Dr. Brett B. Greenky Blog

Partial Knee Replacement

Partial Knee Replacement is an operation that has been around for more than 60years! It actually was the precursor to today’s modern Total Knee Replacement operation. The operation has gone through many evolutions along the way and today is a very technical and highly successful operation when applied to the right patient. This operation enjoys superior results compared to Total Knee Replacement (TKR) in many characteristics including: natural feel, range of motion, stair climbing ability, speed of recovery after surgery and longevity of survivorship. Any individual patient with knee arthritis may or may not be a candidate for this procedure.

In the early 1960’s TKR had not been invented. Uni’s came first. They were simple implants that resurfaced one side of the knee or the other but not both. The implants came only in one size and the tibial side was all plastic. Doctors Savastano and Marmar were early physician innovators and their respective implants turned out to be prototypes for the TKR designs of the 1970’s. The Uni operation turned out to be fairly difficult for the average orthopedic surgeon to perform consistently in a reproducible alignment. The same issue also plagued TKR.

In the 1980’s Dr Hungerford introduced a system of alignment jigs that revolutionized the technical part of TKR surgery such that angles could be accurately measure during the TKR operation. The result was a dramatic increase in the consistency of orientation of the implants. As it turns out, the orientation of the implants was one of the key elements in the operations success both in pain relief and in longevity of function. Today both TKR and Uni surgery uses very sophisticated alignment instruments.

Because the uni operation was far more difficult to consistently apply to a wide range of knee arthritis patients compared to the TKR operation, the procedure lost popularity among many orthopedic surgeons. For those of us who perfected the art of implanting the uni, consistency has been very reproducible. The modern designs of Uni”s have progressed just like TKR designs and today are very sophisticated. Because of the superior results of Uni’s compared to TKR implants, the operation is now one that many orthopedic surgeons are once again interested in. The problem is that the superior results are VERY dependant on experience. Experience matters in several areas. Patient selection is of crucial importance since many knee arthritis patients are NOT candidates. If patientsthat are poor candidates are offered a Uni, they will do poorly. Secondly, the operation is technically demanding and experience is critical in getting a good result.

Over the last 5 years, robotic assisted Uni surgery has come to the marketplace. Despite the direct to patient marketing of this technical advance, the reality is the results of robotic uni surgery is NOT superior to traditional techniques. The use of the robot can however help a less experienced surgeon get closer to the reliable results of an experienced surgeon. This is a repeat of the contribution of Computer assisted surgery in TKR . That advance helped less experienced surgeons get closer to the results enjoyed by experienced TKR surgeons. What is the dividing line between “experienced surgeons” and not experienced surgeons? Research has shown greater than 30 cases per year for TKR and more like 50 cases per year for the Uni operation. Obviously even more experience gains your surgeon even better reliability in the execution of the operation. Surgeons who perform more than 100 cases of any operation per year are even better.

So are you a Uni candidate? There are certain criteria that would exclude you. Age is NOT one of them however. Your Knee needs an intact Anterior Cruciate ligament (ACL). Your knee cannot have greater than 5 degrees of flexion contracture- that means you must be able to nearly complete straighten your knee. Your knee must not have more than 5 degrees of varus deformity- that means not very much bow. Finally, there must not be much arthritis of the kneecap part of your knee.

So what are the take home points?

  1. Partial knee replacement (Uni) is a great operation for the right patient
  2. The surgical technique has evolved progressively over the last 60 years
  3. Surgeon experience and patient selection are the most important factors affecting results
  4. Robotic assistance in the operating room can help the less experienced surgeon
  5. Not everyone with knee arthritis is a good partial knee replacement candidate

Joint Replacement

Metal on Metal

Brett Greenky, MD

Fifteen years ago lab studies revealed that metal-on-metal hip replacements had lower overall wear compared to metal-on-plastic hips. Engineers measured the volume of wear particles produced over simulated 10, 20 and 30-year spans of hip wear in the laboratory. The smallest volume of wear was produced by ceramic balls rubbing against ceramic sockets. Only slightly more wear was produced by metal balls rubbing against metal sockets. The traditional coupling of metal balls against plastic sockets produced far more wear than the other two. As a result, engineers believed that ceramic-on-ceramic and metal-on-metal wear surfaces in hip replacement would exhibit superior long-term performance in patients. That’s not the way things turned out.

