| What Your Doctor May Not Tell You About Hip and Knee Replacement Surgery |
By Ronald P. Grelsamer, M.D.
Genre: Inspirational & Self-Help
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Who Needs a Joint Replacement?
Arthritis, AVN, and Femoral
Neck (Hip) Fractures
There isn't as much deception with joint replacement surgery as there is with outpatient arthroscopies (see What Your Doctor May Not Tell You About Knee Pain and Surgery, Warner Books, 2002). If your doctor has suggested a joint replacement, you are probably a reasonable candidate for the procedure. The only thing to quibble about is timing. Do you really need it now? During an arthritic flare-up, you'll agree to just about anything, including major surgery. Of course, this flare-up will quiet down, especially if it's one of the first. The unscrupulous doctor may quickly sign you up for surgery without informing you that arthritis pain typically waxes and wanes.
Here is a tip: If the doctor looks at your X-ray, throws a doleful look your way, and advises you of the need for a joint replacement, run out of there as fast as your arthritic legs can carry you! A good doctor treats patients, not X-rays! I'm reminded of the ninety-two-year-old man who came to see me a few years ago. He walked in and plopped his X-rays on my desk. They showed some of the worst arthritis I'd ever seen. The bones were so close together that I couldn't quite tell where one started and the other ended. I started to think about the risks associated with performing knee replacement surgery on a nonagenarian. Then he started his story: "Doc, I carry my own golf clubs, and after nine holes my knees are achy. . ." This man obviously enjoyed a great quality of life and didn't need any surgery. So much for the knee replacement. On the other hand, some people whose arthritis is barely visible on X-rays are in severe pain. So once again, I tell my students to "treat patients, not tests." Joint replacement surgery is indicated for patients who suffer from either arthritis or avascular necrosis, also known as osteonecrosis. Certain types of hip fractures are also best treated with a hip replacement.
Like bursitis and tendinitis, the word arthritis is bandied about rather loosely. But it has a specific definition: the wearing out of the articular cartilage covering the ends of a bone. Look at a chicken bone. The shiny white material at the end of the bone is the articular cartilage. It is very, very smooth. Two pieces of articular cartilage gliding along each other exhibit a coefficient of friction eight times lower than two pieces of ice! When cartilage wears out, bone is exposed the way the concrete of a skating rink is laid bare by a spring-time melt. This wearing off of cartilage can be painful but, interestingly, not automatically so. People can live with arthritis for years without a day of pain. And then, one day, some event triggers the pain. Blunt trauma (hitting the knee against a hard object), for example, or a seemingly innocuous twisting injury. The triggering event isn't always obvious. You might come across the term arthrosis. For the purposes of this discussion, the term is synonymous with arthritis.
Not everybody with arthritis requires joint replacement surgery. A number of nonoperative treatment options exist, especially for the knee. And remember: As noted above (and yes, it does warrant repeating), arthritis pain flares up and quiets down. Joint replacement surgery is not indicated until the flare-ups are lengthy and frequent.
OSTEONECROSIS, AKA AVASCULAR NECROSIS (AVN)
It's easy to think of bone as a piece of wood. That's because the only bone you've ever seen (presumably) is on your dinner plate. But bone is a very living tissue. It is richly supplied with blood vessels and it is constantly being broken down and built back up.
When blood is unable to reach part of a bone, that part literally dies. That is because bone is made of cells like any other human tissue, and when cells are deprived of oxygen, they die. This is akin to the bone having suffered a stroke. The term osteonecrosis literally means "bone death." The term avascular necrosis is not as helpful. It is actually a redundancy because the word necrosis already implies death due to a lack of blood supply.
Nevertheless, its abbreviation AVN is commonly used, probably because it is less of a mouthful than osteonecrosis or avascular necrosis. AVN, avascular necrosis, and osteonecrosis all denote the same condition.
For reasons that are not always completely understood, there are bones in the human body that are subject to seeing their blood supply interrupted. In the case of the thighbone (femur), it's not the whole bone that is at risk, just the two ends: the femoral head at the hip and the femoral condyles at the knee.
