Knee Replacement and the Baby Boomers

Personal note.  Three weeks ago I had my left knee replaced.  It is something I’ve thought of doing for many years but finally acted on and I wanted to share with my readers what I’ve learned and experienced about the procedure.  I also want to share some issues about knee replacement, a procedure that may soon become America's most popular surgery.  This peaceful Sunday morning I am cocooned on my couch as the KodiakPak pumps ice water around my knee while the dog warily cuddles, confused about how the Alpha in this pack was brought so low. 

In the past six months, both my wife and I have had a surgery, each for the first time.  For me, these events have cut into the time I use for writing.  After two years of producing these Cascadia Courier essays, publishing about three each month, they have become the center of my work rhythm to which I am now finally returning, my path beyond surgery becoming clear and more easily trod.  Barbara's health has returned fully.  While both of us think the past six months might have been more happily spent, we actually have come to treasure these experiences together. We have learned about the lives of medical professionals, meeting and trusting people we hardly know.  How cool it is to surrender to the love of family and friends, letting their support wash over us without questioning.  Who knew we had so many cooks and dog walkers among them?  How utterly sweet to have a daughter come home and nurse and cook for you.  How calming it is to know for sure that Barbara was paying attention when she said the words "in sickness and in health."

My Knee Hurts!!

Our ancestors had an elegant solution for painful, debilitating knee problems associated with aging.  They died before the onset of these problems.  However, the death solution, while elegant, has little favor today among older, active adults whose post-seventy agendas are defined by work, skiing, hiking, golf, swimming, fishing and travel.  

Ten years ago, my chronically painful left knee, pushed to its edge by an infatuation with running, had me trudging along with little hope while I thought about alternatives without the motivation to really consider them.  Then, on the way to a meeting up one of Seattle’s steep hills, I found I couldn't advance unless I walked up backwards.  That’s what my knee was giving that day so that’s what I took. 

Nodding to my fellow pedestrians staring at me, I offered a silent and sullen “opposite day, you sonofabitch!”  

I soldiered backwards up the hill and tried to find a positive in it, deciding on the fact that I could now enjoy the view of Elliott Bay, which if my knee was not a mess, would be at my back.  Of the many humiliations I experienced fumbling along for years with a bad knee, this one finally prompted action and I turned myself over to the orthopods who diagnosed osteoarthritis – arthritis of the bone, sometimes called the ‘wear and tear’ disease.  This called for serious measures, perhaps not at the time but certainly in the future.  The surgeons soon brightened, however.  The images also showed a tear in the meniscus, the padding between the joints, and they said that a little arthroscopic trimming would provide some relief. 

Bone on Bone

It did, but only for a couple of months.  When I went back to my surgeon he said he’d be happy to provide the same arthroscopy once more.  By now, I had read enough about the effects of osteoarthritis on the knee to know that when bone is grinding on bone, cortisone and a snip here and there is not going to do much.  My solution lay with a knee replacement; the only question would be when.  The timing would be driven by the presumed satisfactory life of the procedure – usually about 15-20 years -- my own age at the time of surgery and my assumption that I would continue an active life until I dropped.   The busy hum of everyday life creates a kind of analgesic effect on chronic pain and I waited some more.

Tons of ice and bottles of painkillers later, I was ready. Then I realized another factor was in play -- when could surgery be scheduled?  The growing use of joint replacement strategies and the great bow wave of wear and tear boomers hobbling through the health care system created some wait times.  

In addition, a fair amount of work-up was needed.  Knee replacement creates higher risks of blood clots and some patients may require surgical procedures or special medicine to mitigate clots.  Doctors also want sophisticated diagnostic imaging to choose among different hardware options and to make the precise measurements needed for a long term successful procedure.  The waiting continued.

A friend of mine has grown tired of the constant conversation about medical topics among the healthy looking adults we run with.  At a fine celebratory dinner, the conversation had quickly found its way to medicine, which explained his tight jaw.   I was thinking about health issues as well, wondering if you had walked into the fun restaurant we were eating at, laughing and drinking in and it was in your reach to switch your health profile to anyone else in the restaurant and take their profile as your own, when would someone of inferior health pick members of our group?  I had no illusions of any of us chosen in the top quartile, but I successfully argued to myself that we’d be definitely chosen in the second.  Okay, not tippy-top of the second, but not at the bottom either.  Looking across the bar to the mirror, we seemed to glow with good health, luminous compared to the neon green pallor of so many other customers.

