1 Principles top
External fixation is used in the treatment of humeral shaft fractures with extensive soft-tissue damage, severe contamination, infection, and/or major bone loss.
External fixation is also used as an element of a salvage procedure in cases with major complications after nailing or plate osteosynthesis.
External fixation can be used as primary treatment in polytrauma patients.
Optimal frame construction
In order to ensure sufficient frame stiffness, consider the following recommendations:
Pins are placed widely separated in each main fracture fragment
Pins are preloaded
Tubes are connected to the pins close to the bone
Two tubes are recommended as they create a stiffer construct than one. In thin patients, one tube may be sufficient.
Modular external fixator
A rod-to-rod construction allows manipulation and reduction of the fracture after pin placement and guarantees sufficient stiffness of the frame. After tightening of the first connecting rod, as shown in the picture, attachment of a second connecting rod is recommended (see general considerations above).
2 Pin insertion topenlarge
Skin incision and soft tissue dissection
Make the skin incisions long enough (1.5 cm) to avoid strain of the skin margins after pin placement, during movement of the shoulder and elbow joints.
Prepare a channel for insertion of the pin, using a straight clamp.
Blunt dissection of the soft tissues and the use of small Langenbeck retractors will prevent damage to muscular, vascular and neurological structures.
Place a drill sleeve with trocar through the prepared soft-tissue channel, and confirm correct positioning. The use of a drill sleeve will prevent damage to soft tissues.
Predrilling avoids thermal damage to the bone and ensures that both cortices are engaged correctly.
Insert pins using the corresponding drill sleeve.
Ensure that both cortices are engaged; feeling the pin thread itself into the opposite cortex confirms correct insertion depth.
Image intensification control in two planes is recommended.
Pitfall: Rod-to-rod connection
In order to permit rod-to-rod connection, and thereby facilitate fracture reposition, it is important to have the pin pairs in different planes.
3 Frame construction topenlarge
The two pins inserted into each main fragment are joined by two short rods.
A rod-to-rod construction is now prepared. It will allow manipulation and reduction of the fracture. Connect the two pin pairs using at first one additional rod and two rod-to-rod clamps, applied loosely enough to allow repositioning of the bone ends. As the pin pairs are not inserted in the same plane, the rod-to-rod connection is facilitated.
Before starting reduction add protective caps to the rod ends, to prevent their slipping out of the clamps.
Using the pin pairs as handles, manipulate the fracture fragments. Confirm
reduction using image intensification.
As soon as an acceptable reduction is achieved, tighten the rod-to-rod clamps to maintain it.
After tightening of the first connecting rod, attach a second connecting rod for additional stability.
4 External fixation as temporary fixation top
If soft tissue has healed
If the soft tissues are healing satisfactorily, the external fixation can be removed.
It is then replaced by internal fixation, using either a plate or a nail.
Requirements for conversion to internal fixation
- No clinical or laboratory signs of active infection
- Good-quality soft-tissue coverage for safe approach to the humerus
Staged conversion to internal fixation
If there is any concern about pin site contamination, the following steps need to be taken:
- Remove the external fixator
- Temporarily stabilize in a cast
- Let the pin tracks heal
Proceed with internal fixation
5 External fixation as final fixation top
In case of persisting infection or problematic soft tissue coverage, external fixation is used as a definitive stabilization. It is left in place until the fracture has healed.
In case of pin loosening, or pin track infection, all involved pins should be removed and replaced in a healthy location. The infected pin tracks must be debrided, irrigated, and cleaned.
In children, fracture healing is often complete in 6-8 weeks. If external fixation is initially chosen, it should remain until fracture healing.