The Amrita Sling Technique
March 5, 2012
School of Medicine, Kochi
The Department of Podiatric Surgery at the Amrita School of Medicine successfully replaced the destroyed foot and ankle bones in a 30-year-old patient with a novel prosthesis using polymethyl methacrylate (PMMA).
The surgery was led by Dr. Ajit Kumar Varma who was assisted by Drs. Mangalandan T.S., Vishak Varma and Sahil.
The prosthesis was affixed through a surgical technique now known as the Amrita Sling Technique.
Dr. Ajit described the process and patient case history and management.
“Four years ago, the patient developed spinal cord injury due to fall from a height. This caused severe neurological deficit of his lower limbs. In some time, muscle strength of the lower limbs improved and he started walking. But when the bones of the right foot and ankle started bearing weight, they developed Charcot’s destruction as they were osteoporotic. He consulted many physicians; they all advised a below-knee amputation.”
“We took three dimentional color CT images of the patient’s normal foot and ankle on the left side. By creating a mirror image of these pictures, we got an excellent idea about how to repair the damaged right foot and ankle bones. We made PMMA moulds of the damaged bones, sterilised them by the proper technique and during surgery, implanted them in the patient’s foot. Seven such damaged bones of the patient’s right foot were replaced.”
“By affixing the PMMA prosthesis, we prevented below-knee amputation and improved the quality of life for the patient.”
The Amrita Sling Technique was devised by the Amrita Podiatry Team for reconstructing and stabilizing destroyed Charcot foot and ankle bones. Caused by Charcots osteoarthropathy, a condition which occurs due to autonomic neuropathy, it is usually seen in patients with diabetes and neurological problems.
In the past one-and-half years, the Department has performed six such surgeries, all with excellent results. PMMA has also been used to replace single foot bones, when these were destroyed by infection.
The doctor explained that in conventional surgeries carried out worldwide, titanium compression screws are used to fix and fuse destroyed foot and ankle bones. “As the bones become severely osteoporotic, the compression screws do not hold well, and once the patient is ambulant for a few months, re-collapse of the bones occurs.”
“Severe peripheral neuropathy makes the foot and ankle bones soft, brittle and of very poor density. In such cases, if the patient starts walking or weight bearing, the bones become eroded with micro-fractures which later lead to severe bone destruction. This finally ends in a below-knee amputation.”
The doctor explained further.
“PMMA replacement prosthesis, as per our extensive literature search, has never been used by any major diabetic foot center in the world for the replacement of destroyed foot and ankle bones. Also known as bone cement, PMMA has excellent tissue compatibility.”
In February 2009, the Online Journal of Diabetic Foot Complications published Dr. Varma’s paper on the Amrita Sling Technique.
Now with PMMA prosthesis, the Department of Podiatric Surgery at Amrita has marked a new beginning in foot and ankle reconstructive and corrective surgical techniques.