Sometimes there exists a clear-cut risk factor for a person to develop AVN: At particular risk are patients with sickle cell anemia and Gaucher's disease (a congenital "lipid storage" liver condition that allows large, vessel-clogging molecules to form), patients who have taken steroid medications (not including injections into tendons and joints), patients who ingest more than moderate amounts of alcohol, deep-sea divers who come up too quickly, and patients who have sustained specific types of trauma.
Some of these risk factors are relatively easy to understand: In sickle cell anemia the red cells clump together and clog small arteries called arterioles. If these arterioles represent the only source of blood for a particular section of bone, it's going to be a bad day for that piece of bone when those arterioles become clogged. The use of steroids is thought to increase the amount of tiny fat globules in the bloodstream, and these tiny globules can block an arteriole just like a clump of red cells.
It is important here to distinguish between different types of steroids. The steroids that can cause AVN are steroids taken by mouth or by injections into muscles (IM injections).
Such steroids are given for a multitude of medical conditions including asthma, inflammatory arthritis (see above), organ transplants, head trauma, and chronic pain. Prednisone is typical of this category. Prednisone and related steroids are very different from the steroid preparations injected directly into a joint, such as Kenalog, Depo-Medrol, and Celestone. The latter are designed to work specifically on the joint that has been injected. They are not supposed to have so-called systemic effects, i.e., effects throughout the entire body. Sure, a small amount is certainly absorbed from the joint into the rest of the body, but by and large this small systemic dissemination has little effect. So with this second type of steroid you don't see the common side effects of prednisone such as swelling of the face, raising of blood sugar, and osteoporosis.
Most significantly, you don't develop AVN from injections into a joint, assuming the injections are given at a reasonable frequency (for most patients three injections per year in a given joint would be considered reasonable).
Alcohol can affect the liver's ability to metabolize fats and it has been postulated that this can also lead to clogging of certain bone arterioles. Fractures can occasionally damage the arteries feeding a certain section of bone. This is particularly true of certain hip fractures. Divers who surface too quickly suffer from a condition called the bends. Nitrogen comes out of solution and forms bubbles. These bubbles, like clumped red cells and fat globules, can also clog arterioles.
But for half the patients suffering from AVN, there is no discernible cause. It just happens. When doctors cannot explain where a condition comes from, they term the condition idiopathic. If the doctor says you have idiopathic AVN, it means he or she can't identify any risk factor that would have caused your bone necrosis. Note that as more risk factors are identified, fewer people with AVN will be said to have the idiopathic variety. For example, I'm willing to bet that in the not too distant future we'll identify a certain gene that predisposes someone to the condition.
Investigators have noted that a bone with AVN builds up abnormal amounts of pressure. It remains to be determined whether this is the result or partly the cause of AVN. How old are patients with AVN? Patients with AVN of the hip tend to be on the younger side, the average age being close to forty. Patients developing AVN of the knee are in their sixties or early seventies. Interestingly, though AVN can take months or years to develop, the pain often comes on precipitously, especially about the knee. Patients report pain coming out of the blue, a lightning bolt out of the sky. Hip AVN is much more common in men, but knee AVN is more common in women.
The natural progression of AVN. Sometimes the part of the bone that is affected by AVN is tiny. Bone being living tissue, it gobbles up the tiny dead part and replaces it with healthy, living bone. You may never have had a day of pain. If the part of the bone that is affected is bigger, you may develop pain, but the body may still be able to heal itself. Once it reaches a certain size, though, the condition progresses: Parts of the bone become rock hard, other parts become soft as the body tries to introduce new bone, and certain areas literally collapse. The collapse usually takes place near the surface-in other words, near the articular cartilage. This is referred to as subchondral collapse. In the hip joint, the bone, instead of being convex, appears concave over the affected area.
This is called the crescent sign. Over time the cartilage deteriorates, and the bones on both sides of the joint rub together, producing a frankly arthritic picture.
The "staging" of AVN. AVN exists in varying degrees of severity. A number of staging classifications have developed over time to assist in communication and treatment. For example, your doctor might indicate in his report that you have Stage III AVN, thus communicating to any orthopedist the extent of your condition. There are four commonly accepted stages for AVN of the hip:
In Stage I, the AVN is not visible on the X-ray but is already visible on an MRI.