 

As we have aged, however, our vocabulary reflected the backgrounds and terminologies of an astounding number of medical conditions.  Our little crowd, lubricated by a substantial upgrade from our everyday wine, was chattering on about lupus, chronic leukemia, a recent knee surgery, a couple of breast cancers, prostate cancer and several other pre-and proto-cancerous dribs and drabs.  As the conversation droned on, I could see our relative position among the quartiles began to sink, soon tumbling into the fourth where I decided not to propose my silly idea.  Besides, it was too late.   

“The medical discussion terminates precisely in five minutes,” my friend said, scanning the wine list he held in one hand while motioning for the waiter with the other.

My new knee

Total knee replacement is rapidly growing and is now among the most common surgeries performed today in America.  There have been 3.25 million of these procedures in the United States over the past twenty years and stands at 700,000 annually today.  When considered with hip replacement surgery, another fast growing, wear and tear procedure, nearly a million people a year turn to these two joint replacement strategies to shore up their deteriorating ambulatory frame.  The average age of a total knee replacement patient is 65.1 years while hip replacement patients have, in the past, averaged around 70 years, though the trends are driving the age average down substantially.  A high percentage of these patients – about 95% -- will use their new body part happily for at least 15 to 20 years with some lasting much longer.  The Washington Hospital Association hospital cost data base indicates that knee and hip replacement patients will participate, depending on insurance, location and many other factors, in a hospital cost of about $35-65,000 across the King County, Washington medical market. Negotiated discounts with insurance providers will reduce this cost variously.   A very high percentage of knee replacement patients return to work after their surgeries -- 98% of them -- while just under 90% actually go back to doing the same  work they had been doing before.   

These surgeries are amazingly beneficial for the patient.  A very high percentage of post-operative outcomes lead to lower weight, better self esteem, a return to a healthier life-style and more active sexual function.  Mortality among hip replacement patients seven years after surgery is half that of the general population.  What’s not to like?

Early attempts at dealing with the problems of chronic knee pain seem crude today, though many of them continue to be used.  A procedure that came to be known as interpositional arthoplasty began in the 1860s in which softer, cushioning materials were inserted between the lower leg bone, the Tibia and the thigh bone, the Femur, augmenting what remained of the natural cartilage, the amazing material that cushions and facilitates the mechanical movements of our skeletal frame.  Skin, fat and other soft materials from the patient’s own body or from donor animals -- chicken wattles are rich in collagen, for example, create a natural cushioning product.  We know collagen, when it is processed with water, as gelatin. 

Today, similar strategies continue in service, though usually as a short term bridge to more permanent replacement strategies.  Injections into the knee with collagen rich material are frequently called “chicken injections” in Europe.

Gluck's Knee

The 19^th century German surgeon Themistocles Gluck was an early advocate of augmenting cartilage with other soft tissues, however, he is best known for his early and remarkable excursions into joint replacement.  In his time, the 1880s, the lack of antibiotics meant that many more infections of the body would migrate to the joints, often leaving no alternative but amputation.  These problems propelled Gluck into the first true joint replacements.  He used ivory as the substitute for bone in his several different joint replacements, including the first knee joint replacement.  In a review of his work in 1891, two of Gluck’s knee transplants had been in place for five years.

Prosthetic knees in the 1950s and 60s were rigid, hinged affairs that loosened frequently.  However, engineers and physicians in the 70s were soon developing products that were far less rigid and more naturally supported by the ligaments and tendons supporting the natural knee.  The first modern knee replacement was done in Great Britain in 1968 and in the US in 1970.  While there have been many changes in materials and techniques, today’s knee replacement hardware is a bit like the Boeing 747, a design from the 1970s whose many component parts and functionalities are quite different  and advanced today but whose basic structure is the same. 

My new knee started with an incision beginning about five inches above the center of the knee cap and extending down a full ten inches.  Soon, two other deeper cuts expose the joint.  The thigh bone, called the Femur, is at the top of the frame and the Tibia, the shin bone, is at the bottom.  The two bones are connected in the front by the huge quadriceps tendon which also covers the kneecap, or Patella.  Other tendons connect along each side of the knee and in the rear.

