Does Pain Around Knee Cap Indicate Osteoarthritis?

Hi Doctor I am from Kerala : Male,45yrs,172c.m, 98Kg ( B.M.I - 33.1 ) - yesterday I was holding a bucket full of water few minutes. After 2-3 hours I felt pain on my Left KNEE ( Pain / discomfort on front knee ) - Pain is mild type only - While climbing staircase is also feel pain - But no pain while sitting. Pain is around KNEE CAP . I used to work in standing position in front of computer for 45 - 60 minutes continuously 2 -3 times daily.
Is it osteo arthritis ?