In Stage II, the dead bone is now apparent on the X-ray, being whiter than the surrounding bone.
In Stage III, the bone no longer has a smooth, round, convex shape. It has collapsed at the edge-the so-called crescent sign on a hip X-ray.
In Stage IV, the bones on either side of the joint have come together as the cartilage has deteriorated. To say that someone has Stage IV AVN is tantamount to saying that they now have arthritis.
Other classifications featuring groups and subgroups have been devised, but the stages I've outlined above are considered classic.
The treatment of AVN. Since we don't always know where AVN comes from, it isn't always easy to come up with a rational plan, and because there are multiple causes of AVN, it would make sense for the medical community to come up with a treatment specific to each cause. It hasn't happened yet.
The normal femoral head is round. Note here how the bone has collapsed and the femoral head is no longer a smooth, round structure. Choices include using crutches to alleviate pain and to allow the bone to heal itself without collapsing, making holes in the bone (more on this shortly), bone grafting (bringing bone from elsewhere), applying electrical stimulation to the affected area, and replacing the joint.
The drilling of holes in the hip is called a core decompression since you take a core of bone out to decompress it. The concept of making holes in the bone comes from the observation that abnormal pressures build up in bones with AVN. This pressure causes pain and can contribute to cell death.
Drilling holes in the affected area lowers the pressure. It may also stimulate the bone to remove the dead bone and replace it with healthy bone. At least so goes the theory. Since new bone is soft bone and soft bone is more prone to collapse, do you really want a large area of fresh, soft bone? Orthopedists have been debating this for years. There is no risk of aggravating the AVN by performing a core decompression, and so it is a commonly accepted procedure.
But by making a hole in the shaft of the femur to gain access to the femoral head, the surgeon creates an area of weakness in the bone. This weakness predisposes you to a serious hip fracture should you take a misstep. Your surgeon will, therefore, have you walk with crutches for six to twelve weeks. Yes, back to the crutches. Cynics say that the core decompression is just a way of enforcing crutch walking that would otherwise be unacceptable to the patient.
Having made a hole in the bone, most surgeons are content to leave that hole unfilled. Another approach, though, is to fill the hole. Some surgeons have used a piece of fibula, the little bone that runs along the lower leg. But that piece of bone dies as soon as it is separated from its blood supply-that's what happens anytime you take a piece of bone out of someone.
Other investigators have, therefore, harvested the fibula along with the main blood vessels feeding it. The vessels are then connected to arteries about the hip joint, thus maintaining the fibular graft alive. This is a relatively complex and time-consuming operation, but at least there is now a live piece of bone inside the femoral head. The extent to which this technique represents an improvement over the straightforward core decompression remains to be determined.
Electromagnetic stimulation was tried in the 1980s. The theory was that coursing a specific electromagnetic field across the affected hip would stimulate the healthy bone to replace the dead tissue. This was not as far-fetched as it seems, since electromagnetic stimulation has been shown to assist in the treatment of hard-to-heal fractures. Some investigators reported success early on, but this success has not been duplicated.
When all else fails and the AVN has reached Stage III or IV, a hip or knee replacement can be contemplated. The question that comes up in orthopedic circles is whether both sides of the hip joint need to be replaced. In other words, in addition to removing the afflicted femoral head, should the surgeon remove the articular cartilage covering the acetabulum and replace it with a cup? Here are the two sides of the argument: Only the femoral head is diseased, so why mess with the healthy cartilage on the acetabular side? Why not simply implant a partial hip replacement, a so-called hemiarthroplasty, the literal translation of which is "half " a replacement?
In a hemiarthroplasty, the femoral head is replaced with a metallic ball that matches the size of the bone that was just removed. This differs from a total hip replacement in two significant ways:
1. The acetabulum is left intact. No cup is implanted. The operation, therefore, takes less time than a total hip replacement.
2. The femoral head will usually measure somewhere between 44 and 54 millimeters as opposed to the 22- to-32-millimeter range found in a total hip replacement. The hip is, therefore, less likely to dislocate (pop out) after surgery.
The large, round metallic ball is the size of the femoral head that has been removed. This metallic ball is not fixed to the acetabulum (pelvis). Only the stem portion is fixed to bone.
