Hip replacement
Encyclopedia
Hip replacement is a surgical
procedure in which the hip joint is replaced by a prosthetic implant
. Hip replacement surgery can be performed as a total replacement or a hemi (half) replacement. Such joint replacement
orthopaedic surgery generally is conducted to relieve arthritis
pain
or fix severe physical joint damage as part of hip fracture treatment. A total hip replacement (total hip arthroplasty) consists of replacing both the acetabulum
and the femoral head while hemiarthroplasty generally only replaces the femoral head. Hip replacement is currently the most common orthopaedic operation, though patient satisfaction short and long term varies widely.
In 1940 at Johns Hopkins
hospital, Dr. Austin T. Moore (1899–1963), an American surgeon, reported and performed the first metallic hip replacement surgery. The original prosthesis he designed was a proximal femoral replacement, with a large fixed head, made of the Cobalt-Chrome alloy Vitallium
. It was about a foot in length and it bolted to the resected end of the femoral shaft (hemiarthroplasty). A later version of Dr. Moore's prosthesis, the so-called Austin Moore, developed in Columbia, SC was introduced in 1952 is still in use today, although rarely. Like modern hip implants it is inserted into the medullary canal of the femur. It depends on bone growth through a hole in the stem for long term attachment.
In 1960 a Burmese orthopaedic surgeon, Dr. San Baw (29 June 1922 – 7 December 1984), pioneered the use of ivory
hip prostheses to replace ununited fractures of the neck of femur
when he first used an ivory prosthesis to replace the fractured hip bone of an 83 year old Burmese Buddhist nun, Daw Punya. This was done while Dr. San Baw was the chief of orthopaedic surgery at Mandalay General Hospital in Mandalay, Burma. Dr. San Baw used over 300 ivory hip replacements from the 1960s to 1980s. He presented a paper entitled "Ivory hip replacements for ununited fractures of the neck of femur" at the conference of the British Orthopaedic Association held in London in September 1969. An 88% success rate
was discerned in that Dr. San Baw's patients ranging from the ages of 24 to 87 were able to walk, squat, ride a bicycle and play football a few weeks after their fractured hip bones were replaced with ivory prostheses. Ivory may have been used because it was cheaper than metal at that time in Burma and also was thought to have good biomechanical properties including biological bonding of ivory with the human tissues nearby. An extract from Dr San Baw's paper, which he presented at the British Orthopaedic Association's Conference in 1969, is published in Journal of Bone and Joint Surgery (British edition), February 1970. With modern hip replacement surgery, one can expect to walk immediately post-op.
The replacement joint, which was known as the Low Friction Arthroplasty
, was lubricated with synovial fluid
. The small femoral head (7/8" (22.2 mm)) was chosen for Dr. Charnley's belief that it would have lower friction against the acetabular component and thus wear out the acetabulum more slowly. Unfortunately, the smaller head dislocated more easily. Alternative designs with larger heads such as the Mueller prosthesis were proposed. Stability was improved, but acetabular wear and subsequent failure rates were increased with these designs. The Teflon acetabular components of Dr. Charnley's early designs failed within a year or two of implantation. This prompted a search for a more suitable material. A German salesman showed a polyethylene gear sample to Dr. Charnley's machinist, sparking the idea to use this material for the acetabular component. The Ultra High Molecular Weight Polyethylene
or UHMWPE acetabular component was introduced in 1962. Dr. Charnley's other major contribution was to use polymethylmethacrylate (PMMA) bone cement to attach the two components to the bone. For over two decades, the Charnley Low Friction Arthroplasty, and derivative designs were the most used systems in the world. It formed the basis for all modern hip implants.
The Exeter hip stem was developed in the United Kingdom during the same time as the Charnley device. This is also a cemented device, but with a slightly different stem geometry. Both designs have shown excellent long-term durability when properly placed and are still wisely used in slightly modified versions.
Early implant designs had the potential to loosen from their attachment to the bones, becoming painful typically ten to twelve years after placement. In addition to the devices loosening, erosion of the bone around the implant was seen on x-rays. Initially surgeons believed this was caused by an abnormal reaction in response to the cement holding the implant in place. That belief prompted a search for an alternative method to attach the implants. The Austin Moore device had a small hole in the stem into which bone graft was placed before implanting the stem. It was hoped bone would then grow through the window over time and hold the stem in position. Success was unpredictable and the fixation not very robust. In the early 1980s, surgeons in the United States applied a coating of small beads to the Austin Moore device and implanted it without cement. The beads were constructed so that gaps between beads matched the size or the pores in native bone. Over time, bone cells from the patient would grow into these spaces and fix the stem in position. The stem was modified slightly to fit more tightly into the femoral canal, resulting in the Anatomic Medullary Locking (AML) stem design. With time, other forms of stem surface treatment and stem geometry have been developed and improved.
Initial hip designs were made of a one-piece femoral component and a one-piece acetabular component. Current designs have a femoral stem and separate head piece. Using an independent head allows the surgeon to adjust leg length (some heads seat more or less onto the stem) and to select from various materials from which the head is formed. A modern acetabulum component is also made up of two parts: a metal shell with a coating for bone attachment and a separate liner. First the shell is placed. Its position can be adjusted, unlike the original cemented cup design which are fixed in place once the cement sets. When proper positioning of the metal shell is obtained, the surgeon may select a liner made from various materials.
To combat loosening caused by polyethylene wear debris, hip manufacturers developed improved and novel materials for the acetabular liners. Ceramic
heads mated with regular polyethylene liners or a ceramic liner were the first significant alternative. Metal liners to mate with a metal head were also developed. At the same time these designs were being developed, the problems that caused polyethylene wear were determined and manufacturing of this material improved. Highly-crosslinked UHMWPE was introduced in the late 1990s. The most recent data comparing the various bearing surfaces has shown no clinically significant differences in their performance. Potential early problems with each material are discussed below. Performance data after 20 or 30 years may be needed to demonstrate significant differences in the devices. All newer materials allow use of larger diameter femoral heads. Use of larger heads significantly decreases the chance of the hip dislocating, which remains the greatest complication of the surgery.
