Why do they call it wrenching your back?

wrench

–verb (used with object)

1.	to twist suddenly and forcibly; pull, jerk, or force by a violent twist: He wrenched the prisoner's wrist.

2.	to overstrain or injure (the ankle, knee, etc.) by a sudden, violent twist: When she fell, she wrenched her ankle.

Apparently, the wildly talented Stephanie wrenched her back by accidentally kicking a chair.  Last Wednesday, I was coming around the recliner -  I missed as I threw my leg around to the front and four of my toes on my foot connected with the base of the chair with such a force that I thought I would die.  The next morning, the throbbing and swelling had almost completely gone away and I thought I was free and clear.  Around lunch-time, I could no longer stand up straight!

The side effects of my gracefulness is on-going and almost a week later, I have yet to recover completely!  LOL!!!