General Guideline for the use of K-wires

1.Indications

The use of K-wires is generally suitable for the following situations:

• Simple fractures: For simple fractures, such as transverse or oblique fractures, K-wires can be used through the fracture line to provide stability.
• Articular fractures: K-wires can also be used in the treatment of articular fractures, especially when the fracture involves the joint surface.
• Small bone fractures: Due to their small size and flexibility, K-wires are particularly suitable for the treatment of fractures in small bones or animals, such as the carpal bones, tarsal bones, or fractures in cats and dogs.
• Complex fractures: For complex fractures, such as comminuted or open fractures, it may be necessary to use multiple K-wires or in combination with other fixation devices, such as internal fixation plates or screws.
• Growth plate fractures: In young animals, K-wires can be used to repair growth plate fractures, as they cause less damage to the growth plates.

The following situations are not suitable for the use of K-wires alone:

• Weight-bearing bone fractures: For bones bearing a significant amount of weight, such as the femur or tibia, K-wires may not provide sufficient stability, so other types of fixation devices, such as steel plates or screws, may be needed.
• Long segment fractures: Long segment fractures often involve extensive bone damage, in which case K-wires may not provide sufficient stability, and other methods, such as internal fixation plates or external fixation devices, may be required.
• High stability requirement fractures: For some fractures that require high stability, such as spinal fractures, K-wires may not provide enough fixation force, and more complex internal fixation devices may be needed.

2.K-wire Principles

The size of the K-wire depends on the pet’s age and the size of the fractured pieces.

The entry point of the K-wire and the correct direction are key to fixation.

For most simple fractures, usually, two or three K-wires can provide enough stability.

The K-wire is required to:

• Be of the right size
• Not cross each other at the fracture site
• Be intramedullary
• K-wire osteosynthesis usually requires additional plaster protection.

Advantages:

• Cheap
• Wide range of applications
• Can be manually inserted (using a T-handle) or inserted with a drill (as long as heat damage is avoided)
• Easy to remove

Disadvantages:

Poor functional stability

3.K-wire Specifications

Selection of K-wire:

• Patient’s age/weight
• Fracture location
• Fragment size
• K-wire insertion direction and path

Patient’s Age/Weight

Consideration of the patient’s weight is important when choosing the diameter of the K-wire.

The diameter of the K-wire is usually represented in millimeters (mm), and different animals may require K-wires of different diameters. Smaller animals such as small dogs, cats may need thinner K-wires, while larger dogs may need thicker K-wires. Common diameters include 0.8mm, 1.0mm, 1.6mm, etc.

Fracture Location

Long bone fractures (such as the femur): In this case, longer and thicker K-wires may be needed to stabilize the fracture. Veterinarians may choose to use two or more K-wires to increase stability.

Articular fractures: Articular fractures may require smaller, finer K-wires to avoid further damage to the joint. In this case, a single or multiple K-wires may be used to ensure the fracture is stable and unlikely to pose problems in future movement.

Pelvic or skull fractures: Fractures in these areas may require particularly small K-wires to accommodate the narrow spaces. Furthermore, as the bones in these areas are relatively fragile, more K-wires may be needed to provide support.

Spinal fractures: Fractures of the spine may require larger diameter and longer K-wires to provide adequate stability. Additionally, veterinarians may use special techniques, such as screws or plates, to enhance stability.

Fragment Size

Large fracture fragments: For larger fracture fragments, larger diameter K-wires may be needed to provide sufficient stability and support. In some cases, multiple K-wires may be used to ensure all fracture fragments are adequately secured.

Small fracture fragments: For smaller fracture fragments, smaller diameter K-wires may be needed to avoid further damaging the bone. Moreover, if the fracture fragments are too small, they may not be able to be secured with K-wires, at which point other surgical techniques may be required, such as internal fixation plates, screws, or capsules, etc.

Multiple fracture fragments: If there are multiple fracture fragments, multiple K-wires may be needed for fixation to ensure all fragments are supported. The veterinarian may choose to insert the wires in a crossed or parallel manner, depending on the fracture situation and location.

4.K-wire Trajectory

Straight trajectory: In some cases, such as simple fractures, the K-wire can be inserted directly from one side of the fracture to the other. In this situation, a longer K-wire may be required to ensure it can pass through the entire fracture area.

Crossed trajectory: When dealing with complex fractures with multiple fragments, a crossed insertion might be necessary to provide stronger stability. This scenario may require the use of multiple K-wires, and the length and diameter of the K-wires may need to be adjusted according to the specific situation of the fracture.

Parallel trajectory: In some cases, such as treating long bone fractures, the method of inserting multiple K-wires in parallel might be chosen. This can better distribute the pressure and reduce displacement of the fracture fragments.

