Disorders of the foot and ankle Flashcards
What is Club foot?
Club foot is technically known as congenital talipes equinovarus (talipes is from Latin talus=ankle + pes=foot; equino-=of or resembling a horse and –varus=turned inward).
Club foot is a developmental deformity of the foot in which one or both feet are excessively plantar flexed, with the forefoot swung medially and the sole facing inward.
The main anatomic abnormality is in the TALUS but screwing up (over-flexing) a bone in the middle of the action messes up everything else: the talo-calcaneo-navicular joints; the soft tissues on the medial side of the foot; and the gastrocsoleus/Achilles; etc
The forefoot is “normal” but because the hindfoot is bad, the forefoot does not strike the ground normally. Patients with (untreated) club foot often appear to walk on their ankles, or on the sides of their feet. Most cases are idiopathic, but some are associated with chromosomal anomalies.
What is a Charcot joint?
If you don’t feel pain, you hand stays in the fire; likewise, if you don’t feel overuse in your joints you won’t let up and will destroy the joint.
Hence: decreased sensation in cases of peripheral neuropathy leads to JOINT DESTRUCTION (mental image: pimple on one butt cheek, sit on the other side or get a bed sore).
An alternative or complimentary theory: micro-vascular disease of DM leads to altered bone metabolism. The main cause of Charoct today is diabetes. Historically, the #1 cause was syphilis (NB: syphilis would tend to support theory of lost sensation as cause, I say, thinking out loud).
Charcot affects the foot mostly, but can be found in other joints.
The presentation may look like cellulitis/infection (which is more likely, also, in patients with diabetes).
There is a vicious cycle: deformity leads to bony prominences leads to ulcers leads to infection leads to more bony deformity.
Why might a 12 year old boy with a swollen ankle and pain on the distal fibula be treated with a cast despite normal xrays? (IMAGES ON WEBSITE HELPFUL)
Ok, so you are 12 year old and twist your ankle medial side up, by partially landing on another player’s shoe. Something’s got to give:
If you have no growth plate, left panel, you sprain your CF ligament; but in a twelve year old, the growth plate is weaker, so it gets injured.
Now, it there are “normal xrays” then by definition this a non-displaced fracture.
This is an urgent medical situation, however, as we want to keep it non-displaced! It needs a cast, typically.
TAKE HOME MESSAGE: 12 year olds don’t get sprains. (OK, Maybe they do, but you have to assume that a sprain is a non-displaced growth plate fracture until proven otherwise.
Why do 40 year old men (in particular) rupture their Achilles tendons? What are the biological and mechanical steps leading to tissue failure?
40+ year olds reside in that strange place of a) having accumulated plenty of tissue damage over the years (walking 1 mile a day for 45 years is almost 100,000,000 steps) yet b) have not quite caught on that they are old and decrepit. So they try to do too much. The Achilles tendon not only gets beaten up, it is about as far from the heart as a tendon can get, impeding the blood supply, so wear and tear damage is imperfectly repaired.
So why does the tendon fail? Well, first consider: what does it do? The Achilles powers plantar flexion but also resists dorsiflexion.
The motion of the muscle on the right is called an eccentric contraction—the muscle actually lengthens as it works (“negative” work is how the weight lifters call it) It turns out that ripping the tendon almost always happens with resisting dorsiflexion, eg, when you land.
We can’t avoid eccentric contraction, because it happens with every step of gait. You land on the ball of your feet, and the gastroc/soleus decelerates your heel as it “lands” on the ground.
The importance of this is that if you wanted to prevent Achilles injuries in middle aged men, you could do this with an extension block on the shoe or with a soft heel cup: the extension block on the TOP of the shoe prevents excessive dorsi-flexion; the heel cup takes it easy on the gastroc.
The phrase “just a sprain” may grossly understate the impairment such an injury imparts. Why might a grade ONE ankle sprain cause long term impairment?
There are two injuries here, really. Tension on the CF ligament and compression on the talus.
Even if the CFL is not torn, you can get damage to the proprioceptive nerve fibers in it and get a sense of unsteadiness despite being intact as well as post traumatic arthrosis (arthritis) of the tibio-talar joint
For the interested student only: An inversion force to the ankle can really injure the bone or the ligament. Which gets injured actually depends on the rate of speed of loading, owing to the bone’s so-call visco-elastic properties:
