Minimally invasive surgery did not improve outcome compared to conventional surgery following unicompartmental knee arthroplasty using local infiltration analgesia

BACKGROUND AND PURPOSE There has recently been interest in the advantages of minimally invasive surgery (MIS) over conventional surgery, and on local infiltration analgesia (LIA) during knee arthroplasty. In this randomized controlled trial, we investigated whether MIS would result in earlier home-readiness and reduced postoperative pain compared to conventional unicompartmental knee arthroplasty (UKA) where both groups received LIA. PATIENTS AND METHODS 40 patients scheduled for UKA were randomized to a MIS group or a conventional surgery (CON) group. Both groups received LIA with a mixture of ropivacaine, ketorolac, and epinephrine given intra- and postoperatively. The primary endpoint was home-readiness (time to fulfillment of discharge criteria). The patients were followed for 6 months. RESULTS We found no statistically significant difference in home-readiness between the MIS group (median (range) 24 (21-71) hours) and the CON group (24 (21-46) hours). No statistically significant differences between the groups were found in the secondary endpoints pain intensity, morphine consumption, knee function, hospital stay, patient satisfaction, Oxford knee score, and EQ-5D. The side effects were also similar in the two groups, except for a higher incidence of nausea on the second postoperative day in the MIS group. INTERPRETATION Minimally invasive surgery did not improve outcome after unicompartmental knee arthroplasty compared to conventional surgery, when both groups received local infiltration analgesia. The surgical approach (MIS or conventional surgery) should be selected according to the surgeon's preferences and local hospital policies. ClinicalTrials.gov. (Identifier NCT00991445).