This study looks at using a special treatment called concentrated bone marrow aspirate (**cBMA**), a type of regenerative medicine, during revision ACL (anterior cruciate ligament) surgery. ACL reconstruction is a common knee surgery but sometimes needs to be redone if it fails. The study wants to see if cBMA can help reduce pain and inflammation, which might prevent the knee from getting worse over time with post-traumatic osteoarthritis (**PTOA**). cBMA contains special cells that might help the knee heal better. Participants will be divided into two groups: one will get cBMA during surgery, and the other will get a pretend treatment for comparison. The study will check how patients feel, look at their knee movements, and take samples of blood and joint fluid to learn about cBMA effects for up to two years.
- Study lasts up to two years with periodic check-ups.
- Participants will be randomly assigned to cBMA treatment or a placebo group.
- Only adults aged 18-55 who had previous ACL surgery can join.