Throughout this treatment option illustrations of generic fracture patterns are shown, as four different types:
A) Unreduced fracture
B) Reduced fracture
C) Fracture reduced and fixed provisionally
D) Fracture fixed definitively
Complete articular fractures are treated in two main steps.
By placing and fixing the plate in the appropriate position on the distal femur, the correct alignment (varus/valgus) is established when the plate is brought down to the proximal femoral shaft.
With a simple extra-articular component, care must be taken to achieve anatomical reduction of the single plane fracture and achieve interfragmentary compression or dynamic compression, giving absolute stability.
Make sure that there is an anatomic reduction between the reduced fracture fragments. Due to the relative stiffness of the condylar VA-LCP, gaps between the fracture fragments can result in higher rates of non-union.
In general, three major deformities must be managed when performing fixation of the distal femur with condylar VA-LCP:
The gastrocnemius typically causes a hyperextension deformity of the distal femoral articular block.
Hyperextension deformity must be corrected before fracture fixation. Aids to correcting this hyperextension deformity include:
The distal femur has a unique anatomical shape. Seen from an end-on view, the lateral surface has a 10° inclination from the vertical, while the medial surface has a 20–25° slope.
A line is drawn from the anterior aspect of the lateral femoral condyle to the anterior aspect of the medial femoral condyle (patellofemoral inclination) that slopes approximately 10°. These anatomical details are important when inserting screws. In order to avoid joint penetration, these devices should be placed parallel to both the patellofemoral and femorotibial joints planes.
The muscle attachments to the distal femur are responsible for the typical displacement of the distal articular block following a supracondylar fracture, namely shortening with varus and extension deformity. Shortening is due to the pull of the quadriceps and hamstring muscles, while the varus and extension deformity is caused by the unopposed pull of the adductors and gastrocnemius, respectively.
The popliteal vessels, the tibial nerve, and the common peroneal nerve lie near the posterior aspect of the distal femur. Because of this, vascular injuries occur in about 3% and nerve injuries in about 1% of fractures of the distal femur.
There are no significant arteries, veins, or nerves on the lateral side of the knee.
There may be bleeding from the lateral genicular arteries, which will need to be controlled using diathermy.
At the posterior aspect of the knee lie the popliteal artery, nerve, and vein. It must be borne in mind that these structures can be damaged by the injury or can be damaged by the surgeon during the reconstruction.
The distal-most fixation for various implants is:
We will here demonstrate the application of the VA-LCP.
When an absolute stability construct is chosen, sufficient proximal fixation of the plate should be obtained. This typically involves four screws.
The number of screws placed in the distal end of the plate should be sufficient to provide appropriate fixation to the distal articular block. A minimum of four screws is typically chosen.
The preoperative x-ray planning template is useful in determining the required length of the condylar VA-LCP and the position of the screws.
This procedure may be performed with the patient in one of the following positions:
The chosen approach must adequately expose the articular surface of the distal femoral condyle.
Reduction aids which are helpful include:
Before definitive fixation is undertaken, more than one clamp is applied. Usually, one to two additional K-wires are inserted, either from medial to lateral, or lateral to medial.
If the K-wires are inserted from medial to lateral, they may either go through small stab incisions in the skin, or through the parapatellar retinaculum.
Definitive lag screws may then be inserted in the distal femoral articular block in several directions:
These screws may be fully threaded 2.7 or 3.5 mm lag screws (shown with gliding hole), 6.5mm partially threaded lag screws, or 4.0/4.5 mm cannulated partially threaded lag screws.
Insertion of screws in this manner leaves an area free of screw traffic or a „free zone“ of bone into which a laterally based plate system can be inserted (dotted circle). Insertion of screws in this manner allows a „free zone“ of bone into which the plate can be placed (dotted circle).
End-on view of the articular block fixation.
Multifragmentary articular fractures may also be characterized with or without a Hoffa injury.
In this case, separate osteochondral fragments are ideally reduced and internally fixed by lag screws. However, in certain cases, the fragment may be either too damaged or too small to be reconstructed. In this case, if a fragment is removed, a position screw rather than a lag screw should be used to avoid over-compression of the articular surface.
In the case shown fragment A has been reduced into the appropriate position. This makes it possible to compress the articular surfaces with lag screws. However, fragment B was too damaged and too small to be accurately repositioned. A void is therefore left in the articular surface. In this situation, a fully threaded 3.5 mm standard screw (position screw) is then inserted between the condyles.
After reconstruction of the articular block, the fracture can be considered a metaphyseal fracture and treated accordingly. In the following illustrations the articular fracture component and it's fixation will not be illustrated.
The key concept in reduction of the metaphysis is that proper application of the Condylar VA-LCP on the distal femur assures correct frontal plane alignment.
Next, length, rotation, and sagittal plane deformity (hyperextension/hyperflexion) must be addressed.
Open reduction is aided by:
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.
With one of the reduction aids listed previously, you can get an approximate alignment of the metaphyseal/diaphyseal fracture.
Place the Condylar VA-LCP onto the lateral femoral condyle.
When the plate lies flat on the lateral surface of the condyle, it has been positioned correctly on the distal femoral articular block.
Readjust plate position if necessary.
Insert a guide wire through the central hole of the plate and check it's position by image intensifier in all planes.
Determine the correct position for the central screw of the LCP with the help of guide wires around the joint. Under image intensifier control, pass one guidewire lateral to medial along the tibio-femoral joint line (red). Pass a second guidewire over the anterior the surface of the knee to indicate the plane of the patellofemoral condyles.
