Preoperative ultrasound-guided infiltration analgesia (US-LIA) with liposomal bupivacaine (Exparel, Pacira) is a safe, effective technique that reduces recovery times and hospital lengths of stay for total knee arthroplasty (TKA) patients, a new study suggests.
“In our institution, patients who have total knee arthroplasty receive an ultrasound-guided local infiltration analgesia,” said Sanjay Sinha, MD, study author and an anesthesiologist at Connecticut Joint Replacement Institute, in Hartford. “This is performed by the anesthesiologist in the block area preoperatively before the patients go into the OR [operating room].”
The researchers said there are no documented safety data for this technique, so they conducted a retrospective analysis to determine the incidence of wound infections and complications (e.g., deep vein thrombosis and urinary retention), compared with patients receiving continuous femoral and selective tibial nerve block. Other measures included postoperative pain scores and opioid use, and the time it took patients to bear weight and walk and be discharged from the hospital.
The study included 1,536 patients who underwent primary unilateral TKA at the institution from April 2014 to December 2015. Patients were separated into two groups: study (n=1,189) and control (n=347). Patients in the study group received a short-acting femoral nerve block with 10 mL of mepivacaine 1% followed by US-LIA with an admixture of 20 mL of liposomal bupivacaine 1.3%, 45 mL of bupivacaine 0.25% and 10 mL of saline. Patients in the control group received a continuous femoral and a single-shot tibial nerve block with a combined total of 25 mL of ropivacaine 0.5% followed by a 48-hour infusion of ropivacaine 0.2% at 6 mL per hour.
“The infiltration technique is performed with ultrasound guidance, and from a conceptual point of view, you can think of it as a ring block that is performed above the knee. It includes iPACK (infiltration between the popliteal artery and capsule of the knee) for controlling pain in the posterior aspect of the knee. And on the anterior and medial side, we infiltrate the muscles in a ringlike fashion to cover the tissues from the bone all the way to the subcutaneous tissue,” Dr. Sinha said. “There is sparing on the lateral aspect because we don’t want to infiltrate close to the common peroneal nerve.”
All patients underwent general anesthesia for surgery and a standardized rehabilitation protocol. Oral oxycodone or intravenous hydromorphone was given for postoperative breakthrough pain. The patients were discharged at the discretion of their treating surgeon and received a 90-day follow-up phone call.
The researchers found that there was no difference in the incidence of wound infections or other complications in the two groups (Table). Patients in the US-LIA group had higher initial post-op opioid consumption and pain scores but reported lower pain scores after 48 hours.
Table. Incidence of Complications
|Complication||Study Group||Incidence Rate in Study Group, %||Control Group||Incidence Rate in Control Group, %||PValue|
DVT, deep vein thrombosis; NS, not significant; UTI, urinary tract infection
“Patients who received the femoral catheter had superior pain control in the first 24 hours or so after surgery. But in that 18- to 24-hour window, the pain in the infiltration group crossed over, and then for the rest of the hospital stay was lower compared to the femoral catheter group,” Dr. Sinha said (Figure).
Figure. Patient pain scores.
The researchers also found that patients in the study group were able to bear weight and walk earlier (16.5 vs. 28.5 hours) and had greater flexion and extension at the time of discharge. Patients in the study group also had shorter hospital lengths of stay (2.6±0.56 days) compared with the control group (3.1±0.37 days).
“Our conclusion is the local infiltration performed by an anesthesiologist preoperatively is a safe technique,” Dr. Sinha said. “[It] doesn’t increase the risk for wound infections and complications, and provides efficacious pain control in these patients.”
The findings were presented at the American Society of Regional Anesthesia and Pain Medicine’s 2016 annual Regional Anesthesiology and Acute Pain Medicine meeting (abstract 1657).