Local infiltration anesthesia in total knee arthroplasty

Total Knee Arthroplasty (TKA) is associated with moderate to severe
postoperative pain. This causes discomfort in mobilization and hospital
discharge is extended. Severe postoperative pain is traditionally treated by
(high doses of) opiates and NSAIDs but the side effects are numerous.
Postoperative nausea and vomiting (PONV) are notorious and generate discomfort
for the patient and extra costs by the need of anti-emetic drugs, longer
hospital stay and nursing care.
Past decade, local infiltration analgesia (LIA) is more and more applied as
part of a multimodal pain management strategy in TKA and seems to have a lot of
benefits. Less pain might results in early mobilisation, less consummation of
opiates and a reduced hospital stay. The optimal dose and way of local
infiltration and of perioperative consummated pain medication are not known. In
the rapid recovery tract in TKA in our hospital an effective combination of
150ml ropivacain infiltration perioperative, 600 mg gabapentin preoperative
and 300 mg gabapentin at day one postoperative are used. These high doses of
ropivacain and gabapentin might cause multiple side effects (headache, nausea,
vomiting, dizziness and sedation). Therefore, we would like to study the
influence of reducing the amount of ropivacain perioperative and gabapentin
pre- and postoperative on pain and side effects. This way, doses of both
medications might be optimized.

Optimizing the amount of ropivacain and gabapentin, used for local infiltration
(LIA) during TKA procedures by measuring the outcomes of pain (by using the 100
mm Visual Analogue Scale (VAS)), adverse effects, length of hospital stay,
cumulative pain medication consumption.

This study is a randomised controlled double blind trial, comparing the
outcomes in patients with TKA and LIA.
Patients with unilateral gonarthrosis who qualify for a TKA will be randomly
divided into four groups;
A. Current protocol: 150 ml ropivacain/epinephrine and 600/300/300 mg
gabapentin pre-operation, 8h after operation and the morning after the
operation.
B. 75 ml ropivacain/epinephrine and 600/300/300 mg gabapentin.
C. 150 ml ropivacain/epinephrine and 300/100/100 mg gabapentin.
D. 75 ml ropivacain/epinephrine and 300/100/100 mg gabapentin.

Local infiltration analgesia (LIA) during TKA procedures.
Perioperative patients will be infiltrated and given painmedication in randomly
divided four doses;
A. Current protocol: 150 ml ropivacain/epinephrine and 600/300/300 mg
gabapentin pre-operation, 8h after operation and the morning after the
operation.
B. 75 ml ropivacain/epinephrine and 600/300/300 mg gabapentin.
C. 150 ml ropivacain/epinephrine and 300/100/100 mg gabapentin.
D. 75 ml ropivacain/epinephrine and 300/100/100 mg gabapentin.

Patients will receive their planned TKA. There will be three more clinical
control moments to measure the VAS and adverse effects in comparison to normal
TKA-patients.: one hour after operation, during and immediatly after first
mobilisation.Patients from all groups will receive their planned TKA. There
will be no extra control moments when compared to TKA patient not participating
in the study. Patients in the lower dosed groups can have more pain when
compared to the patients in the higher dosed groups. All patients will receive
rescue medication when standard pain medication is insufficient. There will be
no extra control moments after discharge when compared to normal TKA-patients.