Anterior Mini-Incision Total Hip Arthroplasty:

This is being pushed as the next best thing in total hip replacement. Unfortunately, it is not a "new" thing at all. The approach has been around for better than 25 years and was tried and abondoned by most surgeons a generation ago. Why all the fuss. Several issues are at the core. Reimbursement is down and niche markets have subsequently been made necessary in several parts of the country (including Savannah oddly enough). Implant companies have invested millions in research and development to come up with a new "angle" to "selling" joints to older americans. In order to create a "market" for your product, you must create "hype". Unfortunately that is all this is at the moment. True, instrumentation has improved in order to reduce incision size, but this is across the board, not just in the anterior approach.

There has been a lot made about the improved outcomes with this approach over traditional posterior incisions. Unfortunately, those skilled in the art of reading medical literature and not company/wall street websites will see propaganda for what it is. The truth is the only reports that show a reduction in pain, hospital stay and function were done by the surgeons/companies putting them in. The peer reviewed literature (the only studies worth knowing about) show no difference whatsoever. What they do not tell you is that your visibility is drastically reduced, you are relying on fluoroscopy (x-ray) to check your cup position, you cannot adequatly test stability even if you wanted to because your leg is strapped into a boot connected to the OR Table and there are several reports of patients developing a permanent limp after surgery. In addition, several studies done with plastic surgeons have shown that while the incisions on average are a few centimeters smaller (for size matched patients), they are uglier and much more prone to infections because you are stretching the skin more during surgery.
Now why all the fuss. I was taught that "if it ain't broke, don't fix it." Well the reason most often given for not doing a posterior appraoach (the one used by most reputable surgeons worldwide) is the risk of dislocation. The truth is, the data being used is not only outdated, it has been recently explained and refuted. Back in the early days of Total Hip Replacement, the posterior stuctures were often times not repaired back to their original position thinking that the scar would take care of the stability. This, in combination with mal-aligned implants, increased the risk of posterior dislocation and the search was on for another approach. However, now that we know the problem was improper closure, the dislocation rates when implants are put in right is almost zero and equivalent to the anterior dislocation rate for the anterior approach (especially with their higher implant malposition rate.)

In summary, the anterior approach in nothing new. There is no respectable literature to support claims it is superior to the standard posterior approach in any way, and in fact, there is some recent literature that shows an increase risk of complication and revision. There is nothing wrong with having your hip done this way by a competent surgeon but there is nothing revolutionary about it either.  Over 97% of surgeons use the conventional (posterior) approach and it is not becuse the anterior hip replacement technique is harder to master, just that there is no compelling scientific data to switch.

For more reliable information on the topics covered go to:

www.AAOS.org and click on "patient information"

  or

www.WebMD.com

Computer Assisted Knee Replacement is another topic recieveing much attention in the lay press these days.

Unfortunately it is not getting much attention in the inner circles of the Orthopaedic Community. It has often bee referred to as "A solution looking for a problem to solve."

Several years ago, several landmark papers looking for the root cause of early total knee replacement failure was published. As well as any paper of the day, it showed that polyethylene wear (from the plastic part of every knee implant design) was the culprit through a process called osteolysis (digestion of bone around the edge of the implant.) Therefore, we began a long exhausing search for a product/process to reduce this devistating problem.

At the time, many people felt it was due to implant materials and some to design issues. Some felt it was due to improper implant alignment, while others felt it was becasue we had, up to that point, ignored the soft tissue balancing problems. We therefore fell into 4 basic camps and began to work on the problem.

The "materials" people starting looking at alternative metals like titanium and even solid ceramic to lower friction rates compared with the standard cobalt-chrome materials. We even changed the molecular structure of the plastic with disastrous effects. These folks have subsequently developed the revolutionary product (which has won several prestigious engineering awards) called Oxinium. See the "bearing surfaces" tab on the website for more information.

The "implant" camp began to develop other Total Knee designs to try to mimic the movements of a healthy knee and reduce the failings of the materials being used (like delamination from implant tangential forces) Their research led to some improved understanding of biomechanics but not much improvement in implant life. A popular design involving a rotating platform was popular for a while and is still used (and advertised) but has had several well done studies revealiing a substantial increase in polyethylene wear; the exact problem we were trying to solve.

The "alingment" camp had the most work to do. The computer technology they needed to solve their dilemma had not been developed yet. Some of it was eventually developed and was based on several different modes of imaging (from x-ray, to CAT Scan, to Fluoroscopy) They were all clunky, cumbersome and hard to reprodcuce in the OR. The next generation, the ones currently being used, are better but still have many drawbacks including increased OR time and increased risk of infection. There is also the "garbage in, garbage out" concept that leads some surgeons to make mistakes because they are basing what they do on measurements taken from the start of the case. If you don't believe in human error as a risk factor in surgery, talk to the family of the girl who died at Duke University when they transplanted the wrong kidney!

Some would argue the whole premise is wrong. Remember when JFK Jr died in a plane crash when he was flying at night and believed his inner ear over his quages while flying. Sometimes intuition is flat out wrong. In fact, the January 2009 Class 1 (the best) data published in the Journal of Bone and Joint Surgery has shown conclusively that the computerized alignment has no value in improving the function or longevity of joint replacement.

The premise of computer assistance is that there should be a perfect biomechanical axis between the center of the hip, knee, and ankle. The theory is that this is what causes joints to wear out and that by correcting this, you will reduce the wear rate. Unfortunately, I have lots of patients without any arthritis who do not have a perfect alignment. It is often times off by 3-6 degrees, the same factor that computer assisted surgery improves alignment over conventional intramedullary guides. This shows the problem is mulitfactorial and not to be solved by computer alignment guides: our intuition is wrong. If malalingment alone is the cause of osteoarthritis then we should be screening children in grade school like scoliosis for biomechanical alignement of the legs and then do early corrective osteotomies to stop the arthritis from ever developing based on this thinking.

Lastly, the "soft tissue" camp including professor Leo Whiteside M.D. from my alma mater Saint Louis University have worked out the necessary soft tissue problems that can overload the replacement and lead to early wear. He has literally written the book on ligament/soft tissue balancing and I am the only surgeon in Savannah to have been trained in this technique in Savannah.

In summary, there are many concepts/options available, some (like computer assisted surgery) which are theoretical at best. It is clearly not the advance that it is sometimes touted to be, although that may change as the systems become better and we work out exactly how important precise axial alignment is to implant survivorship. It is clear that reduced wear (like that offered with Oxinium) and proper soft tissue balancing are definate advances in the surgical management of Total Knee Replacement and ones taken to a new level with the Advent of the Journey Knee System from Smith and Nephew.  I have now done over 100 of these implants in cobalt-chrome and oxinium and there is no surgeon in savannah with better patient outcomes.