Basic principles of plating

1. Introduction

Plating modalities

Plates may be applied in various modes according to the function required. These include:

• Protection (neutralization)
• Compression
• Bridging
• Buttress (antiglide)

Plate designs

Numerous plate designs are accessible, tailored to different anatomical locations and the specific loads they will encounter. These plates may vary in size, thickness, and locking or non-locking screw configurations, depending on the application. Additionally, some plates are specifically designed to enable dynamic compression, while others have reduced contact with the bone. Furthermore, reconstruction plates are crafted to offer greater flexibility in contouring for complex anatomical regions. There are also specialized plates available, each designed for specific anatomical locations.

Plate contouring

The plate should be shaped to match the bone’s contours. In cases where the midshaft of long bones is straight, the plates applied in those regions may not require contouring. However, for most bones that exhibit a flare towards the metaphysis, plates used in those areas generally need contouring.

To facilitate plate contouring, a flexible template can be utilized. When locking screws are employed, the stability of the bone-plate construct is maintained even if the plate is not in direct contact with the bone, reducing the need for precise contouring.

Anatomic plates come pre-contoured to fit the designated region, but it’s essential to note that they are designed for average patients and may still require adjustments to fit individual patients.

2. Protection (neutralization) plates

Function

A protection plate serves the purpose of neutralizing both bending and rotational forces, providing essential protection for a lag screw fixation. This applies equally to plates with locking or non-locking screws, as they all contribute to ensuring the stability and integrity of the fixation.

Application

To treat the fracture, the first step is to carefully realign the broken bone fragments, and then secure them using one or more lag screws. Next, the properly contoured plate is positioned on the bone, and screws are inserted in a neutral manner.

The choice of screws depends on various factors, such as the plate design, bone quality, availability of implants, and the surgeon’s preference. Surgeons may opt for fixed-angle locking head screws, variable-angle locking head screws, or non-locking screws, depending on the specific requirements of the case.

It is not obligatory to fill every hole with screws; the primary goal is to ensure sufficient stability by inserting enough screws to maintain the reduction until the fracture heals completely. This approach allows for effective fracture healing without the need to use screws in every available hole on the plate.

3. Compression plates

Function

The plate produces compression at the fracture site to provide absolute stability.

Application (transverse fractures)

Reduction

Whenever feasible, the fracture will be carefully realigned and temporarily secured using clamps. When doing so, it’s crucial to position the forceps in a manner that they do not obstruct the intended placement of the plate.

Pre-contouring

In situations where the plate is accurately shaped to match the anatomically reduced fracture surface, some gapping of the far cortex may occur when the plate is tensioned by tightening the load screw.

To address this issue, a solution involves deliberately “over-bending” the plate, causing its center to be positioned about 1 to 2 mm away from the anatomically reduced fracture surface. The overbend should align directly over the fracture line. Consequently, when the first screw is inserted, slight gapping of the cortex might happen directly beneath the plate. However, once the fixation process is complete, the plate will make contact with the bone along its entire length, yet it will function as a spring, providing compression at the far cortex.

Screw insertion

The prebent plate is affixed to one of the primary fragments using a screw inserted in compression mode. On the opposing fragment, reduction forceps are employed to secure it in the reduced position against the plate. The first screw is not fully tightened at this stage.

Next, a screw is inserted in compression mode on the opposite fragment to maintain the reduction. To ensure the reduction is maintained properly, it is recommended to gradually tighten the screws while alternating between the two sides.

In the event that there remains a fracture gap even after inserting the two compression screws, a third screw can be added to either side in compression mode. However, before tightening this third screw, the compression screw already placed in the same fragment must be loosened. Once the third screw is fully tightened, the first screw can be re-tightened, and additional screws can be inserted in neutral mode.

Application (oblique fractures)

In the case of oblique fractures, the plate is positioned and fixed using one or more screws inserted in a neutral mode to create an axilla with one of the bone segments. Additionally, a screw is inserted in compression mode into the second fragment. This compression screw helps drive the second fragment into the axilla and effectively compresses the fracture.

When dealing with an oblique fracture, it is crucial to create an axilla with the plate to avoid the risk of fracture displacement during compression. If the fracture pattern and location do not allow for the creation of an axilla with the plate, an alternative approach may be preferable, such as using a lag screw and a neutralization plate.

