Is Recurring Injury To The Same Knee Causing Swelling And Bruising A Cause For Concern?

I keep reinjuring my knee playing sports, always the same knee (left) always swells and bruises. It is becoming difficult to put weight on it, even after the bruises have healed. It is noticeable that my right knee is stronger and can take more weight. Should I be concerned about this, or just take it easy for awhile?