TKR SURGERY

Recently, we had an interesting discussion in one of my TKR forum where we discovered that many people are still very ignorant of Total Knee Replacement (TKR).  This ignorance turned out to be quite hilarious because one member tried to relate to her boss that her surgery was coming up and she was scared about it.  But her boss made light of the surgery by saying that it's just a keyhole surgery. How wrong can that be? So it was suggested that she show a video on TKR surgery to the boss to proof how major the surgery is.  Well, it's the same for me.  When I tell people that I had a bilateral TKR surgery, some of them they will go like... is that possible?  how does it work?  what is it made of?  oh, it sounds like you are a bionic woman!

Yes, ignorance can be humorous sometimes.  It's okay if you are not suffering from Osteoarthritis (OA).  But if you are suffering from severe OA, it's not a laughing matter.  OA can make our life  debilitating and miserable.  Most of us who have gone through TKR tend to be very observant of others who are struggling in pain when they walk.  We will wonder whether they know that their problem can be fixed.  We want to reach out to tell them. Sometimes we do but sometimes, certain circumstances prevent us from doing so.  Maybe they know but the fear factor is too great. Or maybe they know, but they don't know enough.  Or maybe they know enough but do not have the financial means to get the problem fixed.  Whatever it is, the purpose of this blog is to create awareness and hopefully you, as readers can help to spread the awareness.

In this post, I will try to provide some basic information related to TKR surgery.  These information  are based on my own personal experience as well as some research references from UKM Specialist Centre, St. Vincent Medical Centre Joint Replacement Institute and BoneSmart.  The images and videos shown here were obtained from the Internet.

WHAT IS A TKR?

TKR is a surgical procedure whereby the diseased or damaged joint surfaces of the knee is replaced with artificial material that allows continued motion of the knee.

TKR is one of the most successful of all surgical procedures, and a virtual medical miracle.  Prior to the development of TKR technology, patients with advanced arthritis of the knee suffered from chronic pain and loss of functional independence.  Following TKR, more than 90% of patients have no pain, or only slight pain, and their walking is no longer limited by their knees.  Most patients can live a full and independent life.

Our knee consist of three bones.  Our thigh bone (femur) sits on top of our shin bone (tibia).  When we bend or straighten our knee, the rounded end of our thigh bone rolls and glides across the relatively flat upper surface of our shin bone.   Our knee cap (patella) is the third bone and it is attached to the muscles that allow us to straighten our knee.  There is a cushioning layer of tissue called cartilage between the joints that allows the three bones to move without creating friction or wear on the bone surfaces.  However, when the cartilage is damaged or worn out, our bones rub together causing friction, pain and deterioration of the bone surfaces.

In TKR surgery, the parts of the bones that rub together are resurfaced with metal and plastic implants (prosthesis).  The Orthopaedic Surgeon (OS) will use special precision instruments to remove the damaged surfaces of all three bones and replace them with the prosthesis.

Anatomy of a Normal Knee Joint
 

Knee joint After Total Knee Replacement

WHAT ARE THE CAUSES OF JOINT DETERIORATION?

TKR is usually considered for patients whose joints have been damaged by arthritis, trauma or other rare diseases of the joint.  The most common reason for TKR is severe OA of the knees. 

OA is the most common joint disorder affecting mostly weight bearing joints such as hips, knees, ankle and foot. It is usually caused by wear and tear of the joint due to ageing particularly from age 50 and above. But today, it is affecting much younger people.  The problem starts with the deterioration of the cartilage.  When the cartilage deteriorates, the bones rub together causing pain, swelling and stiffness. Eventually, this will cause bony spurs (osteophytes) to be formed around the joints and subsequently, the ligaments and muscles around the joints become weaker and stiffer.

Rheumatoid Arthritis (RA) is an autoimmune disease that causes chronic inflammation of the joints.  While inflammation of the tissue around the joints and inflammatory arthritis are characteristics of RA, the disease can also cause inflammation and injury in other organs in the body.  Autoimmune diseases are illnesses that occur when the body's tissues are mistakenly attacked by their own immune system.  While RA is a chronic illness as it can lasts for years, patients may experience long periods without symptoms.  However, RA is typically a progressive illness that has the potential to cause joint destruction and functional disability.

