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Potential Knee surgery/replacement
therapies
New
advancements in the fields of Anesthesia and surgery have helped
knee replacement surgery turn into a post operative intensive rehabilitation
to nearly same day procedures. The advancements have occurred recently
and as most are improvements on traditional techniques, it will
take less time for them to become more widespread.
The first issue in dealing with total knee replacement is the post
operative pain. A recent study has shown that many patients, especially
those with repeat or prior surgeries, are experiencing more pain
after operation than before. Science Daily reports on the reasons
for this increase in post operative pain:
As millions of Americans take Lortab, OxyContin, and other narcotics
to relieve chronic pain, the daily prescriptions of those drugs
are making it harder to get effective pain management after they've
had major surgery. That's because people who take daily prescription
narcotics develop a tolerance to opioids. This has made recovery
from major surgery more painful for these patients because standard
post-operative doses of morphine haven't worked-until now."(1)
Opioid tolerance is the main factor accounting for increased patient
pain. Therefore, dosages should be increased at a particular rate
for each patient. That's what University of Utah doctors have come
up with. Here was their procedure:
U of
U anesthesiologists have developed a method that takes into account
a patient's opioid tolerance and helps physicians determine the
right amount of medication to stop post-operative pain in people
who already take a daily narcotic prescription.
Swenson and other U anesthesiologists studied 20 opioid-tolerant
patients undergoing back surgery and who received the pain medication
fentanyl immediately prior to their operations. Fentanyl is a synthetic
opioid used for pain control that is 100 times more potent than
morphine.
As each patient was anesthetized, he or she received fentanyl until
respiratory depression was induced. When respiratory depression
had been reached, each patient then underwent general anesthesia.
Using software developed at Stanford University-but modified by
U anesthesiologists Talmage D. Egan, M.D., professor, and Kenward
B. Johnson, M.D., associate professor-the concentration of fentanyl
associated with respiratory depression was determined for each patient.
Once the U anesthesiologists determined the fentanyl dose associated
with respiratory depression in each patient, the software helped
them calculate how much of the drug was needed for pain relief.
By testing each individual's response to fentanyl, the anesthesiologist
was able to predict a safe and effective dose of opioid that was
"tailor made" for each patient.(1)
The results
they found were surprising. The average required dose for a person
subjected to fentanyl was roughly ten times higher than that of
a normal patient. This means that opioid sensitive patients are
receiving on the order of 10 nanograms per millimeter less than
what is needed. This translates into a much harder recovery time
and severely more painful rehabilitation. It may be the dosages
that are creating such longer and more intensive rehabilitation
periods. The University of Utah doctors have also researched another
method of decreasing post operative care by changing the site of
anesthesia.
A fascia iliaca catheter, also called a femoral block, often is
used to control pain following knee replacement and ACL surgery.
But instead of placing the catheter right next to the nerve to administer
local anesthetic, which is the most common way of doing it, U of
U anesthesiologists insert the catheter in a space near the nerve
without touching it. Then they bathe the nerve in a local anesthetic,
and the results for pain control have been dramatic.
Patients given a femoral block after surgery go home from the hospital
a full day sooner because of the pain relief. They're also able
to take pills instead of receiving pain medication intravenously.(1)
Results for this method have also been rewarding. According to Swenson,
patients that usually spend 3 to 4 days in the hospital after surgery
are now leaving the day after surgery. As more hospitals recognize
this technique and the word is spread, many patients undergoing
knee surgery will be a lot better off. One group in particular is
the athletes who languish in the hospitals and rehabilitation centers
trying to return to active roster. Decreasing down time will help
many teams and the individual players remain healthy longer.
Another new technique is a change in incision size. Dr. Albert Olszewski
of the Kalispell regional hospital in Northwestern Montana has developed
a method of reducing the incision size of total knee replacement
surgery from twelve inches to three to four inch incisions. The
results from some of his patients are particularly telling:
"Before,
every step hurt," she said. "Every movement hurt."
