JOINT REPLACEMENT SURGERY – GETTING IT RIGHT

I’ve had knee pain since quite some time. Initially the pain was mild. It used to disappear for months after taking a few pills and doing some exercises. Slowly the pain increased and I had to take a pill every day. However I was still able to do everything I enjoyed like a long walk or a vacation or a family wedding. Now things have become much worse. My legs have become crooked. The pain killers work for a couple of hours at best. The docs say if I continue popping pain killers at this rate my kidney will break down. I cannot walk and have started to gain weight. Just the other day I visited my ortho and he said I need joint replacement surgery. O God, I’m scared. I don’t want surgery. What If something goes wrong? Neetu didi had got one done a few years back and she isn’t even walking anymore. I’d rather bear the pain and forget about surgery.

This is the situation many of us find ourselves in. Are we justified in our fear for surgery and are we better of accepting our handicap and living with it? The answer is NO. Today there is a very good chance that you can have a successful outcome from joint replacement surgery. With these few very logical tips you can maximize your chances of becoming independent and pain free.

Choosing your surgeon

This is the most important decision. For the right outcome the surgery needs to be done correctly. Joint replacement is a technically demanding surgery that requires a deep understanding, good surgical skill and lots of experience. There is a definite learning curve involved. So how do you choose the right guy? Your best chance is with a specialist. A surgeon doing 300 joint replacements a year is much more likely to get it right than one doing only 25. The other thing to look for is his reputation. A good reputation cannot be faked. One can earn it only by doing good work. Try to look for people operated by the surgeon and speak to them regarding their experience. Often you can get this list from the surgeon himself. This goes a long way in building your confidence.

You may come across an occasional patient that had a complication or bad experience. But you have to be statistically intelligent in judging that. It is stupid to drop a surgeon because one out of his 1000 cases went bad. You will never find a perfect surgeon. A good surgeon is enough.

Choosing the hospital

Generally one would leave that to the surgeon. But a patient should be aware that infection can ruin joint replacement surgeries. These surgeries should preferably be carried out in theatres with super aseptic conditions, laminar airflow and Hepa filters. Theatre condition and discipline is the most important determining factor for choosing the right hospital.

Choosing your joint

 Today information is at your fingertips. Newer prosthetic designs are flooding the market. Some promise better function, others better longevity and yet others both. Many of these designs are based on solid research and are really beneficial. However an equal number are marketing gimmicks to promote sales. One has to realize that joint replacement is a major industry and many a times new research is market based. The internet is an advertising platform. Like in any advertisement, information is blown up and full of half truths. Again your surgeon will come to your rescue. He is usually in the best position to help you make a decision. He knows the other side of the coin.

Your surgeon may have a preference for a particular joint. His preference will more often than not be in your best interest. Familiarity with a system is important to ensure the best result.  Forcing your surgeon to use a system he is not comfortable with may lead to a less than optimum result.

Having realistic expectations

This is probably the most important variable affecting the result of surgery. Don’t live in wonderland. You are not going to hop and skip and run around like a 14 year old after your joint replacement. The surgery will eliminate your pain and allow you to walk normally. But it is an artificial joint and will feel like one. Patients describe it in different ways but the underlying sentiment that the new joint doesn’t “feel normal” is constant. Having said that it is still worth getting it done because of the drastic improvement in function achieved after surgery. 

 

 With this better understanding, you can safely opt for joint replacement and become mobile and pain free again. Fear usually stems from ignorance. Once you learn about the surgery, hear from others experiences and understand the benefits and the risks involved, you will wonder why you didn’t opt for it earlier.    

A scary phase in total knee arthroplasty

Total knee arthroplasty(TKA) has revolutionized the care of patients with knee pain. This is one surgery that has given excellent results and has proved to be a boon for the arthritic knee.

Even so, TKA has its problems -

• By nature a prosthesis has a fixed life. One day it is going to fail. Just as a new car becomes old and starts breaking down, similarly a TKA prosthesis will give way in time. Much of the current research is concentrating on improving the life of the artificial joint.
  



• The second problem is that of reproducing the normal knee movements. The normal knee is a complicated joint with sliding, gliding and rotation occurring between the two surfaces as the knee bends. It is difficult for an artificial joint to mimic these movements. Hence an artificial joint is unable to flex (bend) as much. Knee bending is important especially in India for cultural and social reasons. Driven by this patient demand, there is much pressure to make designs which allow more bending (high flexion).