To date, when currently available implants are used, there is no demonstrable difference in performance of cemented versus uncemented stems, and no significant difference in the clinical performance of the various methods of surface treatment of uncemented devices. Uncemented stems are selected for patients with good quality bone that can resist the forces needed to drive the stem in tightly. Cemented devices are typically selected for patients with poor quality bone who are at risk of fracture during stem insertion. Cemented stems are less expensive due to lower manufacturing cost, but require good surgical technique to place them correctly. Uncemented stems can cause pain with activity in up to 20% of patients during the first year after placement as the bone adapts to the device. This is rarely seen with cemented stems.
Once an uncommon operation reserved for frail patients with a limited life expectancy, hip replacement is now common, even among active athletes including race car drivers Bobby Labonte
and Dale Jarrett
, and British Open runner-up, golfer Tom Watson.
. Other indications include rheumatoid arthritis
, avascular necrosis
, traumatic arthritis, protrusio acetabuli
, certain hip fracture
s, benign and malignant bone tumor
s, arthritis associated with Paget's disease
, ankylosing spondylitis
and juvenile rheumatoid arthritis. The aims of the procedure are pain relief and improvement in hip function. Hip replacement is usually considered only once other therapies, such as physical therapy
and pain medications, have failed.
osteotomy. There is no compelling evidence in the literature for any particular approach, but consensus of professional opinion favours either modified anterolateral (Watson-Jones) or posterior approach.
and the short external rotators off the femur. This approach gives excellent access to the acetabulum and femur and preserves the hip abductors and thus minimises the risk of abductor dysfunction post operatively. It has the advantage of becoming a more extensile approach if needed. Critics cite a higher dislocation rate, although repair of the capsule, piriformis and the short external rotators along with use of modern large diameter head balls reduces this risk.
and the gluteus medius.
and tensor fascia latae. Dr. Joel Matta has adapted this approach commonly used for pelvic fracture repair surgery in conjunction with a traction table for use when performing hip replacement. When used with older hip implant systems that had a small diameter head, dislocation rates were reduced compared to surgery performed through a posterior approach. With modern implant designs, dislocation rates are similar regardless of the approach and probably more a function of surgeon experience. There is a 10% rate of numbness in the thigh following this approach due to injury to the lateral femoral cutaneous nerve.
Computer Assisted Surgery
techniques are also available to guide the surgeon to provide enhanced accuracy. Several commercial CAS systems are available for use worldwide. HipNav
was the first system developed specifically for total hip replacement, and included navigation and preoperative planning based on a preoperative CT scan of the patient. Improved patient outcomes and reduced complications have not been demonstrated when these systems are used when compared to standard techniques.
(hip socket). Cartilage and bone are removed from the acetabulum and the acetabular cup is attached using friction or cement. Some acetabular cups are one piece, others are modular. One piece (monobloc) shells are either polyethylene or metal, they have their articular surface machined on the inside surface of the cup and do not rely on a locking mechanism to hold a liner inplace. A monobloc polyethylene cup is cemented in place while a metal cup is held in place by a metal coating on the outside of the cup. Modular cups consist of two pieces, a shell and liner. The shell is made of metal, the outside has a porous coating while the inside contains a locking mechanism designed to accept a liner. Two types of porous coating used to form a friction fit are sintered
beads or a foam metal design to mimic the trabeculae of cancellous bone. Additional fixation is achieved as bone grows onto or into the porous coating. Screws can be used to lag the shell to the bone providing even more fixation. Polyethylene liners are placed into the shell and connected by a rim locking mechanism, ceramic and metal liners are attached with a Morse taper.
(thigh bone). Bone is removed and the femur is shaped to accept the femoral stem with attached prosthetic femoral head (ball). There are two types of fixation: cemented and uncemented. Cemented stems use acrylic bone cement
to form a mantle between the stem and to the bone. Uncemented stems use friction, shape and surface coatings to stimulate bone to remodel and bond to the implant. Stems are made of multiple materials (titanium, cobalt chromium and stainless steel) and they can be monolithic or modular. Modular components consist of different head dimensions and/or modular neck orientations; these attach via a taper similar to a Morse taper. These options allow for variability in leg length, offset and version. Femoral heads are made of metal or ceramic material. Metal heads, made of cobalt chromium for hardness, are machined to size and then polished to reduce wear of the socket liner. Ceramic heads are more smooth than polished metal heads, have a lower coefficient of friction than a cobalt chrome head, and in theory will wear down the socket liner more slowly. As of early 2011, follow up studies in patients have not demonstrated significant reductions in wear rates between the various types of femoral heads on the market. Ceramic implants are more brittle and may break after being implanted.
. This is the loss of bone caused by the body's reaction to polyethylene wear debris, fine bits of plastic that come off the cup liner over time. An inflammatory
process causes bone resorption that may lead to subsequent loosening of the hip implants and even fractures in the bone around the implants. In an attempt to eliminate the generation of wear particles, ceramic bearing surfaces are being used in the hope that they will have less wear and less osteolysis with better long term results. Metal cup liners joined with metal heads (metal-on-metal hip arthroplasty) were also developed for similar reasons. In the lab these show excellent wear characteristics and benefit from a different mode of lubrication. At the same time these two bearing surfaces were being developed, highly cross linked polyethylene plastic liners were also developed. The greater cross linking significantly reduces the amount of plastic wear debris given off over time. The newer ceramic and metal prostheses do not always have the long term track record of established metal on poly bearings. Ceramic pieces can break leading to catastrophic failure. This occurs in about 2% of the implants placed. They may also cause an audible, high pitched squeaking noise with activity. Metal-on-metal arthroplasty releases metal debris into the body raising concerns about the potential dangers of these accumulating over time. Highly cross linked polyethylene is not as strong as regular polyethylene. These plastic liners can crack or break free of the metal shell that holds them.
Metal hypersensitivity is a well-established phenomenon and is common, affecting about 10–15% of the population. Contact with metals can cause immune reactions such as skin hives, eczema, redness and itching. Although little is known about the short and long term pharmacodynamics and bioavailability of circulating metal degradation products in vivo, there have been many reports of immunologic type responses temporally associated with implantation of metal components. Individual case reports link hypersensitivity immune reactions with adverse performance of metallic clinical cardiovascular, orthopedic and plastic surgical and dental implants.
