我的半月板及十字un帶受傷

急証室睇醫生will only write a letter to refer you to orthopaedic outpatient clinic. They will not admit you to hospital in general.
Your scenario is very common. "young people have knee injury, private MRI done and not have enough money for private surgery which is around 100K. You can ask your private doctor to write you a letter and refer you to any orthopaedic clinic of Public hospital for treatment.
If the referral letter clearly write down ACL injury and meniscus injury, you will receive early appointment.
Nowadays, ACL reconstruction is considered to be common orthopaedic operation, don't be too worry!
Best wishes!
If have further question about your condition or problems in getting an early appointment, you can ask me for some advice.

未必～因為好多時都要排期排好奈～