Bent trajectory: In treating fractures in certain special locations, such as near a joint, the K-wire may need to be bent into a special shape to accommodate the insertion trajectory. This may require the use of specially made K-wires, or bending the K-wire during surgery.

If lateral divergence K-wire fixation is not possible, for example, due to soft tissue conditions or risk structures, other stabilization techniques should be used (such as external fixators or steel plates).

Insertion of K-wires

The insertion position and depth of K-wires are typically monitored through intermittent image enhancement.

Incision

A small incision is made at the planned entry point, instead of directly puncturing with the K-wire.

There are several reasons for doing this:

Reduced skin damage: Directly puncturing the skin could cause larger skin damage, thus increasing the risk of infection and scar formation.

Avoiding needle track infection: If the skin is directly punctured, bacteria from the epidermis may be carried into the deep tissues, thereby increasing the risk of needle track infection.

Improved visibility: Through the incision, the veterinarian can see the surgical area more clearly and insert the K-wire more accurately.

5.K-wire Insertion

When performing K-wire (Kirschner wire) surgery, especially when involving the growth plate or other sensitive areas, extra care is indeed needed to avoid damage due to excessive heat generation.

Manually inserting the K-wire can mitigate this risk, as it does not generate a large amount of heat. Another option is to use an oscillating drill, which can maintain good drilling efficiency while reducing heat production. This can lower the risk of damaging the growth plate or other sensitive tissues.

When drilling with a drill bit, a coolant is usually used to reduce the risk of excess heat generation by the K-wire and surrounding tissues.

When performing K-wire (Kirschner wire) surgery with a drill bit, we first manually insert the K-wire through a small skin incision to reach the predetermined skeletal entry point. During this process, we make sure to keep the drill close to the K-wire to maintain the correct tip position.

To prevent the K-wire from bending during insertion, we may use an appropriate drill sleeve. This not only stabilizes the K-wire and protects the surrounding soft tissue, but also ensures that the K-wire is inserted in the best direction.

Reducing the length of the K-wire protruding from the drill bit helps to avoid jitter of the K-wire during insertion and loss of the predetermined trajectory. We should keep the tip of the K-wire perpendicular to the bone surface until the tip of the K-wire gets good support, which can prevent the K-wire from sliding off the predetermined trajectory.

Once the tip of the K-wire has good support, we adjust the angle of the K-wire according to the predetermined trajectory. Throughout the insertion process, we should feel resistance from the bone. If no resistance is felt, it indicates that the K-wire may not have been correctly inserted into the bone. At this time, we would use an image intensifier to check the position of the K-wire in both the frontal and lateral directions.

When the resistance increases, we check whether the tip of the K-wire has passed through the far cortex of the main fracture fragment. The tip of the K-wire should fully penetrate the far cortex, but should not protrude more than 2-3 millimeters to avoid injury to the nerve vessels and soft tissues.

The free end of the K-wire usually protrudes from the skin and is bent 180 degrees. The wound at the entry point is protected by a sterile dressing.

When operating on the growth plate, we usually avoid more than two insertions on the same K-wire. Because multiple attempts at insertion may result in the growth plate being pierced multiple times, thereby affecting the animal’s subsequent growth.

6.K-wire Removal

Assessment: Before considering K-wire removal, veterinarians would determine whether the fracture has healed sufficiently through X-rays or other imaging techniques, as well as evaluating the animal’s clinical presentation.

Preparation: Once the fracture is determined to be healed, the animal would be given general or local anesthesia. Furthermore, the area where the K-wire is planned to be removed would be thoroughly cleaned and disinfected.

Removal: The veterinarian would open the original incision or make a skin incision at the exit of the K-wire. Then, using forceps or other appropriate tools, the K-wire is gently pulled out. If the K-wire is covered by new bone formation, a surgical drill or saw may be needed to cut through the new bone.

Wound Treatment: After the K-wire is removed, the wound would be cleaned, then sutured and bandaged.

Postoperative Care: After the operation, the bandages need to be changed regularly, the wound kept clean and dry, and any signs of infection should be closely monitored. During recovery, the animal may need to take antibiotics and painkillers.

This article is owned by PurrWoof (Changzhou) Pet Medical Co., LTD. The medical education information is provided for reference and information exchange only and does not constitute medical advice or diagnosis. Furthermore, this information may be limited by the knowledge and experience of the authors or relevant professionals and may not cover up to date medical research and practice. Therefore, the user is solely at the risk of relying on the information. No medical education information can substitute for professional medical advice, diagnosis or treatment. Before taking any health-related action, users should consult a qualified medical professional or seek appropriate medical advice.