Formerly, the angled blade plate was the proven work horse of distal femoral fracture surgery. In some countries this device is still the only implant available.
Blade plate usage follows the principles of restoration of the mechanical axis of the femur and compression of the fracture site if possible.
The advantage of the angled blade plate is that it allows the plate to be used as the reduction device. When the surgeon places the blade plate in the distal femoral articular block in the correct position, the restoration of the correct biomechanical axis is ensured. It is also useful in revision surgery of distal femoral fracture fixations, including previous intramedullary nail fixation. Finally it is an implant of choice for corrective osteotomies of the distal femur.
The angled blade-plate devices are strong and can provide very stable fixation, even in poor quality bone. Their correct insertion requires a high degree of surgical discipline and skill. A detailed preoperative plan and a step-by-step tactic are mandatory. Careful adherence to the exact conduct of each step of the procedure is essential for a satisfactory outcome.
Anatomy of the distal femur
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 drawn from the anterior aspect of the
lateral femoral condyle to the anterior aspect of the medial femoral condyle
(patellofemoral inclination) slopes approximately 10°. These anatomical details
are important when inserting screws, or blade plates. 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,
The popliteal vessels, the tibial nerve and the common peroneal nerve lie in
close proximity to 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
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.
In the past two decades, experience has shown that maintenance of the
metaphyseal/diaphyseal soft-tissue attachments in comminuted fractures leads to
higher rates of union. There may be surgical enthusiastic about reducing and
performing lag screw fixation of small intermediate fragments on the medial
aspect of the distal femur. However, in doing so, disruption of the normal
healing process may result. Therefore, appropriate length, angulation and
rotation should be obtained but there is no need to reposition and fix every
small fragment in a comminuted fracture.
Provided the anatomical relationships of the main proximal and distal fragments
are restored, and the biology of the comminuted metaphyseal zone is respected,
satisfactory union is highly likely to occur.
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, to give an approximate estimate of the axis,
The biomechanical axis must be restored and care should be taken to ensure
that there is no malrotation of the distal femur on the proximal femur.
If no traction table is used (i.e., using the freehand technique) the cable
method may be used. In this technique, the electrocautery cord is held 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.
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.
Illustration of the longitudinal axes of the lower limb.
Choice of implant
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
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)
Preparation for correct positioning
Determine the correct blade plate position with the help of guide wires
around the joint. Under image intensifier control, pass one guide wire lateral
to medial along the tibio-femoral joint line (red). Pass a second guide wire
over the anterior surface of the femur to indicate the plane of the
patello-femoral joint (green).
The ideal position of the blade plate is shown by the yellow wire. Note that
this is parallel to the red wire in the frontal plane (and thus leads to the
appropriate varus/valgus) and is parallel to the green line on the end-on view
on the femur. This latter parameter ensures that the plate is flush with the
The ideal insertion point for the blade plate is shown on the diagram. The
blade enters 1.5 cm above the distal end of the femur. It is possible to
position the plate slightly more distally than with a dynamic condylar screw
(DCS; 2 cm). The entry point for the blade plate is crucial. In terms of
anterior/posterior placement the distal femoral condyle should be viewed from
laterally. The distal femur is divided into thirds and the center of the blade
plate entry site is at the junction of the anterior one third and middle one
Insert the third guide wire just distal to the intended place of plate
insertion. This guide wire is parallel to the distal femoral articular surface
in the frontal plane, is perpendicular to the lateral femoral cortex and
parallel to the plane of the patello-femoral joint.
Note: There is a cannulated variation of the blade plate which has a guide wire
which runs through the blade itself. This cannulated blade makes insertion of
the device in the correct axis easier. This technique is not shown here.
Plate length determination
Determine the plate length by measuring from the template.
It should be remembered that the medial aspect of the femur is angled
20°-25° inwards and 15 mm should be subtracted from the apparent length to
ensure that the blade does not perforate the medial aspect of the femur.
Conventional templating has in the past been performed with plain x-rays.
Many departments around the world now have digital pictures archiving
communication systems (PACS). Some companies now provide digital templates to
accommodate these systems.
This procedure may be performed with the patient in one of the following positions:
For this procedure a
There are, in general, two basic methods to reduce the
metaphyseal/diaphyseal component of a distal femur fracture when utilizing a
blade plate. The method utilized depends on the fracture morphology. In the
first method, the fracture of the metaphysis undergoes a direct reduction and
then the blade plate is subsequently inserted. This might be done in a single
plane short spiral or oblique fractures.
In the second method, the blade plate is inserted into the correct position in
the distal articular block of the femur. Then, after manual traction is used to
restore the appropriate length and rotation, the bone is drawn down to the
plate and the proximal screws are inserted. This type of reduction is very
helpful in highly comminuted metaphyseal/diaphyseal fractures.
