Hip Arthritis

A total hip replacement (THR) - also called a hip arthroplasty- is a surgical procedure that re-forms the hip joint.

In THR, the head of the femur (the bone that extends from the hip to the knee) is removed along with the surface layer of the socket in the pelvis (the two large bones that rest on the lower limbs and support the spinal column).

  • The head of the femur, which is situated within the pelvis socket, is replaced with a metal ball and stem. This stem fits into the shaft of the femur.
  • The socket is replaced with a plastic or a metal and plastic cup.

For nearly a century, doctors have been putting various materials into diseased and painful hip joints to relieve pain. Up until the 1960s, outcomes had been unreliable. At that time, the metal ball and plastic socket for the replacement of the hip joint was introduced. Today, the artificial components used in THR are stronger and more designs are available.

There are many different shapes, sizes, and designs of artificial components of the hip joint. For the most part these are composed of chrome, cobalt, titanium, or ceramic materials. Some surgeons are also using custom-made components to improve the fit in the femur.

Facts About Total Hip Replacement

  • There are approximately 150,000 artificial hip joints implanted annually in the United States , with the success rate over 90%.

  • The majority of individuals in need of hip replacement are in their 60s and 70s.

  • Depending on the condition, people in their late teens and in their 90s can possibly be candidates for a hip replacement.

  • obesity, as excess weight means there is more tissue that can be broken down into uric acid

  • New materials used in total hip replacement are very durable and are expected to last more than 10 years in 90% of individuals receiving total hips.

The" Normal" Hip

The hip is a ball-and-socket joint comprised of the following structures:

  • Head of the femur

  • Acetabulum of the Pelvis

  • Ligaments of the hip joint

The head of the femur or "ball" of the hip joint articulates or moves within the cup-like "socket" called the acetabulum of the pelvic bone. Together, these structures are referred to as a "ball and socket" joint. The femoral head and acetabulum are covered by a specialized surface called articular cartilage . This allows smooth and painless motion of the hip joint.

Several strong ligaments help hold the head of the femur within the acetabulum. They are named according to their attachments:

  • The iliofemoral ligament attaches the front of the ilium (pelvic bone) to the femur. It is fan-shaped, resembling an inverted Y and is sometimes referred to as the Y ligament of Bigalow.

  • The pubofemoral ligament attaches from an area on the front region of the pelvis called the pubis and connects to the femur.

  • The ishchiofemoral ligament attaches to a bony area on the rear aspect of the pelvis (where the hamstrings attach) and then connects to the femur bone.

  • The articular capsule, which is very dense and strong, encompasses the entire acetabulum.