After undergoing a new, minimally invasive procedure, Brown repeated
what Dr. Albert Olszewski hears often. She can't believe she put
it off so long.
"It's absolutely and totally amazing," she said. "It's
been almost pain-free."
Just
a few rooms away, Don Eisinger, 81, echoed Brown's praise of Olszewski's
method.
"It's remarkable," Eisinger said. "It wasn't too
painful."
He said a knee arthroscopic treatment he had in the 1970s hurt more
than his total knee replacement. Like Brown, Eisinger was leaving
the medical center two days after the orthopedic surgeon operated
on his knee.
"You're going to have to slow him down," Olszewski said
with a smile to Eisinger's daughter. (2)
This
technique has had very promising results although no formal study
has been done the technique. It is very hard to convince orthopedic
surgeons to change methods. Knee replacement today, although painful
and requiring rehabilitation, is a proven surgery with standard
procedures. Also, newer methods are often unfeasible. Dr. Olszewski
has performed this type of operation fifty times in the past year.
Even so, doctors remain skeptical about the operation. Part of the
disbelief stems from the fact that many doctors believe, "that
smaller incisions are for smaller minded people."(2) On a practical
level, it also seems very difficult to cut the incision size so
small and still be able to fit and join the knee replacement. Dr.
Olszewski states that learning this technique takes time and patience.
Many skeptics liken the procedure to making a ship in the bottle.
Still, surgery takes many hours of practice and this type can be
perfected. And the results of this surgery are less pain and less
incisions. Dr. Olszewski states that part of the reason why knee
replacement surgery is so painful is the damage done to the flexing
muscles of the quadriceps. Also, less narcotics are needed. The
doctor states this here:
With
the flexing muscles left intact, patients have better control of
their leg on the day of surgery and can get in and out of bed by
themselves the day after surgery.
By the second post-operative day, patients, such as Brown and Eisinger,
climb stairs independently and walk supporting themselves with a
walker.
As another benefit, Olszewski said that reduced need for narcotic
pain killers lessens the chance of elderly patients falling during
the recovery period.(2)
If this surgery proves to be viable, it will be a very valuable
asset in the coming years. Dr. Olszewski explains that the upcoming
generation will only bring larger numbers of patients.
A near-epidemic of degenerative arthritis means demand will only
increase over the next decades. The disease gradually erodes the
cushioning in the knee, leaving patients such as Brown in pain with
every step.
"We're very concerned about this X Generation with their extreme
skiing and jumping off cliffs," Olszewski said.
He said they tell him they expect science to come up with new miracles
to repair their damaged joints. Some of the stories from the industry
today border on the miraculous.(2)
The article continues on stating that some doctors have even pushed
the surgery to the same day outpatient level. While this level is
still not common, it offers a bright hope that one day troublesome
knee injuries will only a day's inconvenience.
Despite these recent advances, there still exists controversy over
whether or not minimally invasive surgery is the better procedure.
A recent panel of orthopedic surgeons debated the merits of this
surgery at the annual American Academy of Orthopaedic Surgeons.
Some doctors, like Dr. Richard Berger, are convinced that the promising
results so far are indicative of success on a larger scale. Dr.
Berger even stated that he expects the percentage of minimally invasive
surgery to be at 100% in the next five years. Doctors like Dr. Berger
and Dr. Olszewski have nearly the same success stories and as many
satisfied patients. The only issue of concern is the lack of raw
data. Only one doctor at the conference had clinical data to back
up the stories. Skeptics cite this as an issue of concern and presented
their own study:
Ormonde Mahoney, MD, of the Athens Orthopaedic Clinic at the University
of Georgia, said a tightly controlled study comparing conventional
surgery with less invasive procedures in 148 patients at his clinic
found no difference in length of hospital stay, operating time,
pain-drug use, or pain at two weeks or three months. (3)
Those concerned are also worried about the potential for adverse
affects. Dr. David Hungerford believes that minimal invasion prevents
the doctor from properly aligning the knee. On a widespread scale,
this could lead to higher incidents of improper knee alignment leading
to higher failure rates among the mechanical devices. Perhaps the
key difference from both sides is on how the surgery is being promoted.
