Safer methods for internal bone fixation: keeping both patients and clinicians safe from wirestick injuries.
Many patients return to their orthopedic surgeon when their artificial hip has become worn out or lose. The surgeon makes the necessary incisions and is ready to insert his/her hands into the open wound so that it can be palpated to determine the extent of the damage (see Figure 1). Each time this blind procedure occurs the surgeon has a good chance of being stuck on the cabling wire that is surrounding the bone. At times like this, the surgeon is concerned not only about taking time out from the surgery to replace a compromised glove but is also concerned about the patient's hepatitis or HIV status.
This situation occurs every day for orthopedic surgeons because they frequently insert their hands into a blind area where they are relying on tactile feedback at their fingertips; This places their hands at great risk for a wirestick injury from the metal cerclage cables and wires.
One area where this cabling occurs frequently is hip replacement surgeries. In a normal "ball-and-socket" kept joint, the head of the femur rotates inside the cup-shaped, hollow acetabulum (socket) of the pelvis. The mating surfaces are covered with a slippery tissue called articular cartilage. The tough, lubricious articular cartilage is about 1/8" thick and allows the surfaces to slide against one another without damage. When the hip joint wears out, it is necessary to replace it with an artificial hip. This procedure is called a total hip replacement or total hip arthroplasty.
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The procedure consists of replacing the original joint with a stem which fits into the femur, a ball that replaces the spherical head of the femur and the cup which replaces the worn out acetabular socket.
Surgeons, nurses and technicians are at risk for accidental sharps injuries each time a total hip replacement procedure is performed. Wirestick and other sharps injuries place operating room personnel at the highest risk among healthcare professionals for occupational hepatitis B and C infections because of their frequent exposure to blood. They are also at risk for HIV.
Wires and Cables
At times during these orthopedic procedures, is it is necessary to hold the bone or fragments of bone together to create a stable environment for healing to occur. This is often done by using a material to hold the bone together. Most often this is done with a metal wire or cable called a cerclage (ser-klahzh). A cerclage wire or cable is wound around a bone or bony fragments to hold them together to allow them to heal.
Multi-filament metal cables (see Figure 2) are typically trimmed to length resulting in many sharp ends that can potentially poke holes in gloves, breaking the sterile barrier and placing the patient at risk of infection, while exposing the clinician to blood-borne pathogens. During revision surgery, clinicians are often exposed to the sharp metallic ends of cerclage cables that have broken or frayed.
These wire cerclage cables are frequently used as the primary method of fracture fixation. Unfortunately, there are a number of disadvantages to using these cables. For example, multi-filament cables frequently break due to fatigue. In addition, they fray, releasing metallic particulate debris into the body. At times these fragments intrude into the bearing surface of the hip replacement. At times the broken metal cerclage wires migrate. In one case, a fragment of a broken metal cerclage wire was found in the right ventricle of a patient who was treated 13 years previously for a patella fracture using cerclage wire. (1)
These broken metal wires are not just a safety concern for patients--they also pose a serious risk of injury and subsequent transmission of blood-borne pathogens to clinicians. Monofilament wires are prone to breakage and multi-filaments cables often experience fatigue, failure and fray which potentially can release of metallic particulate debris into the body.
New Surgical Product
A new product (see Figure 3) called SuperCable Iso-Elastic Cercage, was recently introduced to help eliminate these wirestick problems. The cable is manufactured by Kinamed, Inc. (Camarillo, CA) and has been used in several thousand procedures worldwide since being introduced in 2003.
Rather than being a multi-filament wire cable, the SuperCable Iso-Elastic Cerclage is an elastomeric polymer cable consisting of a nylon core encased in a jacket of ultra-high-molecular-weight polyethylene (UHMWPE) braided fibers.
This unique combination results in a flexible, soft cable exhibiting extremely high fatigue strength. The unique design of the SuperCable provides a combination of strength, elasticity and resistance to fatigue failure--which is the primary cause of broken metal wires and cables. I believe that the system offers important benefits and safety features for the patient, as well as the physician and surgical staff.
One of the unique features about the SuperCable system is that it can be re-tensioned effectively when multiple cables are applied (see Figure 4). This is a real time-saver because it can reduce the need to cut off and discard metal cables that have become loose after additional cables have been applied and tensioned. This could reduce the total number of cables required for a given procedure and provide long-term dynamic compressive loading across bone fragments for better healing and increased bone strength. The cables are also easy and quick to manipulate within the wound.
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This polymer-based cerclage system solves many of the inherent problems of traditional metallic wire and cabling systems and its fatigue strength is comparable to metal wire and cables. This potentially reduces complications due to breakage. It can also eliminate cable-generated metal particle debris.
Orthopedic surgeries requiring the use of cerclage cables to help hold bone fractures together while they heal are increasing. Metallic wires and cables fail and fray, exposing both patients and clinicians to sharps injuries. Newer technologies are now available to help minimize tissue damage and prevent unnecessary sharps injuries and bloodborne pathogen exposures.
(1) Biddau et al (2006) Migration of a broken cerclage wire from the patella into the heart. A case report. The Journal of Bone and Joint Surgery, 88-A:2057-2059.
Ron Stoker is the founder and executive director of ISIPS, the International Sharps Injury Prevention Society. He is co-author of the "Compendium of Infection Control Technologies. "For more information, go to http://kunaki.com/Sales. asp ?PID=PX00OLESG1
Mr. Stoker is also providing a number of webinars focusing on sharps injury prevention safety products. For more information, go to www.isips.org/seminars.html. To subscribe to the free ISIPS Newsletter, go to www.isips.org/signup.php