A “human pin” is a metal rod used in orthopedic surgery to stabilize fractured bones by holding the pieces in their correct anatomical position. Unlike external casts and splints, surgical pins provide internal fixation, securing bone fragments from within the body. This internal stabilization allows for earlier movement and helps ensure the bone heals correctly.
Materials and Types of Surgical Pins
Surgical pins are fabricated from materials selected for their strength and compatibility with the human body. The most common materials are stainless steel and titanium alloys, which are durable and rarely cause an allergic reaction. For patients with known metal allergies, such as to nickel, specific material selection is an important consideration.
Beyond traditional metals, some pins are made from bioabsorbable materials. These specialized pins are designed to dissolve safely within the body over time, which can eliminate the need for a second removal procedure. This is particularly useful in pediatric cases or where removal could be complex.
Surgical pins come in various designs, primarily distinguished by their size and shape. Kirschner wires (K-wires) are thin, sharpened wires used for delicate fractures, such as those in the fingers or toes. Steinmann pins are thicker and stronger, making them suitable for larger, weight-bearing bones. These pins can be smooth or threaded, with the threaded design providing a more secure grip on the bone.
Common Medical Applications for Pinning
The primary application for surgical pins is the fixation of broken bones. They are frequently used to treat fractures in small bones, like those in the hands, feet, wrists, and ankles, where larger implants would be impractical. Pins are especially useful for managing fractures with many small pieces, as they can skewer these fragments together to maintain the bone’s overall shape.
Pins are also used in situations beyond simple fractures. In arthrodesis, or joint fusion surgery, pins hold the bones of a joint in a fixed position until they fuse into a single, solid bone. This procedure is often performed to relieve pain in arthritic joints, such as in the ankle or wrist.
Surgeons also use pins as temporary tools during complex reconstructive surgeries. They can act as provisional holders, keeping bones in place while the surgeon prepares to install more permanent hardware. In some cases, pins serve as guide wires, creating a precise path for the placement of larger cannulated screws.
The Surgical Pinning and Removal Process
The insertion of surgical pins is a procedure performed under anesthesia. The surgeon makes a small incision over the fracture site and uses a surgical drill to guide the pin through the bone fragments, securing them in alignment. Depending on the fracture, the end of the pin may be left protruding through the skin. This external portion allows for easier removal later and may be part of an external fixation frame.
Once the bone has healed sufficiently, which takes several weeks, the pins are often removed. If the pin is external, removal is a straightforward process that can be done in a clinical setting. The area is cleaned, and the pin is pulled out, which is quick and causes minimal discomfort.
In some situations, surgical pins are intended to be permanent implants. This is more common when their removal could risk re-injury or damage to surrounding tissues. The decision to leave pins in place is based on the specific fracture, the patient’s age and activity level, and the type of pin used.
Potential Complications and Considerations
The most common complication with surgical pins is infection. When a pin exits the skin, it creates a potential pathway for bacteria to enter the body, leading to a pin-tract infection. Meticulous cleaning and care of the pin site are important to minimize this risk. Signs of infection, such as redness, swelling, or drainage, require prompt medical attention.
Other issues include the pin loosening or migrating from its original position, which can happen due to repetitive stress or poor bone quality. Nerve irritation or damage can occur if a pin is placed too close to a nerve, causing pain or numbness. Joint stiffness is another consideration, as the immobilization required for healing can lead to a reduced range of motion.
Living with surgical pins involves some practical considerations. The metal implants can trigger security alarms at airports, so carrying a doctor’s note may be helpful for travel. Following the surgeon’s instructions for activity limitations and participating in prescribed physical therapy are important for a successful recovery.