Executive Editor: Amy Kapatkin General Editor: Noel Moens

Authors: Bruno Peirone

Femoral shaft 32-C3

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Glossary

1 Indications top

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In the presence of non-reducible fragments or when devitalization of the fragments is likely during reduction, indirect reduction (bridging fixation) such as a plate and rod stabilization technique is indicated.


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2 Principles top

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Illustrations of fracture types

Fracture types:

A) Comminuted, unreduced fracture
B) Comminuted fracture aligned biologically 
C) Fracture aligned and biologically stabilized


Biomechanics of fixation construct

Plate-rod is a biological fixation technique. The intramedullary pin is used as a reduction device to align the fracture and to take the bone to its proper length. The two implants work together; The pin protects the repaired fracture against bending forces while the plate resists axial collapse, rotation, shear and bending.  Without the pin, the bone plate would be subjected to high bending forces because the bone is not sharing any load.

3 Approach top

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OBDNT approach

An open-but-do-not-touch (OBDNT) approach provides direct visualization of the fracture site but the fracture fragments are minimally manipulated.


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MIPO approach

A Minimally Invasive Plate Osteosynthesis (MIPO) technique can be used. A surgical approach to the proximal and the distal femur is performed.

4 Surgical technique top

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Pin selection

The dimensions of the pin should be 35-40%  of the isthmus of the medullary canal. This provides sufficient protection against bending forces while allowing placement of cortical screws. Bicortical screws are preferred and usually possible with this size pin. If a bicortical screw cannot be placed, monocortical screws are acceptable in a plate-rod construct as long as overall, sufficient number of cortices are engaged.


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Pin insertion

The pin is started at a 20 degree angle relative to the axis of the bone to minimize slippage in the trochanteric fossa.


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When using an OBDNT approach

Immediately after the cortex is penetrated, the pin is redirected down the medullary canal along the axis of the bone. The pin is guided through the proximal fragment until it protrudes at the level of the fracture site. The tip of the pin can be cut and then directed into the distal fragment once the fracture is aligned. Cutting the tip of the pin minimizes the risk of penetration through the distal fragment cortex when the fracture is distracted.

Alternatively, the pin is driven in a retrograde fashion into the proximal fragment retracted and cut before reinsertion into the medullary canal of the distal fragment.


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When using a MIPO approach

When using a MIPO approach, the pin  is driven into the distal fragment with a power or hand chuck under imagining guidance until the tip of the pin reaches the bone of the distal metaphysis. The femur is distracted to its full length by pushing the pin against the distal femoral cortex. If intraoperative imaging is not available, an incision at the distal fragment must be made to ensure proper pin placement. If that is done, the pin tip can be cut like in the OBDNT approach


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The pin is driven into the distal fragment with a power or hand chuck until the tip of the pin reaches the bone of the distal metaphysis. The femur is distracted to its full length by pushing the pin against the distal femoral cortex. Alternatively, gentle tapping with a mallet and an intramedullary pin setter until the length of the bone is restored can be used.


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Validation of alignment and rotation

Once the bone length has been restored, it is necessary to check for correct alignment and rotation. Rotational alignment can be judged by palpation or by direct visualization of the greater trochanter and femoral trochlea. The distal part of the femur is held in a true lateral position. The position of the greater trochanter and alignment of the adductor magnus muscle are then inspected.
If the femur is correctly aligned in the axial plane the adductor magnus muscle should be aligned and the greater trochanter should be slightly caudal to the long axis of the bone.


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The alignment can also be checked by confirming the orientation of the femoral neck relative to the plane of the femur.  This is done by inserting a small pin alongside the femoral neck with the femur in a true lateral position. Orientation of the pin should be about 15°-25° in the cranial direction relative to the sagittal plane of the femur.


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Correct alignment and rotation can be checked with intraoperative imaging. The latero-medial projection is used and the whole bone, including the proximal and distal joints, must be visible.
If the femur is properly aligned in the transverse plane, about 1/3 of the femoral head should be visible cranially to the cranial femoral cortex (Image A). Image B shows excessive internal rotation and C shows excessive external rotation of the distal femur.

Comparison with the contralateral unaffected limb can be useful.


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In a properly aligned leg, manual manipulation of the femur will allow 90° of external rotation and 45° of internal rotation of the hip. This method can only be used if the plate has been temporarily secured to the bone.


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Cutting the pin

The protruding part of the pin is cut as close as possible to the level or below the level of the greater trochanter.


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Plate selection

A bone plate is contoured to the shape of the bone. The length of the plate should allow placement at least 3-4 screws in each major fragment.

Note: ideally a plate placed in bridging fashion should span at least ¾ of the length of the bone.

For more information please see "Plate preparation" in "Additional material".


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Temporary stabilization

The plate is secured to the bone with bone clamps and/or bone holding forceps. Rotational alignment is verified again.


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If a locking plate is used, the temporary stabilization is achieved with a push and pull device on each major fragment.


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Plate application

If possible, the plate is secured by inserting at least three bicortical screws in each major segment.
As much as possible, the screws should be oriented is such way that does not interfere with the intramedullary pin.


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If the drill contacts the intramedullary pin, a monocortical screw can be used instead of a bicortical screw. Forcing a drill bit against the pin will likely result in breakage of the drill bit and potentially the screw hole will be unusable.


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Locking plate

A locking plate can be used instead of a traditional bone plate. However, interference between the pin and the locking screws is likely. Using monocortical locking screws or a combination of non-locking and locking screws can provide adequate fixation. If a combination of screws is used, the plate must be anatomically contoured and the non-locking screws should be placed and tightened first because they will compress the plate to the bone.

5 Case example top

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1 yr old Australian Shepherd with a C3 fracture from jumping out of a moving car.


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The fracture was repaired using a 9/64" IM pin and a 12 hole 3.5 broad LCDC.

Alignment: fair/adequate

Apposition: not attempted

Activity: PO


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Postoperative radiographs at 1 month


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Postoperative radiographs at 3 months

Activity: appropriate healing


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Postoperative radiographs at 5 months

Activity: healed

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