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Knee Replacement Surgery FAQs

Dr Jayateerth W Kulkarni

10. How is thrombosis prevented?
Clotting of blood in leg veins can cause swelling and pain in the leg. This is prevented by the use of medications and using mechanical devices like stockings, foot pumps, etc. Other measures to prevent thrombosis include epidural anesthesia, proper hydration during surgery, and early mobilization of the patient. Treatment of thrombosis and embolism involves using blood thinning medications and, very rarely, surgery.

12. Is there a possibility of stiffness following surgery?

Stiffness occurs in patients who have a poor range of mobility before surgery, and in those who do not adhere to the physiotherapy and exercise regimen.
Treatment for stiffness is by physiotherapy or manipulation under anesthesia.
It should be understood that a standard total knee implant cannot give the full range of movements. It is designed to give 95-120 degree of flexion. Newer designs (high flexion knees) can restore near-normal motion in carefully selected patients.

13. Could there be a persistent pain following the surgery?

Persistent pain following surgery could be due to a problem related to the knee itself, like a tight knee or overhanging implant. It may also be due to other problems like spondylosis, diabetic neuropathy or poor circulation in the leg. A thorough assessment is required to determine and treat the cause.

14.How long does the implant last?

Over a period of time, the plastic articulations slowly wear out. The rate of wear is very low and the implant generally lasts around 15 years. Excessive stress like obesity and high impact activities will lead to early wear.
The fixation of the implant to bone can become loose as a result of mechanical forces or as a reaction to plastic wear debris. A variable amount of bone gets resorbed in the process. Wear and aseptic loosening require revision knee replacement.

15. What is the age at which knee replacement is usually done?

Most of the patients are above the age of 60 years. The advanced age does not preclude surgery in most patients. Management of medical problems and epidural anesthesia make this surgery safer.
Joint replacement has also proved successful in younger patients. Young patients with crippling arthritis (which is not amenable to other modes of treatment) can be treated by replacement. This dramatically improves their personal, occupational and psychosocial outlook. These patients will require a revision at a later date. This situation is more common in the hip than the knee joint.

16. What is a Hi-Flex knee replacement?

A standard knee replacement allows 95-120 degrees of flexion. A Hi-Flex knee replacement prosthetic allows more flexion (up to 150 degrees), which even allows the patient to sit on the floor.
The surgical procedure is identical to standard knee replacement. Proper selection of patients is important in ensuring good outcomes after this type of knee replacement. A high flexion implant may not be very beneficial in patients who have a stiff knee to begin with.

17. What is unicompartmental knee replacement?

In some patients only one half of the knee is affected by arthritis, usually the inner half. Replacing only the diseased half of the knee is sufficient to treat this condition. The operation is called unicompartmental knee replacement.
This surgery is done through a smaller incision, and the recovery is relatively faster. The knee function after surgery is also better.
However, the selection of patients for unicompartmental knee replacement has to be very strict. Any arthritis affecting the other side of the knee and knee cap will give rise to pain after surgery. This procedure is not applicable for inflammatory types of arthritis.

18. What is minimally invasive knee replacement surgery?

The usual approach to knee replacement involves splitting the quadriceps muscle in the middle and retracting the kneecap to one side.
Minimally invasive knee replacement is done using an incision that splits a smaller portion of the muscle. This permits a faster recovery, and is generally done for slim patients with good flexibility in the knee. It is difficult to perform this kind of surgery in obese patients and in those who have stiff knees. The procedure requires special instruments. Computer navigation is used to improve the accuracy of the procedure.

19. What is computer navigated replacement?

The instruments and techniques employed in a knee replacement operation are very precise and allow a very accurate procedure to be performed. However, certain landmarks - especially the center of the hip - cannot be determined precisely with these instruments.
Surgical navigation systems utilize an array of cameras, bone markers and a computer to generate a virtual 3-dimensional model of the bones. This is then used to guide the placement of implants.
This improves the accuracy of the procedure, and is especially useful for minimally invasive knee replacement and for pre-existing deformity in the bones of the lower limb.
Dr Jayateerth W Kulkarni is Senior Consultant Orthopedic Surgeon, Apollo Hospitals, Bangalore.


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