AOTrauma Webinar:  Why Do Patients Get Infection?

May 30, 2017 14:00 CET

Main Presenter: Olivier Borens, MD (Switzerland)
Chat Moderator: Stephen Kates, MD (USA)

Surgical site infections after trauma are debilitating and costly. They are feared by the surgeon and the patient alike. The incidence of this complication can be decreased by proper preoperative, intraoperative, and postoperative management.
The goal of this webinar is to present easy-to-use tools and strategies that will lead to a decrease in the incidence of infection.

More information and registration...

Infection

Executive Editor: Chris Colton

Authors: Florian Gebhard, Phil Kregor, Chris Oliver

Distal femur 33-A2 CRIF

back to skeleton

Glossary

1 Principles top

Usage of the Condylar LCP enlarge

General considerations

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 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 utilized. 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.


Hyperextension deformity enlarge

Hyperextension deformity

The gastrocnemius typically causes a hyperextension deformity of the distal femoral articular block.


Correction of hyperextension deformity enlarge

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

 


Condylar LCP fixation enlarge

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.


Potential space beneath the vastus lateralis enlarge

Condylar LCP insertion

The Condylar LCP is inserted using either a lateral parapatellar approach, or standard open lateral approach. In either case, the plate is slid into a submuscular tunnel beneath the vastus lateralis. Final positioning of the plate is confirmed using image intensifier monitoring.


Reduction

It is important to restore axial alignment, length and rotation.

Reduction can be performed with a single reduction tool (e.g., large distractor), or by combining several steps (for example, fracture table +/- external fixator, +/- reduction via the implant, etc.) to achieve the final reduction.

The chosen method will depend on the fracture and soft-tissue injury patterns, the selected stabilization device and the experience and skills of the surgeon.

If a large fragment has separated from the fracture zone and impaled the adjacent muscle, direct reduction may be required.

2 Choice of implant top

Various implant types enlarge

General consideration

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)

Determining the required length of the Condylar LCP enlarge

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 top

Screw hole types enlarge

Plate characteristics

Plate head
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.

Plate shaft
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.

Plate material
Implants are made from 316L stainless steel.


Types of threaded guides enlarge

Instrumentation

There are three types of threaded guides for the Condylar LCP.

  1. 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.
  2. 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.
  3. The 5.0 mm drill guide is used to center the 4.3 mm drill bit in the locking portion of the combi-hole.

Types of cannulated screws enlarge

Screw types

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):

  1. The cannulated 7.3 mm locking screw creates a fixed angled construct.
  2. The cannulated 7.3 mm conical screw (fully threaded) compresses the plate to the lateral femoral condyle.
  3. 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.

  4. The fourth type of screw is the cannulated fully threaded 5.0 mm locking screw which creates a fixed angle construct.
  5. 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.

Locking head 5.0 mm screw and standard 4.5 mm bicortical screw enlarge

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 top

Reduction of the metaphysis enlarge

Reduction aids

Closed reduction is aided by:

  • Early intervention
  • Complete anesthetic muscle relaxation
  • A bolster in the supracondylar region
  • Manual traction

Insertion of Schanz pins enlarge

Reduction can also be aided by:

  • Use of Schanz pins inserted into the medial, or lateral, femoral articular block to correct varus or valgus angulation of the femoral block.
  • Insertion of a Schanz pin from anterior to posterior in the distal femoral articular block, which can be used to correct hyperextension.

Usage of the external fixator/fimoral distractor enlarge

Alternative: external fixator/femoral distractor

Some surgeons find it helpful to use an external fixator (or femoral distractor) spanning from the proximal femur to the proximal tibia.

Due to the pull of the gastrocnemius muscle, the distal femoral articular block has a tendency to be displaced into extension at the metaphyseal fracture area, when distraction is applied.

To avoid this, the knee is brought into full extension and the distal femoral fragment is stabilized in this position to the tibia using a temporary cerclage wire around a Schanz screw in the distal femur and an external fixator pin in the proximal tibia.

Insert the proximal and distal fixator pins carefully, in order not to conflict with the later plating procedure. For this reason, safe positions would be anterolateral, or anterior, on the femur.

5 Plate insertion top

Inserted threaded guides enlarge

Assembly of Condylar LCP

Assemble the threaded guides for the 2.5 mm guide wires into the 5.0 mm and 7.3 mm screw holes in the distal femoral block. This should be done before the Condylar LCP is slid in a submuscular manner.