Even though the wear in metal-on-metal hips was far less in volume than metal-on-plastic hips, it turns out many more particles of wear are produced in the metal-on-metal situation. Particles of wear can produce a biological reaction around a hip implant that can gradually lead to failure. Since all hip couplings produce wear of some sort, the goal is to reduce any long-term side effects of this wear material.

Despite what scientists initially thought, it is not the volume of wear that is most important, but rather the number of particles. Metal-on-metal hips can still perform beautifully, but only in very specific situations. The initial enthusiasm created by the lab data about low-wear volume in metal-on-metal hips has been tempered by clinical experience inferior to metal-on-plastic hips. Registry data from Australia, Great Britain and Sweden have shown much higher early failure rates with metal-on-metal hips compared to the traditional metal-on-plastic. This is especially true for people of small stature and women.

Encouraged by the initial optimistic lab data, the world’s manufacturers of hip implants all produced some metal-on-metal hips. These became initially popular in countries other than the United States. In the United States there use was short-lived over a 5-8 year period. Most metal-on-metal hips are no longer available for clinical use. Although their long term performance can still be stellar, their durability is dependant on much more stringent criteria than ceramic-on-ceramic or metal-on-plastic hips.

The most popular, and still available, metal-on-metal hip arthroplasty is called the Birmingham Hip Resurfacing. This implant was developed in Birmingham, England and is still available worldwide. Its unique application for hip arthritis is most appropriate for young men. This implant still has a higher early failure rate than a traditional hip replacement, but appears to be unique in that, although it is a metal-on-metal hip, it has remained relatively immune from the wear material issues. Candidates for this implant are almost exclusively men whose goal is to return to higher impact activities such as jogging and other recreational sports. The implant has the advantage of a lower rate of dislocation and improved range-of-motion; however, it carries the risk of metal-on-metal articulation. Registry data from Great Britain, Sweden and Australia still show higher early complication rates when compared to traditional hip replacement. There is no long-term data that suggests these implants are more durable than a traditional hip replacement.

In summary, metal-on-metal hips are not appropriate for most patients. And the overall clinical experience has been inferior to traditional hip replacement. Under certain circumstances, the Birmingham Hip Resurfacing operation may be a unique exception. If you are considering a total joint replacement, talk with your doctor about your specific circumstances and the best solution to get you back in motion.

Birmingham Hip Resurfacing: Success in the right patient

Brett Greenky, MD

Metal on Metal (MoM) hip replacement and resurfacing implants have been prominent in the news over the last several years. MoM articulations have been attractive to joint replacement engineers because of the potential advantages of decreased wear when compared to metal on plastic hip (MoP) articulations. The McKee-Farrar MoM implant of the 1970′s showed initial promise, but in the end resulted in much higher rates of failure compared to plastic and metal. New advances in metallurgy (the science that deals with the physical and chemical behavior of metallic elements) have rekindled interest in MoM designs. Laboratory simulations of implant wear have shown dramatic reductions in the overall volume of wear material in MoM hips compared to MoP, however, MoM articulations create many more wear particles (although smaller in size) when compared with MoP. It still remains unclear if MoM will be superior to MoP for most patients. Two implants have gained much attention in the lay media over the last 5 years, one in a positive and the other in a negative manner. Birmingham Hip Resurfacing is emerging as a successful procedure in certain patient populations while the industry "recall" of a MoM Hip Replacement system is controlling overall MoM enthusiasm. (see implant photos at end ofnarrative)

The Birmingham Hip Resurfacingwas approved for use in the USA in 2006 based on an excellent track record largely from one center in Birmingham, England. There, Dr. McMinn the implant’s surgeon-developer gained a cohort of high functioning patients with greater than 8 years of success using his second version of the implant. The first version of this implant developed failures at the 6-8 year mark after surgery. Subsequent modifications of the manufacturing process resulted in preservation of high levels of Carbides in the Cobalt Chrome implants has now resulted in the new version having much bettersuccess.

