1 Principles topenlarge
The Condylar LCP is a modification of the former condylar buttress plate, which was used over the last three decades for treatment of C3-type fractures. The major problem with use of the condylar buttress plate was varus collapse and loss of fixation of the distal femoral articular block, especially with a short distal segment and/or osteoporosis. The major improvement in the Condylar LCP, as compared to the condylar buttress plate, has been the addition of locking-head screws in the plate, producing angular stability.
The locking head screws distally have prevented varus collapse, even in cases of osteoporosis. Locking-head screws both proximally and distally have made loss of fixation rare.
The Condylar LCP can be used in either an open, or a minimally invasive manner. When inserted in an open manner, a lateral approach is used. This is most commonly done for an A-type or C1/C2-type fracture. As with a 95° blade plate, if the plate is positioned on the distal femoral block in the appropriate position, the correct axial alignment (varus/valgus) of the distal femur fracture is ensured. A careful preoperative plan will allow the surgeon to know where the central 7.3 mm screw should be positioned in the distal femoral articular block. This requires preoperative templating of the uninvolved contralateral limb. Thereby, the implant, when placed in the appropriate position distally, helps the surgeon to reduce the fracture.
Alternatively, the implant can also be used in a minimally invasive manner. As with LISS fixation, the reduction of the metaphyseal / diaphyseal component of the fracture should be secured before fixation. Reduction aids are similar to those for the LISS fixation: anesthetic muscle relaxation, supracondylar bolster, manual traction, Schanz pins and external fixation. The advantage of closed reduction / internal fixation is a greater preservation of the fracture biology in the metaphyseal / diaphyseal area. This leads to higher union rates, less infection and fewer wound complications. Closed reduction techniques are generally employed when the surgeon is faced with a complex comminuted metaphyseal fracture. Fractures with a simple, one-plane fracture pattern are generally approached in an open manner, with direct clamp application.
The gastrocnemius typically causes a hyperextension deformity of the distal femoral articular block.
Correction of hyperextension deformity
Hyperextension deformity must be corrected before fracture fixation. Aids to correcting this hyperextension deformity include:
- Muscle relaxation of the patient
- A bolster in the supracondylar region
- Flexion of the operating table leg segment
Using the Condylar LCP for simple plane fractures
Condylar LCP fixation, when performed in a minimally invasive manner, relies
on the principle of bridge plating. It therefore works best in comminuted
metaphyseal fractures (i.e., A3-type fractures.) Anatomical reduction of
intermediate fragments is neither sought nor necessary. If the soft-tissue
attachments to the fragments are preserved and the fragments are relatively
well aligned, healing is unimpaired.
In the cases where the metaphyseal/diaphyseal fracture has one or two simple planes, make sure that there is no major gap between the reduced fracture fragments. Due to the relative stiffness of the Condylar LCP, major gaps between the fracture fragments can result in higher rates of non-union.
The surgeon has to control three major deformities when performing open fixation of the distal femur with Condylar LCP:
- Varus/valgus: The frontal plane alignment is determined by the fixation of the femoral articular block to the Condylar LCP with the distal locking screws. If the central 7.3 mm screw in the plate is parallel with the tibio-femoral joint surface, this ensures appropriate varus/valgus alignment.
- Rotation: Careful monitoring of the rotation of the limb is observed throughout the operative procedure. The rotation becomes established once a distal screw and a proximal screw have been inserted.
- Flexion/extension (sagittal plane alignment): The alignment of the Condylar LCP on the lateral aspect of the distal femur establishes the presence or absence of any extension, or flexion, deformity at the fracture site. After fixation of the plate to the distal femur, the flexion/extension relationship becomes established (“locked-in”) once a second screw is placed in the proximal main femoral fragment.
2 Choice of implant topenlarge
For retrograde femoral nailing to achieve adequate fracture stabilization, the fracture should be at least 6 cm from the joint line to achieve distal locking with two transverse screws or a screw and a spiral blade. In contrast, more distal fixation can be achieved with plates, or locked fixators. For example the distal most screws in a LISS plate, or a condylar plate, may be subchondral.
The distal-most fixation for various implants are:
- LISS plate: subchondral
- Condylar plate: subchondral
- 95° angled blade plate: 1.5 – 2 cm
- 95° dynamic condylar screws: 2 cm
- Retrograde intramedullary nail: 6 cm (for 2 locking screws, or one locking screw and a spiral blade)
Plate length/number of screws
Modern plating techniques result in the maintenance of vascularity around the fracture site and relatively longer plates are used than in previous decades. In general, 4 to 5 screws should be chosen in each of the distal femur and proximal femur. A plate length should be chosen that allows for an approximately similar number of empty plate holes in the proximal femur.
The preoperative x-ray planning template is useful in determining the required length of the Condylar LCP and the positions of the screws.
3 Plate and screw characteristics topenlarge
The anatomically shaped plate head is pre-contoured to match the distal femur, eliminating intraoperative plate modification.
