Pain Treatment After TKA With LIA and Intra-articular Continuous Infusion Pump

Evaluation of Intra-articular Continuous Infusion Pump With Ropivacaine in Addition to Local Infiltration Analgesia (LIA) in Total Knee Arthroplasty (TKA). A Placebo Controlled Randomised Trial.

The purpose of this study is to evaluate the effect on postoperative pain and function by adding intraarticular continuous infusion pump with local anesthetic after total knee arthroplasty where local infiltration analgesia has already been given.

200 patients with osteoarthritis (OA) of the knee necessitating total knee arthroplasty are entered into the study. All patients are given a standard protocol of analgesics pre- and postoperatively. All patients get periarticular LIA-injection (150 ml) with a total of 300 mg Ropivacaine, 30 mg Toradol and 0.5 mg Adrenalin. In the end of the operation all patients get an epidural type of catheter intraarticular with a coupled continuous infusion pump that delivers 2 ml per hour and are disconnected after 48 hours. The University hospital pharmacy has prepared 200 pumps; 100 Active substance pumps with 100 ml Ropivacaine (10mg/ml) and 100 placebo pumps with 100 ml sodium chloride (NaCl). All patients are by computer software randomized to receive either active or placebo pump. Only one nurse, not involved in neither the operation nor the after treatment, has the key to what substance it is in the numbered pumps. Thus, it is a double blinded trial during the whole follow up period. Before the operation the patients are asked to fill out a knee specific outcome questionnaire, the Knee injury and Osteoarthritis Outcome Score (KOOS), and a general outcome questionnaire, the Euroqol (EQ-5D), and the knee range of motion is measured by a physiotherapist. After the operation the patients are monitored at the ward by the nurses and physiotherapists. The level of pain is measured twice daily (noon and 8 PM) according to the Visual-Analog-Scale (VAS). The range of motion and is measured on day 4 and at the day 14 and day 30 follow up. The number of days the patients need to stay in hospital after operation are registered. The amount of extra doses of analgesics the patient requires are registered as well as the complications (illness, wound problems, infections etc). The patients are to be followed clinically for 2 years as well as with outcome questionnaires.

The intra-articular Continuous Infusion Pump is filled with Ropivacaine,10 mg/ml, set at 2 ml/hour for 48 hours postoperatively.

The intra-articular Continuous Infusion Pump is filled with NaCl, set at 2 ml/hour for 48 hours postoperatively.

The patient are asked to grade their pain on a VAS-scale (0-100)twice daily for the first 4 days after the TKA operation and at the 2 weeks follow-up. Changes in pain during this time frame are recorded to see if there are any differences between the two groups.

All extra analgesia consumption are noted during the first 4 postoperative days. All patients have a standard pain management medication (depending on weight, age and sex) and only extra doses are noted.

The range of motion in the affected knee are registered with a goniometer at the preoperative admission for operation, about 2 weeks prior to the operation and then on day 4, 14 and 30 postoperatively.

The patients are asked to fill out the general health questionaire EQ-5D as well as the knee specific questionaire KOOS preoperatively at the admission for surgery (about 2 weeks before the operation) and at 1 and 2 year follow up.

Inclusion Criteria: Primary osteoarthritis of the knee necessitating total knee replacement Patients who understand the conditions of the study and are willing to participate for the length of the prescribed follow-up Exclusion Criteria: Known allergy to local anaesthetics or other contraindication for the use of local anaesthetics. Treatment with Warfarin. Bilateral operation