In some cases, to achieve additional compression, an interfragmentary lag screw can be inserted through the plate. This technique further enhances the stability of the fixation and promotes proper healing of the fracture.

Articulated tension device

As an alternative to obtaining compression using screws inserted in dynamic compression mode, the articulated tension device may be used to provide mechanical compression prior to fixation with screws inserted in neutral mode.

The device may also be used to create distraction.

Compression

To initiate the procedure, carefully align and reduce the fracture as closely as possible. Once the fracture is approximately reduced, securely attach a plate to one of the fragments.

Next, anchor the articulated tension device to the bone by inserting a screw through its articulated footplate. Then, insert the hook on the device into the hole at the end of the plate.

As the tensioning screw is gradually tightened, the two limbs of the device will be drawn together, leading to compression at the fracture site. This compression aids in promoting proper healing and stabilization of the fracture.

Distraction

To distract the fracture, the hook of the device is placed against the plate end, and the tensioning screw on the device turned anti-clockwise.

Application in oblique fractures

In oblique fractures, the plate should be applied to create an axilla following the same principle described above for dynamic compression plates.

Screws are inserted into the second segment in neutral mode and the device removed.

4. Bridge plates

Function

Bridge plating techniques are applied in cases of complex long bone fractures with multiple fragments, when intramedullary nailing or conventional plate fixation is not appropriate.

The main purpose of the plate is to offer relative stability by securing the two primary fragments, ensuring proper length, alignment, and rotation. Importantly, the fracture site is intentionally left undisturbed, which encourages healing through callus formation.

Conventional vs locking head screws

Either conventional or locking head screws may be used.

The advantages of locking head screws compared to conventional screws are:

• They provide more stability in osteoporotic bone by reducing the risk of screw pullout and over-tightening of the screws
• Well reduced fractures stay reduced
• Unicortical screws may be used
• The plate does not need to be perfectly contoured to the bone
• As the plate is not pressed against the bone, the periosteum is not compromised

Extent of surgical approach

To minimize disruption to the fracture site, bridge plates are frequently inserted using a minimally invasive method. This involves either inserting screws through a limited approach, where the plate is only exposed enough for screw insertion, or through small stab incisions.

The most minimal surgical disturbance to the fracture site is achieved when employing a percutaneous technique for plate insertion. This approach involves using small incisions at the skin’s surface to access the bone, ensuring reduced tissue trauma. By adopting this approach, surgeons can maintain the integrity of the fracture site while minimizing impact on surrounding tissues and bone. As a result, patients can benefit from improved healing and a quicker recovery process.

Reduction

Reduce and secure the main proximal and distal fragments in correct length, alignment, and rotation.

This is typically achieved using indirect reduction techniques such as:

• Temporary external fixation
• Reduction devices
• Traction

This will minimise additional harm to the blood supply by allowing manipulation of the primary pieces into the proper location without opening the fracture site.

The use of an external fixator, or distractor, can offer alignment and temporary stability for bridge plating, especially with multifragmentary fractures, without disrupting the soft tissues near the fracture zone.

To avoid obstructing the subsequent plating process, proximal and distal pins should be placed carefully.

Working length

Long plates having a long working length allow bending forces to be distributed across a long section of the plate, which results in a low stress per unit area. By doing so, the danger of plate failure is decreased and excessive stress over the fracture site is avoided.

lengthy plates make it possible to have a lengthy lever arm, which lowers the possibility of screw withdrawal.

Using standard screws that are inserted in neutral mode or locking head screws, secure the plate to the bone.

5. Buttress (antiglide) plates

Function

When metaphyseal shear or split fractures occur in the metaphyseal areas, buttress plates are frequently utilised to enhance lag screw fixation.

The buttress plate can be installed with the lag screws inside or outside of it.

Application

In accordance with accepted practise, reduce the fracture and repair it with one or more lag screws.

Using a washer on osteoporotic bone

Pre-bend the plate slightly so that it follows the contour of the bone; this creates a little space between the plate’s centre and the bone.

By placing a typical bicortical screw in the hole closest to the fracture in buttress mode, you may apply the plate and press it firmly against the bone.

Additional bicortical screws that are put in neutral mode are used to fasten the buttress plate.

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