Advances in
Hip and Knee Replacement
John R. Moreland, M.D.
Over the last 5 to 10 years there have been major advancements in hip and
knee replacement surgery. Three areas are particularly important and
deserve further discussion. Many patients delay hip and knee replacement
because of concern about a long recovery, severe postoperative pain, and
problems with the durability of the replacement. Fortunately, there have
been dramatic advances on all three issues.
Recovery Duration and Minimally Invasive Hip Replacement
The recent advance that has gotten the most publicity is minimally invasive
hip replacement, which utilizes shorter incisions with less muscle and other
soft tissue trauma, allowing and facilitating immediate weight bearing as
tolerated with a quicker return to normal daily activities than in the past.
While not the first surgeon to adopt the new minimally invasive hip
replacement techniques, Dr. Moreland now routinely uses a minimally
invasive surgical approach facilitated by a minimally invasive hip prosthesis.
There are several variations among the new minimally invasive hip
replacement techniques. One major difference is whether the hip is
approached anteriorly or posteriorly. Dr. Moreland prefers an anterior
approach, since it has a lower dislocation rate than the posterior approach
and can be done without cutting any muscles or tendons. The posterior
approach always requires cutting some of the posterior muscles which can
not be repaired adequately.
Some surgeons using the anterior approach strap the patient’s feet in the
boots of a fracture table for operative manipulation and use an image
intensifier x-ray machine to help visualize the hip during surgery. Everyone
in the operating room, except the patient, wears lead shielding to prevent
radiation exposure. The patient can not be shielded and receives radiation in
the important area of the gonads. Dr. Moreland’s minimally invasive
anterior surgical approach is done with the patient on the side on a regular
operating table without the image intensifier and without exposing patients
to the radiation it produces.
Minimally Invasive Knee Replacement
With the success of minimally invasive hip replacement surgeons have also
tried to duplicate that success with minimally invasive techniques for knee
replacement which simply emphasize shorter incisions. It is not clear that
this is a significant advance since there have been many reports of increased
complication rates with very small knee incisions and the resultant decreased
exposure available for the surgeon to do the operation. It has not been
shown that patients recover significantly faster with shorter incisions, since
the tissues receive additional trauma from the severe retraction necessary to
get adequate exposure with very short incisions. Minimally invasive knee
replacement today is actually more marketing than an advance. Knee
replacement patients have always been allowed to bear weight as tolerated
from the first day. Dr. Moreland uses as short an incision as possible
consistent with the need for adequate exposure to do the operation correctly.
No muscles or tendons are cut. Recovery is relatively quick with patients by
one to two weeks after surgery routinely walking with a cane and reporting
that they are already better than before surgery.
Durability of Hip Replacements
Wear of a hip replacement was the last major unsolved problem affecting the
long term durability of hip replacements. New bearing materials have been
developed and are now in common use and the wear of the current
generation of hip replacements is dramatically less than was seen with older
types of hip replacements. Loosening of the implants was the other main
threat to hip replacement durability and was basically solved with the advent
of cementless hip replacement of various designs over 20 years ago. Hip
replacements today should last a lifetime for most patients and even for
those who vigorously and regularly exercise.
Durability of Knee Replacements
Better knee replacement designs along with new materials have also
dramatically increased the durability of knee replacements such that most
patients can expect that their knee replacements will last a lifetime. The best
fixation technique for the knee, in contrast to the hip, remains cementation.
Postoperative Pain Control for Hip and Knee Replacements
Revolutionary postoperative pain control techniques were introduced about
at the same time as minimally invasive replacements and many authorities
believe the pain control techniques are more significant. In the past
postoperative pain was simply treated with narcotics until the patient was
more comfortable. There are many problems with this approach. Patients
need widely varying amounts of narcotics for pain control. Since too large a
dose of narcotics can cause the patient to stop breathing, physicians must
first use lower doses for safety and then gradually increase the dose, if initial
doses are not sufficient. Patents thus can be in a lot of pain before an
adequate dose of narcotics is determined and delivered. Narcotics have
many side effects, including sedation, confusion, hallucinations, respiratory
depression, nausea, vomiting and constipation.
If a patient feels a lot of pain, the brain becomes sensitized to pain and
perceives subsequent pain more intensely. It is important that this brain
sensitivity not be allowed to develop. Today we emphasize treating
postoperative pain before it occurs and also utilize several nonnarcotic pain
medications. Narcotic medications are still used but in smaller doses.
The morning of surgery patients are given Celebrex which is very effective
for postoperative pain. Acetaminophen (Tylenol) is also given along with a
dose of Oxycontin which is long acting, well tolerated, and effective
narcotic. A spinal anesthetic is recommended rather than a general
anesthetic. With a general anesthetic the brain still knows that an operation
is occurring and is being sensitized to postoperative pain. With a spinal the
brain receives no pain impulses. Patients are sedated and are completely
unaware during the operation. Spinal anesthetics also have the advantage of
less bleeding and fewer postoperative problems with blood clots. A small
dose of narcotics is injected with the local anesthetic of the spinal anesthetic.
This can give pain relief for 12 hours or more. The gastrointestinal tract is
not exposed to this narcotic dose and GI side effects are minimized.
At the end of the operation before wound closure the wound is injected with
a long acting local anesthetic similar to the Novocain used by the dentist.
The pain relieving effects of this may last 12 hours or more. Postoperatively
patients receive Celebrex and the long acting narcotic Oxycontin.
Most hip and knee replacement patients with these pain control techniques
have dramatically less pain than in the past with fewer medication side
effects.
More Information
If you would like more information about hip and knee replacement, please
call Dr. Moreland’s office at 310-453-1911 and we can send you copies of
his booklets on hip and knee replacement surgery.