Proponents say that this is a consumer driven market that is widely
spread through word of mouth, while opponents believe that the mechanical
device companies are pushing the issue. In either event, both sides
agree that this surgery requires a certain degree of experience
and should always be carefully monitored by outside parties.
On the horizon are even more aggressive and promising therapies
for knee injuries. Some of them are only temporary fixes and do
not constitute full recovery therapies. The first of these is Autologous
chondrocyte transplantation. Nicholas DiNubile, a spokesperson for
the American Academy of Orthopaedic Surgeons outlines this procedure:
Autologous
chondrocyte transplantation - taking cartilage cells from your body,
growing them in the lab and then replanting them in the knee. DiNubile
likens this pricey joint resurfacing procedure, which he said has
been done for only five to seven years in this country, to repairing
a pothole. Results, he says, can be amazing when a patient doesn't
push his reconditioned part too far.(4)
The only catch is that the person cannot push his or herself too
much or else risk the new cartilage much like the old. Also, the
time it takes to grow cartilage cells in culture does not happen
instantaneously. The patient must wait at least a couple weeks while
a patient undergoing total knee replacement surgery merely undergoes
a one day procedure. Still, the results are promising. Regenerating
cartilage keeps the body functioning as it had prior to the deterioration.
Mechanical devices deform and break. This causes severe pain and
also costs another surgery. Replacing cartilage is minimally invasive.
It does not feature mechanical devices that can wear down and fracture.
Future studies may also prove that it can regenerate itself in the
body. An autologous graft also has zero complications of an immune
system reaction thus canceling any need for immunosuppressive drugs.
Another therapy option is called viscosupplementation.
Viscosupplementation - the injection into the knee of hyaluronic
acid, a thick substance that's part of the fluid in most people's
joints. The fluid acts as a lubricant and shock absorber but can
lose its effectiveness with wear and tear. In viscosupplementation,
preparations that combine hyaluronic acid with rooster combs or
bacterial cultures are injected to replace the depleted fluid, at
a cost of over $1,000.(4)
The obvious problem for this is that it is not a permanent solution.
This therapy may have success in the sporting world where it might
be used as a buffer for knees prone to injury or ones that are showing
signs of deterioration. The last and maybe most controversial surgical
procedure is xenotransplantation.
Xenotransplantation is primarily for ACL injuries. The grafts are
usually taken from pigs and can replace the torn or damaged ACL.
One type of transplantation is called SIS or small-intestinal submucos
transplantation. Basically, parts of the pig intestine are used
to replace the ACL. For reasons not entirely known, the xenotransplant
induces healing factors that promote blood vessel growth. Immunosuppression
is not required as there are no individual pig cells being transplanted
by using a specific process. The first xenotransplant done was in
1998 on James McDonald with great success. So far this is the most
promising aspect of ACL xenotransplantation. It avoids potential
ethical issues by not allowing cells to enter the graft. Many groups
fear that a retrovirus can be transmitted that is potentially devastating.
By eliminating foreign cells, there is no risk of retrovirus contamination.(5)
One last development in knee replacement is the mechanical devices
being constructed. Tissue engineers have developed synthetic materials
that can be used to replace torn ACL and other ligaments in the
knee. They can be tailor made to accommodate any size or shape of
person. The specifics of this material construction are too broad
for this discussion so a link detailing the field can be found here.
Emerging technologies will enable people to live longer and healthier
lives. For athletes, it may someday mean that a knee injury will
never again be season or career ending. It might even be a one day
procedure to have a damaged knee repaired. There are hurdles that
must be tackled first, mainly the lack of raw data to persuade skeptics.
The FDA will not be satisfied until treatments are backed up with
legions of data. There have been many individual successes, but
only a large scale test will validate these new and updated procedures.
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