How many discrete joint capsules are in the foot?

[GH253]

Obviously there are 15 individually encapsulated joints in the digits, but what about the rest of the foot? Do all facets of the subtalar joint share a single capsule? What about the mid tarsal joints and the interlocking joints of the midfoot? If you wanted to hit every joint surface in the foot with a cortisone injection, how many injections would you have to give?

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[bobtheweazel]

If you're counting MTPJs and IPJs then wouldn't the digits have 14 joints since the first toe only has two phalanges? Also, if the fifth toe also sometimes only has two phalanges then that's 13-14 in the digits.

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[GH253]

If you're counting MTPJs and IPJs then wouldn't the digits have 14 joints since the first toe only has two phalanges? Also, if the fifth toe also sometimes only has two phalanges then that's 13-14 in the digits.

Sent from my Nexus 5X using SDN mobile

I stand corrected.

 

[bobtheweazel]

I stand corrected.

Meh, it happens. I am curious as to the actual answer you were looking for though.

 

[AttackNME]

very interesting question! I have read about the greater synovial membrane of the foot which involves the 2nd and 3rd met bases and the navicular-cuneiform joints, so technically a single shot can cover all those joints but clinically I have been taught to just inject whichever joint hurts. All the subtalar facets are within the subtalar joint capsule. The TNJ is separate from the CC joint so each has its own joint capsule. The 4th and 5th met bases and cuboid is its own sac.

 

[ExperiencedDPM]

Ha. When you get the answer, let me know so I can put it in my book of useless facts!!! If you want to drive yourself crazy, open up Saraffian's textbook on lower extremity anatomy, and you'll see the tremendous amount of variants in anatomy, including anamolies.