Distal Femur Fracture Fixation
Melissa A. Christino, MD
Indications
Unstable/misaligned distal femur fractures
Failure/inability to treat closed
Intra-articular fractures with any displacement
Sterile Instruments/Equipment
Radiolucent operating table
Fracture reduction forceps
Implants
4.5 and/or 6.5 mm cannulated screws
Distal femoral locking plate
Supraphyseal plate/pediatric distal femur plate
Distal femoral periarticular plate
Threaded or nonthreaded Kirschner wires
Headless compression screws (2.4/3 mm)
Arthroscopic knee set-up
Patient Positioning
Supine on the radiolucent table (Figure 22-1)
Figure 22-1 ▪ Clinical photo showing positioning on a radiolucent table with entire limb free.
Bump underneath ipsilateral buttock with arms out to the side
Fluoroscopic set-up to visualize the entire limb
Triangle positioner or sterile bump can be useful to assist with fracture reduction
In cases where longitudinal traction is helpful, a fracture table with central post can be used, while maintaining the base of the table as a working surface, as long as this is radiolucent.
Prone positioning
Rare case of completely displaced and extended physeal fracture where forces needed for reduction need to overpower shortened hamstrings
Draping
Many distal femoral fracture patterns may not require extended fixation and extremity draping with an unsterile tourniquet may be appropriate. However, to maximize options for possible extended fixation more proximally in the femur, draping the entire femur up to the hip with sterile U-drapes should be strongly considered.
Sterile tourniquet
Surgical Approaches
Lateral Exposure
Standard lateral incision followed by splitting of IT band. Vastus lateralis is elevated off the intermuscular septum or muscle fibers are split. Curvilinear extensile extensions of incision and exposure depends on the amount needed for reduction/fixation.
Medial exposure
Useful in fractures where the metaphyseal/proximal fragment is significantly displaced medially and buttonholed through facia
Direct medial incision followed by fascial incision and elevation vastus medialis off of septum. Proximal extension requires caution as the adductor canal is present. Distal incision can be curved more anteriorly, if a medial arthrotomy needs to be performed.
Anterior exposure
may be one of the three incision paths: direct anterior, direct anterior proximally, and distally to patella with either curvilinear portion around patella medially or laterally, depending on where the articular surface needs to be exposed (Figure 22-2).
Arthroscopic exposure can be used to assess or aid in reduction of minimally displaced or nondisplaced intra-articular fractures. Standard two-portal can be done with copious irrigation of the joint to aid in eventual arthroscopic visualization of joint congruity and/or reduction
Arthrogram of the knee joint can be used as an adjunct to verify adequacy of intra-articular reduction in skeletally immature patients with intra-articular fractures, where percutaneous fixation techniques have been performed (Figure 22-3).
 Figure 22-2 ▪ Joint visualization with lateral parapatellar arthrotomy. |
 Figure 22-3 ▪ Radiographs of a skeletally mature patient with intra-articular fracture. Fluoroscopic views after arthrogram and screw fixation. |
Reduction and Fixation Techniques
Closed Reduction and Fixation
Fractures may be reduced by traction and applying either a varus/valgus or anterior/posterior force. Usually this is best done with physeal fractures in younger children which are displaced and do not require intra-articular treatment. This is also commonly seen with adolescents and displaced Salter-Harris II fractures (Figure 22-4).
In younger children where the distal fragment is completely displaced anteriorly, putting the patient in prone position can aid in overcoming the hamstrings and the fracture can be reduced by longitudinal traction and knee flexion.
Once reduced, the fracture can either be pinned with K-wires or screw fixation can be used in older children nearing skeletal maturity. Percutaneous pinning can be done either with threaded pins or smooth pins and should be done with pins crossing above the fracture site.
One percutaneous technique involves making two smaller 1 cm incisions just above the joint line directly medial for one and directly lateral to the other. The pins are inserted in a retrograde
manner and may then be fluoroscopically guided to hold the fracture reduced. The pin which starts medially should be directed proximally and laterally to cross above fracture and end up through the far lateral-proximal cortex. The corresponding lateral pin may be placed heading proximally and medially with the goal of ending up through the proximal-medial cortex (Figure 22-5).
Figure 22-4 ▪ Schematic representing means of obtaining closed reduction. (Reprinted with permission from Waters PM, Skaggs DL, Flynn JM. Rockwood and Wilkins’ Fractures in Children. 9th ed. Philadelphia, PA: Wolters Kluwer; 2019.)
These pins are INTRA-ARTICULAR and should be cut and buried beneath the skin to avoid septic arthritis, which may happen when distal intra-articular pins are not buried beneath the skin.
Alternatively, cross pins can be percutaneously advanced in a retrograde fashion and pulled back through the skin proximally so that the distal end of the pin is within the subchondral bone and not intra-articular (Figure 22-6). The starting point for each percutaneous pin is at the inferior surfaces of the medial and lateral femoral condyles. Pins should be directed up the medial and lateral columns, to cross above the level of the fracture site for optimal fixation. Once the far cortex is penetrated, pins continue to be advanced through the skin on the medial and lateral sides. They can then be withdrawn from the proximal skin puncture with the wire driver, to pull the distal end of the pin back into the subchondral bone and avoid intra-articular position of the pin.
Older children frequently have a large Thurstan Holland metaphyseal component of Salter-Harris II fractures and in these cases, we recommend screw fixation starting from the side of the Thurstan Holland fragment (Figure 22-7).
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