On the other hand, if a partial replacement is implanted, the large metallic ball will rub against the cartilage of the acetabulum.
In a relatively young person, this type of repeated rubbing will eventually lead to the wearing out of the acetabular cartilage and to pain, pain that will require the surgeon to return into the hip to insert a cup. If this conversion from a partial to a total hip replacement takes place many, many years after the initial operation, the surgeon will have won his gamble, for the patient will have benefited from a pain-relieving procedure associated with a very low risk of dislocation. If the conversion needs to be done soon, however, it will be argued that the surgeon might as well have performed a total hip replacement right from the start! The problem, as you can see, is that no one knows in any given patient how long a partial replacement will last.
So there you have it. You can see how the arguments balance out. I've tended to favor the total hip replacement approach, but have on occasion opted for the partial replacement in patients at particular risk for dislocations.
FEMORAL NECK FRACTURE
"People come into this world under the brim of the pelvis and leave it by the neck of the femur."
This is a medical adage that goes back many centuries, as hip fractures were terminal events until the advent of surgery. An older person immobilized by the pain of a hip fracture would develop bedsores, pneumonia, or urinary infections, and die. Thus, the primary goal of hip fracture surgery is to save the person's life. The second goal is to allow the patient to walk again. The third goal is to restore the patient to her prior level of function.
Sometimes a family will be disappointed that Grandma isn't good as new. But if she's alive, let alone walking, she's already benefited from one of the miracles of modern medicine.
When a person sustains a hip fracture, you can quibble about whether she fell and broke her hip or vice versa. The most current thinking is that most of the time the impact against the ground causes the fracture. In fact, padded girdles exist that may minimize the risk of such a fracture, but they are neither widely available nor prescribed. There are issues of cost (who will pay for such a device?), acceptance (no one likes to think of themselves as being so old and frail that they need to wear padded protection around both hips), and effectiveness (no study has demonstrated the exact extent to which these pads prevent fractures). From an orthopedic point of view, whether the fall or the fracture comes first is irrelevant-the result is the same.
A hip fracture is a fracture of the upper portion of the femur. American orthopedic surgeons (aka orthopedists) treat 250,000 of these per year, and the numbers will increase as Baby Boomers discover about ten years from now that marijuana expands the mind but not the bone.
A hip can break in one of three places: the femoral neck, the intertrochanteric area, or the subtrochanteric region. Each type of fracture presents the surgeon with a different set of challenges. The intertrochanteric and the subtrochanteric fractures are fixed with plates, screws, or rods, the so-called open reduction and internal fixation, abbreviated ORIF. These procedures range from simple to maddeningly complex. The femoral neck fractures are a breed apart. The femoral neck is a narrow structure with relatively little soft, cancellous, healing type of bone. Therefore, it is at risk for a nonunion, a fracture that refuses to heal. Fractures of the femoral neck are also associated with the potential disruption of the blood vessels supplying the femoral head. Fractures of the femoral neck are, therefore, associated with a condition called osteonecrosis, whereby a section of bone loses its blood supply and dies.
Faced with a femoral neck fracture, the orthopedic surgeon has two choices: Fix it or replace it. Fixing it means putting the pieces back together and stabilizing them (keeping them from moving) with orthopedic screws. Replacement simply means that the surgeon removes the femoral head along with the broken neck to which it is attached.
Within the world of hip replacements, the surgeon has two further options to choose from. He may perform a total hip replacement, or he may perform the hemiarthroplasty (partial replacement) described above.
Fixation of a femoral neck fracture. The advantage of fixing such a fracture is that once the fracture has healed-and assuming that no osteonecrosis develops-you are good as new. It's as if the fracture never occurred.
Of course, there are exceptions. Older patients are frequently knocked down a peg even with perfect healing of their fracture. If they were excellent walkers prior to the injury and surgery, they are now good walkers. Good walkers become fair walkers, etc. But younger patients are often close to being good as new. Once the fracture has healed, there are no restrictions on activities. True, the screws or plate may need to be removed one day (mostly in younger patients), and this will require a period of crutch walking, but those restrictions are temporary.
