When Is Amputation The Salvage Procedure?

While there may be a perception of amputation as a failure in treatment, these authors maintain that amputation salvage procedures do play a role in limb preservation and can enhance the quality of life for patients with diabetes. They address the timing and decision-making with these procedures and review emerging advances in prosthetics.

   Diabetic foot infections can range from a superficial infection on the toe to a raging infection of the entire foot. Given the degree of complexity that can occur with diabetic foot infections, we must work together as a multidisciplinary team to assess the comorbidities that led to the patient’s current condition and try to control or eliminate them.

   When a diabetic foot infection complicates wound healing, we need to consider a variety of questions. Is it because the patient is non-adherent with medications or because the patient has no control over the disease? Does the patient have poor vascular supply to the foot? Does the patient have adequate offloading? Does the patient have the proper footgear for his or her foot type?

   We obviously need to consider all of these things when treating a patient with diabetes. All of our efforts are geared toward expediting wound healing and ensuring limb preservation. The key question: When is amputation the salvage procedure?

   Amputation is a salvage procedure when there are no other means or solutions to resolve an infection. When making the decision to amputate, the patient and the doctor should collaborate together to achieve the best outcome.

   Often, the decision to amputate is straightforward. For example, a patient comes into your office with an infected ulcer on the hallux that probes to bone and is draining purulent material. Following blood work, the erythrocyte sedimentation rate (ESR) comes back at 110. The X-ray shows acute periosteal erosion suggestive of osteomyelitis. One would probably not hesitate to take that patient to surgery to remove all infected bone and soft tissue before progression of the osteomyelitis.

   However, what about the patient who has a persistent but stable non-healing ulcer on the hallux? Should you amputate the hallux because of a non-healing ulcer? What if you have tried a multitude of therapies such as topical therapy, serial debridements and hyperbaric oxygen therapy, and nothing has helped?

   Can the surgeon consider amputation as a treatment option? Of course it is an option, especially if the patient prefers to get back to his or her quality of life. Often, patients are bogged down with extensive treatments and dressing changes. Conservative therapy can be extremely overwhelming and sometimes the patient may not be willing to try.

   Duzgun and colleagues report that four to five months of conservative therapy is a reasonable amount of time to allow a wound to heal.1 However, if you have exhausted all options at this point and the patient still has a chronic wound, one may consider amputation as a treatment option. There is a controversial thought that amputation leads to morbidity and sometimes mortality, but one should also consider that amputation could increase a patient’s quality of life. There is a general misperception among surgeons that an amputation means they failed in their job. However, amputation can certainly equate to saving a patient’s life.

How Adequate Vascular Supply Affects Salvage Procedure Selection

   Also consider amputation in a foot with marginal perfusion or limited vascular outflow secondary to traditional bypass or endovascular procedures. For many patients who have undergone lower extremity revascularization, adequate blood flow may be restored to the midfoot region but there may be limited flow to the digits.

   When considering amputation of the foot or part of the foot, it is important to know the anatomy, particularly the blood supply. Angiosomes of the foot are essentially three-dimensional blocks of tissues supplied by a source artery.2 The foot and the ankle have a total of six angiosomes that are bordered by choke vessels. The main purpose of choke vessels is to allow communication to adjacent angiosomes. The posterior tibial artery feeds three angiosomes (calcaneal artery, medial plantar artery and the lateral plantar artery). The anterior tibial artery feeds one angiosome and the peroneal artery feeds two angiosomes (the calcaneal branch and anterior perforating branch). Revascularization procedures can produce perfusion to one zone and not to another.

   For example, the posterior tibial artery can be patent. This artery provides flow to the hindfoot in addition to the peroneal artery, but the dorsalis pedis may have limited outflow. Due to a lack of revascularization to the anterior tibial artery angiosome, a proximal transmetatarsal amputation would be the salvage procedure.

   The literature has reported that 15 percent of all bypass surgeries fail to heal foot wounds because the bypass failed to revascularize the affected angiosome.2 Studies have also reported that it takes four to 10 days for choke vessels to become patent after a given angiosome becomes ischemic.2 Therefore, paying due consideration to the angiosomes and the vascular supply to the entire foot and ankle is an important factor in planning and deciding upon the level of amputation.