By 2010 reports in the orthopaedic literature have increasingly cited the problem of early failure of metal on metal prostheses in a small percentage of patients. Failures may relate to release of minute metallic particles or metal ions from wear of the implants, causing pain and disability severe enough to require revision surgery in 1–3% of patients. Design deficits of some prothesis models, especially with heat-treated alloys and a lack of special surgical experience accounts for most of the failures. Surgeons at leading medical centers such as the Mayo Clinic have reported reducing by 80 percent their use of metal-on-metal implants over the last year in favor of those made from other materials, like combinations of metal and plastic. The cause of these failures remain controversial, and may include both design factors, technique factors, and factors related to patient immune responses (allergy type reactions). In the United Kingdom the Medicines and Healthcare products Regulatory Agency
commenced an annual monitoring regime for metal-on-metal hip replacement patients from May 2010. Data which is shown in The Australian Orthopaedic Association's 2008 National Joint Replacement Registry, a record of nearly every hip implanted in that country over the previous 10 years, tracked 6,773 BHR (Birmingham Hip Resurfacing) Hips and found that less than one-third of one percent may have been revised due to the patient's reaction to the metal component. Other similar metal-on-metal designs have not fared as well, where some reports show 76% to 100% of the people with these metal-on-metal implants and have aseptic implant failures requiring revision also have evidence of histological inflammation accompanied by extensive lymphocyte infiltrates, characteristic of delayed type hypersensitivity responses. It is not clear to what extent this phenomenon negatively affect orthopedic patients. However for patients presenting with signs of an allergic reactions, evaluation for sensitivity should be conducted. Removal of the device that is not needed should be considered, since removal may alleviate the symptoms. Patients who have allergic reactions to cheap jewelry are more likely to have a reactions to orthopedic implants. It is important to note that there is increasing awareness of the phenomenon of metal sensitivity and many surgeons now take this into account when planning which implant is optimal for each patient.
On February 10, 2011 the U. S F.D.A issued a patient advisory on metal-metal hip implants located here: http://www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/ImplantsandProsthetics/MetalonMetalHipImplants/default.htm
structure, the metal parts to grind against one another, releasing microscopic fragments of cobalt
and chromium
into the patient's bloodstream. There are reports of cobalt toxicity with hip replacement patients.
True leg length inequality may sometimes be caused by improper implant selection. The femoral component may be too large and stick out of the femur further than needed. The head ball selected may sit too proud on the stem. Stiffness in the lower back from arthritis or previous fusion surgery seems to magnify the perception of leg length inequality.
. Conservative management can prevent or delay the need for hip replacement.
). The procedure is performed by removing the head of the femur and replacing it with a metal or composite prosthesis
. The most commonly used prosthesis designs are the Austin Moore prosthesis and the Thompson Prosthesis. More recently a composite
of metal
and HDPE which forms two interphases (bipolar prosthesis) has also been used. The bipolar prosthesis has not been shown to have any advantage over monopolar designs. The procedure is recommended only for elderly and frail patients, due to their lower life expectancy and activity level. This is because with the passage of time the prosthesis tends to loosen or to erode the acetabulum
.
is an alternative to hip replacement surgery. It is a bone conserving procedure that places a metal cap on the femoral head instead of amputating it. There is no long stem placed down the femur so it is more like a natural hip and may allow patients a return to many activities, including marathons and triathlons; some patients have even completed Ironman and Ultraman competitions following hip resurfacing surgery, although patients must have good bone quality to qualify for it. It has been used in Europe for over 17 years and become a common procedure. The first device, the BHR or Birmingham Hip Resurfacing device was approved by the FDA on May 9, 2006.
The Australian Registry hip resurfacing data for 2009, 70 percent of which comes from BHR Hip procedures, indicates that for men under age 65, hip resurfacing performs at the same or a better rate than total hip replacement.
Some believe the future of osteoarthritis treatment is bioengineering, targeting the growth and/or repair of the damaged, arthritic joint. Centeno et al. have reported on the partial regeneration of an arthritic human hip joint using mesenchymal stem cell
s in one patient. It is yet to be shown that this result will apply to a larger group of patients and result in significant benefits. The FDA has stated that this procedure is being practiced without conforming to regulations, but Centeno claims it is exempt from FDA regulation. It has not been shown in controlled clinical trials to be effective, and costs over $7,000.
Surgery
Surgery is an ancient medical specialty that uses operative manual and instrumental techniques on a patient to investigate and/or treat a pathological condition such as disease or injury, or to help improve bodily function or appearance.An act of performing surgery may be called a surgical...
procedure in which the hip joint is replaced by a prosthetic implant
Implant (medicine)
An implant is a medical device manufactured to replace a missing biological structure, support a damaged biological structure, or enhance an existing biological structure. Medical implants are man-made devices, in contrast to a transplant, which is a transplanted biomedical tissue...
. Hip replacement surgery can be performed as a total replacement or a hemi (half) replacement. Such joint replacement
Joint replacement
Replacement arthroplasty [from Greek arthron, joint, limb, articulate, + -plassein, to form, mould, forge, feign, make an image of], or joint replacement surgery, is a procedure of orthopedic surgery in which the arthritic or dysfunctional joint surface is replaced with an orthopaedic prosthesis...
orthopaedic surgery generally is conducted to relieve arthritis
Arthritis
Arthritis is a form of joint disorder that involves inflammation of one or more joints....
pain
Pain
Pain is an unpleasant sensation often caused by intense or damaging stimuli such as stubbing a toe, burning a finger, putting iodine on a cut, and bumping the "funny bone."...
or fix severe physical joint damage as part of hip fracture treatment. A total hip replacement (total hip arthroplasty) consists of replacing both the acetabulum
Acetabulum
The acetabulum is a concave surface of the pelvis. The head of the femur meets with the pelvis at the acetabulum, forming the hip joint.-Structure:...
and the femoral head while hemiarthroplasty generally only replaces the femoral head. Hip replacement is currently the most common orthopaedic operation, though patient satisfaction short and long term varies widely.
