99 patients scheduled for shoulder arthroplasty due to shoulder osteoarthritis were randomized to receive local infiltration analgesia with ropivacaine, ketoprofen, and epinephrine, or an interscalene nerve block. The primary outcome of interest was shoulder pain at rest. Secondary outcomes included opioid consumption, subjective shoulder value (SSV), Constant score, severity of pain, duration of hospital stay and operation time. The only significant differences observed between groups were lower pain at rest severity and opioid consumption in the LIA group compared to the ISB group within the recovery room. Otherwise, there were no significant differences in pain at rest or opioid consumption up to 72 hours post-operation between the two groups. Both groups displayed significant improvements in pain severity, SSV and Constant score at 1 month compared to baseline. There were no significant differences in duration of hospital stay or operation time between the two groups.