The three downsides to fixing a femoral neck fracture are that (1) you may need to use crutches for six to twelve weeks, (2) the bone may not heal, and (3) the femoral head may go on to osteonecrosis. The last two scenarios require a trip back to the operating room for a hip replacement.
Hip replacement. With hip replacement surgery, you don't have to worry about the bone not healing (there are no longer two pieces of bone that need to heal together!) and osteonecrosis is not a concern because the part of the bone that dies (the femoral head) has been removed! And in an older patient, even crutch walking is not an issue because the surgeon will use a technique that doesn't require it.
However, hip replacements have their own set of complications. They can become infected, they can dislocate, and over time, they can loosen and wear out.
Choosing the right operation. First, the surgeon has to decide whether to fix or replace your hip. The factors he will consider include your age, your level of activity, and the "displacement" of the fracture. The older you are, the more likely he is to pick a joint replacement. This is because the older patient is going to be less tolerant of hobbling for two to three months only to find that she needs to return to the operating room. A hip replacement in an older patient is also less likely to loosen or wear out in his or her lifetime.
The surgeon will also lean toward a hip replacement if you are on the less active side, for the less active you are, the less likely your hip is to loosen or wear out.
The specific nature of the fracture is also a factor. The fracture can be of the nondisplaced type, whereby the fracture consists of a simple crack akin to a crack in the wall.
The two pieces are still connected and haven't moved relative to each other. The femoral head can be impacted, i.e., pushed into the femoral neck as a scoop of ice cream might be pushed into a cone. Finally, the fracture can be displaced: The bone has snapped like a pencil, and the two fragments might as well be in different rooms. In the case of the nondisplaced and of the impacted fracture, the surgeon is dealing with a relatively stable situation. With a little luck, the fracture could heal without any surgical intervention. The surgeon need only place a few orthopedic pins across the fracture to prevent displacement of the fracture, something that might happen if you fell again or took a misstep. Clearly, in the setting of the nondisplaced and of the impacted fracture, a hip replacement is overkill. The more difficult decision comes with the displaced fracture, and this is where the surgeon will review your age and your level of activity.
The older and less active you are, the more likely he is to recommend a replacement; the younger and more active you are, the more likely he is to recommend fixation.
If he's decided to replace your hip, your surgeon must now decide between a total hip replacement and a hemiarthroplasty. In the United States, he will choose a hemi-arthroplasty 99 percent of the time. This is because most patients who break their hip are elderly.
A hemiarthroplasty is a quicker operation than a total hip replacement and therefore theoretically safer (less anesthesia time, less bleeding, less exposure to the air).
The issue of the metal ball rubbing against the acetabular cartilage is less likely to be a significant factor in an older, lighter, less active patient.
A hemiarthroplasty is less likely to dislocate (pop out) than a total hip replacement. This is because the femoral head is larger in a hemiarthroplasty, and larger heads are less prone to dislocate.
But an argument can be made for performing a total hip replacement. Some patients who fracture their hip may also have some early arthritis. If they are still relatively young and active (a healthy seventy-year-old woman actuarially speaking, still has many years to live!), the hemiarthroplasty may become painful in short order. The hemiarthroplasty will need to be changed to a total hip replacement. This is called a conversion even though there is no religion involved. Converting a hemi-arthroplasty to a total hip replacement is much harder than performing a total hip replacement right off the bat. It is associated with many of the risks of revision hip replacement.
In a patient with underlying arthritis, the situation is really a no-brainer, and in this particular situation (fracture plus arthritis) the surgeon will, in fact, get reimbursed more for a total hip replacement than for a hemiarthroplasty (this is because "arthritis" codes pay more than fracture codes). The difficult decision-making comes in the setting of a pure fracture devoid of any arthritic component in a patient who is reasonably active in the community. In theory, the surgeon has to weigh all of the above factors and has to discuss them with you before coming to a decision. In practice, a diagnosis of a displaced femoral neck fracture will nearly automatically lead to a hemiarthroplasty. The urgent circumstances of the fracture and admission to the hospital don't allow for much discussion.
This is another time-honored adage, going back to the earliest days of hip surgery. Since prolonged bed rest leads to medical complications, it was recognized early on that prompt surgical treatment and early mobilization of the patient out of bed into a chair saves lives. Ideally, the subject should have her fracture surgically addressed on the same day as her admission to the hospital.
