Final answer:
Arthrocentesis is a procedure to extract fluid from a joint using a needle, while arthroplasty is a joint replacement surgery which replaces damaged joint surfaces with artificial components such as in hip replacements.
Step-by-step explanation:
An arthrocentesis is a medical procedure in which a needle is used to extract fluid from a joint. This can be done for diagnostic purposes, to remove excess fluid, or to administer medication directly into the joint space. It is less invasive than an arthroplasty, which is a joint replacement surgery. Arthroplasty involves replacing damaged articular surfaces with a prosthesis. In hip arthroplasty, for instance, the head and neck of the femur and the acetabulum of the pelvis are replaced with artificial components. The recovery from arthroplasty can enhance mobility and provide relief from chronic pain within months.