Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Emergency assessment is needed for chest pain, sudden shortness of breath, coughing up blood, or a cold, pale, numb foot.
These symptoms are uncommon but may indicate a blood clot, circulation problem, or another condition requiring immediate care.
And for anyone, someone who:
Contact the treating clinician sooner if the knee repeatedly gives way, becomes locked, develops increasing swelling, or loses motion.
After surgery, prompt medical advice is appropriate for worsening wound redness, drainage, fever, new calf swelling, or pain that is not improving as expected.
Follow-up usually checks swelling, knee motion, walking, strength, and stability.
A physical therapist may repeat strength, balance, hopping, or movement tests as recovery progresses.
Keep scheduled visits even if pain improves, because strength and control can lag behind how the knee feels.
Long-term follow-up may include planning a safe return to work, exercise, or sport.
The plan should reflect the demands of the activity rather than using pain relief alone as proof that the knee is ready.
Every sign above is quoted from the sofidex article on Anterior cruciate ligament (ACL) injury. If you are not sure, err upward — it is always reasonable to be checked.