Direct reduction instruments include:
- Large pointed reduction forceps
- Bone repositioning forceps
- Bone hook
Indirect reduction techniques are:
- Manual traction (illustrated)
- External fixator/distractor
Pitfall: osteoporotic bone
In osteoporotic bone indirect reduction techniques, using the angled blade
plate itself, may be preferable as attempts to reduce the fracture directly may
cause severe comminution. Attempts to apply reduction clamps to osteoporotic
bone will potentially crush the bone.
Cutting the channel
To prepare for opening the entry site for the blade, three 4.5 mm holes are drilled in the cortex of the femoral condyle. They only need to penetrate 1 cm., except in young, harder bone, when the surgeon may need to drill almost the full depth of the chosen blade length. The central of the three holes lies at the center of the slot to be prepared, the other 2 holes are drilled on either side of the central hole.
A triple drill guide is available, but this has been designed for the proximal femur and use with 130° angled blade plates: this makes it a little cumbersome at the distal femur. It is easier to drill the holes freehand, as illustrated, using the 4.5 mm single drill sleeve, in an anteroposterior configuration. Drill them as parallel to the third guide wire as you can.
Connect the drill holes with a router
Take care not to damage or displace the guide wire. Then connect the drill
holes with a router.
Round the proximal shoulder of the slot off with a chisel to enable the
plate to be seated fully on the bone.
It may be necessary to use the 4.5 mm drill to deepen the channel into the
femoral condyles in the correct planes.
The seating chisel is meant to be driven exactly parallel to the guide wire
in both planes. The seating chisel is hammered into the distal femur with a
mallet. Particular in the young, the seating chisel “back-slapped” using the
slotted hammer. For each 15 mm of insertion this back-slapping should be
performed. Otherwise, the seating chisel will become jammed in the bone.
Repeatedly check parallelism with the guide wire.
In hard bone, it may become necessary to pre-drill the seating chisel track,
but this requires great care to keep the 4.5 mm drill bit exactly parallel to
the guide wire.
Seating chisel insertion
Insert the seating chisel through its guide into the distal femur. Use the
slotted hammer to control the rotation of the seating chisel in the bone, so
that the tongue of the guide lies in the anatomical long axis of the shaft.
An assistant may need to apply counter pressure on the medial side of the
femur, especially if preliminary lag screw fixation of an intercondylar split
has been performed.
Plate insertion by use of the holding device
Insert the blade plate using the blade plate holding device, fitted so that
the shaft of the device is parallel with the blade.
The blade should follow the path of the seating chisel precisely and remain
parallel with the guide wire. The first half of the blade plate should be able
to be pushed manually into the bone along the previous path of the seating
chisel. If this is not possible the surgeon should question whether a false
path is being developed.
Take care to control the alignment of the blade plate to the longitudinal
axis of the femur.
Maintain counter pressure on the medial side of the distal femur while
inserting the plate.
Impaction of plate to the bone
As the plate comes to within 1.5 cm of the lateral femoral cortex, the blade
plate holding device is removed. At this point the final insertion of the blade
is performed the impactor.
Securing the plate to the distal femur
At least one additional screw is inserted into the distal femoral articular
block. This provides sagittal plane stability.
Reduction of metaphyseal component
The key concept in reduction of the metaphyseal component of the fracture,
when using a blade plate, is that correct insertion of the blade into the
distal femur allows the surgeon to use the plate to achieve the metaphyseal
fracture reduction. When brought down to the femoral shaft the correct frontal
plane alignment has been assured. The surgeon must then control for length and
rotation. Length can be aided by manual traction. The sagittal plane deformity
correction is determined by rotational control, using the slotted hammer,
during seating chisel insertion. Small corrections of extension/flexion
deformity can be achieved by moving the proximal end of the plate forwards or
backwards on the lateral femoral cortex, but there is little room for
Take care to restore the mechanical axis in all planes of the femur. Give
consideration to fracture reduction in:
- Internal/external rotation
Secure the plate to the proximal femur with a Verbrugge clamp.
Articulated tension device
The articulated tension device is very useful to apply controlled
compression across the fracture site. It should be utilized when possible.
Metaphyseal compression can only be applied if there is some contact between
the main proximal and distal fragments after reduction. Throughout compression,
monitor the fracture zone carefully for any unwanted displacement.
It may not be used in situations of severe metaphyseal comminution and/or
Now fix the plate to the proximal femur with at least 4 bicortical standard 4.5 mm screws.
In oblique, single-plane fractures an interfragmentary lag screw should be inserted.
Before wound closure, perform thorough irrigation of the knee wound, in
order to minimize the risk of infection and to remove any debris from the
End the procedure with the closure of the deep tissues and the skin.
Assessment of alignment and knee stability
Before the patient is moved from the fracture table, observe rotation of the
leg clinically and compare it to the contralateral side.
With the femur now stable, it is possible to perform a thorough examination of
the knee joint, in order to exclude associated ligamentous laxity.