Please tell me, could a knee injury cause swollen groin lymph nodes?

Ask your pcp: Isoltated knee injuries ( acl tear, meniscus tear, kneecap dislocations etc.)are not associated w/ inflamed inguinal lymph nodes in my experience.Infections in or around the knee could result in larger inguinal nodes but if u are concerned see your pcp for full evaluation. Best of luck!

Monitoring Centers: Lymphatic system absorbs/carries things too big to go into the arteries/veins like bacteria eaten by white cells and digested food. Lymph nodes "taste" the lymph for anything bad like bacteria/viruses/cancers, etc. When it detects a problem, it alerts the immune system and your body reacts. They enlarge in response to the inflammation they create when they react. They shrink when all is well.