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Foot Amputations

Foot Amputations
Foot or partial-foot amputations can be done in situations of trauma, foot infections or ischemia of the feet.  Historically, the surgeons treated foot infections and gangrene using higher up amputations, such as above or below the knee amputations but advances in antibiotic treatments and surgical treatments have made it possible to cut off only a part or the whole foot without having to sacrifice areas higher up on the leg.  This means that more foot amputations are being done than ever before. 

The most common reason to amputate the foot is an infection and/or ischemia in diabetic patients.  Patient with a peripheral vascular disease can develop dry gangrene of the foot.  Injuries involving lawn mowers or motor vehicles are also reasons to remove all or part of the foot. 

In order to do proper amputation surgery, the surgeon must be able to remove enough bone so that there is skin to cover the end of the wound and the site of the suturing must not be on weight-bearing parts of the foot because these areas lead to scarring and the potential for further irritation and pain at the suture site. 

The surgeon can use techniques like Doppler flow studies and oxygen perfusion studies on skin tissue to see whether or not the circulation is adequate at a particular site on the foot or leg.  Oxygen perfusion studies do not work at the level of the toes but anything proximal to the toes can be checked to see if the oxygen levels will be good enough for healing or for healing aided by hyperbaric oxygen treatment around the time of surgery. 
If the patient has sustained a foot trauma, it makes sense to debride the foot of areas that will definitely not survive and wait for other areas to either begin to heal or become obviously non-viable.  This requires a multi-stage procedure but has the potential to save the foot. 

Surgery on the foot is best if the surgeon thinks of doing a longitudinal surgery rather than a transverse approach.   If the foot can be amputated with some of the toes left on, the level of amputation isn’t as severe when compared to cutting the foot off in a transverse fashion and it is much easier to get a prosthetic foot or special shoe to fit a narrowly cut-off foot than one that has been cut transversely. 

As with any amputation surgery, the surgeon must round off any bony prominences and may have to go into surgery more than once if an infection has traveled up inside the foot and/or ankle.  At the same time as the initial surgery, broad-spectrum antibiotics should be used to kill any infection not initially seen at the time of surgery.  Tendons and ligaments already have poor circulation so they should be removed if they are visible within the wound.  The tendons can later be attached higher up on the foot so the ankle can move up and down without difficulty if the surgery just involves the foot. 

If the amputation involves the great toe, with or without any other toes involved, there may be lifelong balance problems, especially since the great toe is necessary for walking without a limp.  If any of the great toes can be saved, balance is much better.  

A “Ray amputation” involves removing a toe including at least some of the metatarsal within the foot.  It is usually done on the first toe or the fifth toe with the corresponding metatarsals (or parts of them) removed along with the toe.  The foot is then made thinner so that special shoes are required. 

If more than one toe might need a Ray amputation, it is sometimes better to cut off the entire foot at the level of the proximal metatarsals. This disarticulates the metatarsals from the tarsal bones in the back of the foot and ankle.  Barefoot walking is severely impaired; however, with the right shoe, the patient can often walk normally, even with so much of the foot missing. 

In a traumatic situation, it is a good idea to do the surgery in two stages, the first being the debridement stage when foreign material and all dead tissue is removed, and the second being definitive closure when it becomes more clear as to what part of the foot can be saved through adequate circulation and sensation.   
Prosthetics for the Foot
The intact foot is responsible for being able to push off when walking and for taking the weight from the body standing or walking on a surface.  Any time that the foot is cut off and the metatarsals go with it, it is difficult for the remaining foot to hold the body up without undue pressure on the remaining foot and ankle.

There are foot prostheses that are very realistic, with acrylic nails on the toes that can be painted with nail polish like any other toes.  Prosthetics usually come along with an appropriately fitted shoe so that the weight can be spread to the prosthesis and shoe rather than just the hind foot.  If the hindfoot is the only thing left, it cannot bear the load of the body on it and will begin to twist and give in.  A good prosthesis that provides cosmetic appeal is usually added so that there is softer material near the delicate skin of the foot and harder interior material that can assist with load bearing.   
Photo by Pixabay.com
Editor’s Note: This page has been updated for accuracy and relevancy. [cha 10.3.18]