The purpose of this study is to compare two methods of pain control used during total knee
joint replacement surgery. The pain medication that will be used for this study is not
The investigators will compare the single shot femoral nerve block (SSFNB) and Femoral Nerve
Block (FNB) plus continuous femoral nerve catheter (CFNC) to determine which method gives
patients better pain control, increasing the capability to participate in physical therapy
and decreasing the consumption of other pain medication. With either the single shot or the
catheter the local numbing medication called ropivacaine will be used.
The study will be a randomized controlled blinded study with a sham control arm. The
patients will be randomized to either a single shot FNB with placement of a catheter on the
skin (sham control) or a conventional CFNC with catheter.
The group with SSFNB will receive a femoral nerve block before the surgery in the
pre-operative area guided by a nerve stimulator and ultrasound. A bolus of 0.5 % ropivacaine
will be injected around the femoral nerve. A catheter would be placed on the skin, without
penetration, with occlusive dressing applied over the site. A standard size saline bag will
be placed on the pump but will not be turned on. The tubing will be opaque and a bag will be
placed over the pump to blind the patient to the medication, or lack of medication, being
administered. The patient, nursing staff and physical therapists will be blinded to the
presence of a sham catheter. The infusion will be labelled 'Study Drug R' or 'Study Drug N'
in the electronic medicine prescription.
The group randomized with active drug by CFNB would have a continuous femoral catheter
placed using nerve stimulator and ultrasound. Catheter will be bolused with 0.5 %
ropivacaine around the femoral nerve and occlusive dressing applied over the catheter.
After placement of the femoral nerve block patients will be transported to the operating
room and spinal anesthesia with bupivacaine and fentanyl will be performed. Intra-operative
sedation of propofol infusion will be titrated to the discretion of the anaesthesia team.
Patients will receive scheduled as well as rescue analgesia as per clinical pathway
Patients with CFNB will receive ropivacaine 0.2% infusion (the infusion rate will be
dependent on the clinical judgement of the anaesthesiologist) in the post anaesthesia care
unit (PACU) after the spinal anaesthesia has worn off. The infusion will be continued for
the duration of the catheter, 4am POD one. Patients with SSFNB will not receive any infusion
through the sham catheter.
The catheters will be removed on post-operative day (POD) one at about 8 am. Patient's pain
score using visual analogue score (VAS) will be assessed. Functional status will be assessed
by the physical therapist on POD one. The therapist will assess and document the distance
walked, assistive device used, level of assist needed to ambulate, and knee proprioception
or continued recommendation of the knee immobilizer.
Patients will be assessed in the PACU and POD 1 and 2. Recordings will be made of total
opioid consumption in morphine equivalents, VAS score from 0-10 both at rest and on
participation in physical therapy, incidence of nausea and vomiting and functional status
during physical therapy.
- Adults (18-80 years old)
- Scheduled to undergo primary unilateral TKA with Parapatellar approach
- Patient agrees to participate in the study
- Effective femoral nerve block
- No contraindication for spinal or regional anesthesia
- History of opioid dependence or current chronic analgesic therapy (daily use >4 weeks
- Allergy to study medications
- Known hepatic or renal insufficiency/disease
- Peripheral neuropathy
- Morbid obesity (BMI >40 kg/m2)
- Unable to comply with study protocol