The ideal position of the central screw of the LCP is shown by the yellow wire. Note that it is inserted parallel to both the red wire in the frontal plane and is parallel to the green line on the end-on view on the femur. This latter orientation ensures that the plate comes to lie flush with the lateral cortex.
Insert a second guide wire in one of the 5.0 mm screw holes to provisionally fix the plate to the femoral articular block.
Confirm distal plate placement, using visual examination and an image intensifier. Ensure that 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.
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 shape of the distal portion of the plate to that of the condyle. The position of the plate on the distal femoral articular block at this point will determine the final flexion/extension reduction. This reduction is important because this fracture usually falls into extension; this must be prevented.
Advance the guide wires until they reach the medial cortex of the femoral condyle, but they should not penetrate the cortex.
Use the measuring device to indirectly measure the lengths of the screws using the guide wires.
For proper 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 guidewire.
The central wire guide is removed and the central screw (7.3 mm) is inserted over the guidewire, using the torque-limiting power screwdriver. Self-tapping screws are used.
Inserting only one screw at this point allows the correction of small deformities in the sagittal plane (on the lateral x-ray).
After confirming 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.
Regular locking screws or variable angle screws may be chosen based on any previously inserted lag screws.
Use manual traction or femoral distractor to restore length.
Generally, the length may be assessed by evaluating overlap or distraction of the posterior cortex of the femur.
Align the plate with the proximal mid-lateral cortex and secure it in position with a sharp pointed reduction clamp.
Use of a Verbrugge clamp is not advised.
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 or the Bouvier cord method (see below).
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.
It is very important to restore the biomechanical axis of the lower limb. The normal biomechanical axis follows a line from the center of the femoral head, through the center of the proximal tibia and then through the center of the ankle joint. This axis can be checked intraoperatively by using a piece of cable, such as the diathermy cord. The cord is stretched from the iliac spine across the patella to the cleft between the first and second toes.
If rotation is correct, this cord will pass over the midline of the patella, and slightly medial to the tibial eminence. The radiological landmarks of the center of the femoral head, the center of the knee and the center of the ankle joint should all be in line if the mechanical axis of the femur is correct.
Another method of assessing rotational reduction is to compare the cortical thickness above and below the fracture. If a shaft fracture is multifragmentary, the image intensifier cannot be used to compare cortical diameters on each side of the fracture.
Not only must the biomechanical axis be restored, but care should be taken to ensure that there is no malrotation of the distal femur on the proximal femur.
This illustration shows the longitudinal axes of the lower limb.
To ensure that femoral length has been restored, many options exist:
It is strongly recommended to apply controlled compression to the metaphyseal fracture component using the articulated tension device when there is direct contact between the proximal and distal main fragments in simple transverse or wedge fractures.
Multifragmentary or osteoporotic metaphyseal fractures should not be compressed.
After the Verbrugge clamp is loosely applied, the articulated tension device is engaged in the proximal hole of the plate and fixed to the bone with a bicortical screw. An articulating wrench is then used to compress the fracture zone. When this occurs the strain gauge on the device goes from the green zone to the yellow zone and finally to the red zone. During the use of this wrench, the fracture complex must be monitored to ensure that no undesirable displacement occurs.
After the appropriate tension is applied, you may insert a screw into the proximal segment. Place this screw eccentrically in the standard hole to allow for slight additional compression of the fracture site.
Insert additional screws for a total of 4-5 screws distally (locking, variable angle locking head screws) and 4-5 bicortical screws proximally.
Proximally, either standard bicortical screws (as illustrated), or locking-head screws may be used. Locking head screws are only useful in osteoporotic bone. 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.
In oblique, single-plane fractures, an interfragmentary lag screw should be inserted through the plate. Alternatively, the lag screw may be inserted outside the plate prior to plate application.
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.
Impediments to the restoration of full knee function after distal femoral fracture are fibrosis and adhesion of injured soft tissues around the metaphyseal fracture zone, joint capsular scarring, intra-articular adhesions, and muscle weakness.
Early range of motion helps restore movement in the early postoperative phase. With stable fracture fixation, the surgeon and the physical therapy staff will design an individual program of progressive rehabilitation for each patient.
The regimens suggested here are for guidance only and not to be regarded as prescriptive.
Unless there are other injuries or complications, knee mobilization may be started immediately postoperatively. Both active and passive motion of the knee and hip can be initiated immediately postoperatively. Emphasis should be placed on progressive quadriceps strengthening and straight leg raises. Static cycling without load, as well as firm passive range of motion exercises of the knee, allow the patient to regain optimal range of motion.
Touch-down weight-bearing (10-15 kg) may be performed immediately with crutches, or a walker. This will be continued for 6-10 weeks postoperatively. This is mostly to protect the articular component of the injury, rather than the shaft injury. Touch-down weight-bearing progresses to full weight-bearing gradually, over a period of 2 to 3 weeks (beginning at 6–10 weeks postoperatively). Ideally, patients are fully weight-bearing, without devices (e.g., cane) by 12 weeks.
Wound healing should be assessed at two to three weeks postoperatively. Subsequently 6-week, 12-week, 6-month, and 12-month follow-ups are usually made. Serial x-rays allow the surgeon to assess the healing of the fracture.
Implant removal is not essential but should be discussed with the patient if there are implant-related symptoms after consolidated fracture healing.
Thrombo-prophylaxis should be given according to local treatment guidelines.