These advanced joint treatment options are available at the Hip and Knee Center of Excellence.

MINIMALLY INVASIVE HIP REPLACEMENT

The minimally invasive total hip replacement was developed by Dr. Swanson after being introduced to the concept in early 1997. Dr. Swanson began using the technique in May of 1997 and has continued to make improvements that now allow reliable surgery and reproducibly good results in most patients. Standardization of the technique has allowed teaching to other surgeons. Numerous physicians and orthopedic companies have shown interest in promoting “minimally invasive surgery” for total hip replacements.

The minimally invasive technique utilizes a 3-4 inch incision, much smaller than the 8-10 inch approach historically used for hip replacement. Patients require less anesthesia and pain medication, and mobilize more quickly. This results in both quicker recovery for the patient and a lower incidence of complications.

Patients typically recover from minimally invasive surgery in about one-third the time it takes to recover from standard incision surgery (average time to return to normal daily activities was 4.2 weeks compared to 12 weeks historically and in Dr. Swanson’s original series of his first 100 minimally invasive surgery compared to his last 50 standard incision total hip replacements). Dr. Swanson  reported the results of his first 1,000 consecutive minimally invasive total hips in the Journal of Arthroplasty, 2005. In Dr. Swanson’s original series (presented at the 2001 WOA meeting and 2003 AAOS meeting), he found that the overall incidence of complications was reduced from 24% to 13% with the minimally invasive procedure.  

RESURFACING

Since hip resurfacing was re-approved by the FDA for use in the United States, it has gained popularity in the treatment of hip arthritis in the young, active patient.  Although technically a larger procedure than total hip replacement, some claim that it may allow patients to better return to active, competitive sports (e.g. Floyd Landis).  However, other studies now question this assertion.

 At any rate, if you are a young, active male (under the age of 55) without kidney problems, allergic reactions to metals, or a young female who is not planning pregnancy, you may be a candidate for a hip resurfacing.

 The Swanson Hip and Knee Center of Excellence offers hip resurfacing in this subgroup of patients.

ARTHROSCOPY

Not every problem joint needs a hip or knee replacement.  Many techniques are now available to preserve anatomy—called joint preservation procedures.

Arthroscopy is one of those procedures.  Simple problems like meniscus (cartilage) tears in the knee are dealt with very effectively with knee arthroscopy.  Using 2 or 3 tiny incisions, the tear can be visualized with a video camera inserted into the knee, and the meniscus either trimmed or repaired.  Other procedures are now available to restore or preserve worn surfaces.  These include mosaicplasties, Carticel cartilage cell cultures, and osteochondral allografts.

Most recently, the treatment of hip problems using arthroscopy have become very useful.  Acetabular labral tears (the gasket holding fluid into the hip joint) can be managed very effectively using hip arthroscopy through 2 tiny incisions.  A more common abnormality, often leading to labral tears and eventual hip arthritis, femoro-acetabular impingement (FAI) is very effectively treated arthroscopically.

These advanced joint preservation treatment options are available at the Hip and Knee Center of Excellence.

ALTERNATIVE BEARING SURFACES

The bearing surfaces—the artificial femoral head (ball) and cup liner (socket)—are an important determinant of the longevity of your new prosthesis.  In young, active patients, standard polyethylene cup liners used with metal femoral heads tend to wear out quickly, often within 7-10 years.  Several alternative bearing surfaces are available for the young, high-activity patient.

Highly Crosslinked Polyethylene

New, “highly crosslinked” formulations of polyethylene have shown vastly improved results in laboratory testing compared to standard ultra-high molecular weight polyethylene (UHMWPE).  Although a few studies looking at this plastic retrieved from human beings have shown small cracks in the polyethylene after relatively short periods of use, it appears from most clinical studies that highly crosslinked polyethylene will probably wear at least twice as long as standard polyethylene.  This advantage is magnified when used with a ceramic, rather than metal, femoral head.  Longer term clinical studies are now verifying the longevity of highly crosslinked polyethylene.

