What are the components of a hip implants in a total hip replacement?
In a total hip replacement surgery , the painful parts of the damaged hip are replaced with artificial hip parts called a prosthesis, a device that substitutes or supplements a joint. The prosthesis consists of steel components: a socket, ball, and stem.
The outer shell of the socket is usually made of metal and the inner shell consists of plastic, or the entire socket may be plastic. When the metal ball is joined with the socket, the new hip can allow for smooth, nearly frictionless movement.
What are the different hip replacement implant options available?
The materials used in the implant depend on several factors, including the age of the patient, the activity level of the patient, and the surgeon's preference.
Below are brief and generic descriptions of some of the most commonly used hip replacement implants.
Metal and Plastic Implant
These are the most commonly used hip replacement implants. Both the ball and the socket of the hip joint are replaced with a metal prosthesis, and a plastic spacer is placed in between. The metals used include titanium, stainless steel, and cobalt chrome. The plastic is called polyethylene.
• Durable and versatile
• Long, successful clinical history
• Not toxic to the human body
• Adequate toughness for most lifestyles
• May wear down over time, which can lead to inflammation, bone loss, and/or a revision procedure
In this case there is no plastic piece inserted in between. Metal-on-metal implants do not wear out as quickly as the metal and plastic materials.
• Range-of-Motion - allows for use of a larger femoral head providing for greater range-of-motion
• Stability-use of larger femoral head also lowers risk of dislocation
• Longevity-offers a lower risk of inflammation and implant loosening. Metal bearings are less likely than polyethylene bearings to release particles into the body and to wear down over time
• May not be appropriate for those with metal sensitivity.
• There are concerns about the wear debris that is generated from the metal-on-metal implants.
Ceramic bearings are available in 2 configurations: a ceramic femoral head (ball) with a polyethylene liner, or a ceramic femoral head (ball) with a ceramic liner. These are designed to be the most resistant to wear of all available hip replacement implants and they wear even less than the metal-on-metal implants. Ceramics are more scratch resistant and smoother than any of these other implant materials.
• Reduced wear - improved lubrication and reduced friction
• Performance - lower wear rates compared with polyethylene and metal
• More prone to fracture
• Less forgiving in surgery
• More likely to require the removal of greater quantities of healthy bone due to size limitations
• More expensive than other bearing options
Metal and Highly Crosslinked Polyethylene
One of the more commonly used implants are new types of plastic that are designed to be more resistant to wearing out. These so-called highly crosslinked plastics are manufactured in a way that they wear out less quickly than the traditional plastics. However, since these implants have been available only for a few years, no long-term data is present to establish how well they work compared to the traditional plastic implants.
• Performance - wear out less quickly than the traditional plastics
• No long-term data to compare against other implant options
How is the implant affixed in the body?
This is achieved in one of three ways:
• Bone Cement: A special type of bone acrylic cement may be used to secure some or all of the implant components to the bone. If used, the bone cement takes about 15 minutes to set.
• Press-Fit or Cementless: The implants may be “press-fit” into the bone. Press-fit components may have a special porous coating that allows bone tissue to grow up to it for fixation.
• Combination: Depending upon the implant components and condition of the pelvic and thigh bone, a combination of cement and press-fit attachment may be used.
Who are some of the hip replacement implant manufacturers?
Some of the hip replacement implants manufacturers are:
• Johnson & Johnson DePuy
• Smith & Nephew
Click the links above to learn more about them.
Who is a low demand patient?
A low demand patient refers to a patient who has fallen and fractured his/her hip or a patient who has low physical activity.
What are the factors affecting the longevity of a hip joint replacement?
Longevity of the prosthetic hip varies from patient to patient. It depends on many factors, such as the patient's physical condition, activity level, and weight, as well as the accuracy of implant placement during surgery.
As with any mechanical joint, the ball and socket components move against each other. Natural fluid in the joint space, called synovial fluid, helps to lubricate the implants just as it lubricates the bones and cartilage in a natural joint. Still, the prosthetic components do wear as they roll and slide against each other during movement. The rate of wear depends partly on how the hip joint is used. Activities that place a lot of stress on the joint implants, as may be the case with heavier and more active patients, may reduce the service life of the prosthesis. Implant loosening and wear on the plastic portions of the implant can lead to the necessity for revision surgery to replace the worn components, or all of the components.
To achieve longevity and success of your hip replacement, you should:
• Avoid repetitive heavy lifting
• Avoid excessive stair climbing
• Maintain appropriate weight
• Stay healthy and active
• Avoid "impact loading" sports such as jogging, downhill skiing and high impact aerobics
• Consult your surgeon before beginning any new sport or activity
• Avoid any physical activities involving quick stop-start motion, twisting or impact stresses
• Avoid excessive bending when weight bearing, like climbing steep stairs
• Not lift or push heavy objects
• Not kneel
• Avoid low seating surfaces and chairs.
What activities can I do or not do after receiving a hip implant?
• Typically, patients are advised to avoid high impact sports such as jogging, basketball, racquetball, gymnastics, etc.
• Safer activities may include walking, golf, swimming, and bicycling.
Will an implant set off a metal detector?
Hip implants may possibly set off metal detectors as the implants are made of metal. You may be provided with a special card by your healthcare provider to keep in your wallet explaining that you have a hip implant.
What is the MIS (minimally invasive surgery) approach in total hip replacement surgery?
The MIS approach (also known as "keyhole surgery") in total hip replacement (THR) is an alternative to the traditional total hip replacement surgery. Traditional surgery involves a long incision and the surgeon has to cut muscles, tendons and ligaments to access the hip joint. The more tissues that are cut, the longer it usually takes patients to heal. In the MIS approach is a less invasive approach of doing a hip replacement surgery in which the size of the cut is reduced. Newer surgical techniques and tools allow MIS surgeons to place the same hip implant in a manner that allows muscles and tendons to be avoided or separated, rather than cut. This makes rehabilitation faster and less painful and causes less scarring.
What are the benefits of the MIS approach?
Some of the potential patient benefits of the MIS procedure are:
• A single, smaller incision
• Less tissue trauma
• Spares muscles and tendons, allowing for the possibility of a faster recovery
• Faster and less painful rehabilitation
• Shorter hospital stay
• Smaller scar
• Reduced blood loss and less need for pre-surgery blood donation
• Faster return to work and daily activities
Where can I affordably get MIS procedure for THR? How much does total hip replacement cost?
The cost of total hip replacement surgery in India, Mexico, Thailand and some other countries is lower than the cost of THR at most hospitals in the US. Check out medical tourism for total hip replacement surgery overseas. Seeing competition from foreign provides, some US hospitals today are offering to match the lower foreign price for Americans. Contact Healthbase to connect to US or foreign hospitals for affordable total hip replacement surgery.
Find a US/UK trained foreign hip replacement surgeon.