US Constitution the words slave or slavery do not appear in the constitution yet they are certainly referred to it.   1. The 3/5 clause which says that an enslaved person will only count as 3/5 of a person in the census. 2. ban on middle passage slave trade.
Medial compartment arthritis (usually osteoarthiritis) can cause pain on the inner side of the knee. This is usually more of an ache than a sharp catching pain and is present when you walk on the leg. As the arthritis worsens the pain can become continuous and interfere with sleep.
1 Outside of Knee: Pain on the outside of the knee, or lateral side, is commonly caused by lateral meniscus tears, LCL injuries, IT band tendonitis, and arthritis.  Back of Knee: Pain in the back of the knee can be due to the collection of fluid, called a Baker's Cyst.