If you are considering a surgery that involves the cutting and repositioning of bone, or if you need surgery to repair a fracture, there is a good chance that you may need something to hold your bones together, or "fixate" your bones. The most commonly-known way to do this is with a cast, but sometimes additional support for the bone is needed.
The purpose of this section is to provide you with basic information on some of the various methods podiatrists may use to fixate--or hold together--bone.
This page discusses the following terms listed alphabetically:
When bones are broken (fractured) or otherwise need surgery to attach and stabilize them, it is known as "open reduction, internal fixation", or ORIF for short. The name is derived from the process itself, the skin is "opened", the fracture is "reduced" (repositioned), and the bone is stabilized or ("fixated") by some sort of device inside the body (that is "internally").
In contrast, closed reduction is the process of realigning the bones without surgery, by manipulating them, for example. Examples of external fixation would be a splint or a cast.
This web page discusses some
of the various ways that bones may be reattached by internal
K-Wires and Steinman Pins, both often simply called Pins, are probably the most common means of fixating bone. K-wires and Steinman pins are difficult-to-bend surgical steel rods that are inserted into bone to keep the bony fragments from shifting during healing.
The advantage to using pins to fixate bone is that they are inexpensive (always important in this day and age), they come in various sizes, (so the surgeon can tailor the type to the bone that requires fixation), they are easy to insert, they don't traumatize bone much, and they are typically removed following surgery, so the patient has no foreign material left from the surgery.
The disadvantages are that they do not provide compression (in other words, they don't squeeze the bone together, which would speed up the healing process), and they typically stick out of the foot, (which leaves an opening in the foot for a potential infection to develop, and which prevents the patient from bathing for as long as they're in--often 4 or 5 weeks).
Several types of Absorbable Pins exist for patients who cannot tolerate traditional metal materials. Absorbable pins are substantially more expensive than metal materials.
Cerclage Wire is a simple, stainless steel wire that is used to hold bone together. Unlike pins, cerclage wire is very flexible, and can be applied in a variety of creative situations and techniques--sometimes with pins--to provide compression.
Disadvantages are that it may sometimes traumatize bone, it is meant to be permanent (you don't typically remove it), it requires good, solid bone, and it is may be more difficult to insert than pins.
Staples are exactly what they sound like--staples that you can apply to bones to hold them together. Of course, they are specialized staples, but the concept is pretty much the same as those you may use at work.
The advantages of using staples are that they're a very quick way to hold bone together, and they can be quite effective if used in the right settings.
The disadvantages are that they are not always inserted correctly, they are not applicable to all situations, and while they maintain alignment of the bony fragments, they're not as good as other means to compress those bone fragments together, something which speeds healing.
The types of fixation we've discussed, K-Wires, Steinman Pins, Cerclage Wire and Staples have their places, but they are not necessarily the best way to fixate bone. As I mentioned above, the best and fastest way to allow bone to heal is to provide rigid fixation (prevent any movement) and to squeeze the bony fragments together. In order to do that, new techniques were required.
The technique that was developed is called Osteosynthesis or A.O. Fixation. (The initials A.O. stand for "Arbeitsgemeinschaft für Osteosynthesefragen"--so now you know why we just call it A.O.)
Internal Fixation refers to the concept of providing rigid compression to squeeze bone fragments together using screws, plates or other materials that are housed inside the body. (Compare this to External Fixation below.)
Screws are frequently used in podiatric surgery. Most are just like the type that you might have in your workshop, only made out of specialized materials that can be used in the body--and they're a whole lot more expensive.
There are several different types of screws, but most are used to provide compression--the act of squeezing the opposing bone surface together to speed healing.
Several types of Absorbable Screws exist for patients who cannot tolerate traditional metal materials. Absorbable screws are substantially more expensive than metal materials.
While screws are usually very effective in providing compression of bony fragments, at times, screws may not be adequate to stabilize bone by themselves.
In these cases, Plates may be effective. Several different types of plates exist that and are used in podiatric surgery, though because of the small nature of most foot bones, the indications are somewhat limited than for other parts of the body.
Static Compression Plates and Dynamic Compression Plates are both types of plates that compress bones together in certain cases where a screw may not be positioned adequately to hold the bones together well. In contrast, Neutralization Plates are used as an adjunct to regular screw fixation. In these cases, screws are used to provide compression of the bony fragments, and the neutralization plate is applied simply to absorb any disruptive forces that may compromise the screw compression. Buttress plates are used not to provide compression, but to maintain separation of bone during bone grafting procedures to gain or maintain length.
External Fixation refers to the concept of providing stability and/or compression to a bone with the hardware held outside of the body. These devices can be used in the same way plates can be used--to provide compression of bone fractures that don't lend themselves to screw fixation, and to maintain separation of bone during bone grafting procedures or crush fractures--to gain or maintain length.
External Fixators, also known simply as Ex Fix, are the devices that provide external fixation. Most external fixators are large and used more in the leg and ankle than in the foot.
Mini Ex Fix are smaller versions of the larger external fixators, and these are more commonly used in the foot.
Finally, I'll mention Bone cement, or Polymethylmethacrylate (PMMA). Bone cement is a synthetic material that is usually used in gaps between bones to hold them together.
Even though bone cement isn't stable enough to be used alone (it is almost always used in conjunction with mini ex fix, a buttress plate, or some other type of fixation), it can be thought of as a way to provide stability to help fixate bone.