Other Pertinent Considerations With Salvage Procedures

   In addition, when deciding on amputation, keep in mind the potential effect on the contralateral limb. In 2003, Sumpio and colleagues reported that nearly half of all patients who undergo an amputation of one limb will develop limb threatening ischemia of the contralateral limb and may require amputation of that limb within five years.3

   A partial ray/foot amputation or a combination of amputation with flap or skin graft are also salvage procedures. Amputation can be the salvage procedure for those who have had a partial foot amputation that must be converted into a stable parabola or a transmetatarsal amputation.

Can Advances In Prosthetics Enhance Mobility And Quality Of Life?

   The main obstacle to prosthetic use is complications at the stump-socket interface. Poor socket fit can lead to instability, tissue breakdown and pain. However, it is important to remember there have been great advances in prosthetic technology.

   Osseointegration is a new technique that attempts to avoid impediments at the stump-socket interface. Osseointegration incorporates titanium implants into the medullary cavity of the bone. However, the implants extend from the bone, emerging through the skin to create an anchor for the prosthetic limb. This method bypasses skin contact with the prosthesis, reducing pain and tissue damage.

   In one study, Jacobs and colleagues reported that bone-anchored prostheses yielded better perception than socket prostheses.5 This finding could prove invaluable to the amputation patient by improving kinesthetic awareness and increasing the overall responsiveness of limbs. However, this is controversial considering there is a barrier breakdown in the skin.

   Today, the most commonly used prosthetic foot is the solid ankle cushion heel (SACH). Another foot prosthetic is the energy storing and return prosthetic (ESAR) foot. This prosthetic is J-shaped and allows for increased walking speed. With advances in technology, we now have prosthetic feet that provide maximal energy return, shock absorption and quick response time.

   Most prosthetic feet have the J-shape design with a heel-to-toe foot plate and are made of carbon fiber. The expectation is no longer just the ability to walk but to have a prosthesis that allows patients to move quicker, and even run the moment they need or want to do so.

   The most recent prosthetics are the Power Foot and the Spring Ankle with Regenerative Kinetics (SPARKy). The Power Foot is a powered ankle-foot prosthesis designed by the MIT research group Biomechatronics. It has a unidirectional spring, which is configured in parallel with a force controllable actuator with series elasticity. The prosthesis can mimic the normal human ankle walking behavior.

   The SPARKy was designed by the Arizona State University Human Machine Integration Laboratory with team members from Arise Prosthetics, Robotics Group, Inc., and the St. Louis University Human Performance Laboratory. The SPARKy is a device with 2 degrees of freedom (DOF), which incorporates active control of inversion, eversion, plantarflexion and dorsiflexion. With this in mind, one can educate patients on the aftermath of an amputation. After a minor or even a major amputation, patients can have the hope and ability to continue with their lives.

In Summary

   There is a prevailing misperception of the amputation signaling that the surgeon has lost hope and given up. However, it is important to realize that amputation can actually save a patient’s life and restore quality of life. A minor amputation may save a limb and a major amputation may save a life.

   Amputations in the diabetic population are generally the result of infections, avascularity or deformity. When you make the decision to amputate, you need to remove all infected bone and marginal soft tissue, and remove all potential dysvascular tissue. The surgeon should always plan incisions to accommodate for the possibility of future amputations.

Dr. Catoire is in the midst of a PM&S 36 residency at the Yale New Haven Hospital in New Haven, Conn. She graduated from the Ohio College of Podiatric Medicine in 2008.

Dr. Blume is an Assistant Clinical Professor of Surgery in the Department of Orthopaedics and Rehabilitation at the Yale University School of Medicine. He is Director of Limb Preservation at Yale New Haven Hospital in New Haven, Conn. Dr. Blume is a Fellow of the American College of Foot and Ankle Surgeons.

Dr. Sumpio is the Chief of the Section of Vascular Surgery at the Yale University School of Medicine.

References:

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