Adductor canal block for postoperative pain treatment after revision knee arthroplasty: a blinded, randomized, placebo-controlled study.
BACKGROUND
Revision knee arthroplasty is assumed to be even more painful than primary knee arthroplasty and predominantly performed in chronic pain patients, which challenges postoperative pain treatment. We hypothesized that the adductor canal block, effective for pain relief after primary total knee arthroplasty, may reduce pain during knee flexion (primary endpoint: at 4 h) compared with placebo after revision total knee arthroplasty. Secondary endpoints were pain at rest, morphine consumption and morphine-related side effects.


METHODS
We included patients scheduled for revision knee arthroplasty in general anesthesia into this blinded, placebo-controlled, randomized trial. Patients were allocated to an adductor canal block via a catheter with either ropivacaine or placebo; bolus of 0.75% ropivacaine/saline, followed by infusion of 0.2% ropivacaine/saline. Clinicaltrials.gov ID: NCT01191593.


RESULTS
We enrolled 36 patients, of which 30 were analyzed. Mean pain scores during knee flexion at 4 h (primary endpoint) were: 52 ± 22 versus 71 ± 25 mm (mean difference 19, 95% CI: 1 to 37, P = 0.04), ropivacaine and placebo group respectively. When calculated as area under the curve (1-8 h/7 h) pain scores were 55 ± 21 versus 69 ± 21 mm during knee flexion (P = 0.11) and 39 ± 18 versus 45 ± 23 mm at rest (P = 0.43), ropivacaine and placebo group respectively. Groups were similar regarding morphine consumption and morphine-related side effects (P > 0.05).


CONCLUSIONS
The only statistically significant difference found between groups was in the primary endpoint: pain during knee flexion at 4 h. However, due to a larger than anticipated dropout rate and heterogeneous study population, the study was underpowered.


BACKGROUND
Clinicaltrials.gov NCT01191593.
Department of Anaesthesia, Centre of Head and Orthopaedics, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
Pia
P
Jæger
Department of Anaesthesia, Centre of Head and Orthopaedics, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
Zbigniew J
ZJ
Koscielniak-Nielsen
Department of Orthopaedic Surgery, Centre of Head and Orthopaedics, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
Henrik M
HM
Schrøder
Section of Acute Pain Management, Department of Anaesthesia, Centre of Head and Orthopaedics, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
Ole
O
Mathiesen
Department of Anaesthesia, Centre of Head and Orthopaedics, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
Maria H
MH
Henningsen
Department of Anaesthesia, Aleris-Hamlet Hospitals, Copenhagen, Denmark.
Jørgen
J
Lund
Department of Anaesthesia, Aleris-Hamlet Hospitals, Copenhagen, Denmark.
Morten T
MT
Jenstrup
Department of Anaesthesia, Centre of Head and Orthopaedics, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
Jørgen B
JB
Dahl
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000577:Amides / Q000627:therapeutic use*; D016058:Analgesia, Patient-Controlled; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000627:therapeutic use; D000779:Anesthetics, Local / Q000627:therapeutic use*; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009020:Morphine / Q000008:administration & dosage / Q000627:therapeutic use; D009407:Nerve Block / Q000379:methods*; D010149:Postoperative Pain; D012086:Reoperation / Q000009:adverse effects; D000077212:Ropivacaine; D016896:Treatment Outcome
D000577:Amides; D000701:Analgesics, Opioid; D000779:Anesthetics, Local; D009020:Morphine; D000077212:Ropivacaine