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News Letter

ASI Hip Arthroplasty, A Tissue Sparing Approach to Hip Replacement Surgery Print E-mail

Nicholas A. Abidi, M.D.

Hip replacements will make up about 20 percent of the 750,000 total joint replacements in the U.S. each year. Those numbers are increasing as baby boomers seek to retain their active lifestyles, and as implant technology and surgical expertise continue to improve.  

An increasingly popular approach to hip replacement surgery is Anterior Supine Intermuscular (ASI) Hip arthroplasty, performed in the U.S. since the 1980s. Its benefits are significant, with patients seeking out doctors and demanding it. It has the advantage of being a tissue-sparing approach to minimally invasive hip replacement, avoiding detachment of any muscles or tendons. In addition, the technique can include the use of an OSI HANA radiolucent operating room table that assists the surgeon in positioning the patient.

If you’re a candidate for hip replacement surgery, understanding the history of hip replacement as well as the pros and cons of the various surgical approaches—including ASI Hip—can help you understand your doctor’s recommendations and together make the best decision for your health and lifestyle.

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There are several approaches to hip replacement surgery, also known as hip arthroplasty—the direct anterior approach, now known as the ASI Hip approach—as well as the posterior approach and the anterior-lateral approach.

Total hip arthroplasty has been performed worldwide since 1947.  Total hip arthroplasty has been performed worldwide since 1947.  The traditional “Heuter Approach,” first performed by Dr. Robert Judetin France, was a direct anterior approach for hip replacement using a specially designed operating room table. In the mid-1960s, English physician Charnley described approaches to hip replacement that used an osteotomy (bone cut) of a portion of the femur known as the greater trochanter.  Harding described an anterior-lateral approach to hip replacement surgery.  In addition, many authors have described a posterior approach to hip replacement surgery.

The major complication of hip surgery continues to be dislocation of the prosthesis after replacement.  Positioning of the acetabular (cup) and femoral (thigh) components can affect dislocation rates in addition to the soft-tissue destruction associated with various approaches to hip arthroplasty.  Other considerations include blood transfusion rates post-operatively, speed of recovery and long-term survival of the hip components.  

The posterior approach to hip replacement has the highest rate of dislocation.  The posterior approach to hip arthroplasty requires detachment of many of the stabilizing muscles and tendons that surround the hip joint in addition to violation of the posterior hip capsule.

The anterior-lateral approach has a much lower dislocation rate, but involves possible nerve damage and subsequent loss of function of the some of the hip abductor muscles that surround the hip joint anteriorly and laterally. Damage to the nerve and hip abductors occurs because the anterior-lateral approach requires detachment of certain hip muscles in order to expose the hip joint. Patients who undergo this approach can experience a permanent limp post-operatively when the muscle is de-innervated.

The direct anterior approach to hip replacement was introduced to the United States by Dr. Joel Matta, who in 1981 trained in France with physicians who worked underDr. Judet.  This approach, now known as Anterior Supine Intermuscular (ASI) hip arthroplasty, has the advantage of being a tissue-sparing approach to minimally invasive hip replacement, because it avoids detachment of any muscles or tendons.  

In addition, the technique can include the use of an OSI HANA radiolucent operating room table which assists in patient positioning.  X-ray intensification during implant placement allows the surgeon to confirm component positioning during hip arthroplasty. Ideal component placement can result in decreased dislocation rates as well as improved longevity of the hip replacement parts by decreasing abnormal stresses on the metal and plastic hip components.  

Clinical studies by Matta et al, Behrens et al and Kennon, Keggi et al, describe the safe, effective and efficient implantation of total hips via the ASI approach.  The Matta article stresses decreased dislocation rates with ASI hip arthroplasty when compared to historical rates of posterior hip dislocation noted in traditional approaches to hip arthroplasty.  It also notes consistent acetabular cup positioning.   The Behrens paper notes decreased length of hospital stay when compared with another group who had undergone a minimized Harding approach to hip arthroplasty.  The Keggi paper describes performing hip revision arthroplasty through the ASI approach.  

Both Dr. Reynolds and I have performed total hip arthroplasty for many years, and we have performed ASI Hip arthroplasty since 2006.  I have been able to discharge some patients undergoing ASI hip arthroplasty on the day of surgery.  In many cases they are able to go home the next day or by two days after surgery.  Many of these patients have undergone hip replacement on the opposite hip previously.  They comment on how much less pain and dysfunction is experienced with the ASI approach when compared to their prior traditional hip arthroplasty.  

My results have been similar to the published studies where it has been noted that only 20 percent of patients require assistive devices or strong pain medication after two weeks post-surgery.

Patients undergoing traditional hip arthroplasty or even posterior approach to hip replacement that claim to be minimally invasive must observe special seating and activity precautions in order to avoid dislocating after surgery.  In addition, many surgeons are placing larger femoral heads when posterior MIS surgery is utilized in order to avoid hip dislocation. These larger femoral heads are experiencing fretting in certain cases that cause metal particles to be shed locally and systemically in some cases.  

With ASI hip arthroplasty, there are no routine post-operative hip dislocation precautions.  In addition, traditional femoral head sizes can be used with the ASI approach, thus avoiding fretting and shedding of metal particles into the bloodstream. Dr. Reynolds and I utilize total hip and knee components that have been tested with excellent clinical results over a long period of time.  I feel that the goal of the entire experience is to install a total joint replacement that will relieve pain, improve function and last for many years.  

Nationally, there is a trend for total joint arthroplasty to be performed in centers that are dedicated to replacements. I have assembled a team of doctors, nurses, case managers, therapists and administrators who devote a large part of their time to Total Joint Replacement patients within the Total Joint Replacement Center at Dominican Hospital in Santa Cruz. Success in total joint replacement requires high patient volumes and an experienced team. Dominican Hospital provides preoperative total joint classes for patients undergoing total joint arthroplasty.  These classes help to address patients’ medical, physical and social needs prior to undergoing surgery.  Patients who have a plan pre-op tend to do better post-op.


Latest News

Community Talk July 28, 2014 6:30pm

Join Dr. Nicholas Abidi, M.D., Dr. Peter Reynolds, M.D. and  Dr. Christian Heywood, M.D. as they discuss knee and hip pain and the available treatment options.



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