University of Washington

At the end of the Femur are the condyles, the weight bearing interface of the thigh bone. Because of the wearing away of the cartilage and the bone-on-bone contact, this surface has grown tender and it is one of the places in the knee where the arthritis is most severe.  The surgeon removes a slice of the femoral bone condyles and readies a metal plate whose outward shape is like the natural surface.  It also has a groove along the front over which the kneecap can slide while use.  In the back are two metal posts that fit into holes bored into the bottom part of the femur.  It is all connected with a surgical glue.

The Tibial part of the knee reconstruction also starts with a new surface, shaved level by the surgeon as on the Femur, though the plate on top of the new surface is different with a small lip around its edge that faces upward toward the Femur. 

Fitting into this metal on top of the Tibial plate is a hard plastic surface that slides between the two metal surfaces above and below.  This plastic takes on the function of the natural cartilage, the Femur’s new cap sliding along the plastic surface when the knee is flexing while walking.  The surgeons slide all the tendons back into place so that the entire knee is supported to the left and right and by the big quadriceps on the front with the smaller posterior cruciate ligament supporting the back of the knee.  When the operation is complete, the joint is not fused, but stable, flexible and ready to bear all your weight, though on day one that would be very painful.  

The length of the operation is about two hours and it is conducted under a spinal block and a femoral nerve block which does not allow pain transmission from the knee outward.   I actually heard some noises during the operation, but I was unable to connect them to anything.  Having no general anesthesia speeds recovery.

Today’s efforts to push down cost and to free up revenue producing hospital space has reduced the hospitalization associated with this procedure from nine days twenty years ago to about three days today.  I’m not sure what the medical implications of this are, but I am certainly clear about the implications for sleep.  After the operation, devices monitored oxygen levels in my blood, while another device designed to avoid blood clots squeezed both my legs every ten seconds or so.  When they would fall off as I struggled to pee while lying on my back (tip:  next time, allow the catheter) or slipped off as I perspired, alarm bells would begin sounding and the mayhem was complete.  When the monitoring bells stop ringing, it’s time for meds, a blood pressure check or new blood work.  My best night’s sleep was four hours, coming in two, two hour blocks. 

Physical therapy begins the first day after surgery.  The immediate goal of physical therapy is to as quickly as possible regain flexibility in the knee joint.  One of the items I was given there was a thick plastic belt which, when looped at the end, could be used to swing your leg in or out of the bed.  I made a game of it.  I became good at it.  Unlike in the hospital, where you are cared for, in therapy, you have a job to do.  When I met my physical therapist, Franklin,  after returning home, I was showing off with the strap and he took it from me.  He said he would make my knee strong enough after the first hour so that I wouldn’t need the strap.  “This isn’t the hospital,” he said.

After the procedure, my left leg was minus 12 degrees from a perfectly straight 180 degrees.  The ability to straighten your knee is the first step toward eliminating a limp as a future outcome.  The operation should ultimately allow about 120 degrees of flexion in the knee.  The first measurement of my leg showed I could flex it to just 56 degrees which increased to 65 degrees two weeks from my surgery and into the seventies after three weeks. I've talked with people who were at 130 degrees of flexion after a couple weeks and others who never crested 100 degrees.  I’ve done two one hour exercise sessions a day including the physical therapy every other day from professional, in-home PT visits.  Though drug averse, particularly to the opiates, I came to the conclusion that taking enough pain medicine to do quality exercise sessions was important to my recovery.  I will tend to gain my flexibility more slowly due to increased and more persistent swelling in the joint because of blood thinners.  Blood clots are a risk of this surgery and the blood thinner Warfarin, a derivative of rat poison, is used the day surgery begins until three, four or six weeks after surgery. 

Doctors describe the basic progression of healing this way, predicated on regular physical therapy and exercise.  On the afternoon after surgery, or on the next morning, you will begin physical therapy which will occur each day you are in the hospital.  After three days, you will go home and have home physical therapy, usually one hour, three days a week for three weeks, plus whatever you do on your own.  After three weeks, you will be able to use a cane or nothing at all while at home, walking with stiffness, though no pain.  I intend to use the walker while walking on the streets for the time being. Sometime around week five, you will ditch the walker and the cane.  In fact, I never used the cane.

By three months you are walking without pain or other discomfort.  I know some people who played golf at three months.  Assuming you’ve done a good job of continuing your exercise and stretching, you will have forgotten the procedure after a year.  Walking, golf, swimming and other similar exercises are fully within reach, though running and jumping are not recommended.  Some people ski.

