1 Principles of modular external fixation with large pins topenlarge
The modular external fixator is optimal for temporary use. It is rapidly applied without need for intraoperative x-rays and can be adjusted later.
The external fixator for proximal tibial fractures consists of two partial frames, one along the tibial crest and a proximal one parallel to the joint line.
Details of external fixation are described in the basic technique for application of modular external fixator.
Specific considerations for the proximal tibia are given below.
2 Pin insertion (tibial head and shaft) topenlarge
For safe pin placement make use of the safe zones and be familiar with the anatomy of the lower leg.
Pin insertion into proximal tibia and tibia shaft
Insert the proximal pins infradorsally to avoid the joint.
Insert the two distal pins in the sagittal plane medially to the tibial crest.
The AP direction of the pins in the proximal fragment avoids running of these pins intraarticularly. By inserting the pins in the distal fragment in an AP direction, the penetration of muscles can be avoided.
Tibial pin placement
Drilling a hole in the thick tibial crest may be associated with excessive heat generation and there is a risk the drill bit may slip medially or laterally damaging the soft tissues. As the anteromedial tibial wall provides adequate thickness for the placement of pins, this trajectory is preferable. A trajectory angle (relative to the sagittal plane) of 20-60° for the proximal fragment and of 30-90° for the distal fragment is recommended.
Alternatively, in order to avoid the frame catching on the opposite leg, the pins may be placed more anteriorly. The drill bit is started with the tip just medial to the anterior crest, and with the drill bit perpendicular to the anteromedial surface (A). As the drill bit starts to penetrate the surface, the drill is gradually moved more anteriorly until the drill bit is in the desired plane (B). This should prevent the tip from sliding down the medial or lateral surface.