There are many new advances being made in this field. Many of these are truly beneficial, others still to be proved and a few of them are quite useless. Lets review some of these.

1. Unicondylar knee arthroplasty - Here only one compartment of the joint is replaced (usually the medial). The proposed advantages are that the minimal damage is done to the knee, the other 2 compartments are preserved, no ligaments are cut, surgery can be done in a minimally invasive way, revision to a total knee at a later date is easy. The good news is that the results of the unicondylar knee have come in and many centres are showing over 90% survival for 15 years. The bad news is that only a few patients qualify for this surgery (approx 7% of total patients needing surgery for knee arthritis). This surgery has disastrous results in improperly selected patients (beware of the over enthusiastic surgeon). Another thing the surgeon will not tell you is that a high tibial osteotomy, which is a simpler and cheaper procedure, works just as well. Further revision to a total knee has been cited by many authors to be difficult, disproving an earlier claim.
   



2. Minimally invasive surgery (MIS) - There is a lot of interest and media hype about minimally invasive surgery. Unicondylar knees are usually done the MIS way. TKA is also being done with MIS with or without the help of computer navigation. MIS basically means to do the same surgery through a smaller incision with lesser trauma to tissues. Well this concept sounds very appealing, doesn't it ? MIS surgery does allow faster rehabilitation, but the results are the same at the end of 3 - 4 months. Further, because access is not as good as the routine incision, some surgeons have reported errors in making the bone cuts and therefore in the position of the final implants. MIS is not as big an advance as it is being promoted. The advantage gained is not worth it if it is at the cost of implant alignment. I feel a properly aligned routine TKA would work just as well.
   



3. Computer assisted surgery (CAS) - Does computer navigation improve TKA results? The only thing that has been proved, is that it improves coronal alignment. Whether this translates into better longevity of the joint is still to be proved. CAS is as good as the operating surgeon. The surgeon needs to feed the computer information about the patients body parameters. He does this by placing probes at fixed points which transmit information to the computer via infra red rays (referencing). Using this information the computer creates a virtual model of the patient's knee. Over here lies the problem. There are a lot of errors in referencing. If wrong information is fed to the computer, wrong information is going to come out. Garbage in is garbage out. And yes, let me make it clear, the computer is not doing the surgery. To summarise, CAS is here to stay and will be indispensable in the future, but today it is of doubtful benefit in routine cases. However it is very useful in complicated cases, like those with deformities.
   



4. High Flex Knee - This is one of the new knees that have come into the market. As the name suggests it promises a greater degree of bending of the knee by virtue of its design. But post operative knee flexion depends on many things such as the preop range of motion, the type of arthritis, the weight of the patient etc. Some patients will get flexion and some will not, no matter what implant. So all that this implant does is give those patients who were anyways destined to get good flexion, some more flexion. Even this is doubtful as many reports have come in that the results are the same, high flex or no high flex. Besides there is a real concern that this design may actually accelerate prosthesis damage by increasing stresses.
   



5. The rotating platform Knee - This is another attempt to reproduce normal knee movements. By virtue of its design this knee allows some rotation that usually takes place in the normal knee. The proposed advantages are more knee bending and less prosthesis ware and a longer prosthesis life. Unfortunately most reports of long term follow up show no difference in either knee function or prosthesis life.

To conclude there are many attractive & new things happening in knee arthroplasty. A lot of people out there are trying to sell you something new claiming it to be better. But new is not always better. The routine TKA is still the gold standard and it has been proved time and over. This is a very scary phase in TKA surgery and I warn the patient/consumer to do their homework thoroughly before deciding to go ahead with a new and fashionable surgery.

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Prosthetic disc replacement ....is it for you ?

There is a lot of talk nowadays about prosthetic disc replacement (PDR) for low back pain. Should all patients with back pain get their discs replaced ? Is it the new ultimate therapy for back pain ?

PDR is another wonderful advance in the treatment of low back pain. Here the patient's diseased disc is replaced by a prosthetic one, much like a total knee replacement. Chronic low back pain is a big and difficult problem, frustrating for both, the doctor and the patient. In this depressing scenario, the results of PDR look promising. Unfortunately only a few patients would qualify for disc replacement. This is because there are multiple causes for low back pain. Pain could arise from the discs, the facet joints, the ligamentum flavum, etc. Obviously a disc replacement is useless for pain arising from facet arthropathy.

What, then are the indications for disc replacement ?
Disc replacement is advocated in ...

