Fracture Fixation - Types and Procedure

Introduction

The word fracture refers to a break or discontinuity in the skeletal bones. The fractures are classified on various basis -they can be complete or incomplete, open or closed, comminuted or simple fractures. They occur commonly because of road traffic accidents, falls, or sports injuries. Fractures may result in severe pain and deformity. It is essential for the broken bones to be stabilized and supported until they are strong enough to manage weight-bearing activities. The process required to stabilize the broken bones are referred to as fracture fixation. This article discusses fracture fixation in detail.

What Is Fracture Fixation?

When a bone is fractured, they are potentially unstable or deformed out of its alignment. To bring back the broken bone to its original anatomical position, orthopedic surgeons perform a procedure called reduction (“setting the bone”), which is either an open (requiring surgical incision) or closed reduction procedure (non-operative treatment). Various components are required in stabilizing the bone in its proper alignment to facilitate healing which is referred to as fracture fixation. The primary goal in patients with fractures of the lower extremities is to improve the stability of weight bearing. Reimposing the functional upper arm motion is necessary for fractures of the upper extremity.

What Are the Types of Fracture Fixation?

There are two types of fracture fixation namely internal fixation and external fixation:

• Internal Fixation: Internal fixation requires a surgical procedure that involves surgical exposure of the fracture site and insertion of special implants such as screws, rods, and plates at the surgical site.

• External Fixation: External fixation refers to components (casts, splints, and traction) that are externally inserted superficially and adjusted to immobilize and maintain the stability of broken bones and to enable faster healing.

How Is External Fixation Done?

External fixation is mostly performed under general anesthesia to make the patient unconscious and not feel any pain. The components of the external fixation are based on the process of splinting. Only external fixation allows the orthopedic surgeon to adjust the flexibility of the fixation. Components of external fixation involve pins or wires such as Schanz screws, Kirschner wires, and Steinmann pins.

• The initial step involves a surgical incision at the pin insertion site.

• The surgeon places holes into the undamaged parts of the bones using a trocar and drill sleeve. Copious irrigation is performed simultaneously to avoid thermal necrosis (bone cell death due to very high temperatures).

• The external fixation components are placed percutaneously over the bone on both sides of the fracture site. Proper placement of these components is very important.

• These pins or screws should extend from the near cortex (dense outer part of the compact bone), the medullary canal (hollow part of the bone), and onto the far cortex without engaging the muscle compartments.

• They are connected externally to the external fixator such as the stainless steel rods or carbon fiber rods by various clamps.

• Adjustments can be made from the external fixator rods containing ball and socket joints.

Intensive care of the pin-insertion site (cleansing and disinfection) is carried out to prevent infection. Radiographic investigations are used in evaluating the components of external fixation.

What Are the Components of Internal Fixation?

Internal fixation is performed when the extent of the injury is severe and it cannot be treated with cast immobilization and skeletal traction. This technique involves a surgical procedure allowing the orthopedic surgeon to internally set the broken bones (open reduction) and stabilize the fracture in its proper alignment by placing specialized implants. The most commonly performed procedure is the open reduction and internal fixation. The main goal of internal fixation is to restore the functions of the injured limb as much as possible by allowing the faster healing of the broken bones. The components of the internal fixation are made of stainless steel and titanium. These implants are biocompatible with the body and very rarely cause allergic reactions. Some of the specialized implants used in internal fixation are:

1. Pins: Biocompatible fixator pins are used to detain the fracture segments after open reduction. They are commonly used in association with other internal fixation components however they may be used alone in the internal fixation of small bone fractures of hands or feet. They come in various sizes, the most commonly used ones are Steinmann pins.

2. Plates: Biocompatible fixator plates are commonly made of titanium and stainless steel. There are various types of plates that are used both in rigid fracture fixation and flexible fracture fixation. Flexible fracture fixation allows minimum displacement of the fractured fragments in relation to other fragments when a load is applied across the fractured site.

• Plates are used in protecting the lag screws (threaded screws used in compressing fracture fragments) from shear stress, bending, and torsional forces across the fracture site.

• Buttress plates are used in intra-metaphyseal fractures (fractures along the neck portion of the long bone) to support the underlying cortex.

• Antiglide plates are used in diaphyseal fractures to generate axial compression within the fracture while loading.

3. Screws: Biocompatible implant screws are the most commonly used components of the internal fixation. There are various types of screws in different sizes that are partially or completely threaded. They are available in self-taping (screws with cutting ends) or non-self taping. Non-self-tapping screws are convenient to be inserted and removed however it is not a preferred option in fixing fractures with fine cortex. They are often used in combination with plates, rods, or nails.

• Cortical screws are mostly fully threaded and are used in the diaphysis (the midsection of a long bone) of the bone.

• Cancellous screws have a deep thread with increased diameter to improve the withholding power of epiphysis and metaphysis of the bone.

• Interfragmentary screws are the screws that cross perpendicular to the fracture line. This helps to facilitate compression between the fracture fragments to improve stability and bone healing.

• Once the fracture heals, the implant screws are either removed or left in place.

4. Nails or Rods: In cases with long bone fractures, the fracture fragments are stabilized by inserting a biocompatible rod or nail in the hollow space of the bone that normally contains bone marrow (spongy center portion of the bone).

Conclusion

A fracture refers to a break in the bone that often occurs due to road traffic accidents and sports injuries. The healing of a broken bone depends on the callus formation. Medical management of the fracture is by reduction, immobilization, and rehabilitation. The fractured fragments are brought back to their anatomical location by the reduction of the bone and they are maintained and stabilized with the help of fracture fixation in order to promote healing. Each type of fixation has its own limitations and advantages. However, fracture fixation is essential to maintain the alignment of the fractured fragments and promote the natural healing of the broken bone.