Avocado Hand.
What the hell is that?
Who knew that that was even a ting?
Avocado related hand injuries – known officially as “avocado hand” – sent an average
of 24 people every day to the ER in AMerica last year.
What in the world is going on?
B1: Evil avocado meme
Avocados are delicious and nutritious– but why are they sending so many people to the
hospital?
Why are they so damn aggressive?
This fruit, and yes avocados are a fruit, is botanically a large berry that contains
a single seed.
And if you didn’t know that, don’t feel bad, someone on the internet thought it was
a form of meat… pause, eyes looking side to side.
It isn’t.
It IS however an excellent source of monounsaturated fat and vitamin E, and a good source of folate.
It supplies more soluble fibre than other fruit and contains a number of useful minerals
including iron, copper and potassium – all nutrients that contribute to healthy function.
So far so good– sounds harmless, and yet a 2019 study found: “that there were 8,900
avocado related ER visits [in 2018].
Side note, that same study also points out “that over 70% of the injuries were sustained
by women and in cases where race was supported, 80% of injuries were sustained by white people.”
So if you have a middle aged white woman in your life, you should send her this video.
She may be in danger.
In any case, if it’s not the consumption of the alligator pear that is sending people
to the hospital, then what is it?
At first glance, this large berry seems so harmless.
But without a knife it’s difficult to access the nutritional wonders contained on the inside.
Thus our adventure begins:
Can we get a possible knife injury possibility counter somewhere on the screen?
B2: knife injury possibility counter
Initially some people stab through the tough avocado skin and rotate the knife around the
pit to cut the fruit in half (1).
Then the pit is revealed, resting innocently at the centre of the meat.
For a quick, clean removal, most people deliver a quick thwack to the pit, lodging the knife
therein, and with a twist they are halfway to dinner (2).
Others at this stage opt for a stabbing motion– though that’s practically a deathwish.
Once the pit is removed, many people like to slice the avocado into cute little bits
while it rests in its shell.
Bear in mind that the body of the avocado is 73% water, 15% fat, with the rest composed
of fibre and protein – meaning it doesn’t offer much resistance to the pressure of the
knife.
With every single stab and slicing motion there is (3) a risk (4) of stab (5) and slice
(6) injury…
You get it.
The hand is a very delicate and complex structure, containing 27 bones, 27 joints, 30 muscles
and over 100 ligaments and tendons, not to mention the associated blood vessels and nerves
– all working in concert to perform fine motor tasks as our primary physical interface
with the world.
In the aforementioned study, “the majority of injuries were lacerations implying that
the injuries occured with the blade edge” not the knife tip.
It is also possible that patients with puncture wounds weren’t as quick to seek medical
care.
The study goes on to say that “Several patients presented with infection associated with their
avocado-related knife injury, suggesting that delayed infection after injury is common…probably
because people were too embarrassed to initially present themselves to the Emergency Department
after they had stabbed themselves so carelessly.
Additionally, several patients in this study injured critical structures” and that Emergency
Department physicians should “consider vascular injury, nerve injury, and tendon injury in
any patient with an avocado related knife injury to the hand.”
Tendon and nerve injuries are serious and often subtle and the author suggests that
medical providers should have a low threshold to consult a hand surgeon for injury evaluation.
In this table, we can see that injury is more prevalent in the left (typically non dominant)
hand than the right, occurring about half the time in the fingers and half the time
in the palm.
Of the digits, the index finger is the most at risk while the thumb, middle and ring are
less likely to be injured..
Pinky fingers rejoice– the odds are in their favour.
B3: Pinky fingers @ stadium rejoicing.
So now that we know the basics– what specific injury patterns might constitute a bloody
case of avocado hand?
Flexor tendon injuries are a suitable place to start as they could be injured in both
digit or palm lacerations to the hand.
These strong smooth cords connect the muscles of the forearm to the bones in the fingers
and thumb.
These tendons run inside tunnels at the wrist and in the fingers, and they bend your fingers
in the manner of a bicycle brake cable.
The fingers have two while the thumb only has one.
A cut or ruptured tendon in the palm or finger will make it difficult and maybe impossible
to bend one or more joints in a finger.
SImilar to an elastic band, flexor tendons are under tension as they connect to muscle
and bone and when they are torn or cut, the ends recoil away from the location of the
laceration.
For this reason, a fully cut tendon cannot heal on its own– a gap is created between
the two ends.
In some cases a flexor tendon may only be partially cut.
When this happens it may be possible to bend your finger to some degree– thought it probably
won’t feel very good.
Depending on the degree of the partial laceration, there is a chance that the tendon can heal
without surgery.
The hand will be immobilised in a splint during the rehabilitation process.
