Effect of Pregabaline and S-Ketamine on knee function after total knee arthroplasty.

Background:

TKA often produces severe postoperative pain. Reduction of pain is an important factor in the early rehabilitation of these patients. There is some evidence, that the addition of pregabalin and s-ketamine may not only reduce the acute postoperative pain, but also the incidence of chronic postoperative pain in these patients. Some studies also show that the intra-articular injection of corticosteroids may be beneficial and even shorten the hospital stay. Lately, there are randomized, controlled studies showing that intra and peri-articular infiltration with local anesthetics, after TKA, due to its simplicity and low complication risk, may be a good alternative to different loco-regional techniques such as femoral block and epidural analgesia.



Methods:

This study is a prospective, randomized, double blind, controlled evaluation of two methods of analgesia after TKA. The patients will be operated under spinal anesthesia. The intra- and peri-articular local anaesthetic infiltration with ropivacaine/adrenaline/kenacort®, will be given ( during the operation) to the study group, with the addition of pregabalin and s-ketamine in the first postoperative days. In the control group, the same local anesthetic knee infiltration will be performed during the surgery. Only, instead of pregabalin per os, the control group is getting placebo and instead of s-ketamine normal saline infusion.
For the process of randomization computer generated random numbers will be used. Our research question is:
Can the addition of s-ketamine and pregabalin reduce the acute pain and enhance the range of motion in the early postoperative period after TKA? The secondary goal is to determine if the edition of s-ketamine and pregabalin can reduce the incidence of chronic pain after TKA and improve the long term functional results?

The goal of this study is to determine whether we can achieve any functional benefits by addition of pregabaline and s-ketamine to local intra-articular analgesia (LIA).

Our primary research question is: Can the addition of s-ketamine and pregabaline to LIA reduce the acute pain and enhance the range of motion in the early postoperative period after TKA?

The secondary goal is to determine if the edition of s-ketamine and pregabaline to LIA can reduce the incidence of chronic pain after TKA and improve the long term functional results.

1. Day of surgery;

2. The first five postoperative days;

3. Day of discharge;

4. 6 weeks after TKA;

5. 3 months after TKA;

6. 1 year after TKA.

In the study group, 150 mg of pregabalin will be given per os with premedication. It will be continued, twice a day during the first three postoperative days. The dose will be reduced to 75 mg two times a day in elderly patients. The control group will get placebo.



At the beginning of the surgery, the study group will also receive an intravenous bolus of 5-10 mg S-ketamine. This will be followed by a 24 hours continuous infusion, at the rate of 5-10 mg/hour (dose reduction for elderly).The control group will get normal saline infusion instead.