Condylar LCP insertion enlarge

Condylar LCP insertion

After approximate closed reduction of the metaphyseal fracture, the Condylar LCP is ready to be inserted. Slide the Condylar LCP into the submuscular tunnel between the vastus lateralis muscle and the periosteum (= epiperiosteal space).

Advance the Condylar LCP proximally under the vastus lateralis muscle, ensuring that its proximal end remains in constant contact with the bone. Position the distal end of the plate against the lateral condyle. To identify the correct position, move the Condylar LCP proximally and then back distally until the plate perfectly fits the lateral condylar surface.


Position on the distal femur enlarge

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 femoral articular block.

Readjust plate position, if necessary, and insert the central guide wire into the distal femoral articular block. A second guide wire in one of the 5.0 mm screw holes will secure provisional fixation of the plate to the femoral condyle. Its position can then be confirmed radiographically.

Prior to proceeding, confirm plate head placement. Use clinical examination and the image intensifier to confirm 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.

Proper plate placement enlarge

Additionally, check that the plate is properly orientated on the condyle using lateral image intensifier monitoring. Because the shaft of the femur is frequently out of alignment with the distal fragment, proper plate placement can only be determined by matching the plate head shape to that of the condyle. Fixation of the plate head to the distal femoral articular block at this stage will determine final flexion/extension reduction.

6 Preliminary plate fixation top

Palpation of the proximal aspect of the plate enlarge

K-wire insertion in proximal fragment

Make an incision over the proximal two holes of the plate. Deepen this incision through the iliotibial band and the vastus lateralis muscle belly to allow palpation of the proximal aspect of the plate on the lateral aspect of the femur.


K-wire insertion enlarge

Insert a K-wire through one of the two proximal plate holes into the lateral cortex in order to hold the plate loosely on the lateral aspect of the femur.


Screw length measurement in distal fracture fragment enlarge

Screw length measurement in distal fracture fragment

Once you have confirmed that the proximal end of the plate is appropriately aligned on the femur and the distal end of the plate is appropriately placed, insert the distal screws. Use the measuring device indirectly to determine the appropriate screw length from 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. Determine the appropriate 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 enlarge

Distal screw insertion

After the appropriate screw length has been determined, remove the threaded wire guide from the head of the plate and insert the central screw (7.3 mm) over the guide wire, using the torque limiting power screw driver. Inserting only one screw at this point allows the correction of small deformities in the sagittal plane (on the lateral x-ray).

7 Intraoperative radiological assessment top

Establishment of length and rotation enlarge

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.


Profile of the lesser trochanter enlarge

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.


Malrotation enlarge

Malrotation

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.


Correct matched lesser trochanters enlarge

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.

8 Fixation of plate to proximal fragment top

First proximal screw insertion enlarge

Insertion of first proximal screw

After ensuring that the appropriate length and rotation have been obtained, insert a standard bicortical screw into the proximal segment. Generally, use the most proximal plate hole through the previously made approach to the femur.

Remove the previously inserted K-wire. Palpate and maintain the position of the plate on the lateral aspect of the femur.

Drill, measure screw length and insert the chosen self-tapping screw through both cortices.

 


Sagittal plane alignment enlarge

Sagittal plane alignment

Once a second screw has been inserted into the main proximal segment, the sagittal plane alignment is fixed. Therefore, check the reduction on the lateral image intensifier image before the second proximal screw is placed. A common deformity is that the distal end of the proximal segment is projecting anteriorly and must be pushed down into appropriate reduction. This is often accomplished by pushing with a mallet.


Insertion of standard bicortical screw enlarge

Insertion of additional proximal screws

Insert further standard bicortical screws through one or more 1.5 cm stab incisions.


Drilling of hole enlarge

Insertion of percutaneous bicortical standard screws

  • Make a 1.5 cm stab incision through the skin, subcutaneous tissue, iliotibial band and muscle belly of the vastus lateralis.
  • Use the 3.2 mm drill bit and its guide to drill a hole in both cortices through the nonlocking portion of the plate hole.

 


Insertion of the self-tapping screws enlarge
  • Under image intensifier guidance (as necessary) insert the chosen self-tapping 4.5 mm screws. (Their lengths can be estimated, but must be checked, and are generally 38 to 42 mm.)

 

9 Completed osteosynthesis top

Additional screw placement enlarge

Additional screw placement

Insert additional screws proximally and distally for a total of 4-5 screws in the distal fragment and 4-5 screws in the proximal main fragment.

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.

Wound closure
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.

v1.0 2008-12-03