History
The earliest recorded attempts at hip replacement (Gluck T, 1891), which were carried out in Germany, used ivory to replace the femoral head (the ball on the femur).In 1940 at Johns Hopkins
Johns Hopkins
Johns Hopkins was a wealthy American entrepreneur, philanthropist and abolitionist of 19th-century Baltimore, Maryland, now most noted for his philanthropic creation of the institutions that bear his name, namely the Johns Hopkins Hospital, and the Johns Hopkins University and its associated...
hospital, Dr. Austin T. Moore (1899–1963), an American surgeon, reported and performed the first metallic hip replacement surgery. The original prosthesis he designed was a proximal femoral replacement, with a large fixed head, made of the Cobalt-Chrome alloy Vitallium
Vitallium
Vitallium is a trademark for an alloy of 60% cobalt, 20% chromium, 5% molybdenum, and other substances. The alloy is used in dentistry and artificial joints, because of its light weight and resistance to corrosion. It is also used for components of turbochargers because of its thermal resistance....
. It was about a foot in length and it bolted to the resected end of the femoral shaft (hemiarthroplasty). A later version of Dr. Moore's prosthesis, the so-called Austin Moore, developed in Columbia, SC was introduced in 1952 is still in use today, although rarely. Like modern hip implants it is inserted into the medullary canal of the femur. It depends on bone growth through a hole in the stem for long term attachment.
In 1960 a Burmese orthopaedic surgeon, Dr. San Baw (29 June 1922 – 7 December 1984), pioneered the use of ivory
Ivory
Ivory is a term for dentine, which constitutes the bulk of the teeth and tusks of animals, when used as a material for art or manufacturing. Ivory has been important since ancient times for making a range of items, from ivory carvings to false teeth, fans, dominoes, joint tubes, piano keys and...
hip prostheses to replace ununited fractures of the neck of femur
Femur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
when he first used an ivory prosthesis to replace the fractured hip bone of an 83 year old Burmese Buddhist nun, Daw Punya. This was done while Dr. San Baw was the chief of orthopaedic surgery at Mandalay General Hospital in Mandalay, Burma. Dr. San Baw used over 300 ivory hip replacements from the 1960s to 1980s. He presented a paper entitled "Ivory hip replacements for ununited fractures of the neck of femur" at the conference of the British Orthopaedic Association held in London in September 1969. An 88% success rate
was discerned in that Dr. San Baw's patients ranging from the ages of 24 to 87 were able to walk, squat, ride a bicycle and play football a few weeks after their fractured hip bones were replaced with ivory prostheses. Ivory may have been used because it was cheaper than metal at that time in Burma and also was thought to have good biomechanical properties including biological bonding of ivory with the human tissues nearby. An extract from Dr San Baw's paper, which he presented at the British Orthopaedic Association's Conference in 1969, is published in Journal of Bone and Joint Surgery (British edition), February 1970. With modern hip replacement surgery, one can expect to walk immediately post-op.
The replacement joint, which was known as the Low Friction Arthroplasty
Arthroplasty
Arthroplasty is an operative procedure of orthopedic surgery performed, in which the arthritic or dysfunctional joint surface is replaced with something better or by remodeling or realigning the joint by osteotomy or some other procedure.-Background:Previously, a popular form of arthroplasty was...
, was lubricated with synovial fluid
Synovial fluid
Synovial fluid is a viscous, non-Newtonian fluid found in the cavities of synovial joints. With its yolk-like consistency , the principal role of synovial fluid is to reduce friction between the articular cartilage of synovial joints during movement.-Overview:The inner membrane of synovial joints...
. The small femoral head (7/8" (22.2 mm)) was chosen for Dr. Charnley's belief that it would have lower friction against the acetabular component and thus wear out the acetabulum more slowly. Unfortunately, the smaller head dislocated more easily. Alternative designs with larger heads such as the Mueller prosthesis were proposed. Stability was improved, but acetabular wear and subsequent failure rates were increased with these designs. The Teflon acetabular components of Dr. Charnley's early designs failed within a year or two of implantation. This prompted a search for a more suitable material. A German salesman showed a polyethylene gear sample to Dr. Charnley's machinist, sparking the idea to use this material for the acetabular component. The Ultra High Molecular Weight Polyethylene
Polyethylene
Polyethylene or polythene is the most widely used plastic, with an annual production of approximately 80 million metric tons...
or UHMWPE acetabular component was introduced in 1962. Dr. Charnley's other major contribution was to use polymethylmethacrylate (PMMA) bone cement to attach the two components to the bone. For over two decades, the Charnley Low Friction Arthroplasty, and derivative designs were the most used systems in the world. It formed the basis for all modern hip implants.
The Exeter hip stem was developed in the United Kingdom during the same time as the Charnley device. This is also a cemented device, but with a slightly different stem geometry. Both designs have shown excellent long-term durability when properly placed and are still wisely used in slightly modified versions.
Early implant designs had the potential to loosen from their attachment to the bones, becoming painful typically ten to twelve years after placement. In addition to the devices loosening, erosion of the bone around the implant was seen on x-rays. Initially surgeons believed this was caused by an abnormal reaction in response to the cement holding the implant in place. That belief prompted a search for an alternative method to attach the implants. The Austin Moore device had a small hole in the stem into which bone graft was placed before implanting the stem. It was hoped bone would then grow through the window over time and hold the stem in position. Success was unpredictable and the fixation not very robust. In the early 1980s, surgeons in the United States applied a coating of small beads to the Austin Moore device and implanted it without cement. The beads were constructed so that gaps between beads matched the size or the pores in native bone. Over time, bone cells from the patient would grow into these spaces and fix the stem in position. The stem was modified slightly to fit more tightly into the femoral canal, resulting in the Anatomic Medullary Locking (AML) stem design. With time, other forms of stem surface treatment and stem geometry have been developed and improved.
Initial hip designs were made of a one-piece femoral component and a one-piece acetabular component. Current designs have a femoral stem and separate head piece. Using an independent head allows the surgeon to adjust leg length (some heads seat more or less onto the stem) and to select from various materials from which the head is formed. A modern acetabulum component is also made up of two parts: a metal shell with a coating for bone attachment and a separate liner. First the shell is placed. Its position can be adjusted, unlike the original cemented cup design which are fixed in place once the cement sets. When proper positioning of the metal shell is obtained, the surgeon may select a liner made from various materials.
To combat loosening caused by polyethylene wear debris, hip manufacturers developed improved and novel materials for the acetabular liners. Ceramic
Ceramic
A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...
heads mated with regular polyethylene liners or a ceramic liner were the first significant alternative. Metal liners to mate with a metal head were also developed. At the same time these designs were being developed, the problems that caused polyethylene wear were determined and manufacturing of this material improved. Highly-crosslinked UHMWPE was introduced in the late 1990s. The most recent data comparing the various bearing surfaces has shown no clinically significant differences in their performance. Potential early problems with each material are discussed below. Performance data after 20 or 30 years may be needed to demonstrate significant differences in the devices. All newer materials allow use of larger diameter femoral heads. Use of larger heads significantly decreases the chance of the hip dislocating, which remains the greatest complication of the surgery.
