RESUMEN
BACKGROUND: A combined regimen of adductor canal block (ACB) and multimodal periarticular infiltration (MPI) with local anesthetic (ropivacaine) is a known effective method of controlling pain in the first 6-8 h after total knee arthroplasty (TKA); however, managing breakthrough pain after their combined effect wears off can be challenging. We hypothesized that, by additionally leaving an intra-articular epidural catheter (IAEC) inside the knee with intermittent infiltration of local anesthetic in conjunction with ACB and MPI, it would help manage the breakthrough pain when their combined effect wears off. METHODS: We did a prospective study in our institution between December 2015 and August 2016 on a total of 206 patients undergoing primary unilateral TKA. The initial consecutive 106 patients received ACB + MPI (Group 1, n = 106), and the subsequent 100 patients received ACB + MPI + IAEC (Group 2, n = 100). The primary outcome measure was pain using visual analogue scale (VAS) recorded at 6, 12, 24 and 48 h, and the secondary outcome measures were requirement for rescue analgesics and repeat adductor canal block and length of hospital stay. RESULTS: There was no statistically significant difference in VAS scores between the two groups at 6 h but at 12, 24 and 48 h; there was a statistically significant difference between the two groups in terms of VAS scores, rescue analgesic requirements, repeat adductor canal block and shorter hospital stay favoring the ACB + MPI + IAEC group. CONCLUSION: Intermittent knee infiltration with ropivacaine is a safe, reproducible and effective method to control pain in the first 48 h postoperative period after TKA.