Joint replacement surgery has proven to be one of the most effective surgical treatments for arthritis. There are about as many joint replacement options as there are joints, but I will use the knee and hip as examples because the knee and hip are the most common joints replaced.
The knee actually has three compartments - one on the medial (or inner side of the knee), one on the lateral (outer side of the knee) and one underneath the kneecap, i.e. the patellofemoral compartment. Some people do not wear out all three compartments at the same time and may qualify for a partial joint replacement.
We call a partial joint replacement a hemi arthroplasty. A complete joint replacement would be called a total joint arthroplasty.
In a partial knee replacement, the most common area that is replaced is the medial or inner compartment. This is often done through a much smaller incision, and we are now performing this as out-patient surgery. It doesn't mean that they are not without risks and do not require rehabilitation, but they are definitely less invasive and leave the knee feeling more “normal.”
Lateral compartment hemi arthroplasty can also be performed but is a little bit more technically difficult. Patellofemoral hemi arthroplasty to replace the “kneecap” joint is much less common and much less successful. Because of the excessive forces under the kneecap, these partial joint replacements tend to wear out faster and fail quicker.
The most common form of knee replacement is a total knee replacement. Actually it is more of a re-surfacing than an actual replacement. In other words, the entire knee is not cut out, just the ends of the bone are cut off in a fashion that a metal cap can be cemented onto the thigh (femur) bone. A metal plate is cemented onto the shin (tibia) bone and a piece of high density polyethylene plastic gets inserted on the shin bone plate to basically function as the “new cartilage.” The patella is replaced most of the time with a piece of plastic cemented on its surface as well.
In contrast, hip replacements do indeed replace the entire hip joint. The hip joint is a ball and socket joint and therefore the ball, along with the neck of the femur/thigh bone is removed and the socket is reamed into a spherical shape. A metallic cup is usually impacted into position for the new socket. Most of the time these are actually not cemented, but many times they are. There are various forms where the bone grows into the metal.
The femur is a hollow bone so the new metal ball is actually attached to a metal stem which is either impacted down the hollow femoral shaft or cemented down the femoral shaft. A piece of high density polyethylene plastic is inserted and locked into position in the socket and there are different size metal balls that can be used for the new femoral head. Both hip and knee replacement surgery require physical therapy/rehabilitation.
While not always a definite fact: hip replacements are usually “easier” to recover from than knee replacements.
With knee replacements patients often actually lose some range of motion of their knee, but the good news is both surgeries are very good at pain relief. They can't always relieve 100 percent of the pain, but usually anywhere between 80 to 95 percent.
Any type of joint replacement has restrictions - such as running, jumping, etc. are not recommended due to the fact that they put excessive stresses on the metal and plastic and can cause increased wear, earlier wear and tear, earlier loosening and failure. Because joint replacements are made out of metal and plastic as well as cement, many times they eventually do wear out. The average life span for a knee or hip replacement is somewhere around 15 years. Partial joint replacements for the knee usually last five to 10 years, and then most of the time can be converted to a complete knee replacement.
Revision joint replacements can be performed but the surgery is often times much more difficult with greater blood loss, more scarring, they don't last as long and there are more potential complications.
Most joint replacements are made out of either cobalt, chrome, and/or Titanium. There are various ceramic replacements but that technology is still evolving.
There are some hip replacement re-surfacing surgeries that are making a come back due to better technology.
Dr. Marc P. Pietropaoli is a board certified/fellowship trained orthopedic surgeon/sports medicine specialist and is president of Victory Sports Medicine & Orthopedics in Skaneateles .
We call a partial joint replacement a hemi arthroplasty. A complete joint replacement would be called a total joint arthroplasty.
In a partial knee replacement, the most common area that is replaced is the medial or inner compartment. This is often done through a much smaller incision, and we are now performing this as out-patient surgery. It doesn't mean that they are not without risks and do not require rehabilitation, but they are definitely less invasive and leave the knee feeling more “normal.”
Lateral compartment hemi arthroplasty can also be performed but is a little bit more technically difficult. Patellofemoral hemi arthroplasty to replace the “kneecap” joint is much less common and much less successful. Because of the excessive forces under the kneecap, these partial joint replacements tend to wear out faster and fail quicker.
The most common form of knee replacement is a total knee replacement. Actually it is more of a re-surfacing than an actual replacement. In other words, the entire knee is not cut out, just the ends of the bone are cut off in a fashion that a metal cap can be cemented onto the thigh (femur) bone. A metal plate is cemented onto the shin (tibia) bone and a piece of high density polyethylene plastic gets inserted on the shin bone plate to basically function as the “new cartilage.” The patella is replaced most of the time with a piece of plastic cemented on its surface as well.
In contrast, hip replacements do indeed replace the entire hip joint. The hip joint is a ball and socket joint and therefore the ball, along with the neck of the femur/thigh bone is removed and the socket is reamed into a spherical shape. A metallic cup is usually impacted into position for the new socket. Most of the time these are actually not cemented, but many times they are. There are various forms where the bone grows into the metal.
The femur is a hollow bone so the new metal ball is actually attached to a metal stem which is either impacted down the hollow femoral shaft or cemented down the femoral shaft. A piece of high density polyethylene plastic is inserted and locked into position in the socket and there are different size metal balls that can be used for the new femoral head. Both hip and knee replacement surgery require physical therapy/rehabilitation.
While not always a definite fact: hip replacements are usually “easier” to recover from than knee replacements.
With knee replacements patients often actually lose some range of motion of their knee, but the good news is both surgeries are very good at pain relief. They can't always relieve 100 percent of the pain, but usually anywhere between 80 to 95 percent.
Any type of joint replacement has restrictions - such as running, jumping, etc. are not recommended due to the fact that they put excessive stresses on the metal and plastic and can cause increased wear, earlier wear and tear, earlier loosening and failure. Because joint replacements are made out of metal and plastic as well as cement, many times they eventually do wear out. The average life span for a knee or hip replacement is somewhere around 15 years. Partial joint replacements for the knee usually last five to 10 years, and then most of the time can be converted to a complete knee replacement.
Revision joint replacements can be performed but the surgery is often times much more difficult with greater blood loss, more scarring, they don't last as long and there are more potential complications.
Most joint replacements are made out of either cobalt, chrome, and/or Titanium. There are various ceramic replacements but that technology is still evolving.
There are some hip replacement re-surfacing surgeries that are making a come back due to better technology.
Dr. Marc P. Pietropaoli is a board certified/fellowship trained orthopedic surgeon/sports medicine specialist and is president of Victory Sports Medicine & Orthopedics in Skaneateles .
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