Total Hip Replacement Terms Click on Term to read definition |
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Acetabulum: 
The cup of the hip in which the ball, or head of the femur, rotates when the hip is in motion. During hip replacement surgery, the acetabulum is reamed out and a metal cup is implanted to replace diseased bone. 
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Arthoplasty:
The surgical replacement or repair of a damaged joint. Hip arthroplasty is also known as hip replacement surgery, THR or total hip replacement. |
AVN Avascular Necrosis of the femoral head:
AVN is a one time event in which a strikingly similar sector of necrosis occurs in most femoral heads ( anteo supero lateral part) due to blockage of presumably the same vessel. This sets off a series of changes which are is marked by sectoral collapse. 
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BHR Birmingham Hip Resurfacing:
Birmingham Hip Resurfacing device by Smith & Nephew 
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Bone Spurs:
Abnormal projections of bone, also known as osteophytes. Bone spurs are commonly seen in patients with arthritis. 
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Bovie, Bovie Pencil:
A device used to electrically cauterize, or burn and seal the ends of blood vessels that are bleeding into the surgical field. 
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Capsule:
The strong, fibrous, flexible sac that surrounds the hip joint and contains the synovial membrane. The synovial membrane produces sinovial fluid, a liquid that lubricates the joint. 
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Cartilage:
A smooth material that covers bone ends at a joint to cushion the bone and allow the joint to move easily without pain. |
| Ceramic on Ceramic: This material was been introduced in 1970. It was first implanted by Pierre Boutin in France, afterwards by Mittelmeier in Germany. The purpose was to reduce the production of wear particles in order to obtain better results in the young patient. In the meantime, more than 150.000 ceramic-on-ceramic devices have been implanted, especially in Europe.  |
External Rotator Muscles:
A series of muscles connected to the back of the femur near the greater trochanter that are responsible for rotating the leg outward away from the midline of the body. |
Femur:
The thigh bone or upper leg bone. |
Femoral Head:
The top of the femur bone, also known as the ball of the hip. This rotates inside the acetabulum to allow the hip to move. |
Gluteus Maximus:
A large muscle that covers the rear hip, also sometimes known as the butt muscle. This is a superficial muscle that is cut through and pulled back to access the bones of the hip during hip replacement surgery. 
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Gluteus Medius:
A broad Muscle located near the gluteus maximus. About 1/3 of this muscle lies under the gluteus maximus. The lower edge of the medius is near the piriformis muscle. Both the gluteus medius and the piriformis are attached to the greater trochanter and this flap of muscles must be pulled back during hip replacement surgery in order to access the bones of the hip. |
Gluteus Minimus:
A small muscle that occurs just below portions of the gluteus maximus. The gluteus minimus is attached to the greater trochanter and is part of the flap of muscles that must be pulled back during hip replacement surgery in order to access the bones of the hip. |
Greater Trochanter:
A large projection on the end of the femur near the hip. Numerous muscles attach to the femur at this location. 
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Hemi-Arthroplasty System or Hemi-Hip Resurfacing:
A Hemi-Hip Resurfacing is not used often today. There were many revisions required because only the femur was capped. This led to the metal cap of the femur rubbing on the acetabulum of the hip. There was not a cup placed in the acetabulum. Hemi-resurfacing was used for younger adult patients with early osteonecrosis of the femoral head, preserving the acetabulum, proximal femoral bone, and medullary canal. 
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Intramedullary Canal or Medullary Canal:
The canal that runs up the center of the femur. The prosthetic stem is placed in this canal as part of hip replacement surgery. |
Lap Sponge:
A sterile gauze pad used to absorb blood and fluids or clean surgical areas during surgery. |
MOM:
Metal on Metal is a type of total hip replacement device. Metal on Metal hips were introduced in the US in 2002. They had been used in other countries for many years before the were approved in the US. The ball and socket of the Metal on Metal (MOM) hip devices are made of Cobalt-Chrome alloy.
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Osteoarthritis OA:
The most common type of arthritis. It affects many joints in the body, including the hip. It is a chronic disease and is characterized by destruction of cartilage, overgrowth of bone, bone spur formation and impaired function. This type of arthritis occurs when bone rubs against bone. Many people develop osteoarthritis as they age. |
Osteophytes:
Abnormal projections of bone, also known as bone spurs. Osteophytes are commonly seen in patients with arthritis. |
Osteotome:
A chisel-like surgical instrument used to remove osteophytes or bone spurs during hip surgery. |
Plastic Liner:
This goes inside the metal acetabular cup and cushions the metal ball of the total hip prosthetic. The liner serves much the same function as cartilage does in a healthy hip – it prevents the metal parts of the prosthetic from rubbing against each other. |
Piriformis Tendon:
The tendon that connects the piriformis muscle to the head of the femur. |
Piriformis Muscle:
The piriformis muscle travels behind the hip joint, running horizontally from the lower spine to the top of the femur. The piriformis runs over the sciatic nerve and it aids in external rotation, or turning out, of the hip joint. 
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Prosthesis (plural, Prostheses):
An artificial body part designed to supplement or replace natural parts. In hip replacement surgery, the prosthetic components replace the end of the femur, the ball of the hip (head of the femur) and the cup of the hip, or acetabulum. |
Range of Motion ROM:
The acceptable amount of movement a joint should be able to perform. Range of motion tests are performed in all joint replacement surgeries to ensure that the prosthetic joints work appropriately. |
Rasp:
A surgical tool used to remove small amounts of bone by shaving or sanding the bone down. Rasps are used to size the femur to accept the stem prosthetic in hip replacement surgery. |
Rongeur:
A surgical instrument used to remove osteophytes, or bone spurs, during hip replacement surgery. |
Sciatic Nerve:
The largest single nerve in the human body. The sciatic connects to nearly all of the skin of the leg, the muscles of the back of the thigh, the leg and the foot. It passes out of the pelvis below the Piriformis muscle. It descends the back of the thigh to about its lower third, where it divides into two large branches. 
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Stem:
The metal prosthetic piece that goes in the femur during a hip replacement surgery. |
Subcutaneous:
Literally under the skin. In surgeries, this usually refers to this usually refers to the layer of fat that exists just beneath the skin. This layer is often sutured together separately from the skin to make the surgical closure more secure. |
Template:
A plastic guide used to help surgeons determine the correct size of replacement prosthetics to use for a patient. The surgeon uses the plastic template to measure the size of the acetabulum and the canal in the femur by holding it up against an enlarged x-ray. |
Tensor Fascia Lata:
Aids in muscle movements and can also provide an attachment site for muscles and act as a cushioning layer between them. The tensor fascia lata runs from the hip down the thigh and provides stability for the leg as well as medial rotation, or rotation in toward the other leg. 
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Total Hip Replacement THR:
Also known as total hip arthoplasty. In this procedure a portion of the femoral neck and the entire femoral head are removed and replaced by a prosthesis. The acetabulum (socket) is prepared with reamers and a metal prosthetic cup is press fit in place. The metal ball on the femoral prosthesis articulates (rubs against) an acetabular liner that matches the size of the femoral head. Traditional head sizes for total hip replacement are 28-32 mm. 
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Total Hip Resurfacing:
In this procedure the head of the femur is retained and prepared with specialized reamers. The prepared femora lhead has a metal resurfacing component cemented in position. The acetabulum has a metal prosthetic cup inserted. This type of surgery preserves more bone than a traditional total hip replacement does. Femoral head sizes for surface replacement often range from 44-54 mm (substantially larger than traditional total hip replacements). 
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