MIO - Compression plating

Compression plating can be used for any transverse, two-part, tibial fracture.

It is ideal for the treatment of diaphyseal fractures in children with open growth plates, where significant displacement is present, and anatomical reduction is indicated.

Minimally invasive osteosynthesis (MIO) techniques are indicated for select transverse fractures where a closed reduction technique effectively restores an anatomical reduction.

Cautious use of MIO may permit compression plating in the case of compromised soft tissues if they are sufficiently fit to withstand the procedure and the size of the planned hardware. Submuscular plating may be safer than subcutaneous in these situations.

Tibial shaft fractures near the knee or ankle may require plate fixation. MIO techniques are advantageous because they preserve fracture site biology. By limiting skin incisions and surgical dissection, using indirect reduction techniques and basic plating concepts, adequate fixation and alignment can be obtained without significant damage to the bone or soft-tissue envelope. While multifragmentary fractures require a bridging technique, short oblique or transverse fracture patterns should be fixed with compression plating to achieve absolute stability and avoid the high-strain situation that occurs when a simple fracture is fixed without compression.

Preoperative planning is of utmost importance and should include all steps of the procedure (including appropriate approaches, reduction techniques, instruments, and implants). Anatomically shaped plates are helpful but not necessary for this technique. Straight plates can be contoured to fit the bony surface.

With limited windows through the skin and no direct visualization of the fragments, image intensifiers are a key surgical tool for MIO. The image intensifier field of view should be as large as possible to allow assessment of alignment. Alternatively, full length standard x-rays may also be required. Always inspect both limbs visually as an additional check for alignment errors.

The position of the C-arm is critical in order to achieve orthogonal views during surgery. This should be tested before surgery.

The patient is placed in a supine position on a radiolucent table or a standard operating table with a radiolucent extension. A pad is placed underneath the buttock to prevent external rotation.

A large foam bolster or cushion is placed under the affected leg to raise it above the opposite leg so as to facilitate lateral C-arm images.

If the soft tissues allow, a medial approach is preferred because it is easier to pass the screws percutaneously with less soft-tissue interference.

The lateral approach should be chosen if the medial soft tissues are compromised. Conversion to an open method is sometimes required when closed methods do not achieve a sufficient reduction.

The key to all fracture reduction is restoring axial length.

Length can be gained with:

• Manual traction
• Distractor/external fixator
• Reduction forceps
• Articulated tension device (ATD)
• Push-pull screws

Apply longitudinal traction to the foot.

After correct length and axial alignment have been achieved, evaluate and correct the rotational deformity. One should determine the correct rotation from the uninjured extremity preoperatively.

Manual traction can be effective in fresh fractures but may be ineffective in fractures with soft-tissue contractures, significant shortening, or early fracture healing.

If manual traction is not successful, use a large distractor for closed reduction. Place Schanz pins in the proximal and distal fragments. Distraction is applied across these pins by turning the nut on the threaded rod.

If the plate is to be placed medially, then the distractor should be placed anteriorly.

With transverse fractures, reduction forceps cannot be applied to compress the fracture surfaces. In this situation, percutaneous pointed reduction clamps, one in each bone segment, are helpful to adjust the fracture.

To use the articulated tension device (ATD) in distraction mode, a precontoured plate is applied to the main fracture fragment. A distracting force is applied with the ATD against the opposite end of the plate.

Distraction aids precise fracture surface reduction.

With the fracture satisfactorily reduced, the ATD is used in compression mode to load the fracture and achieve interfragmentary compression and absolute stability.

Depending on where the plate is positioned in relation to the fracture plane, the plate may need to be over-contoured slightly at the fracture site so that compression occurs opposite as well as adjacent to the plate.

A pre-contoured plate is applied to one of the main fragments. A bicortical push-pull screw is then placed proximal to the end of the plate, and a laminar spreader is used to apply a distraction force through the plate. This distracts the fracture site so that it can be reduced.

Fracture site compression can be applied using a Verbrugge clamp between the push-pull screw and the plate. Compression is applied once the fracture is satisfactorily reduced.

Depending on where the plate is positioned in relation to the fracture plane, the plate may need to be over-contoured slightly at the fracture site so that compression occurs opposite as well as adjacent to the plate.

Rotational alignment must be considered when applying all the reduction methods described previously.

The distractor and simple external fixator are uniplanar devices. Rotation of the fracture fragments cannot be adjusted significantly once the pins have been placed and attached to the device.

Thus, the pins should be placed so that the fracture is reduced when they are in the same plane.

Final reduction of the fracture may be difficult with pointed reduction forceps due to the short obliquity or transverse nature of the fracture.

Once length has been restored, translation of the fragments can be corrected using either manual force, percutaneously placed Schanz screws, a ball spike pusher, or clamps. The illustration shows the use of two ball spike pushers.

After translation has been corrected, the distraction force can be removed. In many cases, the fracture will remain reduced due to the transverse orientation of the fracture line.

In some cases, over-distraction is required to correct the translational deformity.

Reduction can also be achieved by reducing the fracture to the plate. With the plate positioned against one fracture fragment, the adjacent fracture fragment can be pulled to the plate with a well-placed cortical screw. In this way, translation of the fracture fragments is corrected.

