External fixation is a surgical procedure used to stabilize severe fractures, allowing the bone to heal while maintaining proper alignment. It involves the insertion of metal pins or wires into the bone, which are then connected to a rigid frame located outside the body.
Understanding External Fixation
External fixation is a versatile orthopedic technique primarily employed for managing complex fractures, especially those involving significant soft tissue injury or when internal fixation (plates, screws, rods inside the body) is not immediately feasible. It acts as a scaffolding, holding bone fragments in place and enabling initial stability and healing.
The Procedure for External Fixation
The process of applying an external fixator involves several critical steps, typically performed under general or regional anesthesia. The primary goal is to provide rigid stabilization of the injured bone while minimizing further trauma to the surrounding tissues.
1. Pre-operative Assessment and Planning
Before the procedure, the orthopedic surgeon will conduct a thorough assessment, including:
- Imaging studies: X-rays, CT scans, and sometimes MRIs are used to accurately visualize the fracture pattern, assess bone quality, and identify any associated injuries.
- Patient evaluation: A comprehensive medical history and physical examination are performed to ensure the patient is fit for surgery.
- Fixator design: The surgeon plans the optimal configuration of pins and the external frame based on the fracture type and location.
2. Anesthesia
The procedure is typically performed under either:
- General anesthesia: The patient is completely unconscious.
- Regional anesthesia: The specific area of the body is numbed, often combined with sedation to keep the patient comfortable.
3. Surgical Incision (Minimally Invasive)
Often, only small puncture wounds are made for pin insertion, minimizing the need for large incisions. In some cases, a small incision may be necessary to gain better access or to address specific soft tissue issues.
4. Pin or Wire Insertion
This is a crucial step where the stabilization elements are introduced. The surgeon will meticulously insert metal pins or wires into the bone above or below the injury site. These pins are carefully placed to avoid nerves, blood vessels, and joint capsules.
- Schantz pins: These are threaded pins often used in larger bones.
- Kirschner wires (K-wires): Smooth wires typically used in smaller bones or for temporary fixation.
The entry and exit points for these pins are strategically chosen to maximize stability and minimize soft tissue damage.
5. Reduction and Alignment
Once the pins are in place, the surgeon will carefully manipulate the bone fragments to achieve anatomical reduction (realigning the broken bone ends). Imaging, such as fluoroscopy (real-time X-ray), is used throughout this stage to confirm proper alignment.
6. Frame Assembly and Connection
After the pins are inserted and the bone fragments are properly aligned, the external frame is constructed. The pins are attached to a metal bar (or bars) outside of the body. This external frame consists of various components, including:
- Connecting rods: Often made of carbon fiber or aluminum, these connect the pins.
- Clamps: Used to secure the pins to the rods and allow for adjustments.
- Frame components: Depending on the fracture and system used, these can vary from simple unilateral frames to more complex circular or delta frames.
The external fixator frame will keep the injured bone stable and aligned throughout the healing process. The rigidity of the frame is critical for providing the necessary mechanical support.
7. Wound Closure and Dressing
After the frame is assembled and tightened, the pin insertion sites are cleaned and dressed. Sterile dressings are applied around each pin to prevent infection. The skin around the pin sites is carefully monitored.
8. Post-operative Care Instructions
Patients receive detailed instructions on how to care for their external fixator, including:
- Pin site care: Daily cleaning to prevent infection (a critical aspect of managing an external fixator).
- Weight-bearing restrictions: Instructions on how much weight, if any, can be placed on the affected limb.
- Pain management: Medications to control discomfort.
- Follow-up appointments: Regular visits to monitor healing and adjust the fixator if necessary.
Indications for External Fixation
External fixation is commonly used for:
- Open fractures: Fractures where the bone has broken through the skin, as it allows access for wound care and minimizes further contamination.
- Polytrauma patients: For temporary stabilization of multiple fractures in severely injured patients until definitive surgery can be performed.
- Pelvic fractures: To stabilize unstable pelvic ring injuries.
- Limb lengthening or deformity correction: Gradual adjustment of the frame can lengthen bone or correct deformities over time.
- Fractures with significant soft tissue swelling: When swelling prevents immediate internal fixation.
- Infected non-unions: To stabilize a fracture that hasn't healed and is infected.
Advantages of External Fixation
- Minimally invasive: Often requires smaller incisions than internal fixation.
- Allows access for wound care: Crucial for open fractures.
- Adjustable: The frame can be adjusted post-operatively to improve alignment or facilitate limb lengthening.
- Load sharing: Provides stability while allowing some physiological loading, which can promote bone healing.
- Removable: Can be removed once the fracture has healed, often without a second major surgery.
For further information on external fixation, you can refer to resources like the American Academy of Orthopaedic Surgeons (AAOS) OrthoInfo.