In the real world, the surgery often takes place the following day or evening. If the patient is not "medically cleared," i.e., suffers from a condition that won't allow surgery, the surgery is delayed until that condition is cleared up or stabilized. But generally speaking, complications increase with the length of the delay.
Here then is the dilemma: Operate soon and avoid bed-sores, pneumonia, and urinary tract infections, or operate later to evaluate and fully understand, say, the temperature that your mother has been running, or her cardiac function. Your family doctor and the anesthesiologist will usually vote for the latter. This is in part because they don't want intraoperative complications (who does?) and in part because they don't always appreciate the risks associated with delaying the surgery.
HOW DOCTORS MISS FEMORAL NECK FRACTURES
"Can you believe they missed my mother's fracture over at City General? Sent her right out of the emergency room!!!
We took her to County General a few days later, where they said the fracture was very clear."
If I had a dollar for each time I've heard this story... So how does this happen?
First of all, missed fractures occur in every part of the body. And the reason is simple: They don't necessarily show up initially. They start off as a tiny, invisible crack. The body's initial response to a fracture is to "resorb" bone at the edges of the fracture; i.e., bone at the edge of the fracture is taken away.
Remember: Bone is a living tissue that is constantly breaking itself down and rebuilding. This resorption of bone at the fracture edges leads the fracture to temporarily widen, thus making it more visible. Consequently, a fracture is sometimes more visible on Day 4 than it is on the day of the injury.
For many parts of the body, missing a little fracture is of no great importance. If the doctor treats you for a bad bruise of the shoulder or a bad sprain of the ankle, the treatment will be the same as for a small, hard-to-see fracture. But the hip is different- at least the femoral neck portion of the hip. A small crack across the femoral neck can be treated with pins that look like knitting needles. These are put in through a small skin incision, the blood loss is negligible, you can put all your weight on the leg immediately, and healing is essentially guaranteed.
If you are young and healthy enough, it can be an out-patient procedure. If the crack goes unrecognized, however, the neck of the hip can snap in two. Now you need a hip replacement- a very different operation. It is, therefore, critical for emergency room doctors to detect the slightest fracture of the femoral neck. The way for them to do so in the twenty-first century is to obtain an MRI. The MRI is the most sensitive test for a hip fracture; in other words, it is the test most likely to detect a fracture. Although I've gone on record as stating that MRIs are seriously abused in the United States, the finding of a normal X-ray in the face of severe hip pain readily justifies an MRI.
Orthopedists as well as a growing number of emergency room doctors will, therefore, quickly resort to an MRI in this setting. If you are not able to undergo an MRI, a CT scan is the next best option.
PATIENT SATISFACTION IS IN THE EYE OF THE BEHOLDER
Who is more satisfied with her hip replacement? The patient suffering from arthritis or the one who's broken her hip? The one with arthritis.
The patient with arthritis has been suffering a long time. Pain walking. Pain going up and down stairs. Pain clipping toenails and putting on socks. Any significant relief is welcome.
If the pain score goes down from a 10 to a 3, the patient thanks his lucky stars. If the operated leg is a little long, so be it. Not so the patient with a hip fracture. The day before sustaining her fracture, Mrs. Smith had no pain whatsoever in her hip. Her leg lengths were identical. She expects the surgeon to return her to that exact state, especially if she is relatively young.
A pain score of 3 is not as acceptable nor is a slight difference in her leg lengths. Also, in the setting of a fracture the surgeon hasn't had the time to review these subtleties with his new patient (nor has the patient had the time to read this book!).
Summary: Arthritis is the number one condition necessitating a total hip replacement. Partial hip replacements are most commonly used for hip fractures. AVN is relatively uncommon compared to arthritis and hip fractures. Both total and partial hip replacements are utilized for this condition.
Excerpted from What Your Doctor May Not Tell You About Hip and Knee Replacement Surgery , by Ronald P. Grelsamer, M.D. . Copyright (c) 2004 by Ronald P. Grelsamer, M.D. . Reprinted by permission of Little, Brown and Company, New York, NY. All rights reserved.Back to top