To date, when currently available implants are used, there is no demonstrable difference in performance of cemented versus uncemented stems, and no significant difference in the clinical performance of the various methods of surface treatment of uncemented devices. Uncemented stems are selected for patients with good quality bone that can resist the forces needed to drive the stem in tightly. Cemented devices are typically selected for patients with poor quality bone who are at risk of fracture during stem insertion. Cemented stems are less expensive due to lower manufacturing cost, but require good surgical technique to place them correctly. Uncemented stems can cause pain with activity in up to 20% of patients during the first year after placement as the bone adapts to the device. This is rarely seen with cemented stems.
Once an uncommon operation reserved for frail patients with a limited life expectancy, hip replacement is now common, even among active athletes including race car drivers Bobby Labonte
Bobby Labonte
Robert Alan "Bobby" Labonte is an American race car driver in the NASCAR Sprint Cup Series. He currently drives the #47 Kroger/Clorox/Kimberly-Clark/Kingsford/Reese Towpower Hitches Toyota Camry for JTG Daugherty Racing. He currently resides in Trinity, North Carolina. He is married to his wife...
and Dale Jarrett
Dale Jarrett
Dale Arnold Jarrett is a former American race car driver and current sports commentator known for winning the 1999 NASCAR Winston Cup Series championship...
, and British Open runner-up, golfer Tom Watson.
Indications
Total hip replacement is most commonly used to treat joint failure caused by osteoarthritisOsteoarthritis
Osteoarthritis also known as degenerative arthritis or degenerative joint disease, is a group of mechanical abnormalities involving degradation of joints, including articular cartilage and subchondral bone. Symptoms may include joint pain, tenderness, stiffness, locking, and sometimes an effusion...
. Other indications include rheumatoid arthritis
Rheumatoid arthritis
Rheumatoid arthritis is a chronic, systemic inflammatory disorder that may affect many tissues and organs, but principally attacks synovial joints. The process produces an inflammatory response of the synovium secondary to hyperplasia of synovial cells, excess synovial fluid, and the development...
, avascular necrosis
Avascular necrosis
Avascular necrosis is a disease where there is cellular death of bone components due to interruption of the blood supply. Without blood, the bone tissue dies and the bone collapses...
, traumatic arthritis, protrusio acetabuli
Protrusio acetabuli
Protrusio acetabuli is an uncommon defect of the acetabulum. The acetabulum is the socket that receives the femoral head to make the hip joint. The hip bone of the pelvic bone/girdle is composed of three bones, the ilium, the ischium and the pubis. The socket is too deep and may protrude into...
, certain hip fracture
Hip fracture
A hip fracture is a femoral fracture that occurs in the proximal end of the femur , near the hip.The term "hip fracture" is commonly used to refer to four different fracture patterns and is often due to osteoporosis; in the vast majority of cases, a hip fracture is a fragility fracture due to a...
s, benign and malignant bone tumor
Bone tumor
A bone tumor refers to a neoplastic growth of tissue in bone. Abnormal growths found in the bone can be either benign or malignant .-Classification:...
s, arthritis associated with Paget's disease
Paget's disease
Sir James Paget, a surgeon and pathologist, described several diseases, including:* Paget's disease of bone * Paget's disease of the breast* Paget-Schroetter disease* Extramammary Paget's disease...
, ankylosing spondylitis
Ankylosing spondylitis
Ankylosing spondylitis , previously known as Bekhterev's disease, Bekhterev syndrome, and Marie-Strümpell disease is a chronic inflammatory disease of the axial skeleton with variable involvement of peripheral joints and nonarticular structures...
and juvenile rheumatoid arthritis. The aims of the procedure are pain relief and improvement in hip function. Hip replacement is usually considered only once other therapies, such as physical therapy
Physical therapy
Physical therapy , often abbreviated PT, is a health care profession. Physical therapy is concerned with identifying and maximizing quality of life and movement potential within the spheres of promotion, prevention, diagnosis, treatment/intervention,and rehabilitation...
and pain medications, have failed.
Techniques
There are several different incisions, defined by their relation to the gluteus medius. The approaches are posterior (Moore), lateral (Hardinge or Liverpool), antero-lateral (Watson-Jones), anterior (Smith-Petersen) and greater trochanterGreater trochanter
The greater trochanter of the femur is a large, irregular, quadrilateral eminence and a part of the skeletal system.It is directed a little lateralward and backward, and, in the adult, is about 1 cm lower than the head...
osteotomy. There is no compelling evidence in the literature for any particular approach, but consensus of professional opinion favours either modified anterolateral (Watson-Jones) or posterior approach.
Posterior approach
The posterior (Moore or Southern) approach accesses the joint and capsule through the back, taking piriformis musclePiriformis muscle
The piriformis is a muscle in the gluteal region of the lower limb. It was first named by Spigelius, a professor from the University of Padua in the 16th century.- Origin and insertion :...
and the short external rotators off the femur. This approach gives excellent access to the acetabulum and femur and preserves the hip abductors and thus minimises the risk of abductor dysfunction post operatively. It has the advantage of becoming a more extensile approach if needed. Critics cite a higher dislocation rate, although repair of the capsule, piriformis and the short external rotators along with use of modern large diameter head balls reduces this risk.
Lateral approach
The lateral approach is also commonly used for hip replacement. The approach requires elevation of the hip abductors (gluteus medius and gluteus minimus) in order to access the joint. The abductors may be lifted up by osteotomy of the greater trochanter and reapplying it afterwards using wires (as per Charnley), or may be divided at their tendinous portion, or through the functional tendon (as per Hardinge) and repaired using sutures. Although this approach has a lower dislocation risk than the posterior approach, critics note that occasionally the abductor muscles do not heal back on, leading to pain and weakness which is often very difficult to treat.Antero-lateral approach
The anterolateral approach develops the interval between the tensor fasciae lataeTensor fasciae latae
The tensor fasciae latae or tensor fasciæ latæ is a muscle of the thigh. The English name for this muscle is the muscle that stretches the band on the side...
and the gluteus medius.
