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Hip replacement

Hip replacement is a surgical procedure in which the hip joint is replaced by a prosthetic implant, that is, a hip prosthesis.[1] Hip replacement surgery can be performed as a total replacement or a hemi/semi(half) replacement. Such joint replacement orthopaedic surgery is generally conducted to relieve arthritis pain or in some hip fractures. A total hip replacement (total hip arthroplasty or THA) consists of replacing both the acetabulum and the femoral head while hemiarthroplasty generally only replaces the femoral head. Hip replacement is one of the most common orthopaedic operations, though patient satisfaction varies widely. Approximately 58% of total hip replacements are estimated to last 25 years.[2] The average cost of a total hip replacement in 2012 was $40,364 in the United States, and about $7,700 to $12,000 in most European countries.[3]

Hip replacement

Hip arthroplasty

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Medical uses[edit]

Total hip replacement is most commonly used to treat joint failure caused by osteoarthritis. Other indications include rheumatoid arthritis, avascular necrosis, traumatic arthritis, protrusio acetabuli,[4] certain hip fractures, benign and malignant bone tumors,[5] arthritis associated with Paget's disease,[6] ankylosing spondylitis[7] and juvenile rheumatoid arthritis.[8] The aims of the procedure are pain relief and improvement in hip function. Hip replacement is usually considered only after other therapies, such as physical therapy and pain medications, have failed.[9]

Female sex

Younger age

Previous without complete dislocation

subluxation

Previous trauma

Substantial weight loss

Recent onset or progression of or a neurological disorder

dementia

Malposition of the cup

Liner wear, particularly when it allows head movement of more than 2 mm within the cup compared to its original position

Prosthesis loosening with migration

Acetabular inclination.[88] This parameter is calculated on an anteroposterior radiograph as the angle between a line through the lateral and medial margins of the acetabular cup and the transischial line which is tangential to the inferior margins of the ischium bones.[88]

Acetabular inclination.[88] This parameter is calculated on an anteroposterior radiograph as the angle between a line through the lateral and medial margins of the acetabular cup and the transischial line which is tangential to the inferior margins of the ischium bones.[88]

Acetabular inclination is normally between 30 and 50°.[88] A larger angle increases the risk of dislocation.[14]

Acetabular inclination is normally between 30 and 50°.[88] A larger angle increases the risk of dislocation.[14]

Acetabular anteversion.[89] This parameter is calculated on a lateral radiograph as the angle between the transverse plane and a line going through the (anterior and posterior) margins of the acetabular cup.[89]

Acetabular anteversion.[89] This parameter is calculated on a lateral radiograph as the angle between the transverse plane and a line going through the (anterior and posterior) margins of the acetabular cup.[89]

Acetabular anteversion is normally between 5 and 25°.[14] An anteversion below or above this range increases the risk of dislocation.[14] There is an intra-individual variability in this method because the pelvis may be tilted in various degrees in relation to the transverse plane.[14]

Acetabular anteversion is normally between 5 and 25°.[14] An anteversion below or above this range increases the risk of dislocation.[14] There is an intra-individual variability in this method because the pelvis may be tilted in various degrees in relation to the transverse plane.[14]

Leg length discrepancy after hip replacement is calculated as the vertical distance between the middle of the minor trochanters, using the acetabular tear drops[88] or the transischial line[14] as references for the horizontal plane. A discrepancy of up to 1 cm is generally tolerated.[88][14]

Leg length discrepancy after hip replacement is calculated as the vertical distance between the middle of the minor trochanters, using the acetabular tear drops[88] or the transischial line[14] as references for the horizontal plane. A discrepancy of up to 1 cm is generally tolerated.[88][14]

Center of rotation: The horizontal center of rotation is calculated as the distance between the acetabular teardrop and the center of the head (or caput) of the prosthesis and/or the native femoral head on the contralateral side.[88] The vertical center of rotation instead uses the transischial line for reference.[88] The parameter should be equal on both sides.[88]

Center of rotation: The horizontal center of rotation is calculated as the distance between the acetabular teardrop and the center of the head (or caput) of the prosthesis and/or the native femoral head on the contralateral side.[88] The vertical center of rotation instead uses the transischial line for reference.[88] The parameter should be equal on both sides.[88]

Post-operative projectional radiography is routinely performed to ensure proper configuration of hip prostheses.


The direction of the acetabular cup influences the range of motion of the leg, and also affects the risk of dislocation.[14] For this purpose, the acetabular inclination and the acetabular anteversion are measurements of cup angulation in the coronal plane and the sagittal plane, respectively.

Alternatives and variations[edit]

Conservative management[edit]

The first line approach as an alternative to hip replacement is conservative management which involves a multimodal approach of oral medication, injections, activity modification and physical therapy.[90] Conservative management can prevent or delay the need for hip replacement.

