Many patients have questions about the hardware that is often used in foot and ankle surgery. If you are having foot or ankle surgery, ask your physician if you will need implants like those discussed below.
What are implants?
Implants are substances that are placed inside or on the surface of the body. In the field of orthopedics and in foot and ankle surgery in particular, implants refer to objects which are used to hold bones together, strengthen tendons and ligaments or attach them to bone, and replace bone.
What are they made of?
Implant material depends on the application. There are two main groups: biologic and non-biologic.
Biologic materials are similar to human tissue and used primarily to replace or strengthen damaged tissue, such as bone or tendons. It also includes materials which eventually transform to scar and thus “disappear” over time.
Non-biologic implants are made from materials that are not intended to change over time. The most commonly used screws and plates that over the last few decades have been made of metals. More recently there has been increasing use of plastics and composite materials. This article will for the most part focus on non-biologic implants.
Is there a benefit of one material or design over another?
The broad answer depends on the application as well as other factors such as cost, ease of use, etc. Some principles apply: Titanium alloy may be stronger than stainless steel. It can therefore be made as a slightly thinner plate than stainless steel. Your body is a saltwater environment so any implant needs to be able to withstand salt corrosion. This is why a high-grade stainless steel is used than you would typically find at a hardware store. The screw threads are designed to have a certain spiral and a certain ratio between the shaft and the thread to obtain the best hold on bone.
Plastic and biologic materials do not show up on an X-ray. This may make them harder to see if they have loosened or had some other problem, but they have the advantage of not “hiding” the normal bone. Your doctor will help decide which is the most appropriate implant for you.
Does an implant need to come out?
No. As a general rule, implants do not rust, move, poison your system or have other negative consequences. However, occasionally an implant may cause pain or limit motion after it has served its purpose. It may be recommended to have it removed after the tissues have healed sufficiently.
Will it set off alarms at the airport?
Not with the current sensitivities of these testing devices. It would require a very large amount of material to be detectable.
How is it removed?
Usually, an incision will be made in the previous scar but usually not as large as the original cut. The tissue is dissected until the hardware is reached and then devices are used to accomplish the removal.
Are there risks associated with hardware removal?
Yes. Any surgery has the risks associated with anesthesia, infection, etc. There is scar tissue from the original surgery which makes the identification of nerves or other structures in the area difficult during the surgical exposure. This at least slightly increases the risk of damage to these structures. Sometimes the hardware is difficult to identify as it is covered with scar or bone. It may require a greater amount of dissection to be uncovered. It may be so fixed in the bone that it has to be chiseled or drilled out. Removal may weaken the structure that the implant was securing, at least temporarily.
Do I need to take precautions if I decide to have it removed?
Many factors influence this. A small screw or wire may require little or no limitation of activity. High stress activities such as marathon training and jumping might be restricted for a period of time. Removal of ankle fixation hardware may require usage of a walking cast boot or similar brace for four weeks. Your surgeon will tell you whether any precautions are needed.
Does the area where the implant was located heal?
The space occupied by the implant does not convert to normal bone, at least initially. It fills in with dense scar that structurally is similar to bone. In individuals who have not completed their growth, it may quickly fill in with bone.
Do most people have hardware removed?
It depends on the site and the individual factors. Site issues include matters such as screw heads which are sitting above the level of the bone. These are rarely problematic when covered by a thick layer of cushioning tissue which experiences little direct pressure. Conversely, the same prominence on a bone with less cushioning which also receives direct shoe pressure would be more likely to be symptomatic. If one uses shoewear which places direct pressure over a prominent screw, the choices would be to either change your type of footwear, pad the area or proceed with removal of the hardware.
What is the relationship between hardware and infection?
There is no evidence that the current implants used in orthopedic surgery result in an increased risk of infection. Surgery itself results in disruption of the blood supply and other damage to structures in the area and there is an increased risk of infection simply to place the implant. Previous trauma can compound this. There is continued debate within the medical community about whether hardware in the area is a benefit or detriment to successful treatment of orthopedic infection. The decision to remove hardware is best handled on a case-by-case basis.
Does hardware ever break?
Until the bone is healed the forces normally handled by the bone will be applied to the hardware. If enough repetitive motion and stress occurs the hardware will eventually break. The effect is similar to that of repetitively bending a paper clip back and forth. The presence of a broken implant is not necessarily a disaster. Sufficient healing may take place after the screw has broken to achieve structural stability. In some cases, it is anticipated that hardware will break or loosen. This can cause concern when seen on an X-ray but may not be associated with symptoms or other consequences.
The American Orthopaedic Foot & Ankle Society (AOFAS) offers information on this site as an educational service. The content of FootCareMD, including text, images and graphics, is for informational purposes only. The content is not intended to substitute for professional medical advice, diagnoses or treatments. If you need medical advice, use the "Find an Orthopaedic Foot & Ankle Surgeon" tool at the top of this page or contact your primary doctor.