1. Patients with severe & disabling pain with degenerative disc disease who have failed at least 6 months of non operative treatment. (anti-inflammatory and analgesic medication, physiotherapy, injections, acupuncture, bed-rest, back school training) with

2. Objective evidence of disc disease in the form of x rays and MRI with

3. A positive provocative discography as confirmation (preferable)

4. In patients between 18 to 60 years of age.
   

Disc replacement is not for ...

1. Patients with facet arthropathy.

2. Patients with osteoporosis.

3. Patients with spinal deformities and instabilities (spondylolisthesis, post op instability)

4. Patients with morbid obesity.

5. Patients with disc bulges that significantly compress the spinal cord & nerve roots causing leg pain and weakness.

6. Patients with infection.

7. Patients with failed back syndrome and epidural fibrosis.
   

As is obvious, PDR is useful for a limited population of patients. In fact only 5% of of patients qualifying for lumbar spine surgery meet the criteria for disc replacement.

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Bone mineral density

Early diagnosis and treatment of osteoporosis can reduce fracture risk. RadiologyInfo has an excellent page on bone densitometry and DEXA scans for osteoporosis. A dexa scan is currently the gold standard for measuring bone mineral density (BMD). There is growing interest in quantitative ultrasound as an alternative, but it still needs to go a long way to prove itself. Other less widely used techniques are peripheral quantitative computed tomography, quantitative magnetic resonance (QMR) and magnetic resonance microscopy.

The WHO recommendations for who to test for BMD are
for women -

1. In postmenopausal women if there is x ray evidence of demineralisation, evidence of vertebral fracture/deformity or if steroid therapy for more than 3 months is contemplated.

2. In all postmenopausal women above 65 years of age.

3. In postmenopausal women below 65 years of age if they have risk factors like maternal history of fragility fractures, low body weight or medical conditions associated with bone loss like premature menopause, hyperparathyroidism, hyperthyroidism, chronic renal failure, chronic liver disease, malabsorption or use of anti convulsants.

4. In premenopausal women who have medical conditions associated with bone loss listed above.

5. In healthy premenopausal women, BMD testing is not indicated.

for men -

1. BMD testing is definitely indicated in the presence of vertebral deformity, fragility fracture, hypogonadism or chronic steroid therapy.

2. BMD is less definitely indicated in case of alcohol abuse, low weight, x ray evidence of demineralisation or medical conditions associated with bone loss listed above.

3. BMD testing is not recommended for healthy men with no risk factors.

BMD testing is not for everyone. Consider getting it done only if you fall in one of the above categories. Potential harms of DEXA are radiation and cost. Bone mineral density should be measured only to assist in making a clinical management choice.

Besides DEXA quality matters. BMD measurement is not a simple procedure & errors can lead to therapeutic decisions that can harm patients.

BMD measurements have today become essential for fracture prevention and osteoporosis treatment, but due care is needed in utilising this asset.

computer assisted surgery in orthopaedics ?

Computer navigation or computer assisted surgery (CAS) is the major new thing in orthopaedics.

What is computer navigation or CAS ?

As the name suggests, the surgeon uses the computer to help him in surgery. This is done with the help of sensors which are placed at specific points on the part to be operated. For eg. the knee. These sensors send information via infra red rays to the computer. With this information the computer reconstructs a visual of the patients anatomic part. On the visual, the computer guides the surgeon on how much to cut the bone? at what angle? where to place the implant? etc.

What are the advantages of computer navigation ?

With CAS, the accuracy of the surgery increases. For example, in a total knee replacement, the accuracy of the placements of the components is better with CAS.
CAS also enables the surgeon to perform the same surgery through a smaller incision (minimally invasive surgery)

Are there any disadvantages ?

Though accuracy is better with CAS, whether this translates into better functional results or improves long term survival of the joint (in cases of joint replacement) is still to be proved.
Besides the technique requires expensive instrumentation and has a learning curve. CAS usually increases surgery time.

I cannot afford computer navigation, is my surgery doomed ?

CAS is still in its infancy. An experienced surgeon will achieve acceptable accuracy with conventional instrumentation. CAS today is an option not a necessity.

When is CAS most useful ?

It is especially useful in cases of bony deformities, retained hardware or when convential instrumentation cannot be used to gain proper alignment.

CAS is useful in which orthopaedic surgeries ?

It is most useful and currently used in total or unicondylar knee arthroplasty & hip arthroplasty. Surgeons have started using it to guide placement of pedicular screws in spine surgery. It is becoming popular in fracture care

If you have any further questions on CAS, send them to me at orthindia@gmail.com