The purpose of the study was to find out the extent of pain relief after giving mobilization to the joint, as well as the extent of range of motion at osteoarthritis knee joint. It also aimed to find out the significant changes in the girth after the conventional treatment and after mobilization given to the joint. A brief survey of the literature is also made to know the status of the research on the range of motion, pain and girth changes with respect to osteoarthritis knee joint. In the research design, data was collected, using a random sample of 11 male osteoarthritis patients and 19 female osteoarthritis patients, age 40–60 years. Based on the periodical assessments starting from 0 day, 5th day and 10th day treatment, two studies namely—conventional group and experimental group were compared. In the experimental study the conventional treatments (Ultrasonic therapy, TENS and active knee exercise) and knee joint complex mobilization were included. The variables related to the range of motion, pain and girth were analyzed using a 2 (control/experimental) × 3 (pretreatment, day 5, day 10) repeated measures analysis of variance (ANOVA). The study explored that the range of motion increased in both the groups significantly, though comparatively the experimental group was more significant. In case of pain, it significantly decreased in both the groups, though comparatively the pain in the experimental group was decreased more, in comparison to the conventional group. In case of girth, it was investigated that there was no significant improvement in the girth of thigh in both the groups. The study finally suggested that that for more better results, the sample size as well as the duration of the treatment for both the group need to be increased.