Step 4: Read and complete the decision guide to learn more about your symptoms.
To recap, you are older than 45, no other joints are bothering you besides the sore knee, and there is swelling in the sore knee.
There's just one more question in this guide and it deals with "mechanical symptoms," such as locking or giving way. When present, these symptoms raise the possibility of torn cartilage or an injured ligament.
This question has two parts:
1) Do you have locking of the knee? That is, are there times, even briefly, when you cannot move your knee at all?
2) Are there times when your knee will not support you?