Five threaded 5.0 mm peripheral screw holes accept locking screws
The central 7.3mm screw has an angle of 95° to the plate shaft. Its insertion should therefore be parallel to the tibio-femoral joint surface.
Combi-holes combine a dynamic compression unit (DCU) hole with a locking-screw hole. This allows the surgeon either to insert a standard bicortical screw, or a locked screw.
Straight plates are available with 6, or 8, combi-holes.
Curved plates are available with 10, 12, 14, 16, 18, 20, or 22 combi-holes, to accommodate fracture patterns that include shaft fractures in conjunction with articular fragments.
Curved plates are precontoured to mimic the anterior convexity (1.1 m radius) of the femur.
Plate design permits the use of a minimally invasive surgical techniques.
Limited-contact design provides minimal periosteal disruption.
Implants are made from 316L stainless steel.
There are three types of threaded guides for the Condylar LCP.
- The 7.3 mm wire guide is cannulated for a 2.5 mm guide wire and screws into the central hole on the distal aspect of the plate.
- The 5.0 mm wire guide is cannulated for a 2.5 mm guide wire and can be
screwed into any of the remaining holes in the head of the Condylar LCP.
These guides may be screwed into the plate with a hexagonal cannulated screw driver.
- The 5.0 mm drill guide is used to center the 4.3 mm drill bit in the locking portion of the combi-hole.
There are five types of cannulated screws that can be inserted into the head of the Condylar LCP. Of these, 3 are different types of screws which fit into the central hole of the plate. These 3 screws are characterized by the type of head (threaded versus conical) and the length of thread (fully threaded versus partially threaded):
- The cannulated 7.3 mm locking screw creates a fixed angled construct.
- The cannulated 7.3 mm conical screw (fully threaded) compresses the plate to the lateral femoral condyle.
- The cannulated 7.3 mm conical screw (partially threaded) compresses the
plate to the lateral femoral condyle and provides interfragmentary compression
across the intercondylar split.
There are two types of screws which fit the peripheral holes in the head of the Condylar LCP.
- The fourth type of screw is the cannulated fully threaded 5.0 mm locking screw which creates a fixed angle construct.
- The cannulated 5.0 mm partially threaded conical screw compresses the plate to the lateral femoral condyle and provides interfragmentary compression across the intercondylar split.
As with any combi-hole the surgeon chooses to use either a locking head 5.0 mm screw (1) or a standard 4.5 mm bicortical screw (2).
Note: choice of locking versus standard screw
If the alignment of the fracture is appropriate and the plate stands a little away from the bone surface, a locking-head screw should be inserted. In this situation, the use of a standard cortical screw will draw the bone to the plate and deform the fracture reduction.
If the surgeon wishes to align the bone to the contour of the plate, a standard cortical screw should be utilized.
4 Reduction of the metaphysis/diaphysis topenlarge
Reduction of metaphyseal component
The key concept in reduction of the metaphyseal component of the fracture when using a Condylar LCP is that proper application of the Condylar LCP on the distal femur allows the surgeon to use the plate to achieve the metaphyseal fracture reduction. When brought down to the proximal femoral shaft, the correct frontal plane alignment has been assured. The surgeon must then control length, rotation, and sagittal plane deformity (hyperextension/hyperflexion). When performed in an open manner, length can be aided by manual traction. The sagittal plane deformity correction can be aided by supracondylar bolsters.
Open reduction is aided by:
- Bolsters posterior to the supracondylar region, which help correct the hyperextension deformity of the distal femoral articular block.
- Manual traction which helps restore length of the limb.
- Direct pointed reduction forceps placement (particularly helpful in spiral fractures of the metaphysis).
- A Hohmann retractor, which may be used as a lever to correct translational displacement.
- The plate itself; by applying the plate in the correct position on the distal femur, appropriate alignment is established when the plate is fixed to the proximal femur.
Assembly of Condylar LCP
Screw the threaded wire guides for the 2.5 mm guide wires into the 5.0 mm and 7.3 mm screw holes of the plate head.
Frontal plane alignment
With one of the reduction aids listed previously, you can get an approximate alignment of the metaphyseal/diaphyseal fracture, once the articular block has been reconstructed. Then, with the open technique, the next priority is to establish the correct placement of the plate on the distal femur. Place the Condylar LCP onto the lateral femoral condyle. On the AP view, the guide wire placed through the central hole should be parallel to the tibio-femoral joint surface.
Note: The distal edge of the Condylar LCP is usually 1.5 cm from the distal condylar articular surface.
Position on the lateral femoral cortex
The Condylar LCP is adjusted manually so that the plate lies flush on the lateral femoral condyle.
The anterior edge of the head of the Condylar LCP is usually 1.0-1.5 cm from the anterior aspect of the medial femoral condyle.
Proper position check - position on the distal femur
When the plate lies flat on the lateral surface of the condyle, it has been positioned correctly on the distal femur.
