|
|
 |
|
 |
Dr. Murphy most commonly performs total hip arthroplasty
using a technique that he developed beginning in 2002 called
a superior capsulotomy. This technique is considered a method
of "minimally invasive surgery" although primary
goal of the surgery is to safely perform total hip arthroplasty
while minimizing the effects on the surrounding soft tissues.
This is the technique used in 97% of primary total hip arthroplasties
that Dr. Murphy performs currently. The philosophy behind
and evolution of this technique is described in many sources
below. This technique has been performed more than 350 times.
Current data demonstrate that the technique, when combined
with surgical navigation, is actually safer than as conventional
total hip arthroplasty and results in a dramatically accelerated
recovery. The clinical results of this technique, compared
to a conventional technique, has been published in the peer-reviewed
literature:
Please see below for more information about the philosophy
and evolution if this surgical technique and also the other
methods of performing "minimally invasive" total
hip arthroplasty. Links to additional publication are also
available below.
Note: You must have Adobe Reader 6 to save PDFs
to your personal computer and to print them.
Information about Less and Minimally Invasive Total Hip
Arthroplasty Techniques:
Performing total hip arthroplasty while taking steps to
minimize trauma to the surrounding tissues has great potential
for facilitating recovery after hip arthroplasty. I currently
use tissue preserving, minimally invasive techniques when
performing total hip arthroplasty in more than 90% of patients.
Nearly all of this surgery is also performed with computer-assisted
surgical navigation. Patients who would be inappropriate for
this surgery are generally those with more dramatic deformities,
previous hardware or previous surgery. Tissue preserving surgery
can often be performed in larger patients as well.
Minimally invasive total hip replacement is a broad term
that is used to describe a wide variety of surgical techniques.
Some techniques are traditional operations performed through
smaller incisions while others are fundamentally new operative
techniques. Some techniques are relatively safe while others
have a track record of causing significant problems for a
large percentage of the patients. If appropriate techniques
are used by an experienced surgeon, minimally invasive total
hip arthroplasty can be safe and very beneficial. Conversely,
patients can also have outcomes that are far worse than they
would have had if minimally invasive techniques were not attempted,
so both the potential benefits and potential harm to the patient
can be increased. Exactly who does the surgery and how the
surgery is done is of great importance when considering having
a total hip arthroplasty using minimally invasive techniques.
Since "minimally invasive hip replacement" can mean
many things, it is important to learn something about the
anatomy of the hip joint and the different techniques of replacing
the joint to understand these issues better.
The hip joint itself is surrounded by a hip joint capsule
which is much like a thick skin that surrounds the femoral
head and socket. Outside of the hip joint capsule there are
small muscles in the back of the joint that are called the
short external rotators. The back ½ of the hip joint
capsule and the short external rotators are important structures
that serve to prevent dislocation following total hip arthroplasty.
On the side are the gluteus medius and minimus muscles that
together are called the abductors. If these muscles are weak
either before or after surgery, the patient will limp. On
the front of the joint there are several powerful muscles
including the iliopsoas muscle, the sartorius muscle, the
tensor fascia femoris muscle, and the rectus femoris. These
muscles allow the leg to be lifted forward in a lying, sitting,
or standing position.
There are many ways to get into the hip joint to perform
a total hip replacement which makes the joint a very interesting
one to work on, but a little confusing to learn if you are
not a surgeon. Below is a brief description of common hip
exposures and their advantages and disadvantages. After explaining
these, you may better understand why we’ve developed
the minimally invasive technique that we use.
The Posterior Approach
The posterior approach to the hip is probably the most common
method of getting to the hip joint used in the United States
for hip replacement. Basically, the back half of the hip joint
capsule and short rotators are incised to give access to the
joint. This surgery can be done very quickly and easily. It
is safe and reliable. The problem with the technique though
is that since the back of the hip joint capsule and short
rotators are incised, the hip is susceptible to dislocation.
This technique has the highest incidence of hip dislocation
of any hip replacement technique. Two methods are used try
to compensate for that problem. One is to instruct the patient
to restrict hip joint motion after surgery by giving the patient
“dislocation precautions”. The second method is
to attempt to repair the hip joint capsule and short external
rotators back to near where they belong. Even if both of these
methods are used, the patient cannot pursue unrestricted motion
after surgery because the repair could disrupt. Since unrestricted
motion after surgery is one of the important goals when trying
to improve hip replacement surgery, this method doesn’t
really afford the opportunity to achieve that goal. Many surgeons
employ what is called a mini-posterior exposure. This technique
is simply the same technique performed through a smaller incision,
but all of the same issues apply.
