This kind of internal fixation is mostly used for long bone fractures, which is more reliable and has more clinical applications. However, the disadvantage is that the incision is long, the soft tissue and periosteum are widely separated, the blood supply at the fracture end is seriously damaged and the healing is slow.
1. Transverse or oblique fracture of long bone shaft of limbs, failure of manual reduction and external fixation or other reasons.
2. If it is difficult to treat multiple fractures of the whole body or multiple fractures of one bone with manual reduction and external fixation, and 1 ~ 2 fractures that are difficult to maintain alignment with manual reduction or external fixation, plate and screw internal fixation can be considered.
3. When fracture malunion or nonunion requires surgical treatment (such as osteotomy, bone transplantation, etc.). ), steel plate should be used for internal fixation at the same time to restore bone scaffold.
4. After osteotomy of bone deformity (such as subtrochanteric osteotomy of femur or supracondylar osteotomy of femur and humerus), it can be fixed with prefabricated angled steel plate or pressurized angled steel plate (such as condylar steel plate, etc.). ).
5. Some long oblique, spiral and butterfly-shaped comminuted fractures can also be fixed with compression screws and balance steel plates, which can effectively offset torsion, scissors difference and bending stress.
6. In order to protect the transplanted bone and bone fragments from compression, supporting steel plate can be used to fix the comminuted fracture or defect of metaphyseal end, which can play a bridging role and ensure the healing of bone graft.
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Preoperative preparation
1. The steel plate requires that the cross section of the steel plate is arc-shaped and closely adheres to the circular bone surface, and the hole of the steel plate should have an inclined concave part, so that the semi-countersunk screw head can be embedded correspondingly, which can increase the fixation effect and reduce the pain caused by the protrusion of the screw head. Figure 2.
2. There are many kinds of steel plates, as shown in Figure 3. The variety with good fixation effect should be selected according to the fracture position, shape and bone diameter. Steel plates are divided into ordinary steel plates and pressurized steel plates according to their properties. The latter has round hole (static pressure), self-pressure steel plate (dynamic pressure) and many special specifications. The following are some common types of steel plates:
Straight long steel plate: mostly used for long shaft fractures. The length of the selected steel plate should be 4 ~ 5 times the diameter of the broken bone. Generally, there are 8 holes in femur, 6 holes in tibia and 4 holes in humerus.
Horn plate: mostly used for supracondylar fracture of femur or intertrochanteric osteotomy of femur.
Angle steel plate: used in orthopedic surgery for long bone cutting.
Rotor plate: used for internal fixation after intertrochanteric osteotomy of femoral neck fracture.
Trident plate: used for Y-shaped or T-shaped fracture of condyle.
Compressed steel plate: wider than ordinary steel plate. When it is used, it is equipped with a compression cortical bone screw, and the fracture end is pressed and fixed firmly by a compression device or a specially designed steel plate (automatic compression steel plate).
3. Screw selection is the same as screw internal fixation.
4. The pressurizer consists of a pressurizer hole, a hook and a pressurizing screw, and is equipped with a adjustable wrench and a bit guide (pilot drill). Use Figure 4.
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Surgical procedure
(A) ordinary steel plate screw internal fixation
1. After placing the fracture reduction plate, according to the size of the plate, peel off the local periosteum, put the plate on the back of the fracture, put the plate on the bone surface, and tighten the sliding part of the fracture anchor. The fracture part and the plate can be temporarily fixed together, but pay attention to exposing all the holes of the plate for drilling.
2. Drill holes and screw in screws. First, drill a bone hole at each end of the steel plate. The drill bit should be drilled vertically in the center of the steel plate hole. After drilling through the cortical bone on both sides, measure the diameter of the bone with a bone hole sounder, and add the thickness of the steel plate. According to this length, select screws with the same length (except the nail tip) and screw them in along the drilling direction. Then drill bone holes according to each hole on the steel plate, screw in screws and tighten them in turn. The method of drilling and placing screws is the same as "screw internal fixation".
(2) the pressurizer pressurizes the steel plate and the screw for internal fixation.
After fracture reduction, the compression steel plate was placed and fixed with bone fixator. A hole with a diameter of 3.2mm was drilled on the steel plate hole about 1.0cm away from the fracture line in the short fracture segment, and the cortical bone on both sides was drilled. Measure the depth of the hole with a depth gauge so as to select the appropriate length of screw. Knock out the grain of bone hole and screw in 1 cortical bone screw. After resetting and fixing the fracture end and the steel plate, place the drill guide of the pressurizer and drill a 3.2 mm bone hole. Adjust the pressurizer, hook the end hole of the pressurizing steel plate, align the hole of the pressurizer with the bone hole, and screw in 1 common screw to fix the pressurizer. While maintaining anatomical reduction, gently tighten the pressurizer with a socket wrench to preliminarily longitudinally pressurize the two folded ends. Then, drill a hole through the guide with a drill with a length of 40mm and a diameter of 3.2mm, knock out the bone hole line, and screw the second and third cortical bone screws into the remaining two holes of the compression steel plate. Pay attention to the center of the hole on the steel plate when drilling, and protect the tap sleeve when tapping to prevent the tap from being stuck or involved in the surrounding soft tissue. Further tighten the pressurizer with a wrench to make the fracture ends tightly connected, and the pressure can reach 40 ~ 50kg. After pressurization, check whether there is displacement at the fracture end. If there is no displacement, screw the fourth and fifth cortical bone screws into the steel plate in the same way with a compression device. Finally, loosen and remove the pressurizer, and screw in the sixth short cortical bone screw to fix a cortical bone to reduce stress opening and shielding. For short inclined fractures, compression screws must be used to obliquely penetrate the fracture line through the hole of the steel plate to enhance the fixation effect.
