The living dead: new embalming method aids surgical training
An embalming technique pioneered in Austria that produces near life-like cadavers for medical use is set to improve surgical skills and accelerate the adoption of new surgical techniques and technology.
Using a process developed over several decades, the so-called Thiel soft-fix embalming method retains the body's natural look and feel.
Skin and muscles remain flexible, allowing the limbs to be moved, while the body's internal organs are clearly identifiable and respond to the surgeon's scalpel as if alive.
Conventional methods of preservation using formaldehyde leave the body stiff and fragile, and complicate the understanding of how the body will respond to a particular surgical procedure.
Like any practical skill, practice is crucial to learning surgery.
Enabling surgeons to try out a technique on a dead body before operating on a live patient allows surgeons to understand anatomy, minimise potential damage and rehearse the procedure before trying it for real.
"The benefits for surgeons are absolutely massive," says Sue Black, head of the Centre for Anatomy and Human Identification at Dundee University, which recently brought the Thiel technique to the UK.
"There is no doubt surgical skill-sets are incredibly enhanced, while it also allows for innovation," she says.
Prof Black says patients will benefit from the more rapid adoption of new surgical products and methods.
Until 2006 it was illegal in the UK to practise surgery on cadavers. This meant that surgeons had to practise their skills on synthetic models or the carcasses of animals such as cats, dogs, rabbits and pigs.
Frozen body parts were also used, but they carry a high risk of infection and disintegrate in a day or two.
Prior to 2006, cadavers could be used for dissection but not practising surgery, out of respect for the deceased.
Using animals is never ideal as their anatomy is not always a good match for the human body. Similarly, bodies preserved using formaldehyde, a toxic solution, are never as good as the real thing.
"A formaldehyde-preserved body is not like a real body," says Dr Lena Vogt, a foot surgeon from Germany.
"It starts with the skin. You just touch it lightly with the scalpel and it falls apart."
She says that the bodies lack colour and the layers of tissue stick together making it "difficult to decide if [it] is a nerve, an artery or a vein."
Eureka moment at the butcher's
Typically, a break is needed every 20 minutes to escape the fumes.
The ones from the Austrian institute which pioneered the technique are far superior, she says.
"They look more like in the operating room. It is close to reality. You have the opportunity to understand the body much better; that helps you do surgery much better. Surgery is all about practice."
Up until the late 19th century, bodies had been preserved using arsenic, a very toxic poison.
This was replaced with formaldehyde after its discovery in 1867 by German chemist August Wilhem von Hofman.
However, it too is highly toxic and carcinogenic. Its use is restricted in many countries and discouraged by a 2007 EU ruling.
In the early 1960s, an anatomist called Walter Thiel, who was head of the Graz Anatomy Institute in southern Austria, began to look for an alternative.
His starting point was his local butcher's shop where he noticed that local "wet cured" ham preserved in a solution of salts had a superior texture to the formaldehyde-preserved flesh in his lab.
It took 30 years to perfect, starting with prime cuts of beef, more similar to human flesh than pork according to Thiel, before progressing to whole human bodies.
In all it took at least 1,000 donated bodies to get it right, says Friedrich Anderhuber, the late Prof Thiel's protégé and successor as head of the institute.
It was a lengthy matter of trial and error. A body would be injected with a preserving fluid and then soaked in the liquid for two years.
It was a matter of finding the right compromise between preserving of one part of the body and another, says Anderhuber.
"If you feel a muscle or a liver of a cadaver, it must feel like a muscle or a liver," says Anderhuber. The joints and tendons must also move like those of a living body he says, so surgeons can understand how they work.
Thiel eventually settled on a colourless and almost odourless solution of salts, antiseptic boric acid, ethylene glycol, an antifreeze, and a very low level of formaldehyde.
It is so effective in killing bacteria and fungi that it is safe to dissect the body without gloves and the cadavers can be kept at room temperature.
In the basement of the Graz anatomy institute a dozen bodies lying like sardines on a metal rack hauled up from a preservation tank in the cellar are noticeably limp.
Numbered plastic tags are attached to their thumbs, toes and earlobes, so they can be brought together for burial.
These have been in their tanks for a year. Once the soaking process is complete, they are transferred into plastic bags, the subsequent loss of fluid making the flesh more elastic and lifelike.
Altogether the basement houses around 250 bodies at any one time; around a year's supply for the institute.
In the next room, six newly arrived corpses lie on stainless steel tables. An assistant is shaving one because the hair would turn to slime in the preservation fluid.
The bodies of two elderly men and one woman are mid-preparation, heads propped on sections of blue plastic tubing.
These are jaundiced and slightly swollen from the fluid being fed into blood vessels in the neck and skull.
Each needs around 20 litres (five gallons) of preserving fluid, says Dr Anderhuber. Later, red dye is injected to give the blood vessels and flesh a realistic colour.
Fifty years since Dr Thiel's first experiments with pieces of steak his method is slowly catching on elsewhere.
According to Dr Anderhuber there is also interest in learning the method from Australia, Canada, the Czech Republic, Ghana, Spain, Switzerland and West India.
Prof Black's centre in Dundee, the first place to adopt Thiel embalming in the UK, recently used its last formaldehyde-preserved cadaver and will use only Thiel bodies from now on.
It has 11 tanks which can submerge 44 bodies at any one time and rack space for around 100.
The apparently ghoulish art of preserving the dead can help transform surgery to improve and prolong life.