Anterior approach
The anterior approach utilises an interval between the sartorius muscleSartorius muscle
The Sartorius muscle – the longest muscle in the human body – is a long thin muscle that runs down the length of the thigh. Its upper portion forms the lateral border of the femoral triangle.-Origin and insertion:...
and tensor fascia latae. Dr. Joel Matta has adapted this approach commonly used for pelvic fracture repair surgery in conjunction with a traction table for use when performing hip replacement. When used with older hip implant systems that had a small diameter head, dislocation rates were reduced compared to surgery performed through a posterior approach. With modern implant designs, dislocation rates are similar regardless of the approach and probably more a function of surgeon experience. There is a 10% rate of numbness in the thigh following this approach due to injury to the lateral femoral cutaneous nerve.
Minimally invasive approach
The double incision surgery and minimally invasive surgery seeks to reduce soft tissue damage through reducing the size of the incision. However, component positioning accuracy and visualization of the bone structures is significantly impaired. This can result in unintended fractures and soft tissue injury. Surgeons using these approaches are advised to use intraoperative x-ray fluoroscopy or computer guidance systems.Computer Assisted Surgery
Computer assisted surgery
Computer assisted surgery represents a surgical concept and set of methods, that use computer technology for presurgical planning, and for guiding or performing surgical interventions...
techniques are also available to guide the surgeon to provide enhanced accuracy. Several commercial CAS systems are available for use worldwide. HipNav
HipNav
HipNav was the first computer-assisted surgery system developed to guide the surgeon during total hip replacement surgery. It was developed at Carnegie Mellon University....
was the first system developed specifically for total hip replacement, and included navigation and preoperative planning based on a preoperative CT scan of the patient. Improved patient outcomes and reduced complications have not been demonstrated when these systems are used when compared to standard techniques.
Implants
The prosthetic implant used in hip replacement consist of different parts, the acetabular cup, the femoral component and the articular interface. Options exist for different patients and indications. Correct selection of the prosthesis is important.Acetabular Cup
The Acetabular cup is the component which is placed into the acetabulumAcetabulum
The acetabulum is a concave surface of the pelvis. The head of the femur meets with the pelvis at the acetabulum, forming the hip joint.-Structure:...
(hip socket). Cartilage and bone are removed from the acetabulum and the acetabular cup is attached using friction or cement. Some acetabular cups are one piece, others are modular. One piece (monobloc) shells are either polyethylene or metal, they have their articular surface machined on the inside surface of the cup and do not rely on a locking mechanism to hold a liner inplace. A monobloc polyethylene cup is cemented in place while a metal cup is held in place by a metal coating on the outside of the cup. Modular cups consist of two pieces, a shell and liner. The shell is made of metal, the outside has a porous coating while the inside contains a locking mechanism designed to accept a liner. Two types of porous coating used to form a friction fit are sintered
Sintering
Sintering is a method used to create objects from powders. It is based on atomic diffusion. Diffusion occurs in any material above absolute zero, but it occurs much faster at higher temperatures. In most sintering processes, the powdered material is held in a mold and then heated to a temperature...
beads or a foam metal design to mimic the trabeculae of cancellous bone. Additional fixation is achieved as bone grows onto or into the porous coating. Screws can be used to lag the shell to the bone providing even more fixation. Polyethylene liners are placed into the shell and connected by a rim locking mechanism, ceramic and metal liners are attached with a Morse taper.
Femoral Component
The femoral component is the component that fits in the femurFemur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
(thigh bone). Bone is removed and the femur is shaped to accept the femoral stem with attached prosthetic femoral head (ball). There are two types of fixation: cemented and uncemented. Cemented stems use acrylic bone cement
Bone cement
Bone cements have been used very successfully to anchor artificial joints for more than half a century. Artificial joints are anchored with bone cement. The bone cement fills the free space between the prosthesis and the bone and plays the important role of an elastic zone...
to form a mantle between the stem and to the bone. Uncemented stems use friction, shape and surface coatings to stimulate bone to remodel and bond to the implant. Stems are made of multiple materials (titanium, cobalt chromium and stainless steel) and they can be monolithic or modular. Modular components consist of different head dimensions and/or modular neck orientations; these attach via a taper similar to a Morse taper. These options allow for variability in leg length, offset and version. Femoral heads are made of metal or ceramic material. Metal heads, made of cobalt chromium for hardness, are machined to size and then polished to reduce wear of the socket liner. Ceramic heads are more smooth than polished metal heads, have a lower coefficient of friction than a cobalt chrome head, and in theory will wear down the socket liner more slowly. As of early 2011, follow up studies in patients have not demonstrated significant reductions in wear rates between the various types of femoral heads on the market. Ceramic implants are more brittle and may break after being implanted.
Articular Interface
The articular interface is not actually part of the either implant, rather it is the area between the acetabular cup and femoral component. The articular interface of the hip is a simple ball and socket joint. Size, material properties and machining tolerances at the articular interface can be selected based on patient demand to optimise implant function and longevity whilst mitigating associated risks. The interface size is measured by the outside diameter of the head or the inside diameter of the socket. Common sizes of femoral heads are 28 mm, 32 mm and 36 mm. While a 22.25 mm was common in the first modern prostheses, now even larger sizes are available 38–54+. Larger diameter heads lead to increased stability and range of motion whilst lowering the risk of dislocation. At the same time they also are subject to higher stresses such as friction and inertia. Different combinations of materials have different physical properties which can be coupled to reduce the amount of wear debris generated by friction. Typical pairing of materials includes metal on polyethylene (MOP), metal on crosslinked polyethylene (MOXP), ceramic on ceramic (COC), ceramic on crosslinked polyethylene (COXP) and metal on metal (MOM). Each combination has different advantages and disadvantages.Risks and complications
Risks and complications in hip replacement are similar to those associated with all joint replacements. They can include dislocation, loosening, impingement, infection, osteolysis, metal sensitivity, nerve palsy, pain and death.Dislocation
Dislocation is the most common complication of hip replacement surgery. At surgery the femoral head is taken out of the socket, hip implants are placed and the hip put back into proper position. It takes eight to twelve weeks for the soft tissues injured or cut during surgery to heal. During this period, the hip ball can come out of the socket. The chance of this is diminished if less tissue is cut, if the tissue cut is repaired and if large diameter head balls are used. Surgeons who perform more of the operations each year tend to have fewer patients dislocate. Doing the surgery from an anterior approach seems to lower dislocation rates when small diameter heads are used, but the benefit has not been shown when compared to modern posterior incisions with the use of larger diameter heads. Patients can decrease the risk further by keeping the leg out of certain positions during the first few months after surgery. Use of alcohol by patients during this early period is also associated with an increased rate of dislocation.Osteolysis
Many long term problems with hip replacements are the result of osteolysisOsteolysis
Osteolysis refers to an active resorption of bone matrix by osteoclasts as part of an ongoing disease process.-Osteolysis in joint replacement:...