Standard polyethylene is a resilient substance that performs very well for the typical hip replacement patient, who is elderly and somewhat sedentary.  It also gives good service for younger patients whose daily activity is restricted by multiple joint problems, such as in rheumatoid arthritis, or by other chronic diseases that limit one’s activity level.  However, for younger patients with no limitations other than an arthritic hip, standard polyethylene will not hold up like highly crosslinked polyethylene does.

As polyethylene wears, billions of microscopic particles are generated and released into the joint space. These foreign particles tend to provoke an inflammatory response that slowly destroys bone around the artificial joint replacement, resulting in holes in the bone that resemble Swiss cheese.  This reaction is called “osteolysis” and is difficult to detect on x-ray until the bone damage is well advanced.  The result is progressive bone loss and a painfully loose implant.

The Data on Polyethylene

Ceramic on Ceramic

In contrast to the wear characteristics of UHMWPE, medical-grade alumina ceramic wears approximately 1,000 times less.  The following chart shows the relative wear rates of different bearing couples–the ball (head) and socket liner–for total hip replacement: 

Further, tissue studies directly comparing identically sized particles of UHMWPE and alumina ceramic have shown that wear particles from alumina ceramic are associated with very little inflammatory response from the body.  The favorable wear characteristics of ceramics make it possible, at least in theory, that a ceramic total hip replacement could last a young, active person the rest of his/her life.

Although ceramics for use in total hip replacement have been available since 1970, the quality of the ceramic has improved drastically.  The most utilized ceramic material in 2009 is alumina—termed Biolox Forte by its manufacturer, Ceramtec.  As of 2009, all ceramic-on-ceramic total hips use Biolox Forte alumina for the ball and liner of the socket.

The mention of ceramic conjures, in some people’s minds, associations with fragile dinnerware.  However, modern medical grade ceramic is literally “industrial strength” and is extremely strong.  Biolox Forte alumina has been in clinical use in Europe since 1994 and has shown excellent long-term results in young, active patients.  Currently, data from multiple studies suggests that the risk of a ceramic fracture in the hip is as low as 1 in 5,000 to 1 in 10,000.  However, when a ceramic component fractures in the body, it requires immediate revision surgery and creates other potentially long-term problems. 

Recently, a new type of ceramic has been released for use in total hip replacement.  Biolox Delta ceramic is hard and smooth like Biolox Forte, but is much tougher and resistant to cracking and breakage.  Delta ceramic heads were approved by the FDA in 2006, and delta hip socket liners are sure to be approved soon.

The Data on Ceramic

Metal on Metal

Metal on metal total hips are gaining popularity recently, particularly with the FDA approval of resurfacing arthroplasty, which uses a metal ball against a metal socket.  There is no doubt that metal against metal bearing surfaces wear much better than metal or ceramic against polyethylene (see graph above).  In fact, metal on metal wears almost as well as ceramic on ceramic without the remote risk of fracture that ceramics carry.

So what are the downsides?  Basically, 3 issues have lead to some hesitancy using metal-metal bearing couples across the board for young, active patients.

• Metal-metal wear particles, create the highest levels of metal ions (i.e. atoms) in the bloodstream and other body tissues.  Furthermore, these metal ions must be cleared from the body by the kidneys.  So anyone who has kidney problems or who may develop kidney problems in the future may not be an ideal candidate for a metal-metal hip.  The problem is that we don’t know who will develop kidney problems in the future for reasons unrelated to their hip replacement.
• Although not entirely compelling, there is some literature that has suggested that these metal ions can potentially cause cancer.  If this is an issue, it occurs in an extremely small number of patients and may not justify the worry.
• Allergic (hypersensitivity) reactions to the metal particles have been documented in some patients.  Allergic reactions can cause pain and osteolysis around the total hip replacement, not unlike that seen with polyethylene wear.  Again, this is not a common problem and may be related to the specific type of cobalt-chrome metal used.

Other concerns include the potential risks of high metal ion levels to an unborn fetus if used in a woman of childbearing years.  Many of these risks are in theory only and will take years of follow-up studies to know whether any detrimental effects of metal ions outweigh the benefits of metal-on-metal total hip replacements.