New technique to prevent diabetic lower-limb amputations
April 22, 2013
Today, in India, there are more than 63 million people living with diabetes, second only to China, as per the latest 5th
Diabetes Atlas statistics. Being a disease of the blood vessels diabetes affects all organs. By the time the blood
supply to the foot has been compromised due to peripheral obstructive vascular disease, the heart is also involved. The
use of prosthesis in a patient living with diabetes increases the cardiac strain to over 15%, leading to cardiac failure
over a period of time. World statistics show that when walking even with the best of prosthesis, mortality at 5 years
after unilateral below knee amputation is 50%, and there is 50% mortality after above knee amputation in 3 years, due to
cardiac failure.
The prevalence of osteomyelitis in the diabetic foot has been found to vary from 18% to 68%. The diabetic foot is also
very prone to Charcot’s osteo-arthropathy (‘Charcot’s Foot’ is a severe complication of diabetes, which leads to soft
and brittle foot and ankle bones). Both these conditions result in the destruction or excision of foot bones which leads
to deformed feet with altered biomechanics and the appearance of new pressure points in regions of the foot unaccustomed
to bearing such forces. This results in formation of recurrent calluses and ulcers, which can get infected. The
infection and progression of these ulcers very often lead to loss of the limb in the immune compromised patients of
diabetes. Arthrodesis of the foot and ankle may be the only alternative when the joints are destroyed. Amputation above
the infected part may have to be considered when limb salvage is not possible. Amputations of the toes and/or part of
the foot and limb not only place limitations on the physical activity of the patient, but are also not cosmetically
appealing. An estimated 50,000 amputations occur every year in India due to diabetes related foot problems.
The concept of re-shaping of a deformed foot or toes by surgical correction has evolved recently and is presently being
done routinely only in a few countries worldwide, (like the U.S, U.K, Russia, Germany, Spain and Australia) through
internal fixations, supported by external fixators for a few months. However external fixators can frequently cause pin
tract infections leading to disastrous consequences. In osteopenic bones of many deformed Charcot foot and ankle
patients, internal fixation with compression screws, plates and staples can lead to high rates of re-collapse and
further complications, within one and a half to two years of patient starting ambulation.
The Department of Endocrinology and Podiatric Surgery at the Amrita Institute of Medical Sciences (AIMS), Kochi, Kerala,
is the only centre in India where a new type of reconstructive and corrective foot and ankle surgery is being performed
in large numbers in high-risk diabetic foot patients under the able guidance of diabetic lower limb and foot and ankle
reconstructive surgeon Professor Dr Ajit Kumar Varma. He has pioneered a novel foot and ankle reconstruction surgery,
using PMMA (Poly Methyl Methacrylate), also called Bone Cement, as foot bone replacement prosthesis for severely
destroyed foot and ankle bones. By employing these novel surgical techniques, a large number of amputations in patients
living with diabetic foot ulcers and deformed diabetic feet are being prevented. As a result, AIMS has been able to
maintain a lower-limb salvage rate of 91.5%, in diabetic foot and ankle diseases, which is comparable to the best
centres in the world, said Dr Varma to Citizen News Service – CNS.
PMMA is a powder that hardens with an exothermic reaction when a monomer reagent is added to it, forming a hard
substance with a consistency similar to bone. Before setting and hardening completely it may be moulded to the desired
shape. This material is almost inert and has excellent tissue compatibility.
Poly Methyl Methacrylate Antibiotic Laden Cement (PMMA-ALC) is formed when bone culture specific heat stable antibiotics
are added to the bone cement in cases with osteomyelitis. This modality has been shown to be very effective in chronic
and acute osteomyelitis where sustained higher bone and tissue concentrations can be achieved compared to systemic
administration.
Prophylactic antibiotics may be added when the prosthesis is made for replacing the non-infected, destroyed bones of a
Charcot foot.
PMMA is approved by the FDA for human use, and is being extensively used in many surgeries including, total hip
replacement, knee replacement surgeries, spinal and maxillofacial surgeries. However, except for AIMS, PMMA Replacement
Prosthesis has probably never been used by any other major diabetic foot centre in the world for the replacement of
destroyed foot and ankle bones.
Amrita Sling Technique
In the last three years, the destroyed foot and ankle bones in over fifteen patients have been successfully replaced at
AIMS with the help of this technique. The prosthesis is fixed to the lower end of the Tibia to form an ankle joint,
through a surgical technique named the ‘Amrita Sling Technique’, devised by the Amrita Podiatric Surgery Team for
stabilizing after reconstruction. Patients have not reported any complications after these foot and ankle reconstruction
surgeries using PMMA prosthesis, and all the operated patients are now able to walk normally, using prescribed diabetic
footwear. This new surgical technique has been published in the international ‘Journal of Diabetic Foot Complications’,
in December 2012.
Dr Varma has another innovation to his credit. A few months back, he did a reconstruction with PMMA for severely
destroyed ankle bones, creating a mobile ankle joint. This PMMA replacement prosthesis for destroyed Charcot's foot and
ankle bones is the first of its kind in the world. The surgical video can be viewed online at: http://www.youtube.com/watch?v=U4tIu6TONbo
The technique of prosthetic replacement and arthroplasty is an effort to salvage the diabetic foot by replacing the
damaged bones rather than simply removing them. With good patient compliance the results have been very encouraging.
Being cosmetically more acceptable and having the potential to provide the patients with a biomechanically stable and
functional foot is a major advantage of the procedure.
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Shobha Shukla is the Managing Editor of Citizen News Service - CNS. She is a J2J Fellow of National Press Foundation
(NPF) USA. She received her editing training in Singapore, has worked earlier with State Planning Institute, UP and
taught physics at India's prestigious Loreto Convent. She also authored a book on childhood TB, co-authored a book
(translated in three languages) "Voices from the field on childhood pneumonia", reports on Hepatitis C and HIV treatment
access issues, and MDR-TB roll-out. www.citizen-news.org