I know of two people from my TKR forums who had undergone bilateral TKR at the age of 28 and 31 years old.  One has RA and the other has Psoriatic Arthritis which is a form of RA.  These people had such a debilitating and miserable life to the extent that they were unable to work.  They may be young but their knees were that of an 80 year old.  And they had a hard time finding an OS who would do the surgery.  They were told to come back in 10, 20 years time because they were too young to do a TKR.  Fortunately, they managed to find their OS who were willing to do bilateral TKR because they believed that the consideration for better quality of life outweighs the age factor.  

Comparison of Normal and Arthritic Joints

IS TKR FOR YOU?

TKR is usually recommended if non-surgical treatments such as physiotherapy and exercise, taking pain medication or using physical aids like a walking stick, no longer help to reduce pain or improve mobility.

X-ray is the best way to know the condition of the knee joints.   According to my OS, there are 5 stages of OA and both of my knees were at stage 4 when I did my bilateral TKR. At stage 4, the pain was already unbearable for me so I cannot imagine ever reaching stage 5. He also examined my knees, my range of motion and any deformities in my legs. Yes, my knees were bowed inwards so he said he will correct the alignment during the surgery. That sounded like getting my car tyres aligned! He also asked about my medical history. Based on all these examinations, it was determine that I was a candidate for a bilateral TKR.

Bilateral means that two knees are replaced at the same time. I did not hesitate at all to do a bilateral TKR because it seemed to be the most logical thing to do. But it's not very common to have the arthritis in both knees reaching the same degree at the same time. So its quite common for people to do TKR years apart. I learnt that some OS does not advocate doing both knees at the same time even though they are equally bad. I think this is to prevent risk of complications. So there are people who had TKR for both knees done in a matter of days and months apart. I have great admiration for these people who had the courage to do this.

WHAT ARE THE RISKS OF TKR?

There is no surgical procedure without risks.  Two possible major risks for TKR are blood clot and infection.  However, it's important to note that the percentage of these incidences are very small.

Infection can occur following any type of surgery as well.  My OS said that if I have any infection from cold, flu, dental problems or any illnesses, then they cannot proceed with the surgery until it is treated.  In order to minimise the potential for infection to occur at the time of surgery, antibiotics are given before and after the surgery.  During the surgery, there are preventive measures taken as well.

Blood clots can form in the large veins of the legs and pelvis following TKR which may lead to pulmonary embolism.  Therefore, certain medication may be given to prevent this and the PT will  encourage you to move your legs to ensure blood circulation.  Of course, there is always the risk of general anaesthesia as with any surgery.  Other risks includes damage to nerves or blood vessels which is usually temporary, bleeding from the wounds and scar tissue. 

HOW LONG DOES IT TAKE TO RECOVER?

This is the most common question. TKR surgery would normally require 4 to 5 days stay in the hospital. Recovery may take up to 3 months. You are required to take pain medication for a period of time and do some physiotherapy exercises either on your own or with the help of professional PT. Swelling and stiffness of the knees are a normal experience particularly if you overdo PT. Therefore, you are required to rest, ice and elevate as much as possible. Initially, you are able to walk around with a walker. Gradually, you will progress to a cane. Finally, you will be able to walk without any aids. The time that you will take to do all these will vary with each individual.

Some people in early recovery can be very impatient. They will usually complain why they are still not feeling normal after 6 or 8 weeks. And they are unable to rest or recuperate as they have to get back to work in a relatively short time. That's partly why they overdo their PT thinking that they will heal faster. Then they get disappointed when they do not see progress or they may even experience a set back in their recovery. Sometimes, people do not realise that they just went through a major surgery and their knees are injured (not unfit) and need lots of healing and tender loving care, not training. That's why it's important to understand about recovery which requires a lot of patience and a positive mindset. It's also beneficial to ask questions and learn about other people's experience in recovery. So joining a support group would be most helpful.

Actually, there are two stages in recovery i.e. short and long term recovery. Short term recovery involves getting off pain medication, able to walk without walking aids and able to walk around and outside the house without pain. This would take around 3 months. Long term recovery involves the complete healing of surgical wounds and internal soft tissues. When you are able to return to work and daily activities, you are on your way to achieving full term recovery. Another indication is when you finally feel normal again. Some OS considered their patients fully recovered when their current status has improved much beyond their arthritic pre-op pain level and dysfunction. This can take up to 3 to 6 months or even up to a year for some people.  Not everyone has the same rate of recovery or same experience in recovery for that matter.

