Evident from a randomized blinded study, motor-sparing blocks of knee with long-term analgesic effects present better outcomes as compared to intraoperative standard periarticular infiltration in patients underwent TKA. Pain following total knee arthroplasty (TKA) is serious and can inhibit rehabilitation. Motor-sparing analgesic techniques such as periarticular infiltrations and adductor canal blocks have been popularized for knee analgesia since they conserve motor strength and permit early mobilization.

The study was randomized 82 patients scheduled for elective TKA. Patients received either the preoperative motor-sparing block (0.5% ropivacaine, 10 mg of morphine, 2.5 μg/mL of epinephrine, and 30 mg of ketorolac) or intraoperative periarticular infiltration (0.3% ropivacaine, 10 mg of morphine, 2.5 μg/mL of epinephrine, and 30 mg of ketorolac). Reform the ultrasound-guided adductor canal block by collaborating it with a lateral femoral cutaneous nerve block and posterior knee infiltration for the motor-sparing block. The patients, surgeons, anaesthetists control the blocks, and outcome reviewer all remained blinded to group allocation. The main conclusion was the duration of analgesia (time to first rescue analgesia). Secondary outcomes included quadriceps strength, function, side effects, satisfaction, and length of hospital stay.

The duration of analgesia was consequently prolonged (mean differentiation, 8.8 hours [95% confidence interval = 3.98 to 13.62], p < 0.01) for the motor-sparing-block section (mean [and standard deviation], 18.1 ± 1.7 hours) differentiate with the periarticular infiltration group (mean, 9.25 ± 1.7 hours). The infiltration group had consequently higher scores for pain at rest for the first two postoperative hours and pain with knee movement at 2 and 4 hours. There were no significant differences between groups about any other secondary outcomes. Undergoing a TKA, patients had a motor-sparing block produce longer analgesia than periarticular infiltration with retention of quadriceps muscle strength, patient satisfaction, function, and a short hospital stay.