The Direct Lateral Exposure
The Direct Lateral Exposure is another common technique
for hip replacement. This is the exposure that I routinely
used for hip replacement surgery from 1991 and until 2002,
and during that period of time, I felt that this was the best
exposure for most routine total hip replacement operations.
The technique involves spreading the gluteus medius muscle
fibers and moving the front part of the gluteus medius, hip
joint capsule and gluteus minimus muscle from the front of
the femur. The implants are inserted through this interval.
The advantage of this technique is that the back half of the
hip joint capsule and the short external rotators are undisturbed
and so the hip is extremely difficult to dislocate. The incidence
of dislocation is less than 1 in 200, even when the patient
is not advised to restrict hip joint motion in any way. Once
the gluteus medius and gluteus minimus muscles heal, the hip
joint is very close to the way that it was, with all of the
important muscles around the hip joint back where they were.
I still feel that this is the best technique for total hip
replacement for some circumstances.
The disadvantage of this technique is that the patient has
to protect the muscles around the hip after surgery to ensure
that everything heals. The problem is that a lot of people
don’t have very much pain a few weeks after surgery
and don’t like to use the crutches. Bearing weight too
early causes muscle contraction that can pull the muscle repair
apart before it heals. This can lead to a limp and pain. Although
this doesn’t happen very often, the ideal hip operation
would be able to tolerate both unrestricted motion and unrestricted
muscle contraction immediately after surgery. The mini-direct
lateral approach can be considered a minimally invasive technique
too, but again, it is basically the same operation through
a smaller incision. If you are really interested in how this
surgery is done, the Video Journal of Orthopedics, together
with the Journal of Bone and Joint Surgery, produced a video
that recorded me performing one of these operations. It is
available on line at http://www.vjortho.com/cgi/content/abstract/4059.
The Anterior Exposure
Anterior exposures to the hip joint have been commonly used
since the 1960's before hip replacement was commonly performed
in the United States. This technique was employed mainly for
cup arthroplasty surgery, an earlier version of hip prosthesis
surgery. Anterior exposures to the hip are used currently
for joint preserving surgery such as periacetabular osteotomy
for hip dysplasia or surgery to relieve femoro-acetabular
impingement. Anterior exposures have also been used for total
hip replacement and were popularized by Judet in Paris.
Minimally-invasive total hip replacement surgery using the
anterior exposure is becoming increasingly popular in Europe
and in some parts to the United States. Joel Matta, M.D. from
Los Angeles and William Hozack, M.D. from Philadelphia use
this method very effectively for their patients.
The anterior exposure for total hip replacement is especially
good for placement of the socket component but it has significant
limitations for implantation of the femoral stem component
into the femur. While it is a good surgical technique, it
is not the one that I use routinely.
The Two Incision Minimally Invasive Techniques
While there is more than one two-incision technique, the
technique that was popularized, mainly out of Rush-Presbyterian
Hospital in Chicago, has received a lot of media attention
over the past few years. It involves putting the socket in
through the front of the hip joint, and putting the femoral
stem in through a small incision in the back. My personal
opinion is that this technique is not as reliable as it needs
to be and is potentially very harmful. The basic problem is
that, while it is easy to put the cup into the socket, the
stem is placed into the femur in a blind fashion because it
cannot be directly seen by the surgeon. The abductor muscles
are perhaps the most important muscles around the hip joint
and they are not directly visualized or protected during the
surgery. This means that they are susceptible to injury which
can be a very dramatic problem for some patients who have
had this surgery. One recent study showed that muscle injury
from this particular minimally invasive technique was much
greater and much more variable than for traditional techniques.
Mardones
et al, Muscle Damage After Total Hip Arthroplasty Done with
the Two-Incision Minimally Invasive and the Mini-Posterior
Techniques.
