1 Principles topenlarge
A thorough knowledge of the anatomy is mandatory to perform the correct placement of the K-wires. All important neurovascular structures run in the posterior half of the cross section.
Wires should be positioned as proximal as possible but not through the joint. The most proximal wire should be at least 14 mm below the articular surface because of the distal capsular insertion.
2 Patient preparation topenlarge
This procedure is normally performed with the patient in a supine position.
3 Proximal ring application topenlarge
As wires go through both cortices, good knowledge of anatomy is mandatory (see the safe zones). Carefully choose wire corridors. At least two wires have to be used.
Reduce articular fracture
Reduce the articular fracture and preliminarily secure it with large pointed reduction forceps. Check the reduction under image intensifier control.
For intraarticular fractures needing compression choose spade-point reduction wires with an “olive”. At least two wires have to be inserted.
Connect wires with ring
Connect the wires with the ring and tighten clamps. Thereby, the articular fracture component is fixed.
After the wires are tightened, the pointed reduction forceps can be removed.
4 Inserting pins into tibial shaft topenlarge
Mid shaft level
The neurovascular bundle (the anterior tibial artery and vein together with the deep peroneal nerve) run anterior to the interosseous membrane close to the posterolateral border of the tibia.
They are at risk if the pin is inserted in the direction as indicated by the red dotted line approximately half way between the anterior crest and the medial edge of the tibia.
Distal shaft level
When inserting pins in the distal zone take into account the position of the anterior tibial artery and vein. Percutaneous insertion of pins in this area is dangerous. A minimal incision will allow preparation and safe insertion.
The peroneal bundle is located very close to the posterolateral border of the tibia and therefore at risk if pins are inserted in this direction.
Pins at this level should be inserted as shown in the illustration from anteromedial to posterolateral. A second pin can be inserted from medial to anterolateral, ventral to the fibula.
Standard Schanz screws
Drill through both cortices with a 3.5mm drill bit.
Use measuring device to determine diameter of bone.
Insert Schanz screw.
Pin insertion depth
Make sure that the Schanz pins are not penetrating excessively through the far cortex, so as to avoid injury to either the neurovascular structures or soft tissues.
Image intensification control in two planes is recommended.
Insert four pins into the tibia two at each level.
Place the proximal Schanz pins as close as possible to the fracture. The second Schanz pin pair must be positioned as distally as possible. The further the pin pairs are apart, the more stable the construction will be.
5 Finalizing the external fixator topenlarge
Connect the Schanz screws with the two rings. Then, interconnect all three rings with tubes. The clamps are left loose to allow manipulation.
Use the rings to reduce the fracture by manipulation under image intensification.
Before manipulation, loosen the distractors.
After successful reduction, tighten clamps.