TYPE AND DURABILITY OF IMPLANTS

There are many brands and types of implants but usually we do not have any option to choose.  Each hospital will carry their choice of implants but they will keep you informed about it and encourage you to read up about the product.  The implants are made of specially designed, high strength bio compatible metals and plastics.  The metal that is most commonly used is Cobalt-chromium alloy. The plastic cartilage is made of ultra-high-molecular-weight polyethylene plastic and the under surface of the kneecap may also be replaced with a round disc made of the same polyethylene plastic.  The components are attached to the bone with a specialised polymer commonly referred to as "bone cement' which consist of antibiotics to prevent infection.

In the past, most people believed that the implants would last about 10 years and that's why it was confined to older patients.  As the time passed, it became apparent that the great majority of knee implants would last approximately 20 years and even longer.  Improvements in surgical technique, material, implant designs and fixation have escalated over the past two decades resulting in increased durability of knee implants well beyond 20 years.  There are still active patients whose knee prosthesis were put in as long as 30 - 40 years ago.  However, as with any medical question, the longevity of a knee implant will vary from patient to patient, due to differing physical condition, activity and weight.  The skill of the surgeon in placing the implant is another important factor for longevity.  My OS was happy with the result of my x-ray post TKR as there were no gaps showing in the implants.  If there were gaps, then there is a high risk of loosening.  So it's important that we do a research to find an experienced OS who has performed lots of TKR with great success.

WILL I NEED A SECOND TKR?

Although it is anticipated that a TKR will last for many years, a small percentage may fail sooner than expected.  Revision TKR is the replacement of the previous failed prosthesis with a new prosthesis.  The reasons that cause failure of knee implants includes loosening, wear, infection, fracture, instability and patient related factors such as age, activity level, surgical history and weight.   Wear was always considered a primary problem but statistics show that wear on the plastic cartilage is less of a problem now because of the nature of the bearing which is flatter than in the hip joint which has very deep bearing that causes more wear problem.  

I asked my OS before that if the plastic cartilage deteriorated after many years, why can't I just have the plastic replaced instead of the whole implant?  Apparently, we can't do that because these implants comes in a set and they may be obsolete by the time we need a revision.  And newer generation of implants may be developed by then and their lifespan may be much longer.

A failed knee implant is usually indicated by an increase in pain or a decrease in knee function which may result in a limp, stiffness or instability.  Those who demonstrate these symptoms and signs may be a candidate for a revision.  Sometimes, we may not be able to feel anything so it's recommended that we take an x-ray once in a while to verify the condition of our implant.  And if there is any problem, early treatment would definitely be an advantage. 

Revisions may take longer to perform than the primary procedure because of the removal of the implant.  Also if there has been significant bone loss, then bone grafts may be necessary.  According to my OS, there is a limit of about  3 to 4 revisions because each time we do a TKR, they need to cut a little of the bone.  So beyond this limit, the joints would not be able to hold the prosthesis.  Of course, this would also depend on a lot of other factors including patient related factor.

More than 90% of patients who undergo revision TKR can expect to have good to excellent results. Of course, there will always be a small percentage of patients who may not have complete pain relief and restoration of function.

WHAT IS THE COST OF TKR?

This is a tough one to answer.  The cost of TKR would vary between countries and the type of hospitals.  But TKR can be done not only in private but also in general hospitals.  In private hospitals, the cost can be quite substantial.  In my home country, it may cost about RM20K + for one TKR in a private hospital.  But most medical insurance should cover the cost of such surgeries within the limit of the policy.  So you should check on the terms of your insurance policy  for confirmation.

CONCLUSION

While many people are enjoying better quality of life after TKR, there are many people still suffering out there either through a lack of awareness or other factors.  I realised that one of the main reason that prevent people from doing TKR is fear.  Fear of the surgery, risks, complications, pain, recovery etc.  Therefore,  I believe that if you have an adequate knowledge on TKR surgery, its success rate and a positive mindset, you may be able to gather the courage to make a change for yourself.  As a result of this change, you can look forward to a better quality of life.

Here are two videos showing TKR surgery.  For those faint-hearted ones, I suggest you watch the animated video just below which gives you a reasonable understanding of TKR.  As for the brave ones, go ahead and watch the second video on a real TKR surgery which is very enlightening.

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