1 Principles top
External fixation is used in the treatment of distal humeral fractures with extensive soft-tissue damage, severe contamination, infection, and/or major bone loss.
External fixation can be used as primary treatment in polytrauma patients.
External fixation is only very rarely used as the definitive treatment in distal humeral fractures.
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 higher stiffness than one. In thin, non-muscular patients, one tube may be sufficient.
Modular external fixator
A tube-to-tube construction allows manipulation and reduction of the fracture after pin placement and yet provides sufficient stiffness of the frame. Once the position is satisfactory and the first tube-to-tube link has been tightened, a second linking tube can bee added for additional stiffness in muscular, restless, or non-compliant patients.
2 Pin insertion topenlarge
Skin incision and soft tissue dissection
Make the skin incisions long enough (1.5 cm) to avoid stretching on the skin margins after pin insertion, during movement of the shoulder and elbow joints.
Use small scissors to prepare a track for insertion of the pin.
Blunt dissection of the soft tissues and the use of small Langenbeck retractors will prevent damage to muscular, vascular and neurological structures.
Be especially careful of the radial nerve, which twists around the humeral shaft and, in the distal third, pierces lateral intermuscular septum.
Predrilling of the near contex avoids thermal damage to the bone.
The use of a trocar during drill sleeve insertion procedure will prevent damage to muscular, vascular and neurological structures.
Insert each pin through the drill sleeve. Do not use power tools, but insert the pins by hand through the near cortex. Once the screw reaches the far cortex, which can be felt easily, turn it for another half rotation to anchor the tip of the screw.
3 Frame construction topenlarge
The two pins inserted into each shaft are joined by a short rod. In order to increase stability, a second rod is added.
Loosely join the two frame pairs with a connecting rod without tightening its clamps.
Using image intensification, manipulate the rods to achieve fracture reduction.
When satisfactory reduction has been obtained, tighten the rod-to-rod clamps.
Once the rod-to-rod champs have been fightened, a second linking tube can be added for additimal frame stability in muscular, restless, or non-compliant patients.
Pearl: protective cap
Add protective caps to the rod in order to prevent it from slipping out.
Pearl: non-bridging fixator
If the fracture is far enough from the joint and there is good bone quality, sometimes it is possible to apply the external fixator only to the humerus, leaving the elbow joint free.
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 and then replaced by internal fixation.
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
Pitfall: pin track infection
If there is any concern about pin site infection, the following steps need to be taken:
- Remove the external fixator
- Temporarily stabilize in a cast
- Give appropriate antibiotics
- Let the pin tracks heal
- Proceed with internal fixation