Preoperative care[edit]

Preoperative education is an important part of patient care. Some evidence indicates that it may slightly reduce anxiety before hip or knee replacement, with low risk of negative effects.[91]

Prevalence and cost[edit]

Total hip replacement incidence varies in developed countries between 30 (Romania) and 290 (Germany) procedures per 100,000 population per year.[99] Approximately 0.8% of Americans have undergone the procedure.[100]


According to the International Federation of Healthcare Plans, the average cost of a total hip replacement in 2012 was $40,364 in the United States, $11,889 in the United Kingdom, $10,987 in France, $9,574 in Switzerland, and $7,731 in Spain.[3] In the United States, the average cost of a total hip replacement varies widely by geographic region, ranging from $11,327 (Birmingham, Alabama) to $73,927 (Boston, Massachusetts).[101]

Prosthesis from 1960: The "Gosset-style" prosthesis was first introduced in 1949, although the specific example was made by Lusterlite Ltd of in 1960.  It has a perspex "ball" and simple rod-like shaft made of nickel-plated stainless-steel.[110]

Leeds

Examples of prostheses from 1970 to 1985: Examples provided by Hospital, UK are made of Vitallium (Co/Cr alloy) with curved standard or slender femoral stems.[115][116] One example has a studded cup.[117]

Ipswich

Examples of prostheses from the 1990s: Examples, some of which were developed at the Redhill Group of Hospitals and Dorking Hospital, include a ringed titanium hip prosthesis with a screw stem and porous cup, a modular hip prosthesis with a textured femoral stem to aid bone grafting (material unspecified),[119] two Thompson-type prostheses made of Vitallium alloy[112][113] and an Austin Moore type prosthesis (material unspecified), with a porous metal femoral stem.[114]

[118]

Example of acetabular cup prosthesis from 1998: Example of a prosthetic socket, from Sulzer Orthopedics Inc., is the Inter-Op Hemispherical Shell. This is made from materials not recognised by the human body, so the body's immune system does not attack and reject the joint.

[120]

Examples of prostheses from 2006: Examples made by include an "Anthology" titanium prosthesis, which has a flat-tapered stem placed in the thigh bone, and an "Echelon" (cobalt-chrome prosthesis for both cementless and cemented arthroplasty. Both have porous coating to promote bone adhesion.[121][122]

Smith & Nephew Orthopedics

The earliest recorded attempts at hip replacement were carried out in Germany in 1891 by Themistocles Gluck (1853–1942),[102][103] who used ivory to replace the femoral head (the ball on the femur), attaching it with nickel-plated screws.[104] Subsequently, he used a cement made from plaster of Paris, powdered pumice and glue.[105]


Molded-glass implants were introduced in the 1920s by Smith-Peterson in the USA. Although these showed good bio-compatibility, they were mechanically fragile so he started experiments with metallic prostheses in the 1930s.[105][106] In 1938, Philip Wiles of Middlesex General Hospital, UK carried out a total hip replacement using a stainless-steel prosthesis attached by bolts.[107] In 1940, Dr. Austin T. Moore (1899–1963)[108] at Columbia Hospital in Columbia, South Carolina performed a hip replacement using a prototype prosthesis made of the cobalt-chrome alloy Vitallium; it was inserted into the medullary canal and "fenestrated" to promote bone regrowth. A commercial version known as the "Austin Moore Prosthesis" was introduced in 1952; it is still in use today, typically for femoral neck fractures in the elderly.[105] Following the lead of Wiles, several UK general hospitals including Norwich, Wrightington, Stanmore, Redhill and Exeter developed metal-based prostheses during the 1950s and 1960s.[107]


Robert Juditt was the first to perform hip replacements via the anterior approach in 1947 in Paris. He taught this method to Émile Letournel. Joel Matta, who had studied with Letournel, brought this approach to the United States and went on to popularize it.[109]


Metal/Acrylic prostheses were tried in the 1950s [105][110] but were found to be susceptible to wear.  In the 1960s, John Charnley[111][105][106] at Wrightington General Hospital combined a metal prosthesis with a PTFE acetabular cup before settling on a metal/polyethylene design. Ceramic bearings were developed in the late 1970s.[105][106]


The means of attachment have also diversified.[105][106]  Early prostheses were attached by screws (e.g. Gluck, Wiles) with later developments using dental or bone cements (e.g. Charnley, Thompson[112][113]) or cementless systems which relied on bone regrowth (Austin-Moore,[114] Ring[106]). The choice of alloy, bearing material, attachment and detailed geometry has led to the wide variety of prosthesis designs available today.[105][106][107]


The London Science Museum has a collection of hip prostheses which reflect developments in the US, UK and elsewhere. These show the use of different materials and different designs for different circumstances (e.g. cemented and uncemented arthroplasty.)  Some are on display in the museum's "Medicine: The Wellcome Galleries". 


The items include:


The Science Museum's collection also includes specialised surgical tools for hip operations:

2010 DePuy Hip Recall

Abductor wedge

Femoroacetabular impingement

Gruen zone

Hip examination

Edheads Virtual Hip Surgery + Surgery Photos