Trial to Compare Femoral Nerve Block With Local Anaesthetic Injection for Post-operative Pain After Knee Replacement.

Summary

Pain after a knee replacement can impair recovery and use of the new knee. Having an injection to numb the femoral nerve is known to give good pain relief after the operation but may lead to slower mobilisation as it also prevents the patient from moving the knee. Recent studies have shown that infiltration of local anaesthetic (LIA) within the new knee joint may also give good pain relief. The null hypothesis is that there is no difference in primary or secondary outcome measures between femoral nerve block and LIA, as anaesthetic techniques for knee replacement.

Conditions

• Arthritis Knee

Interventions

PROCEDURE

Femoral nerve block

Supine position If using peripheral nerve stimulator for localisation of the femoral nerve: 50 mm insulated needle Peripheral nerve stimulator set at 2 Hz with pulse width 100μs When quadriceps muscle twitch is present with a stimulated current between 0.2 and 0.5mA, inject 20ml 0.375% (3.75mg/ml) Levo- bupivacaine If using ultrasound for localisation of the femoral nerve: High frequency linear array probe Short bevelled nerve-block needle, using in or out of plane technique Inject 20ml 0.375% (3.75mg/ml) Levo-bupivacaine underneath fascia iliaca ensuring adequate spread of local anaesthetic

PROCEDURE

Local Infiltration Analgesia

Local infiltration analgesia to be administered by surgeon towards the end of operation: 40ml of bupivacaine 0.25% with adrenaline 1:200 000, diluted to 150ml with saline 0.9%. This is then divided into thirds; 50ml into the posterior capsule before cementing, 50ml into the medial and lateral capsules and 50ml into subcutaneous tissues and in and around the vastus medialis and sartorius muscles (where it may block the saphenous nerve).

PROCEDURE

Sub arachnoid analgesia

Patients in both arms of the trial will be given sub arachnoid anasthesia of 2.5-3.0ml of plain bupivacaine 0.5% using a 25G Whitacre needle. Patients may have 0-4mg midazolam and/or 0-1mcg/kg fentanyl and/or 0-4mcg/ml propofol sedation using the Marsh protocol if required for this procedure as deemed appropriate by the anaesthetist.

PROCEDURE

Sedation or general anaesthesia

After insertion of the sub arachnoid anaesthesia the patient may choose to be fully asleep or sedated. If they choose to be fully asleep, they may have up to 2mcg/kg fentanyl in total (including any given at time of subarachnoid injection), muscle relaxation as indicated for facilitation of intubation where needed, airway control using LMA or tracheal tube where needed, and general anaesthesia maintained using inspired oxygen concentration of 0.3-0.7 with propofol up to 5mcg/kg (Marsh protocol) or isoflurane or sevoflurane. If the patient chooses to have sedation they may have additional midazolam up to a total dose of 4mg and/or a propofol infusion (Marsh protocol) of 0-4mcg/ml.

DRUG

Pre-medication

All patients will receive 1g paracetamol pre-operatively. Those on non steroidal anti inflammatory drugs may continue to take them. Apart from these, no other pain relieving pre-medications are to be used. Patients may be given anxiolysis using temazepam 10-20mg or diazepam 2-5mg by mouth if required. Antacid premedication is permitted using ranitidine, metoclopramide or proton pump inhibitors.

DRUG

Intra-operative medication

If paracetamol has not been given pre-operatively, it will be given intraoperatively 1g IV. Where 2 or more of the following risk factors are present; female, non smoker, previous post operative nausea or vomiting, intra operative opiates, the patients will be given 4mg dexamethasone and or 4mg ondansetron IV. Vasopressor drugs may be given at the anaesthetist's discretion to maintain an appropriate blood pressure. Intraoperative fluid infusion is at the discretion of the anaesthetist. Antibiotic prophylaxis is as per the hospital protocol (currently 6mg/kg Teicoplanin IV and 3mg/kg gentamicin pre induction). Tranexamic acid will be given as per unit protocol, (currently 1g pre-operatively IV and 500mg orally at 8 hours post op. unless contraindicated by a high risk of thrombosis.)

DRUG

Post-operative analgesia - morphine

Patients will all be given a morphine pump which will give 1mg every 5 minutes. This is to be discontinued after 48 hours and changed to oral morphine 10-20mg if weight 50-70kg, 20-30mg if weight \>70kg 2 hourly.

DRUG

Post-operative analgesia - ibuprofen and paracetamol

All patients will be given 1g paracetamol 6 hourly and 400mg ibuprofen 8 hourly unless there are contraindications. If patients are on an alternative non-steroidal anti inflammatory drug then this may be substituted for ibuprofen.

DRUG

Regular anti emetics

All patients will receive 4mg ondansetron regularly for 2 days. They will be prescribed 50mg cyclizine as an addition to this if needed.

Sponsors & Collaborators

• Royal Devon and Exeter NHS Foundation Trust

  lead OTHER

Principal Investigators

• Fiona Martin, MBCHB · Royal Devon and Exeter NHS Foundation Trust

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

SINGLE

Model

PARALLEL

Eligibility

Min Age

19 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2015-03-31

Primary Completion

2018-07-01

Completion

2018-07-01

Countries

• United Kingdom

Study Locations