I never heard of such a thing....what is the injection?
Here is a link about CCL tears:
Yorkie Haven Rescue - Cranial Cruciate Ligament Tear Info
I strongly encourage you to have your pup seen by a board certified orthopedic surgeon with experience in luxating patellas and cruciate ligament tears. Your pup will develop severe arthritis if this injury is not repaired surgically. There is no other fix for this painful injury!
If money is an issue, you can apply for credit here:
Healthcare and Medical Financing for Consumers | CareCredit™
Good luck!