The second major problem is that the fit between the femoral
stem and the femur itself is a critical issue. If the stem
is not firmly fitted, it can loosen right away. If the stem
is too firmly fitted, the femur can break. Very skilled surgeons
who have adopted this technique have reported breaking the
femur in 20% of the patients that they operate on when they
are first starting to use this method. If that happens, the
incision has to be extended even more that it might have been
if a traditional method was used to begin with. In addition,
if any of the soft-tissues that surrounds the opening in the
femur gets interposed between the femur and the femoral prosthesis
when it is inserted, the femoral bone may never have a chance
to grow into the surface of the prosthesis.
The third problem with the technique is that it can’t
be applied to the vast majority of patients that need hip
replacement surgery. Many patients, for size or other reasons,
can’t have their surgery done using the method.
While this technique had gained popularity in 2001 and 2002,
the many design flaws of this surgical technique have been
better appreciated over the past several years and the technique
has been progressively abandoned by surgeons that used to
use it.
The concept of Tissue Preserving Total Hip Arthroplasty
All of this attention to minimally invasive hip replacement
techniques really raises the question of what is important
and what isn’t important. Hip replacement surgery in
it’s traditional form is superbly reliable. If we are
going to try to improve it, we have to protect patients from
any significant increase in the likelihood of being worse
off than they would have been had traditional techniques been
employed. What is really important is to allow patients unrestricted
motion after surgery (as patients can have with the direct
lateral approach) and to allow unrestricted muscle strengthening
after surgery (as patients can have with the posterior approach).
It is also important to be able to see and protect the major
muscles around the joint and to be sure that the components
fit and are well seated, without breaking the bone. If this
is accomplished, patients will recover rapidly and reliably.
Starting in the Fall of 2002, with increased focus on trying
to place total hip replacement components while trying to
minimize impact on the surrounding soft tissues, it became
clear that the femoral stem could be inserted through a small
incision in the superior hip joint capsule, behind the strong
abductor muscles and in front of the posterior capsule and
short rotators. This was done by preparing the femur for the
stem before the femoral head was removed. The advantages of
doing this became progressively clear and they include the
following issues:
The femur is more stable and stronger if the head is still
in place which makes it less likely that the femur will crack
during surgery.
Exposure is easier since instruments can be placed around
the neck of the femur since it's still in place.
The hip never needs to be dislocated to do the surgery.
This means that the leg is never placed in a position that
a normal hip can't be placed in. This also means that the
surrounding tissues don't need to be disturbed as much.
With the stem being placed through a small incision in the
superior hip joint capsule, the cup was initially placed through
the front, underneath the strong abductor muscles.
This method allowed insertion of the components while preserving
all of the important structures around the hip joint –
the posterior hip joint capsule and short rotators that protect
against dislocation, and the abductor muscles that provide
the strength for walking without a limp. This technique proved
very easy for patients to recover from.
After gaining more experience with this method in 2002
and early 2003, it also became clear that if the right surgery
instruments were made, both the socket and the stem could
be safely implanted through a single incision in the superior
hip joint capsule in between the short external rotators and
abductors in nearly all patients. After we made those instruments,
the second incision became unnecessary. These operations have
been nearly always been performed in concert with computer-assisted
surgical navigation, although the method can also be done
without computer assistance. The surgical technique and clinical
results of this method have been presented at many national
and international meetings and have been published in several
journals and textbooks, including peer-reviewed scientific
journal (Clinical Orthopedics and Related Research).
This work was recognized by the International Society for
Computer Assisted Orthopedic Surgery in 2005 with the award
for Best Clinical Presentation at the Annual Meeting in Helsinki,
Finland.
While there are many ways to get to the hip joint to perform
a total hip replacement, I feel that this method is the safest
and most efficient way to preserve and protect all of the
important structures around the hip joint and to facilitate
both early recover and long term function.
The following links are all either manuscripts or abstracts
that we have been published on the topic of tissue-preserving
total hip replacement using a superior capsulotomy. These
are listed generally from most recent to least recent. Please
note that publications posted are for educational purposes
only and should not be reproduced without permission of the
publisher.
Murphy
SB and Tannast M. Evolution of Total Hip Arthroplasty:
Computer Assisted, Minimally Invasive Techniques Combined
with Alumina Ceramic-Ceramic Bearings. In D'Antonio J and
Dietrich M eds. Bioceramics in Joint Arthroplasty. Darmstadt,
Germany: Steinkopff Verlag. pp119-129, 2005.
.
|
|
 |
| |
|
