The surgical placement of an artificial joint is known as

Arthroplasty

Explanation:

The restoration of function of a joint is called Arthroplasty. The bone functions are restored by maintaining the  bones through resurfacing. Some times artificial joints are also used instead of resurfacing the existing bones.

Arthroplasty is a method to cure Osteoarthritis, or degenerative joint disease where joint cartilages reduces with age.

Also when medical treatments no longer make any impact on the joints of bone pain then Arthroplasty is done.

an active site is a region that is present on an enzyme where the reactants or the substrate molecules we can say bind and experience a chemical reaction. the substrate is basically a reactant whose concentration is changing and that is converting into a product after binding at the active site of an enzyme

the answer is d p: cell, q: organ, r: organ system, s: tissue