Preventing Injured Knees From osteoArthritis: Severity Outcomes

Inclusion Criteria: 1. Age 25-45 or Age 18-24 with preoperative KOOS Pain \<80 (0-100, 100 best) recorded at least 14 days after the day of ACL injury 2. Plan to undergo ACL reconstruction within 12 months of injury Exclusion Criteria: 1. Inflammatory arthritis 2. Pregnancy and/or lactation, or plans to become pregnant in the next 12 months 3. Known contraindication to metformin 4. Current use of metformin or topiramate 5. Diabetes mellitus or diabetic ketoacidosis 6. Acute or chronic renal insufficiency 7. History of prior ACL tear on the index knee, with or without reconstruction 8. History of ACL tear on the contralateral knee within the past 12 months 9. Applying for or receiving Workers' Compensation for their knee injury 10. Joint space narrowing AND definite osteophyte(s) on weightbearing radiograph on index knee 11. Tibial plateau fracture on index knee 12. Concomitant avulsion fracture of index knee that will be treated surgically 13. Concomitant posterior cruciate ligament, medial collateral ligament, or lateral collateral ligament injury on index knee requiring surgical repair/reconstruction 14. Contraindication to MRI 15. Unable to speak and understand English 16. Diagnosis of cognitive impairment or otherwise unable to provide informed consent 17. Insufficient time for recruitment and drug titration: Surgery scheduled for \<14 days from the time of screening 18. Date of injury more than 6-months ago, relative to date of screening 19. Presence of a condition or abnormality that in the opinion of the surgeon investigator would compromise the safety of the patient or the quality of the data 20. Plan for allograft at time of consent