Hip resurfacing’s unique attraction when compared to traditional Hip Replacement is that the femoral head is largely preserved. The femoral head (the uppermost part of the thigh bone) is reshaped and resurfaced in the procedure rather than removed and replaced with a manmade head in traditional hip replacement. Theoretically, the femoral head bone that is preserved during the resurfacing procedure allows more options at a later time if additional surgery is ever needed. It also permits the leg bones to accept weight in a more natural way than with the stem version of replacement. The rationale is that the less invasive resurfacing operation with its bone preservation will allow the operation to be performed on younger patients who will enjoy higher activity levels and if revision is
ever needed, the surgery will be easier because the femoral head was preserved during the initial procedure. The future will reveal whetherthese claims will be proven true.

In the United States, we do not have a National Joint Replacement Registry. A registry is a data bank which holds the records for all joint replacement surgeries performed and tracks the results. The database allows healthcare professionals to detect implant designs or surgical techniques that are underperforming at an early date! Such registries have established and functional for decades in Australia, the United Kingdom and Sweden. The registries in these countries have documented an excellent track record for the Birmingham device! When applied to the correct patient and when the surgery is performed perfectly, the results are as good as any of the traditional hip replacement devices. It is also true that patients, young men in particular, enjoy very high functional activities with the implant. Whether the success in these patients is completely due to the Birmingham procedure itself, or if it should be attributed to "selection bias" remains to be seen. Selection bias is a
process in which the patients most likely to have high functional activities (irrespective of the type of operation performed) are getting resurfacings rather than the more invasive replacements, and thus making the resurfacing group look better rather than from actually from thesuperiority of the procedure or the implants used.

There have been other resurfacing issues illustrated both by the foreign registries, as well as our own experience here in the United States. The resurfacing operation is somewhat larger and technically more difficult to perform than replacement. There is a steep learning curve for the surgeon. This is not an operation for the occasional hip surgeon, but rather for the Joint Replacement Specialist. Postoperative fracture of the femoral neck (the flattened section of bone connecting the femoral head with the long part of the femur) occurs 1% of the time in the hands of the seasoned specialist, and much more frequently with the occasional hip surgeon. Wear rates (the speed of material change due to wear) at the ball-socket interface are related to the alignment of the implants more in MoM implants than when compared with MoP interfaces. Orthopedic experts suggest that at least 30 cases are critical for the surgeon to gain the necessary surgical experience. Both foreign registries and surgeon experience in the US have shown a much higher complication rate with resurfacing compared with hip replacement. Experienced surgeons do have lower complication rates as do hospitals performing high volumes of these procedures. The data also shows that the resurfacing operation is not for most women. The complications are much higher in women even when under the care of the experienced surgeon. The risk of needing a second operation within 3 years of a resurfacing procedure is 3 times higher for women than men. This phenomenon has been noted in the registries maintained in Australia, England and Sweden. Here in the US, the same problems for women have been noted and reported by researchers at Rush University Medical Center in Chicago. The etiology of the gender difference is not completely known. Lower bone density in women (and older men) certainly increases the risk of the femoral neck fracture complication. Smaller size hip sockets are also associated with higherrates of problems, and certainly women in general have smaller socket sizes.

Overall, the Birmingham Resurfacing surgery does have excellent results in the correct patient population. Increasingly apparent is that the target population for this procedure is men below the age of 60 who want to continue with higher impact activities after the surgery. Women candidates need bone density testing and consultation with an experienced surgeon to make sure they understand the increased risks.

Further Reading:

Birmingham Hip Implant

Metal on Metal Total Hip Implant

A Lingering memory from a day long ago

Brett Greenky, MD

It was August 1990, the days when beepers simply beeped and cell phones housed a whole suitcase. I sat in the emergency room waiting for the inevitable consequence of a smoldering Syracuse summer day. The sunset is especially appreciated in our city of long winters and gray skies. A cooling breeze arose as the heavy sun drifted lower, dragging a shadowacross the cityscape. The desire to be outside was irresistible.