When a tendon is fully cut, surgery is necessary.
The sooner this surgery is performed the better the chance of recovery.
Once a tendon is cut, the ends will begin to form scar tissue, making them less amenable
to reattachment and since the ends must be touching to heal,
time is of the essence.
Also, bear in mind that a severed tendon is still attached to the muscles and bones on
either side of it and if those muscles activate the tendon will respond and recoil further
away from the location of the laceration.
Imagine you’ve cut a flexor tendon in your finger, and you go to make a fist: the muscles
in your forearm pull on this tendon, but instead of pulling the digit into a fist position–
they pull the severed tendon deeper into the palm of your hand.
This is a complicating factor for surgeons, who will need to cut into your palm until
they have found the severed tendon, which they will then stretch and reattach.
It’s like hide and seek.
But the seeker is a scalpel and the hider is a slippery little elastic cord inside your
body.
Fun!
Before surgery, a doctor may administer antibiotics and a tetanus jab (depending on the nature
of the injury) to prevent infection.
They will then put a tourniquet around the upper arm to minimise bleeding.
Now, tendon repair surgery can be performed under general anaesthetic and local anaesthetic
which means that you may be awake as someone plays jigsaw on your hand.
B4: saw meme.
No matter if your tendon has been severed horizontally or at an angle the surgery will
likely require special sutures or stitches to reconnect both ends.
An article in the Journal of Hand surgery pegs “fiberwire and stainless steel as the
most biomechanically suitable suture materials for flexor tendon repair whereas nylon is
the least suitable…
Suture material strongly influences the biomechanical performance of multistrand tendon repair and
is an important consideration for the surgeon.”
A biomechanical analysis of suture materials and their influence on a four-strand flexor
tendon repair.
Once the surgeon has chosen the reparative materials, they will then choose a repair
technique.
There are many methods of tendon repair by many different names but all of the techniques
have a common goal as surgeons attempt to place as many suture limbs across the site
of rupture as possible.
Typically there are between 4 to 8 suture limbs spanning across this site with surgeons
constantly innovating new methods of suture application to improve upon this procedure.
The more suture limbs, the better the connection between severed ends– but there are two
major limiting factors.
1) the tendon is a small chord of (somewhere between 2.5 and 5mm thick) and can only sustain
so many sutures. 2) The tendons live inside a sheath within the hand and fingers that
guides them as they move.
If too much reparative material is placed inside that sheath then reduced function will
result.
Once the doctor is finished they’ll stitch you up and your hand will be placed in a rigid
plaster splint to protect the tendons.
A simple flexor tendon repair takes between 45 and 60 minutes.
Now when someone takes a knife to their hand, tendons are not the only structures at risk.
Nerves and blood vessels are also very close to the tendons and run through the fingers
and palm of the hand.
Two palmar arches, the superficial and the deep palmar arches, run through your palm
in an upside down U shape, supplying the vessels of each individual finger with blood.
A blood vessel that has been severed would need to undergo either microvascular repair
by a plastic surgeon, or be ligated (cut off completely).
Ligation is typically reserved for smaller blood vessels that won’t damage other structures
if cut off (ie.
preferably not the palmar arches).
An injured palmar arch could go either way depending on the discretion of the surgeon
since there are two.
In some cases, your body can function with only one of these arches intact, but of the
two, the superficial arch is the most important so it is more likely to be repaired than the
other.
When ligation is necessary, the surgeon may ligate the injured vessel (ie.
tie off the ends of the vessel) and leave the remaining arch to adapt to the increased
demand in blood flow.
It is also possible for a laceration to the hand to injure a nerve causing numbness, loss
of feeling and weakness in the hand or digits.
Sometimes, these sensations may be caused by bruising or swelling around the nerve,
resulting in a neuropraxia, or a mild injury to an intact nerve, rather than a transection
of a nerve, known as a neurotmesis – either way you’ll know because if it the nerve
is transected, the feeling just won’t come back.
Period.
When a nerve is lacerated, the surgeon must determine if it is possible to repair it.
If it can be repaired, they will remove damaged nerve endings if necessary and stitch it back
together with special sutures– so long as there is ample length to allow for repair
without tension.
This procedure is delicate since nerves can stretch a small amount, and you really don’t
want your principal sensory organ under excess tension.
That equals pain.
If a nerve is too far gone, they will remove the damaged section and either: reconnect
healthy nerve ends or implant a piece of nerve from another part of your body, a nerve graft.
Isn’t science wonderful?
We started off talking about fruit-inspired injuries, and ended up talking about microvascular
repair and nerve grafts.
Okay, interns.
So now it’s your turn.
What did you learn today?
(pause)
Comment down below one thing you took away from today’s video!
Outro!