1 Principles topenlarge
Spiral fractures of the tibial diaphysis can be treated nonoperatively. However, some shortening must be expected. The initial x-ray usually shows the expected final shortening. Displacement of more than 30%, particularly for distal fractures, suggests an increased risk of secondary displacement with nonoperative treatment.
Malrotation is a risk which must be looked for and corrected, particularly during the first weeks of nonoperative treatment.
Operative treatment with a nail
Nailing is usually a good option in tibial fractures. However, in long spiral fractures, malrotation can be a problem and must be addressed by the surgeon.
Operative treatment with lag screws and protection plate
For the treatment of simple spiral fractures in the diaphyseal area, absolute stability is recommended. For this, anatomical reduction and interfragmentary compression are necessary. Interfragmentary compression is achieved with at least two lag screws, but the strength of this fixation is often insufficient for clinical use.
Bending, shearing and torsional forces acting on an unprotected lag screw may cause screw loosening, loss of compression, or fracture of the bone. In order to protect the lag screw from these forces, a protection plate should be applied.
2 Preoperative planning topenlarge
Lag screws should always be inserted as perpendicular as possible to the fracture plane where they cross it.
Lag screws inserted through a plate give better stability than screws outside of a plate. Whenever possible, plan the plate position so that one or two screws can be inserted through the plate and still perpendicular to the fracture.
However, in some situations, one, or both, lag screws have to be inserted outside of the plate, depending on fracture geometry and surgical access.
If the anteromedial skin is completely free of injury, a plate can be positioned on this tibial surface. When in doubt about the soft tissues, an anterolateral plate may have less risk of wound breakdown.
An anteromedial, subcutaneous plate does not require muscle elevation, as would be necessary anterolaterally, but with some loss of periosteal blood supply. Furthermore, this location also allows a more distal position of the plate.
The plate should be long enough to span the fracture zone, usually with at least 3 screws proximal and distal.
A narrow, large-fragment (4.5 mm screws) plate is usually chosen. It will need to be bent and twisted to fit the selected tibial surface.
3 Open reduction topenlarge
Open, or direct, reduction is necessary to achieve the required anatomical reduction.
Leave the periosteum on the bone, except elevate just enough around the fracture edges to confirm the reduction.
Pointed reduction forceps are preferred because they do less damage to the soft tissues.
In a first step, length and rotation must be restored. This may be possible with manual traction. Otherwise, mechanical aids such as a large distractor, or bone spreader, should be considered.
In a second step, once length and rotation are restored, pointed reduction forceps are used to compress and anatomically reduce the fracture. The forceps tips should be applied perpendicular to the plane of the fracture, just like a lag screw.
4 Preparation topenlarge
Sometimes the fracture is in a plane that makes it impossible to insert the lag screws through the plate perpendicularly to the fracture plane. In such cases, the lag screws are inserted outside of the plate. Depending upon fracture location and soft-tissue condition, the plate is then applied to either the anteromedial, or the anterolateral surface.
Provisional fixation with the pointed reduction forceps
Use the pointed reduction forceps to provisionally stabilize the fracture. Select a position for the forceps that will not interfere with the planned position of the screws, or plate.
Remember, the forceps can be placed either medially or laterally. Choose the position that allows the most stability with the least soft-tissue damage.
5 Drilling and tapping topenlarge
Gliding hole for the first lag screw
Using a 4.5 mm drill guide and a 4.5 mm drill bit, drill a gliding hole in the near cortex.
Ensure that the direction of the drill is as perpendicular to the fracture plane as possible.
Drilling the thread hole
Insert the 4.5 mm / 3.2 mm drill into the gliding hole. Use a 3.2 mm drill bit to drill a thread hole just through the far cortex.
Countersinking in diaphyseal bone
There are two important reasons for countersinking:
- Countersinking ensures that the screw head has a maximal contact area with the bone, so that its compressive forces are widely distributed.
- A countersunk screw head is less prominent and tender.
No countersinking in the metaphysis
Do not countersink the screws in the metaphysis as its cortex is very thin.
Countersinking through a thin cortex removes the bone surface on which the screw head must rest. Instead, a washer should be considered.
Measure for screw length
Use a depth gauge to measure for screw length.
Measure the longer side of an oblique drill hole, as shown, to ensure sufficient screw length.
A screw should protrude 1-2 mm through the opposite cortex to ensure thread purchase. However, too long a screw may be tender, or injure soft tissues.
Tap the thread hole
Use a 4.5 mm tap and the corresponding drill sleeve to tap the thread hole.
6 Screw insertion topenlarge
Lag screw insertion
Insert the first lag screw and carefully tighten it. Ensure that the fracture remains reduced, and is compressed.
Insertion of the second lag screw
Insert the second lag screw following the same steps as for the first lag screw:
- Drill the gliding hole with a 4.5 mm drill bit and drill guide as perpendicular to the fracture plane as possible.
- Insert the 4.5 mm / 3.2 mm drill guide into the gliding hole.
- Drill the thread hole with a 3.2 mm drill bit.
- Countersink the near cortex.
- Measure for length.
- Tap the thread hole with a 4.5 mm tap.
- Insert the screw.
7 Plate placement topenlarge
Plate selection and preparation
The correct length of the straight 4.5 mm DCP should allow at least 3 screw holes proximal and 3 screw holes distal of the fracture site.
Usually a 10-12 hole straight 4.5 mm DCP is used. The plate has to be twisted and bent to perfectly adapt to the shape of the anteromedial distal tibia.
Insertion of diaphyseal plate screws
The screws closest to the fracture zone are inserted first. Insert the remaining screws alternately, working your way outwards. Remember that it is not necessary to fill every screw hole, but those closest to and furthest from the fracture must be used.
For all diaphyseal screws, use cortical screws, observing the following steps:
- Drill both cortices using the appropriate drill guide to ensure a central drill hole with the 3.2 mm drill bit.
- Measure for screw length.
- Tap both cortices using the 4.5 mm tap and appropriate drill sleeve.
- Insert the screw.
Insertion of metaphyseal plate screws
In the metaphysis, use screws with cancellous threads.
Observe the following steps:
- Drill using the appropriate DCP drill guide to ensure a central drill hole with the 3.2 mm drill bit. Do not penetrate the far cortex (or the joint).
- Measure for screw length.
- Tap just the near cortex using the 6.5 mm tap and appropriate drill sleeve.
- Insert cancellous screws and carefully tighten them.
Metaphyseal screws should be as long as possible but must not penetrate the far cortex, or the joint.