A 19-year-old girl, home from work in the third floor apartment she shared with three friends, watched the sun’s descent as she waited for her roommates to arrive. The last beads of the day’s perspiration evaporated as a new convertible drove up below her and she lingered on the fire escape. A boy she knew distantly from school had stopped below her with anew red sports car.

" You want to go for a ride?" he asked.

"No, I better not. My roommates are coming home soon and we’re gonna go out tonight," she replied.

"Come on, we’ll just go for a quick spin. I’ll have ya back in 20 minutes. I just got my first car, isn’t it slick?"

"Yea it’s really nice," she admitted. "I have to wait for my roommates."

"Come on, you will be back before they even get home. Leave a note," hegestured with a waving hand.

"Ok, but really quick cause I gotta be back in 20 minutes."

The stairs are always faster in the hospital; less competition than the elevator, and no unscheduled stops. She lay on a stretcher, quite calmly actually, IV in place as I watched from the doorway. The ER Physician softly whispering to me the situation:

  • No nerve function in either leg
  • Hemodynamically stable
  • Neck pain only, collar in place
  • Foley catheter in and no blood in the urine
  • Spine and pelvis X-ray being developed

No reason to go in there until I see the X-ray’s I thought, since questions will be asked, and the answers will depend on the films. I wandered to the X-ray display and startled. The films were all fine except the cervicalspine. She had bilaterally jumped facets at C5/6.

The boney spine is like articulating armor around the spinal cord. Think of a concrete embankment around a highway, protecting the traffic. There are a lot of entrances and exits in certain areas like
downtown and long stretches of highway with few exits. The spine is best protected in the long thoracic area (the part from your shoulders to your waist) by the stiff facet joints and the presence of the ribs. As a consequence, traumatic injury in the middle of the thoracic spine is rare. The cervical (neck) and lumbar (low back) parts of the highway have lots of exits and entrances for the nerves to the arms and legs. In addition these areas need a lot of flexibility for motion. These areas are much more vulnerable to trauma. The most risk exists at the junctions between stiff and flexible spine segments. Where the flexible cervical spine meets the stiffer thoracic spine is especially at risk. Bilaterally "jumped" facets result in a 50% reduction of the spine diameter at that level. Usually that pitches the spinal cord so much that permanent loss of nerve function below the level of injury is inevitable: quadriplegia. "Hi, I’m doctor Greenky, one of the bone doctors here at the hospital. Do you have pain?" "My neck hurts but that’s it. Why can’t I move my legs?" "You have an injury to your spine and your spinal cord in your neck. It’s too early to tell about improvement right now," I responded. "OK, but I have to work on Monday so I have to be out of here soon." "I understand. Can we call your parents and let them know you are here." "I don’t want to call them. They will be mad I went for a ride in that car. I will tell them later next week when I’m all better and back to work." The nurse and I checked the "bulbocavernous reflex" using the Foley catheter. This presence of the reflex represents the end of spinal cord shock. If the spinal cord is in shock and not recovered then reversal of some, and in rare cases most, of the nerve deficit is possible. The presence of the reflex means no recovery will occur. Her reflex was present. Our hearts fell. Her quadriplegia was going to be permanent. I knew it immediately and felt a wave of nausea. I smiled and held her hand.

"We need to stabilize your spine with an operation. We need to talk to your parents now." "Ok, but they are going to be mad," she reluctantly responded.

"I know. My parents have been mad at me lots of times but they got over it," I said. "How about moving my legs?" "It’s too soon to know for sure," I answered again. "Lets take one thing at a time." "OK." As I walked to the OR to book the case, a glimpse of the red sun slipping below the horizon left me with the feeling that a long darknight had just only begun.

Blood Conservation During Joint Replacement Surgery

Brett Greenky, MD

Everyone undergoing joint replacement surgery is concerned with preventing the need for blood transfusion. There are compelling reasons to minimizethe need for blood transfusions which include:

  • Increased postoperative infection rates
  • Possible disease transmission

Anxiety about the risk of transfusion related problems include the unlikely possibility of disease infection, however, the risk of HIV orHepatitis B or C transmission is quite remote

  • Allergic reactions
  • Potential for administration errors
  • Lung injuries
  • Increased postoperative length of stay in the hospital
  • High cost

Approximately $200 for the blood unit itself but with processing andhandling the overall cost is upwards of $1000 per unit.

