Comparison of femoral nerve block with posterior capsule infiltration versus anterior and posterior capsule infiltration after total knee replacement.

Total knee arthroplasty (TKA) is a surgical procedure to replace the knee
joint. In the Netherlands over 20.000 TKAs were effectuated in 2010. The most
common indication for a TKA is arthrosis but other indications include
posttraumatic disorders, osteonecrosis, malignancy, disabling pain or severe
movement restriction.(1)
Pain after TKA is usually severe, difficult to manage, and insufficient
pain relief may delay recovery. Postoperative pain management after TKA is
often multimodal and includes oral analgetics, intravenous (i.v.) opioids,
peripheral nerve blocks or epidural analgesia. These treatments are associated
with side effects, such as nausea, sedation, hypotension, partial motor block
and urinary retention. Local infiltration analgesia with ropivacaine is an
alternative treatment with good functional recovery.(2,3)
Femoral nerve blocks(FNB) are presently the gold standard for an effective
analgesia approach in TKA.(4,5) FNB should be supplemented with oral opioids.
Another option for additional therapy is a posterior capsule infiltration. (6)
Recent studies on application of local anesthetics into the knee have shown
that this approach has several advantages compared to other regional or purely
systemic approaches.
In a blinded study (Bianconi et al. 2003)2, 37 patients were randomized
to receive intraoperative infiltration with ropivacaine or placebo. Intensity
of postoperative pain, consumption of rescue analgesics, and length of hospital
stay were significantly reduced in the group that received ropivacaine. Open
studies have shown similar results. (Rasmussen et al 2004(6), Isaac et al.
2005(7)) Another study compared local infiltration analgesia with a continuous
femoral nerve block (Toftdahl et al. 2007)3 Pain scores during physiotherapy
and postoperative were significantly better in the local infiltration analgesia
group.
A preoperative single shot femoral nerve block(SFNB) is the standard care
for analgesia after TKA in the St. Lucas Andreas Hospital and many other
hospitals. Although a SNFB gives a satisfied analgesia, the mobilization can be
limited by (partial) motor block. Hence, the present study aims to compare two
treatments for TKA analgesia: a new treatment with anterior- and posterior
capsule infiltration (LIA) and the standard treatment including a single shot
femoral nerve block (SFNB) with posterior capsule infiltration. Postoperative
mobilization and pain will be measured every day. Moreover, the quality of
analgesia will be assessed by consumption of opioid and with VAS score for
pain. Secondary outcome measures will be adverse effects of oral and/or i.v.
analgesics, length of stay and satisfaction.
REFERENCES
1. De Waal MC, Gaasbeek RDA, Koëter S, et al. Richtlijn totale
knieprothese(concept). Nederlandse Orthopaedische Vereniging 2014.
2. Bianconi M, Ferraro L, Traina G C, Zanoli G, Antonelli T, Guberti A, Ricci
R, Massari L, Pharmacokinetics and efficacy of ropivacaine continuous wound
instillation after joint replacement surgery. Br J Anaesth 2003; 91(6): 830-5
3. Toftdahl K, et al. Comparison of peri- and intraarticular analgesia with
femoral nerve
block after total knee arthroplasty. Acta Orthopaedica 2007; 78(2): 172-9.
4. Chan EY, Fransen M, Parker DA, Assam PN, Chua N. Femoral nerve blocks for
acute postoperative pain after knee replacement surgery (Review). The Cochrane
Library 2014, Issue 5.
5. Bauer MCR, Pogatzki EM, Zahn PK. Regional analgesia techniques for total
knee replacement. Curr Opin Anesthesiol 2014, 27:501-506
6. Rasmussen S, Kramhoft M U, Sperling K P, Pedersen J H. Increased flexion and
reduced hospital stay with continous intraarticular morphine and ropivacaine
after primary total knee replacement: open intervention study of efficacy and
safety in 154 patients. Acta Orthop Scand 2004; 75 (5): 606-9
7. Isaac D, Falode T, Liu P, I*Anson H, Dillow K, Gill P. Accelerated
rehabilitation after total knee replacement. Knee 2005; 12 (5); 346-50.

This prospective randomized controlled trial designed to compare the quality of
analgesia offered by SFNB and LIA and their effects on morphine consumption,
mobilization and pain control postoperatively. Our first hypothesis concerning
opioid use is a significantly reduced opioid use in the SFNB group. Secondly,
we hypothesize that with respect to the mobilization there is no significant
difference between SFNB en LIA group. The outcome of this study may lead to a
future modification of the protocol in pain relief for TKA in the St. Lucas
Andreas Hospital.

This prospective randomized controlled trial compares the SFNB group with the
LIA group. The SFNB group gets a femoral nerve block with ropivacaine 0.375%
and 75 microgram clonidine, and furthermore recieves 50 cc ropivacaine 0.2%
with epinephrine 1:100.000 in the posterior part of the capsule. The LIA group
recieves local infiltration with 50 cc ropivacaine 0.2% in the anterior capsule
and 50 cc ropivacaine 0.2% in the posterior capsule. And the third injection in
the subcutis with 50 cc ropivacaine 0.2% without epinephrine to prevent tissue
necrosis. Patients meeting the inclusion criteria will receive information
about the study and informed consent letters at the anesthesiology outpatients
department. The eligible patients receive a call a week after visiting the
outpatients department to obtain permission. Informed consent documents will
be signed before surgery by the patient and the investigator/anesthesiologist.
Patients will be randomized just before the surgery to the SFNB or LIA group
(see flowchart).
All patients will receive the same pain medication post operatively:
acetominophen 1000 mg QID and naproxen BID, and a single dose of intravenous
metamizol 1000 mg (dipyrone) . Moreover all patients receive a patient
controlled analgesia pump with morfine. Every morning at 10.00 am the
painconsulent and/or the researcher will note how much morphine is consumed. At
the post-anesthesia care unit (PACU) the patients were instructed that no pain
and worst possible pain equal to 0 and 10, respectively, on the visual analog
scale (VAS). This VAS score is measured at the PACU until day 3 after surgery,
and is noted by the patient in their patient journal during rest, flexion
exercises and during walking. Side effects like nausea, vomiting, drowsiness,
pruritus, paresthesia (day 1 to 3) and obstipation (at discharge) are
registered by the patient in their patient journal as well as by the clinician
in the medical file in EPIC.
A total of 90 patients will be included by interviewing them at the time of
intake and asking informed consent. Power calculations showed that 80 patients
are needed to show a difference in opioid consumption.

Patients in the SFNB group will get a femoral nerve block with ropivacaine
0,375% and 75 microgram clonidine, and furthermore will recieve 50cc
ropivacaine 0,2% with epinephrine 1:100.000 in the posterior part of the
capsule. The LIA group will receive 3 local infiltrations: 50cc ropivacaine
0,2% in the anterior capsule and 50cc ropivacaine 0,2% in the posterior
capsule, and the third injection in the subcutis with 50cc ropivacaine 0,2%
without epinephrine to prevent tissue necrosis. Ropivacaine is a local
anestheticum which is favorable considering its low cardiovascular and
neurologic toxicity comparing to bupivacaine. Moreover it has less motor
blokkade compared to bupivacaine.

Contribution of patients will take approximately 1 hour of their time for
filling in the patient diary. Patients will receive similar treatment as
patients who are not included in the study.