. This is the loss of bone caused by the body's reaction to polyethylene wear debris, fine bits of plastic that come off the cup liner over time. An inflammatory
Inflammation
Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
process causes bone resorption that may lead to subsequent loosening of the hip implants and even fractures in the bone around the implants. In an attempt to eliminate the generation of wear particles, ceramic bearing surfaces are being used in the hope that they will have less wear and less osteolysis with better long term results. Metal cup liners joined with metal heads (metal-on-metal hip arthroplasty) were also developed for similar reasons. In the lab these show excellent wear characteristics and benefit from a different mode of lubrication. At the same time these two bearing surfaces were being developed, highly cross linked polyethylene plastic liners were also developed. The greater cross linking significantly reduces the amount of plastic wear debris given off over time. The newer ceramic and metal prostheses do not always have the long term track record of established metal on poly bearings. Ceramic pieces can break leading to catastrophic failure. This occurs in about 2% of the implants placed. They may also cause an audible, high pitched squeaking noise with activity. Metal-on-metal arthroplasty releases metal debris into the body raising concerns about the potential dangers of these accumulating over time. Highly cross linked polyethylene is not as strong as regular polyethylene. These plastic liners can crack or break free of the metal shell that holds them.
Metal sensitivity
Concerns are being raised about the metal sensitivity and potential dangers of metal particulate debris. There are new publications that have demonstrated development of pseudotumors, soft tissue masses containing necrotic tissue, around the hip joint. It appears these masses are more common in women and these patients show a higher level of iron in the blood. The cause is unknown and is probably multifactorial. There may be a toxic reaction to an excess of particulate metal wear debris or a hypersensitivity reaction to a normal amount of metal debris.Metal hypersensitivity is a well-established phenomenon and is common, affecting about 10–15% of the population. Contact with metals can cause immune reactions such as skin hives, eczema, redness and itching. Although little is known about the short and long term pharmacodynamics and bioavailability of circulating metal degradation products in vivo, there have been many reports of immunologic type responses temporally associated with implantation of metal components. Individual case reports link hypersensitivity immune reactions with adverse performance of metallic clinical cardiovascular, orthopedic and plastic surgical and dental implants.
By 2010 reports in the orthopaedic literature have increasingly cited the problem of early failure of metal on metal prostheses in a small percentage of patients. Failures may relate to release of minute metallic particles or metal ions from wear of the implants, causing pain and disability severe enough to require revision surgery in 1–3% of patients. Design deficits of some prothesis models, especially with heat-treated alloys and a lack of special surgical experience accounts for most of the failures. Surgeons at leading medical centers such as the Mayo Clinic have reported reducing by 80 percent their use of metal-on-metal implants over the last year in favor of those made from other materials, like combinations of metal and plastic. The cause of these failures remain controversial, and may include both design factors, technique factors, and factors related to patient immune responses (allergy type reactions). In the United Kingdom the Medicines and Healthcare products Regulatory Agency
Medicines and Healthcare products Regulatory Agency
The Medicines and Healthcare products Regulatory Agency is the UK government agency which is responsible for ensuring that medicines and medical devices work and are acceptably safe....
commenced an annual monitoring regime for metal-on-metal hip replacement patients from May 2010. Data which is shown in The Australian Orthopaedic Association's 2008 National Joint Replacement Registry, a record of nearly every hip implanted in that country over the previous 10 years, tracked 6,773 BHR (Birmingham Hip Resurfacing) Hips and found that less than one-third of one percent may have been revised due to the patient's reaction to the metal component. Other similar metal-on-metal designs have not fared as well, where some reports show 76% to 100% of the people with these metal-on-metal implants and have aseptic implant failures requiring revision also have evidence of histological inflammation accompanied by extensive lymphocyte infiltrates, characteristic of delayed type hypersensitivity responses. It is not clear to what extent this phenomenon negatively affect orthopedic patients. However for patients presenting with signs of an allergic reactions, evaluation for sensitivity should be conducted. Removal of the device that is not needed should be considered, since removal may alleviate the symptoms. Patients who have allergic reactions to cheap jewelry are more likely to have a reactions to orthopedic implants. It is important to note that there is increasing awareness of the phenomenon of metal sensitivity and many surgeons now take this into account when planning which implant is optimal for each patient.
On February 10, 2011 the U. S F.D.A issued a patient advisory on metal-metal hip implants located here: http://www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/ImplantsandProsthetics/MetalonMetalHipImplants/default.htm
Nerve palsy
Post operative sciatic nerve palsy is another possible complication. The incidence of this complication is low. Femoral nerve palsy is another but much more rare complication. Both of these will typically resolve over time, but the healing process is slow. Patients with pre-existing nerve injury are at greater risk of experiencing this complication and are also slower to recover.Chronic pain
A few patients who have had a hip replacement suffer chronic pain after the surgery. Groin pain can develop if the tendon that raises the hip (iliopsoas) rubs against the edge of the acetabular cup. Bursitis can develop at the trochanter where a surgical scar crosses the bone, or if the femoral component used pushes the leg out to the side too far. Also some patients can experience pain in cold or damp weather. Incision made in the front of the hip (anterior approach) can cut a nerve running down the thigh leading to numbness in the thigh and occasionally chronic pain at the point where the nerve was cut (a neuroma).Metal toxicity
Most hip replacements consist of cobalt and chromium alloys, or titanium. Stainless steel is no longer used. All implants release their constituent ions into the blood. Typically these are excreted in the urine, but in certain individuals the ions can accumulate in the body. In implants like the DePuy ASR, which involves a metal-on-metal ball-and-socket jointBall and socket joint
A ball and socket joint is a joint in which the distal bone is capable of motion around an indefinite number of axes, which have one common center...
structure, the metal parts to grind against one another, releasing microscopic fragments of cobalt
Cobalt
Cobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal....
and chromium
Chromium
Chromium is a chemical element which has the symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable...
into the patient's bloodstream. There are reports of cobalt toxicity with hip replacement patients.