Let’s examine the HISTORICAL facts:

  1. No single transmission of HIV (the AIDS virus) has been reported in a joint replacement surgery associated with a transfusion in the past 15 years according to the Centers for Disease Control (CDC). This is because of the now routine and sophisticated testing of donated units over the last 15 years.
  2. There is no test for Hepatitis C presence in donated blood. Although the transmission risk is remote, a very small risk persists. Donators of blood units are questioned about the risk factors for the presence of Hepatitis C and are subsequently excluded from donation.
  3. The risk of a transfusion related problem resulting from receiving a transfusion from a family member is the same as it is for receiving a blood transfusion from the general public. Family designated donation for upcoming surgery is NOT safer than getting blood from the general American Red Cross blood bank. As a result of this fact, nearly all large joint replacement programs have discontinued designated donor programs.
  4. Donating your own blood to be available for later surgery (Autologous Blood Donation) has NOT been successful in reducing the need for blood transfusion from the bank. Additionally, autologous transfusion is not without health risks:

Lowering your blood count near the time of your surgery

Decreased effectiveness related to cold storage and processing

Potential clerical/handling errors

As a result, nearly all large joint replacement programs have discontinued autologous donation programs.

What is the present "State of the Art" nationally for Joint Replacement Programs?

  1. A national transfusion rate of approximately 25% is noted for joint replacement surgery. The rate of transfusion is a slightly higher for total hip replacement than for total knee replacement.
  2. Patients that require blood transfusions have slightly longer hospital stays than patients that do not need a transfusion.
  3. Blood products are a precious resource in which the demand exceeds the available supply. Transfusions are costly to the health care system when used for elective surgery and also deplete our supply of banked blood for emergency situations.

The St. Joseph’s Hospital Health Center Joint Replacement Program has successfully and dramatically reduced the need for transfusion far beyond the average hospital. We have done this with a multifaceted approach. Our goal is to even further reduce the need for transfusion. We were recently awarded the 2011 Red Cross Home Town Hero Award for a 400% reduction in the
use of blood products for patients in our joint replacement program! The transfusion rate at St. Joseph’s for our total joint replacement patients is below 8% which equates to less than 0.2 units of packed red blood cellstransfused per patient.

How this was achieved:

(Preoperative, Intraoperative, and Postoperative Measures)

  1. Development of a formal Blood Management Program in 2005 which includes a dedicated blood conservation nurse.
  2. Preoperative screening for all elective joint replacement patients includes testing of Iron reserves and reticulocyte counts (young red blood cells). Patients who are anemic or low in Iron stores receive supplements PRIOR to the surgery to boost them.
  3. Appropriate anemic patients receive Erythropoietin, a natural hormone that boosts red blood cell counts prior to surgery.
  4. Preoperative nutritional counseling and guidance to build iron stores.
  5. Blood salvage machines collect, wash, and re-transfuse the patients’ red blood cells both during and after surgery, minimizing the amount of lost cells.
  6. Use of an intraoperative tourniquet during knee replacement surgery.
  7. Spinal anesthesia administration
  8. Maintenance of normothermia (body temperature regulated within a controlled range)
  9. Our newest strategy involves the use of Tranexamic Acid, a medicine which helps reduce operative bleeding, during the operation.
  10. Elimination of "routine" blood transfusions and instead transfusing patients when their symptoms/condition necessitate it.

Our goal is to totally eliminate the need for transfusions for elective joint replacement surgery while continuing to provide safe and optimalsurgical outcomes for our patients.

Joint Replacement Materials: What’s in an implant?

