Background : Currently, various techniques are used to overcome postoperative pain after total knee arthroplasty. A local analgesic infiltration with periarticular multimodal drug injection (PMDI) is favorable because of its simplicity, safety, and efficacy. The present study compared the efficacy of a PMDI at the anterior vs posterior compartments.

          Methods : Forty-six patients were randomized to receive the PMDI at either the anterior or posterior compartment with the contralateral knee receiving the PMDI at the opposite compartment. The PMDI injected to the posterior capsule, medial and lateral meniscal remnant, was defined as the posterior compartment injection, whereas the injection to the medial retinaculum, quadriceps muscle, pes anserinus, and retropatellar fat pad was defined as the anterior compartment injection. Pain scores at rest, knee flexion angle, quadriceps function, and drainage blood loss were evaluated in both groups.

          Results : The anterior PMDI group had significantly lower pain scores at rest during 96 hours postoperatively. On the day of discharge, 19 patients (41.3%) favored the knee with the anterior PMDI, which was superior to 9 patients (19.6%) who favored the knee with the posterior PMDI. The anterior PMDI demonstrated a superior recovery of quadriceps function during the same period, but there was no significant difference in terms of other parameters.

          Conclusion : The PMDI at the anterior compartment can reduce pain after total knee arthroplasty with potentially better quadriceps function compared with that in the PMDI at the posterior compartment. We recommend infiltrating the anterior compartment with a greater amount of PMDI than the posterior compartment.