The plate must be shaped to fit the bony surface for this technique to be effective.

The surgeon must also ensure that reduction is adequate in the opposite orthogonal plane (correct on the lateral view, as well as the AP view shown here).

Plate length is based upon symmetry above and below the fracture zone. At least 3–4 screw holes on either side of the fracture are necessary.

Another guideline, when fracture location permits, is that the plate should be roughly three times the length of the fracture zone.

Generally, longer plates with fewer screws are most effective.

When the fracture zone is very distal or proximal, there may not be enough room for symmetric plate length in the segment nearest the articular surface. In this situation, a plate with multiple hole options in the metaphysis is chosen to improve fixation in the short periarticular segment.

A locking plate may be indicated if the bone quality is poor or if the fracture extends into softer metaphyseal bone.

Traditionally a 4.5 mm plate has been advised for the tibial shaft. Advantages include increased plate thickness and larger screw size for added strength. These plates are more difficult to contour and may be too prominent.

A 3.5 mm plate offers improved contourability and multiple screw options in metaphyseal (end-segment) zones. As these plates are thinner, they are less stiff than the large fragment plates.

Another consideration is the choice between an anatomically precontoured plate or one which the surgeon contours. For plates that need to be contoured, the following steps must be employed.

The anteromedial surface of the tibial shaft twists internally approximately 20° as it approaches the medial malleolus.

The first step of plate contouring is to twist the plate so it matches the tibial surface upon which it will lie.

If the plate is bent before it is twisted, the process of twisting will alter the bend that has been created.

Depending upon the plate location, more or less bending of the plate will be required to match the contour of the intact (or reduced) bone. Much of the medial tibial shaft is quite straight, so little bending is required, however, the distal medial surface has a significant concavity, with a typical radius of curvature of 20 cm, as illustrated.

A 20 cm radius can be drawn on a sterile drape and used as a template for plates to be used in this location.

The plate can be bent with bending irons alone, but bending with a bending press is preferable because it gives more control.

In either case, the bending is done in small steps to produce a smooth contour. Contouring only takes place over the distal 10–12 cm of the plate. When finished, the plate should match the 20 cm radius of curvature.

An incision is made over the distal tibia, and the plate is slid under the subcutaneous tissues, as shown.

If a locking plate or an anatomically contoured plate is used, the specifically designed end of the plate will facilitate this passage. With a conventional Limited contact dynamic compression (LCDC) plate, it may be necessary to use a periosteal elevator to create a subcutaneous tunnel.

This image shows the inserted plate.

If available, a subcutaneous tunneling device could be used.

The position of the plate is adjusted on both the AP and lateral views of the tibia. At this point, the plate can be provisionally held with K-wires.

Through an image-directed stab wound, place the first screw according to antiglide principles (closing any gap between bone and plate to resist axial displacement) to improve axial alignment.

This image shows the percutaneous insertion of a screw through a medially-based plate.

Reduction will only result if the correct length has been achieved first.

Check both AP and lateral views of the tibia.

The initial screw must engage both cortices so it can securely apply the plate to bone. As the plate is typically not apposed to bone when it is applied, the first screw may be found to be too long once the plate has appropriate contact (as seen here). It should be exchanged later, after additional screws are placed.

Fracture compression is applied after reduction. This may be done with the articulated tension device or a push-pull screw and Verbrugge clamp.

Additional compression can be applied to a well-reduced fracture using a screw in the opposite main bone fragment. This is placed eccentrically in a dynamic compression (DC) plate hole with an appropriate guide.

Place the remaining screws at appropriate intervals.

Remember that fixation is better with longer plates and that in the diaphyseal segment, fewer screws are required.

Exchange any screws that are too long for those of the proper length.

Perioperative antibiotics may be discontinued before 24 hours.

Attention is given to:

• Pain control
• Mobilization without early weight bearing
• Leg elevation in the presence of swelling
• Thromboembolic prophylaxis
• Early recognition of complications

A brief period of splintage may be beneficial for protection of the soft tissues but should last no longer than 1–2 weeks. Thereafter, mobilization of the ankle and subtalar joints should be encouraged.

Active, active assisted, and passive motion of all joints (hip, knee, ankle, toes) may begin as soon as the patient is comfortable. Attempt to preserve passive dorsiflexion range of motion.

For fractures treated with plating techniques, limited weight bearing (15 kg maximum), with crutches, may begin as tolerated, but full weight bearing should be avoided until fracture healing is more advanced (8–12 weeks).

For fractures treated with intramedullary nailing, weight bearing as tolerated, with crutches, may begin immediately.

Follow-up is recommended after 2, 6, and 12 weeks and every 6–12 weeks thereafter until radiographic healing and function are established. Weight bearing can be progressed after 6–8 weeks when x-rays have indicated that the fracture has shown signs of progressive healing.

Implant removal may be necessary in cases of soft-tissue irritation caused by the implants. The best time for implant removal is after complete bone remodeling, usually at least 12 months after surgery. This is to reduce the risk of refracture.