Brett Greenky, MD

The future evolution of joint replacement materials promises to bring newer materials with hopes of longer implant life and less wear characteristics. One example of new technology advancement is a hybrid metal-ceramic material. Through special manufacturing conditions, the surface of the metal material can be converted to ceramic which results in an implant with the favorable characteristics of both metal and ceramic. More discoveries of this nature are undoubtedly on the horizon. Long term clinical studies are essential to prove that any improvements in materials actually lead to
longer lasting implant life with improved outcomes.

Conclusion

Joint replacement surgery is currently a highly successful procedure resulting in exceptional outcomes. There is no combination of materials that works best in all joints for all patients. Your surgeon will
determine the implant materials that are are optimal for your individualsituation.

For more information about this topic, watch YNN, Ch. 10 news on Saturday, July 16th to hear Dr. Brett Greenky discuss implant materials used in hipand knee replacement surgery.

Musings on Nepal

Brett Greenky, MD

Namaste. (nah-mah-stay). This simple Hindu greeting is expressed by pressing the palms of the hands together in front of the heart. The head is bowed slightly as the word is spoken. It literally means "the spirit orlight within me recognizes and honors the spirit or light within you."

We very recently returned from a journey to Kathmandu, Nepal, a valley burrowed deep in the recess of the Himalayas, the highest mountains on earth. Our primary purposeā€”to assess the medical facilities and prepare for Operation Walk Syracuse’s November trip to Nepal to perform desperatelyneeded hip and knee replacement surgery.

The stark contrasts of reality that we witnessed are staggering and pervasive in both city and village life. The region and the people are primordial, yet caught in the throes of modernization. It is a place of breath-taking beauty and unspeakable poverty. Sanitation is more than apervasive issue.

Kathmandu lies deeply isolated in a valley surrounded by mountains. City roads are dangerously crowded, unguided due to the lack of traffic signs and signals. Travel by car, bus, or motorbike is a treacherous, grueling affair. Most mountain villages are reachable only by dirt roads andfootpaths.

The pollution is pervasive. Noxious fumes hang low over the city and we observed many people struggling to protect their airways through the use ofmasks or scarves placed over their mouths and noses.

The hospital environment will be challenging. The medical facility falls far short of those we comfortably use in the U.S. The challenges in providing effective medical and surgical care are very apparent. Paucity of resources, a hospital physical plant that is lacking hot water, adequate toileting facilities, and up-to-date equipment and supplies add to thealready challenging care environment.

By contrast, the physicians and orthopedic clinical staff areknowledgeable, enthusiastic, motivated, and committed to meet the needs of their patients. We were warmly greeted and welcomed to the Medical College. Our hosts were extraordinarily gracious. We collaboratively planned for our November surgical joint replacement marathon which will include our team of nearly 40 health care providers who will travel with us to Nepal. In addition to the cordial welcome from the medical staff, hospital administration, and the Minister of Health, we were warmly greeted by twenty of the prospective patients. We left the hospital bearing the x-rays for fifty (50) patients who are hoping to receive ninety-three (93) joint replacement procedures during our abbreviated visit in November. Adaunting and overwhelming task is at hand.

We saw so very little during our short visit but more than enough to make us appreciate what we have here, and how much we take that for granted eachand every day.

It was all about the people. We were struck by the extremes of everything they experience, yet are sincerely welcoming and positive. Ox-drawn carts and cows share the roads with taxis and other motorized vehicles. T-shirt clad teenagers sell roadside wares next to sari-clad women washing clothes at a public well. As we wandered through the narrow brick streets of Bhaktapur, an ancient city with Hindu and Buddhist temples that seem unchanged for centuries, or gazed across the terraced-fields that lie at the gateway to Everest after hiking to the highest point of Nagarkot, we
remained most in awe of the remarkable inhabitants of this country.

As we departed Kathmandu dreading the long, jet-lag filled return to Syracuse, we were energized by what we had seen and what promises to lie ahead. We eagerly look forward to the next time that we will be met with the greeting we received from everyone in Nepal, rich or poor: Namaste. This humbling gesture is meant to recognize that we essentially are all on equal standings. We are one with these people as we prepare to travel more than 7,500 miles to the other side of the world on this life-altering trip. Until then, we will hold on to the people of Nepal and so many ofthe lessons learned.

Himalayas