Joint pain is a primary symptom in knee osteoarthritis (OA), but the effect of pain and pain relief on the knee joint mechanics of walking is not clear. In this study, the effects of local knee joint analgesia on knee joint loads during walking were studied in a group of knee osteoarthritis patients. A group of healthy subjects was included as a reference group. The joint loads were calculated from standard gait analysis data obtained with standardised walking speed (4 km/h). The gait analyses were performed before and after pain relief by intra-articular injections of 10 mL lidocaine (1%). Pre-injection measurements revealed lower joint loads in the OA group compared to the reference group. Following injections pain during walking decreased significantly and the joint loads increased in the OA group during the late single support phase to a level comparable to the reference group. Although the patients walked with less compressive knee joint forces compared to the reference group, the effects of pain relief may accelerate the degenerative changes.