A cruciate ligament tear is not a medical emergency. Although the injury is a serious one, the early mangement is relatively uncomplicated:
If pain and swelling are not too bad
If the skin is not damaged in the injury, and pain and swelling are not too severe, most clinicians will recommend the RICE (or PRICE) regime for the first few days of almost any knee injury, ie Protection, Rest, Icing, Compression, Elevation.
If pain and swelling are severe
If the pain and swelling are severe, then it is possible that there is tense blood within the knee cavity (haemarthrosis) and a visit to the Accident & Emergency unit is recommended. The doctor there may chose to aspirate the blood (suck it out with a syringe and needle), a procedure that can give considerable relief.
When the knee is painful and swollen it is difficult for any doctor to fully examine and evaluate the knee. Once the injury has settled down, maybe after a week or so, then it is much easier to examine. Most surgeons will not operate anyway when the knee is still inflamed.