The AO Surgery Reference team is delighted to announce that we have received a grant from the AO Strategy Fund to produce three pilot modules of a Pediatric AO Surgery Reference.

The first material is expected online at the end of 2016.

Executive Editor: Chris Colton

Authors: Peter V Giannoudis, Hans Christoph Pape, Michael Sch├╝tz

Femur shaft 32-B3 External fixation midshaft/distal shaft

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1 Principles top

Principles enlarge

Important module-wide statement

Where appropriate, a “generic” fracture zone will be illustrated and not necessarily the specific fracture morphology under consideration. Where the fracture morphology determines the fixation technique, the specific morphology will be shown.

General considerations

External fixation can be used as definitive treatment of femoral shaft fractures in cases of extensive soft-tissue damage, severe contamination and prolonged patient length of stay in intensive care unit, due to the severity of the multiple injuries sustained.

Principles enlarge

Optimal frame construction

In order to ensure adequate maintenance of fracture reduction and frame stiffness, consider the insertion of three pins into each main fracture fragment. Also consider the following recommendations:

  1. Pins are placed widely separated in each main fracture fragment.
  2. Pins are preloaded.
  3. Tubes are connected to the pins close to the bone.
  4. Two tubes are recommended as they create a stiffer construct than only one. In thin patients, one tube may be sufficient.

Equipment needed

5 and 6 mm Schanz type pins can be used. The pins are usually self-drilling and can be inserted without predrilling.

For the construction of the frame, carbon fiber rods or metal tubes, with tube-to-tube and pin-to-tube clamps are needed.

Simple or segmental fracture patterns

Consider the fracture location in the midshaft segment as well as any proximal, or distal, associated fractures of the femur, in order to decide the ideal distance between the pin placements. In the presence of ipsilateral associated fractures of the pelvis and/or tibia in the polytrauma setting, where the principles of damage control surgery are applicable, consider connection of the pins from the pelvis to the distal tibia. In cases of subtrochanteric, or even more proximal fracture patterns, pins can be inserted through the greater trochanter into the femoral neck. Similarly, in the presence of fractures affecting the superconductors femoral region, pins can be inserted into the proximal tibia.

2 Frame design top

Options to build solid frames

Various configurations of external fixator frames can be applied, depending on the fracture location and the surgeon’s preference and experience. Usually unilateral, uniplanar, single or double – tube fixators are used.

Frame design enlarge

Unilateral uniplanar double tube fixator

The illustration shows a diaphyseal femoral fracture stabilized with a unilateral uniplanar double tube frame.

Frame design enlarge

Unilateral uniplanar double tube modular fixator

The three pins in each fracture fragment are connected by two tubes. These four tubes are interconnected by two short tubes, using tube-to-tube clamps.

3 Pin insertion top

Pin insertion enlarge

Initial deformity correction

Prior to pin insertion, it is advisable to correct by manual traction any rotational deformity as well as any overlap of the fracture fragments. By maintaining axial traction, it will be possible to optimize pin placement, thereby facilitating the subsequent reduction maneuvers.

Pin insertion enlarge

Pin positioning

The pins should be inserted at least 2-3 cm away from the fracture line.

Pin insertion enlarge

Skin incision and soft tissue dissection

It is imperative that the skin incisions are sited to allow safe and correctly located pin placement. For this reason, the use of the image intensifier is recommended to select the place and to premark the skin with a pen so that safe pin placement can be expected.

Make transverse skin incisions long enough (1.5 cm) to avoid strain of the skin margins after pin placement, due to movement of the hip and knee joints.

Blunt dissection of the soft tissues and the use of small Langenbeck retractors will minimize muscular damage.

Using a straight clamp, prepare a channel for the insertion of the pin.

Pin insertion enlarge

Pin insertion

Place the Schanz pin in the power driver and, using a protecting sleeve, gently advance the pin to the far cortex with the aid of the image intensifier.

Pin insertion enlarge

Pin insertion depth

Make sure that it is not penetrating excessively through the far cortex, so as to avoid both injury to the neurovascular bundle and soft-tissue irritation.

Image intensification control in two planes is recommended.

4 Frame construction top

Frame construction enlarge

Connecting tubes to pins

Two small tubes are assembled connecting three pins in each main fragment. This construction will allow manipulation and reduction of the fracture. The two pin triplets will be connected with one or two additional tubes using tube-to-tube clamps.

Pearl: insert only two pins initially

In each fragment insert only two pins initially and link with the two tubes, each fully loaded with three clamps. After tightening the clamps on the initial two pins, insert the third pin through its relevant clamps. If all three pins are inserted at once, it may prove impossible to link all three to the tubes, if they are in slightly different alignments.

Frame construction enlarge

Connecting tubes

The two pin triples are connected with one or two interconnecting tubes, using tube-to-tube clamps. The clamps should be initially left loose.

Pearl: add protective caps before reduction is carried out

Before starting reduction, add the protective caps to the tube ends to prevent their slipping out of the clamps.

Frame construction enlarge


Reduction can be achieved with appropriate manipulation of the fracture fragments, using the two pin triplets as joysticks. Confirm reduction using image intensification.

Frame construction enlarge


As soon as an acceptable reduction is achieved, tighten the tube-to-tube clamps.

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Final frame construction

A second interconnecting bar is usually added to increase frame stability.

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Alternative: frame construction without interconnecting tubes

An alternative frame construction is to link both pin triplets with two tubes, without interconnecting tubes. This demands a careful sequence of pin insertion and tube/clamp linkage.

Insert one pin into each main fragment and link these with two tubes, already loaded with all 12 clamps. Tighten the clamps onto the pins after reduction of the fracture.

Frame construction enlarge

Insert a second pin into one main fragment, through the relevant clamps. Check reduction and tighten the clamps.

Frame construction enlarge

Insert a second pin into the other main fragment through its clamps and tighten the clamps.

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Repeat for a third pin …

Frame construction enlarge

… in each main fragment.

Frame construction enlarge

A completed alternative fixation with only two interconnecting tubes is shown here.

v1.0 2007-12-02