(3) automatic compression steel plate and screw internal fixation
When the steel plate is automatically pressurized, there is no need to use a pressurizer. Because the steel plate holes are designed and manufactured according to two semi-cylindrical patterns. Its principle is to use the spherical sliding principle, that is, when the screw is screwed in from the inclined cylindrical end, its screw head moves to the horizontal sliding surface along the inclined bearing surface of the steel plate hole, and the fracture end moves to the centripetal horizontal direction, thus generating a compression action diagram.
After placing the steel plate, under the guidance of a neutral pilot drill, drill a hole at the fracture end near the fracture section, screw in the first cortical bone screw, but do not tighten it, accurately reset the fracture, insert the hook into the hole of the steel plate, and pull the steel plate to the far end, so that the first screw is in the eccentric position of the hole of the steel plate. Then use an eccentric pilot drill (load-bearing pilot drill) to drill an eccentric hole at the fracture end of the distal fracture segment, and the drilling position is as close as possible to the distal end of the steel plate hole. Screw in the second cortical screw and tighten it in the same way, and then tighten the first screw, so that the fracture ends are closed together and pressure is generated. Then, screw in the remaining screws at the center or slightly eccentric position of the steel plate hole.
(4) Bone transplantation
For fractures that have been injured for more than 3 weeks, especially those parts that are difficult to heal (such as the lower radius, the upper ulna and the lower tibia), bone transplantation should be carried out at the same time of internal fixation to promote healing.
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Matters needing attention in operation
1. The separation of soft tissue and the peeling of periosteum should be reduced as much as possible, so that it can be exposed for placing steel plates to reduce the damage to the blood supply at the fracture end.
2. The steel plate should be placed on the flat side of the spine and must be close to the bone surface, so that the fracture ends are close together; For example, the radius should not be put in the back. Try not to let the straight steel plate deform to adapt to the bending of bones, so as not to reduce its strength.
The placement of compressed steel plate should be based on the tension band principle, that is, when the steel plate is placed on the tensile side of the fracture, the steel plate bears tension, and after the steel plate is compressed, the tension on the tensile side of the fracture is converted into pressure. In the load-bearing state, the tension side is on the opposite side of the human body's center of gravity, such as femoral shaft fracture, and its tension side is on the opposite side of the femoral neck, that is, slightly behind the lateral side; Under the condition of no load, the tension side can be judged according to the function of muscle group and the characteristics of fracture. If the steel plate is placed on the opposite side of the tension side by mistake, it will increase the tension on the tension side and separate the fracture ends, which will easily cause the steel plate to break and affect the fracture healing.
3. The steel plate should be placed on the bone surface covering the muscles to avoid direct contact between the steel plate and the skin and causing pain.
4. The drill bit must be drilled vertically in the center of the hole of the steel plate, and the pilot drill should be used when applying the pressurized steel plate. If there is deviation, the screw head cannot be tightly screwed into the concave part of the steel plate hole, and the fixing efficiency will be weakened.
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Polizel's therapy
External fixation should be performed immediately after operation until the fracture heals. No external fixation is required when using pressurized steel plates. Start crutch weight-bearing exercise after taking out stitches. When the X-ray shows the shadow of bone healing, the crutch is changed to 1 ~ 2 months, and then the crutch is discarded. After the fracture is healed, the steel plate is taken out. Usually, the compression steel plate after the operation is 1. Take it out two years later.
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Prevention and treatment of postoperative complications
1. The causes of bending and fracture of steel plates are mostly due to the fact that external fixation is not needed or the external fixation time is too short, and the steel plates rely too much on the limited fixation force of steel plates to carry loads or move, resulting in bending or fracture of steel plates. Once it happens, it should be re-operated, the steel plate should be taken out and fixed internally.
2. The steel plate cannot be taken out. Sometimes it is difficult to take out the steel plate. The main reason is that the screw head groove is damaged and the screwdriver can't play its role. The bone cortex around one end of the screw should be chiseled to a little thickness. Press down the steel plate with wire cutters to expose a little screw, then lift the steel plate and take out other screws in turn in the same way.
3. After rigid internal fixation with compression steel plate, due to the great difference in elastic coefficient between steel plate and bone, most of the bearing stress of limb is transmitted through steel plate instead of the bone below it, which leads to bone atrophy at the fixed part of steel plate, and it is easy to fracture at the junction of normal bone and atrophic bone at the end of steel plate or fracture again after taking out steel plate. Therefore, after the steel plate is taken out, it still needs to be properly protected for 3 ~ 6 months to avoid fracture. Re-fracture often occurs at the nail hole at the distal end of the steel plate. To prevent it, the screw at the distal end of the steel plate can only pass through one side of the cortical bone. In this way, it can avoid the stress of limb bearing concentrated at the end of steel plate and gradually transition from bone to steel plate, thus buffering the sudden change of elastic coefficient between the bone fixed by steel plate and normal bone.