Deep in the outback, far underground, lives a small frog that could soon be hopping its way into surgical theatres around the country. The Holy Cross frog secretes a sticky substance from its back that orthopaedic surgeons are excited about – could it be used as a medical adhesive for muscular skeletal injuries? The frog normally uses this glue to ensnare biting insects for food, but researchers have discovered that it’s stronger than any non-toxic medical adhesive on the market.

TRANSCRIPT

Narration: In the deep, dark Australian outback lives an amphibian with a very strange talent. Herpetologist Mike Tyler and I are on a late night mission to track this elusive creature down.

Maryke Steffens: Quite possibly it could be the next big thing in orthopaedic surgery.

Narration: Mike has studied thousands of species of amphibians, but THIS one in particular has caught his eye.

Mike Tyler: Isn’t it beautiful?

Maryke Steffens: He’s lovely actually.

Narration: Meet Notaden Benittii or the Holy Cross frog who emerges from his hibernation one metre below the surface for just a few months each year.

Mike Tyler: They rush around, mate, feed and then they go down again.

Narration: Digging in the dirt requires a well-honed gymnastic backwards manoeuvre.

Mike Tyler: On their feet are little spades. And what they do is push the earth from side to side and they live very happily underground. You can see why it’s called the Holy Cross frog because it’s got a crucifix on its back.

Maryke Steffens: Oh yeah.

Narration: Based in Adelaide, Mike’s fascination with frogs began as a child. He went on to discover 50 new species and has no less than 6 named after him.

Mike Tyler: My study of frogs has enabled me to observe and sometimes discover things which are just so fantastic that other people wouldn’t believe they were true.

Narration: One such fantastic event occurred two years ago when Mike was out in the bush, handling a Holy Cross frog. It secreted an extremely sticky substance onto his fingers.

Mike Tyler: Wash with soap, wash with abrasives, I could not get it off. I found the only way to remove this glue from my fingers was to cut it off with a knife.

Narration: Right there and then at the campsite, Mike began experimenting by gluing other objects together, including full cans of beer.

Mike Tyler: Paper and cardboard and plastic, I tried all those and it stuck them all together. And I found that it would stick things together whether they were wet or dry, cold or hot. So really what we’ve got is a glue that we may use for repairing the leg on a table but probably has much more significant potential in the field of medicine.

Narration: Professor George Murrell performs a dozen orthopaedic operations every week. As head of a medical research team, he’s jumping at the opportunity to explore using a glue that might improve current surgical techniques.

Professor George Murrell: I said well oh yes, it would be helpful for gluing menisci back together, gluing cartilage back together, maybe for gluing tendons back together. We know that muscular skeletal injuries in general account for about 6 out of 10 times a patient sees a doctor.

Narration: And that translates to a lot of surgery, the most vulnerable areas being the knee, the back and the shoulder.

Professor George Murrell:So in the shoulder the most common injury is to the rotator cuff tendons, which are a set of tendons that surround the ball part of the ball and socket joint, and it usually gets damaged by getting pulled off the bone so it gets retracted. Currently we use sutures and anchors to reattach this tendon to bone. The problem is that you don’t necessarily get a good attachment and it would be very helpful to have a glue for instance that might allow it to heal to the bone over period of time, let’s say 6 to 8 weeks.

Narration: For this type of surgery there are currently no glues that are both non toxic and strong enough to hold together robust joints. Could this tiny frog be the sticky answer to a tricky problem? For Notaden bennittii its glue is a matter of survival against predators.

Mike Tyler: Imagine a large amount or ants or termites attack the frog. It lets the glue out, sticks their little jaws together and the poor little creatures die on the outside. Once a week, twice a week the frog changes its skin, swallows all the ants at the same time and gets a meal whereas he was suppose to become a meal himself.

Narration: And if that’s a bizarre recipe, try this for a frog glue experiment – 30 sheep shoulders, some arthroscopic medical equipment and one perplexed frog.

Maryke Steffens: Neil it’s pretty odd that you’ve got to have a frog right next to the operating table.

Dr Neal Millar: Yeah well, it’s because the glue sets so quickly once we take it off the back of the frog.

Maryke Steffens: How long have you got?

Dr Neal Millar: Oh about 30 seconds or so.

Narration: After cleaning out the local butcher’s supply of sheep shoulder bones, doctor Neal Millar is running phase two of the frog glue experiments using the same surgical procedures as those in the human operating theatre.
Dr Neal Millar: We’ve put some stitches in already and we’ve passed the stitches into this device and then we put this anchor into the pre-drilled hole so it goes right down. And then we just fire it so that the anchor is now in the bone.

Narration: Normally the tendon would then simply be stitched back onto the bone but this is where sticky little Notaden Bennettii makes his grand entrance.
It’s a race against the clock to butter the super-fast drying glue onto the area where the tendon will contact the bone and then wind the tendon back into position before it hardens.

Dr Neal Millar: So that helps to stick that down and that’s it fully repaired now.

Narration: The shoulder bones will need to be strength tested and compared with non-glued sutured joints before its real effectiveness can be proven. But earlier studies by professor Murrell have already revealed great promise.

Professor George Murrell:The first set of experiments we did I got a sheep knee from the local butcher. What we did was to make a cut, a radical cut along the meniscus similar to what you would see in humans and then glued that either with the frog glue, or with super glue, or with fibrin glue and then pulled them apart in a machine to test the strength.

Narration: While the cyanoacrylate or superglue was the strongest, it’s toxic. Compared to the remaining surgical glues, the frog glue was impressively superior in strength and other properties.

Professor George Murrell: Because it’s nice and runny you might be able to put it in a special syringe for instance and deliver it just to the right place. The other advantage is that it sets up both in air and aqueous environments, in water environments. Now when we arthroscope knees and shoulders we use water to help us in that process so if we can use a glue that will set up in water there is obviously a big advantage.

Narration: All exciting stuff, but don’t expect to see this frog in the operating theatre when you next need an operation.
Professor George Murrell:The next step is to make a synthetic version and do more animal experiments and then one would have to do simple experiments working up to more complex experiments in humans. So it might be at least 5 years, probably more like 10 years before a glue like this gets used in humans.

Narration: In the meantime, little Notaden bennittii will be trying his best to stay out of the limelight.

Related Info

Story Contacts

Mike Tyler
University of Adelaide

Professor George Murrell
Orthopaedic Surgeon
Department Orthopaedic Surgery

Dr Neal Millar
Orthopaedic Surgeon

St George Hospital Orthopaedic Research Institute

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