Leg Length Inequality
The leg can be lengthened or shortened during surgery. Unequal legs are the most common complaint by patients after surgery with over lengthening the most common problem. Sometimes the leg seems long immediately after surgery when in fact both are equal length. An arthritic hip can develop contractures that make the leg behave as if it is short. When these are relieved with replacement surgery and normal motion and function are restored, the body feels that the limb is now longer than it was. If the legs are truly equal, the sense of inequality resolves within a month or two of surgery. If the leg is unequal, it will not. A shoe lift for the short leg, or in extreme cases, a corrective operation may be needed.True leg length inequality may sometimes be caused by improper implant selection. The femoral component may be too large and stick out of the femur further than needed. The head ball selected may sit too proud on the stem. Stiffness in the lower back from arthritis or previous fusion surgery seems to magnify the perception of leg length inequality.
Conservative management
The first line approach as an alternative to hip replacement is conservative management which involves a multimodal approach of medication, activity modification and physical therapyPhysical therapy
Physical therapy , often abbreviated PT, is a health care profession. Physical therapy is concerned with identifying and maximizing quality of life and movement potential within the spheres of promotion, prevention, diagnosis, treatment/intervention,and rehabilitation...
. Conservative management can prevent or delay the need for hip replacement.
Hemiarthroplasty
Hemiarthroplasty is a surgical procedure which replaces one half of the joint with an artificial surface and leaves the other part in its natural (pre-operative) state. This class of procedure is most commonly performed on the hip after a subcapital (just below the head) fracture the neck of the femur (a hip fractureHip fracture
A hip fracture is a femoral fracture that occurs in the proximal end of the femur , near the hip.The term "hip fracture" is commonly used to refer to four different fracture patterns and is often due to osteoporosis; in the vast majority of cases, a hip fracture is a fragility fracture due to a...
). The procedure is performed by removing the head of the femur and replacing it with a metal or composite prosthesis
Prosthesis
In medicine, a prosthesis, prosthetic, or prosthetic limb is an artificial device extension that replaces a missing body part. It is part of the field of biomechatronics, the science of using mechanical devices with human muscle, skeleton, and nervous systems to assist or enhance motor control...
. The most commonly used prosthesis designs are the Austin Moore prosthesis and the Thompson Prosthesis. More recently a composite
Composite material
Composite materials, often shortened to composites or called composition materials, are engineered or naturally occurring materials made from two or more constituent materials with significantly different physical or chemical properties which remain separate and distinct at the macroscopic or...
of metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...
and HDPE which forms two interphases (bipolar prosthesis) has also been used. The bipolar prosthesis has not been shown to have any advantage over monopolar designs. The procedure is recommended only for elderly and frail patients, due to their lower life expectancy and activity level. This is because with the passage of time the prosthesis tends to loosen or to erode the acetabulum
Acetabulum
The acetabulum is a concave surface of the pelvis. The head of the femur meets with the pelvis at the acetabulum, forming the hip joint.-Structure:...
.
Hip resurfacing
Hip ResurfacingHip resurfacing
Hip resurfacing has been developed as a surgical alternative to total hip replacement . The procedure consists of placing a cobalt-chrome metal cap, which is hollow and shaped like a mushroom, over the head of the femur while a matching metal cup is placed in the acetabulum , replacing the...
is an alternative to hip replacement surgery. It is a bone conserving procedure that places a metal cap on the femoral head instead of amputating it. There is no long stem placed down the femur so it is more like a natural hip and may allow patients a return to many activities, including marathons and triathlons; some patients have even completed Ironman and Ultraman competitions following hip resurfacing surgery, although patients must have good bone quality to qualify for it. It has been used in Europe for over 17 years and become a common procedure. The first device, the BHR or Birmingham Hip Resurfacing device was approved by the FDA on May 9, 2006.
The Australian Registry hip resurfacing data for 2009, 70 percent of which comes from BHR Hip procedures, indicates that for men under age 65, hip resurfacing performs at the same or a better rate than total hip replacement.
Viscosupplementation
Current alternatives also include viscosupplementation, or the injection of artificial lubricants into the joint. Use of these medications in the hip is off label. The cost of treatment is typically not covered by health insurance organizations.Some believe the future of osteoarthritis treatment is bioengineering, targeting the growth and/or repair of the damaged, arthritic joint. Centeno et al. have reported on the partial regeneration of an arthritic human hip joint using mesenchymal stem cell
Stem cell
This article is about the cell type. For the medical therapy, see Stem Cell TreatmentsStem cells are biological cells found in all multicellular organisms, that can divide and differentiate into diverse specialized cell types and can self-renew to produce more stem cells...
s in one patient. It is yet to be shown that this result will apply to a larger group of patients and result in significant benefits. The FDA has stated that this procedure is being practiced without conforming to regulations, but Centeno claims it is exempt from FDA regulation. It has not been shown in controlled clinical trials to be effective, and costs over $7,000.
See also
- Hip examinationHip examinationIn medicine, physiotherapy, and chiropractic, the hip examination, or hip exam, is undertaken when a patient has a complaint of hip pain and/or signs and/or symptoms suggestive of hip joint pathology...
- 2010 DePuy Hip Recall2010 DePuy Hip Recall2010 DePuy Hip Replacement Recall was instituted when DePuy Orthopaedics, Inc., a division of Johnson and Johnson, recalled its ASR XL Acetabular metal-on-metal hip replacement system on August 24, 2010.-Background:...
- Femoral Acetabular ImpingementFemoral Acetabular ImpingementFemoroacetabular Impingement or hip impingement syndrome is a condition affecting the hip joint in young and middle-aged adults. Impingement occurs when the ball shaped femoral head rubs abnormally or doesn't have full range of motion in the acetabular socket...
- Abductor wedgeAbductor wedgeAn abductor wedge is designed to separate the legs of a patient. It is often used after hip surgery to prevent the new hip from "popping out"....