A Prospective, Randomized, Double-Blind, Controlled Trial Comparing Liposomal Bupivacaine with Ropivacaine in Adductor Canal Block for Total Knee Arthroplasty Patients
Post-operative pain control for total knee arthroplasty (TKA) patients is of paramount importance to accelerate early rehabilitation and achieve patient satisfaction. Adductor canal nerve blocks (ACB) as single-shot injections and continuous infusions have gained popularity over the past several years as part of a multi-modal analgesia protocol. Recently, the usage of liposomal bupivacaine (LB) has continued to grow in both intra-articular injections and as nerve blocks (off label use in nerve blocks). To date, no previous study has compared ropivacaine with LB in ACB for TKA.
Materials and methods
The study proposal was approved by our institutional review board and registered at clinicaltrials.gov (ID number: NCT02607579). Patient informed consent was obtained and all patient protected health information has been de-identified.
A prospective, randomized, double-blind, controlled trial was performed on patients undergoing primary TKA. Two hundred consecutive patients were screened and randomized to either an ACB with ropivacaine (20 ml of 0.5%) or LB (10ml of 1.3%). The block was performed immediately after surgery. All patients received a peri-articular infiltration of LB, bupivacaine, and saline mixture by the operative surgeon before the tourniquet was deflated. The primary outcome measure was mean pain scores over the first three post-operative days. Additional outcomes included pain scores q4 hours, length of hospital stay, distance walked during physical therapy, maximum knee flexion, and breakthrough opioid use.
One hundred and ninety-two patients met study criteria and were randomized to receive either LB (n=97) or ropivacaine (n = 95). The mean post-operative VAS pain score on day 0-1 (0-24h) was not statistically significant between groups (3.62 vs 3.72, p=0.7356 ANOVA). The mean post-operative VAS pain score over days1 -3 was statistically lower with LB versus ropivacaine (3.41 vs 4.23, p=0.0052 ANOVA ).
Opioid use was lower with LB vs ropivacaine: 19.13 vs 23.67, p = 0.020 (T-test). Distance walked and knee flexion was greater with LB vs ropivacaine, but statistically significant only on day 2 (157ft vs. 132ft, p=0.0187, t-test; 96 degrees vs. 91 degrees, p=0.0174, t-test, respectively). There was no significant difference in LOS between groups.
Total knee replacement is associated with moderate-to-severe post-operative pain. Therefore a multi-modal pain regimen is important to decrease pain and increase initial post-operative mobility. Clinical trials have shown that when used in local infiltration, LB provided a longer duration of pain relief without altering wound healing.1 A recent study by Mont et al. demonstrated that LB significantly reduced pain and opioid use when used as infiltration compared with bupivacaine in TKA.2 To our knowledge, there are no published studies comparing LB to ropivacaine in ACB for patients undergoing TKA.
Our study showed that compared to ropivacaine, LB administered via an ACB decreases overall pain scores with the maximal effect observed 24-68 hours post-operatively. In addition, ambulation distance and knee flexion was greater during the same time period in the LB group. Patients receiving LB required fewer opioids for breakthrough pain than those receiving ropivacaine.
We found ACB with LB enhanced our patients’ recovery after TKA to a greater extent than ACB with ropivacaine alone .
More recently we have been adding 10ml of 0.25% bupivacaine to the 10 ml of LB and have noticed a faster onset with a similar duration
1. Baxter R, Bramlett K, Onel E, Daniels S: Impact of local administration of liposome bupivacaine for postsurgical analgesia on wound healing: A review of data from ten prospective, controlled clinical studies.Clinical Therapeutics2013;35.
2. Mont MA, Beaver WB, Dysart SH, Barrington JW, Del Gaizo DJ: Local infiltraton analgesia with liposomal bupivacaine improves pain scores and reduces opioid use after total knee arthroplasty: results of a randomized controlled trial. J Arthroplasty. 2017:1-7. Doi:10.1016/j.arth.2017.07.024.