The hip joints bear our entire body’s weight as well as forces exerted by hip and leg muscles. Except for our shoulder joint, it has the widest range of flexibility and motion allowing us to walk, run and jump. No wonder it is considered one of the most important joints in the human body. Replacement of hip joint with an artificial implant is considered one of the top achievements of its generation in the field of orthopedics. Multiple attempts with variety of materials including metal, ceramic and polymeric materials, spread over at least 300 years, allowed this progress. However, revolutionary advances in materials and implant designs starting in the 1960s, due to the efforts of pioneers such as Sir John Charnley, led to the development of the first top hit replacement or arthroplasty implants. Here is a little bit more on the what and how of top hip replacement.
Total hip replacement or arthroplasty involves replacing a patients hip ball and socket joint (see right figure top) with a mechanical implant. This joint consists of a cup-shaped socket called acetabulum, which is part of the pelvic bone, and a ball which is the head or top of the thigh bone or femur (Right Figure bottom). A cartilage layer is at the interface between the femoral head and acetabulum to minimize the friction at the joints. It also acts as a shock absorber that prevents the bones from colliding with each other. A fluid called synovial fluid is also present between the cartilage layer that lubricates the joint.
During total hip replacement, (right figure a-d), the top of the femur bone 
is cut open (figure a). An implant called acetabulum cup is inserted into the socket of the pelvic bone. A mechanical ball is inserted into the top of the femur stem (figure b). The femoral ball fits snugly with the acetabulum cup (figure c) and creates a new artificial joint (figure d) that allows rotation of the hip. The implant is designed to replicate the human anatomy of the hip and can be ultimately pain-free. Under normal circumstances, depending upon the patient’s condition and activities, modern hip implants should last between 10-30 years.
Before the advent of modern hip replacement implants in the 1960s, patients with diseased hips had very little improvement in their quality of life. Patients were forced to live a sedentary life and live through the constant pain. However, since then, fantastic progress in surgery techniques, research and engineering breakthroughs and advances in manufacturing methods have continuously advanced the effectiveness and lifespan of these implants and consequently improved the quality of life for patients.