My knee popped in the back of the knee now i am having a hard time straightening or bending the knee would this indicate a meniscus tear?

Knee pop/ locked: Could be.Likely at 51 it was frayed before the final tear. Would consider an MRI as that is the only way to tell for sure. Treatment could be a simple as PT, occasional brace unless it does not resolve. F/u/ w/ MD

Possibly: That is always a possibility. But it can be other areas of the knee. The best way to evaluate this is a physical exam and possible MRI depending on what is found on the exam.