Anatomy Mini-Lesson – Popliteal Aneurysm!

Greetings Outlander anatomy students!

Much time has passed since my last post partly because I am nursing broken bones of my left ankle. I am working off an iPad, instead of my desktop computer, so it is slow going. 😱

Today’s lesson details Mr. Walter Woodcock’s dilemma as presented in Outlander episode 705, Singapore.

You will recall, Walter lies in the infirmary at Fort Ticonderoga with a significant injury to his right foot. The wound has turned gangrenous so an amputation is required.

Claire arrives to witness a medical dispute between Dr. Denzel Hunter and the pompous, Lieutenant Stactoe.

Curious Claire asks, what is going on? 🤔

Denzel recommends an above-knee amputation for Walter. Stactoe is adamant that a below-knee amputation makes for a more functional limb.

Stactoe is correct that in most circumstances, every attempt is made to salvage as much of a limb as is possible.

However, Denzel explains that Walter has a popliteal aneurysm, thus, an above-the-knee amputation is necessary! Claire palpates Walter’s calf and agrees with Denny.

Oh, oh! This changes everything! 🤔

There ensues a wee strammash when Stactoe says Claire will not use boiling water on HIS instruments. This is a direct quote from Diana’s An Echo in the Bone:

You will ruin the temper of the metal, subjecting it to boiling water!”

“No,” I said, keeping my own temper—for the moment. “Hot water will do nothing but clean it. And I will not use a dirty blade on this man.”

“Oh, won’t you?” Something like satisfaction glimmered in his eyes, and he clutched the blade protectively to his bosom.”

In the episode, Stactoe stomps off. But, no worries, Denzel to the rescue with his own set of fine surgical instruments!

To understand the implications of a popliteal artery aneurysm, let’s look at the anatomy of the arterial supply to the knee.

Essentially all of the lower limb is supplied by the huge femoral artery which begins at the groin and descends through the front of thigh. Near the top of the knee, the artery passes to the back of the knee and is renamed the popliteal artery (next figure). It then descends behind the knee joint. At the bottom of the joint, it splits into two and then into a third artery, all of which receive new names and supply lower leg and foot.

The hollow behind the knee joint is the popliteal fossa.

Try This:  Make a fist, bend opposite knee slightly, and tuck your fist into the hollow behind your knee. This is the popliteal fossa. Remove your fist and insert middle and ring fingers into the hollow. Press. You may be able to feel the pulsing of the popliteal artery in the popliteal fossa.

Feel it? Good job, students! 🤗

   
Next. The aneurysm! 🤓

A popliteal artery aneurysm, known by the acronym PAA, is a weak spot in the wall of the popliteal artery. Pressure exerted by arterial blood causes the weak spot to balloon into a palpable bulge behind the knee joint. This is of concern because if the aneurysm should burst, the blood loss would be difficult to control especially in an amputee.

Some causes of PAA are:

• Atherosclerosis
• High blood pressure
• Wear and tear of the popliteal artery due to over use of knee joint
• Weakening of the artery wall

The image show a couple different types of PAA.

Now, back to the episode!

Claire palpates Walter’s leg and agrees with Denzel. An above-knee amputation is best to avoid the aneurysm bursting with uncontrolled hemorrhaging.

A clear view of his damaged, gangrenous foot can be seen in the next image.

Unfortunately, Claire places her hands on either side of his calf. She cannot feel a PAA in this location because there is no popliteal artery behind the calf. Her hands should be up in the hollow of the knee.

Nevertheless, she gets an A+ for trying! 🤩

Also, in real life, the stench of gangrene would likely require them to mask and use some type of ointment under the nose to distract from the odor. 😮

And, today, imaging modalities would be used to determine the type and extent of a PAA.

In the final scene with Walter, Claire breaks the sad news that his condition does not permit him to be evacuated with the other patients.  He is to be left behind. 😢

Claire has a wonderful bedside manner which comes from her compassionate and caring heart. Hopefully,  the British will treat Walter well. 🤞🏻

Mercy! 😉

I hope you enjoyed today’s lesson. Just remember, if you ever feel a pulsing bulge behind  the knee, make an appointment swiftly or get into urgent care. A PAA is no joke!

The deeply grateful,

Outlander Anatomist

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Photo creds: Sony/Starz, www.myclevelandclinic.org, www.uptodate.com