approach of proximal femur and the area of exposure to medial proximal femur.Combined with its advantages,the proximal femoral structure was dissected in detail,and the medial plate was placed and fixed to determine a surgical approach with small incision,full exposure and high safety.Results: During the operation of 4 sides of the approach between the femoral nerve and the lesser trochanter region of the femoral vascular space,2 sides of the medial circumflex femoral artery were injured,and 1 side was injured to the lateral femoral cutaneous nerve during the operation,because the approach finally separated the femoral vascular nerve bundles to both sides.There is potential damage to nerves and blood vessels.During the operation of DAA approach on 4 sides of specimens,2 sides of lateral femoral cutaneous nerve were injured,and there was no obvious vascular injury,during the operation,many anterior and lateral muscle groups were pulled to the medial side,and more muscle groups were aggregated to the medial side.It has a great influence on the fixation of medial plate,and may cause important vascular and nerve injury in the process of fixation.The medial plate was successfully placed on 4 sides of the modified medial approach to the proximal femur,and there was no significant vascular and nerve injury during the operation.Conclusion: Through the surgical approach of medial support and fixation of the proximal femur,after entering the depth through the space between the sartorius muscle and the tensor fasciae lata,the rectus femoris muscle was cut off and opened to the medial side together with the femoral nerve and the femoral vascular bundle.In order to achieve the lesser trochanter and deeper medial part of the proximal femur,the injury to the lateral femoral cutaneous nerve and superior gluteal nerve can be effectively avoided during the operation.In the process of placing steel plate,certain protective measures should be taken to protect the medial vascular nerve bundle,which can effectively avoid the injury of important blood vessels and nerves,especially the medial circumflex femoral artery,in the process of screw drilling and plate fixation.Thus it can be seen that the medial support fixation approach of the proximal femur is an effective approach for the placement of the medial plate of the proximal femur. |
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