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Knee anatomy

The knee is a complex joint, as opposed to the hip which encloses the upper thigh in the pelvis.

The complexity of the joint lies in the fact that two flat surfaces, the thigh and the tibia, must have flexion and rotation in order to serve the needs of walking.

This is achieved with the ligaments, inside and out sideways, the cruciate ligaments and menisci which, in addition to balancing the weight of the body on the tibia, move back and forth when walking

Both the hip and the knee are the two main joints of walking.

During simple walking, the hip receives loads of about 180 kg in each step, the same accepts the knee.

Overweight people put even more weight on the hip and knee, which is equivalent to four times the extra weight.

That is, a person who weighs 100 kg while it should be 80, the difference of 20 kg is multiplied by x 4 to give us the extra load of the knee and hip when walking

Arthritis

The smooth movement of the joints is due to the cartilage that covers the movement surface.

The production of synovial fluid also helps in the lubrication and the better movement of the joint.

Over the years, the articular cartilage is subject to wear and tear, with the result that the movement of the joint is not so smooth and there is pain when walking.

Visually, the knee changes axis and many times the presence of synovial fluid creates swelling.

Joint fluid is normally present in the joint but when there is pain, the body tries to produce more, believing that better lubrication of the joint will reduce the pain.

However, as the knee swells, the internal tension increases, which in turn increases the pain, as the pain increases the body produces even more fluid and the joint enters a vicious cycle of pain and increased synovial fluid production.

This is called a water article (or  fluid in the knee ).

The clinical picture of an arthritic knee depends on how high the arthritic burden is.

In the early stages there is a little pain at the beginning of the movement which reappears after fatigue.

Over the years the knee gets worse, it bends and there is a noticeable abnormality in the movement of the bend and the extension.

When the axis of the knee is significantly deformed, then there is instability when walking, especially when one tries to go down a ladder.

So far we have talked about the typical osteoarthritis which is due to aging.

In rheumatic diseases, such as rheumatoid arthritis, the damage does not start from the cartilage but from the soft molecules (tissues) of the joint, with the result that the cartilage is eventually destroyed.

Rheumatism is a common disease of the collagen and usually affects many joints.

The final treatment of a deformed joint is the same as in osteoarthritis, ie total arthroplasty.

But before we get there, the patient must be monitored by a rheumatologist and get the right medication to slow the disease.

Surgery indications

When we operate.

The international criteria for knee arthroplasty surgery is pain and inability to walk more than 200,300 meters. Also gait instability needs immediate treatment.

The diagnosis of the disease is easy with the clinical examination.

We observe the axis of the knee, the range of motion, the instability and the crease during the bending and extension.

Simple x-rays of the knees in an upright position are sufficient.

Magnetic resonance imaging is rarely necessary.

If it does, it will most likely show a meniscus rupture, in addition to the degenerative lesions of the knee.

It is a mistake at an age when we normally do knee arthroplasty to do arthroscopy and correction of the menisci, as the main problem is the arthritis of the knee and not the damage of the menisci that is a product of arthritis.

The smart knee, our choice, gives excellent results and allows us to operate at the age of less than 60, with the certainty that the implant will have longevity.

Types of arthroplasty

Many years ago, we believed that a hinge-type mechanism was enough to place a damaged knee joint to restore movement.

But the knee is a complex joint that does not only bend and stretch.

Old hinge arthroplasties, except in very special cases, are no longer used.

Grafts have prevailed where only the damaged surface of the knee is changed.

We usually change the entire surface of the knee except in a few cases where only the inner side is changed with semi-arthroplasty (or partial).

The latter is only 6% of all total arthroplasty and has very limited indications.

In Greece, patients come to the doctor very late, since the whole joint has been destroyed.

Superficial or modern arthroplasty.

The operation consists of removing the worn surface of the joint polygonally, with special guides.

We cover it with a metal case that moves on a "plastic" meniscus.

The knee is aligned and walking is painless.

Many have gone to the dentist and put a case in an unrepairable tooth.

This is the best analogy for, how it works and what a knee arthroplasty is.

Placing the prosthesis in the classic way can give great results, but many patients complain of pain when walking.

It is due to the inaccurate placement of the implant on the axis of rotation of the knee.

Robotic techniques solve this problem, although many doctors claim that in the classical way, they weigh the knee movement better.

All the years we operated in the classic way, the knee weighing can be done wonderfully with the new techniques and we would definitely not go back.