A second guide wire in one of the 5.0 mm screw holes will secure provisional fixation of the plate to the femoral articular block.
Prior to proceeding, confirm plate head placement, using visual examination
and an image intensifier. Ensure that:
- the guide wire inserted through the 7.3 mm central hole is parallel to both
the tibio-femoral joint plane and the patellofemoral joint
- the guide wires inserted through any of the four most distal 5.0 mm screw holes in the head of the plate are parallel to the tibio-femoral joint plane.
Additionally, check that the plate is properly orientated on the lateral femoral condyle. Because the shaft of the femur is frequently out of alignment with the distal femoral articular block, proper plate placement can be determined by matching the plate head shape to that of the condyle. The position of the plate on the distal femoral articular block at this point will determine final flexion/extension reduction.
5 Preliminary plate fixation topenlarge
Screw length measurement in distal femoral articular block
Use the measuring device indirectly to measure the lengths of the screws using the previously inserted guide wires.
Although screws may be inserted in any order, it is usual to start with the central 7.3 mm screw. Advance the guide wire until it reaches the medial cortex of the femoral condyle. Measure for screw length using the measuring device. For proper screw length measurement, the measuring device must contact the end of the threaded wire guide. This will place the tip of the screw at the tip of the guide wire.
Pearl: self-drilling/self-tapping screws
The self-drilling, self-tapping flutes of the 7.3 mm and 5.0 mm screws make predrilling and pretapping unnecessary in most cases. In dense bone, the lateral cortex can be predrilled, if necessary.
- Use the 5.0 mm drill bit for 7.3 mm screws.
- Use the 4.3 mm drill bit for 5.0 mm screws.
Distal screw insertion
With the central guide wire parallel to the tibio-femoral joint surface and the plate flush on the lateral femoral cortex, the central 7.3 mm screw may be inserted. This will establish the varus/valgus angulation of the fracture.
After the length of the screw is determined, the wire guide is removed from the plate head and the central screw (7.3 mm) is inserted over the guide wire, using the torque-limiting power screw driver. Inserting only one screw at this point allows correction of small deformities in the sagittal plane (on the lateral x-ray).
After you have confirmed that the plate is in the correct position on the distal femur, when viewed on a lateral x-ray, the additional screws (5.0 mm) should be inserted into the distal femoral articular block.
Now reduce the proximal portion of the Condylar LCP with a combination of maneuvers:
- Manual traction provides length restoration
- The plate is aligned to the proximal mid-lateral cortex and is held into position with a Verbrugge clamp.
6 Intraoperative radiological assessment topenlarge
Establishment of length and rotation
Recognize that, once a screw is inserted into the proximal segment, both the length and the rotation of the fractured limb are established. In general, a standard bicortical screw is first inserted into a proximal segment to bring the plate down to the bone. The length and rotation will have been corrected by the closed reduction techniques.
Generally, the length may be assessed by evaluating overlap or distraction of the posterior cortex.
Place a bolster underneath the buttock of the involved extremity. A simple “rule-of-thumb” is that the foot should be externally rotated 10° after fixation of the supracondylar fracture. If the rotation is correct, the anterior superior iliac spine, the center of the patella and the second toe should be in line. Additionally, and more precisely, the rotation can be assessed using the image intensifier with the lesser-trochanter sign.
Assessment of rotation
Compare the profile of the lesser trochanter with that of the contralateral leg (lesser trochanter shape sign), holding the leg so that the patella faces anteriorly on both sides.
Before positioning the patient, store the profile of the lesser trochanter of the intact opposite leg (patella facing anteriorly) in the image intensifier.
The illustration shows the lesser trochanteric profile of the intact opposite side.
In cases of malrotation, the lesser trochanter is of a different profile when compared to that of the contralateral leg.
Take care to assess rotation with the patella facing directly anteriorly.
Matching of the lesser trochanter shape
After securing the plate to the distal femur, correct any malrotation by rotating the distal femur. Ensure that the profiles of the lesser trochanters are matched.
7 Fixation of plate to proximal fragment topenlarge
Insertion of proximal screws
You may insert either standard bicortical screws (as illustrated), or locking-head screws, through the proximal plate. A standard screw is inserted after drilling with a 3.2 mm drill bit. A 5.0 mm locking-head screw is inserted after drilling with a 4.3 mm drill bit through the threaded drill sleeve.
8 Completed osteosynthesis topenlarge
Additional screw insertion
Insert additional screws proximal and distal for a total of 4-5 distal and 4-5 proximal screws.
Final check of fracture reduction and fixation
Gently move the knee through a full range of motion. Carry out a clinical assessment of the rotational profile. Finally, perform a radiographic assessment of the frontal-plane alignment (varus/valgus) and sagittal-plane alignment (extension/flexion).
Examine the knee for any ligamentous instability.
Irrigate all wounds copiously. Close the iliotibial tract using absorbable sutures. The use of suction drains may be considered. Close the skin and subcutaneous tissue in the routine manner.