Things do go wrong.  Three percent of the new joints fail each year from mechanical loosening or component failure.  An additional 1-2% of these joints require revisions or replacement because of infection that moves to the new joint.  In hips, failure rates are somewhat less, in the past about 1%/year, though the recent problems with the recalled metal-to-metal hip recently sold by Johnson and Johnson will skew those averages for now.

Though I spent considerable time talking with doctors, other health care professionals and friends and acquaintances who had experienced the surgery, I had several surprises during the real thing.  First, perhaps because most of my previous conversations focused on recovery, I was not prepared for what is truly a major surgery.  The pain was major league.  The difficulty of getting out of bed, to the bathroom, the pain of standing for relatively short periods of time, the fatigue from lack of sleep or from the trauma of the operation, the pain of the early physical therapy, all conspired to create an uncomfortable anxiety that led to a serious questioning of the decision to do the surgery.  After the second week, however, the results of the exercise began kicking in – the legs growing stronger, the routine of stretching and strengthening paying off, the arrival and therapeutic placement of the blessed ice, created a rhythm that seemed to be heading somewhere, a place where I could see the redemption of the procedure’s considerable benefits. 

I’ve been thinking about the intersection of this procedure with the 77 million baby boomers who, like me, are moving to a time in their lives when they will choose this surgery.  A 2006 study released at the American Academy of Orthopaedic Surgeons annual meeting created a bit of a sensation when it predicted the number of first time total knee replacement surgeries would increase nearly seven times by 2030, to 3.5 million/year.  The study also predicted hip replacements would nearly double in 2030 to nearly 600,000/year.  In addition to new replacement therapies, the study saw strong growth in second hip and knee surgeries, called revisions, in which old equipment installed in the 80s and 90s must be replaced.  The study's fundamental questions are:  

"Do we have enough orthopaedic surgeons to do the work?  Do we have enough money?  Is longer life, better sex and higher self-esteem a set of good trade-offs for the social and financial costs?"

What the study didn't consider is the escalating use of medical imaging and other pre-operative work that must be done prior to this astounding increase in knee replacements.

The cost of serving these additional patients is very significant, into the many billions of dollars.  Managing the growing cost of knees and hips among all the other rising medical costs depends on finding new and better treatment outcomes.  The development of implants that last longer is a priority.  Understanding the humble cartilage that, when healthy, saves us so much pain.  Unfortunately, cartilage is a highly unusual material.  It is avascular – it has no blood supply – and, when it is damaged, it is a poor healer.  After absorbing a certain amount of energy over time, cartilage begins to break down.  Adult stem cell research is a major focus now for the development of artificial replacement cartilage.  Controlling obesity is a big opportunity for joint health and longer lasting outcomes as is better and more consistent pain management that can more effectively delay surgery.

Medical tourism is another tool for demand management.  The cost of total knee replacements in many countries is far less than in the United States.  Hospitals in Columbia, Costa Rica, Jordan and India charge about 15% of a US joint replacement while Korea, Mexico, Singapore and Thailand charge about a quarter of US cost. 

A fair amount of political management is also necessary.  A very large portion of the 77 million boomers will seek the benefits of this procedure are medicare and medicaid patients.  As we cut these programs over time, are we implicitly making choices about who receives chronic pain relief and the other benefits of knee or hip replacement?  How do we deal with obese patients, whose weight reduces the efficiency of the replacement system?  Do we set upward limits on weight?  Do we also have an upward limit on the age of knee or hip replacement patients?  Do we establish implicit wait times for this procedure, as the Canadian health care system establishes explicitly?  Demand there rises at 7%/year for the past several years and the system is frequently not able to meet the six month wait time the Canadians have established.  

When combined with extremely beneficial patient outcomes, as in knee and hip replacement, medical technology becomes its own boss, dictating its own terms and moving at its own pace.  While we want to exert control over its cost implications, we are forced to the margins of control by the pressure of patient demand and by the zeal of the medical profession to meet it.

While my daughter was here, we talked a bit about the implications of this technology for the health care system.  Putting on my insurance company hat, I said:

"You could argue that this might be an example of too much of a good thing."

"Daddy," she said.  "Listen to me.  This is a good thing."