ACL Reconstruction

ACL reconstruction replaces a torn anterior cruciate ligament with a tendon graft, restoring stability to a knee that gives way. It is one of the most studied operations in orthopedics, and the research now answers many of the questions patients ask: who needs surgery and who can do well with rehabilitation alone, which graft to use, when an added lateral procedure lowers the risk of re-tear, and how long to wait before returning to sport. This page summarizes that evidence. For the injury itself, including symptoms and diagnosis, see our ACL injury page.

Do you need ACL reconstruction?

The answer depends on your knee and your goals. Randomized trials have compared early reconstruction with an initial course of rehabilitation (with surgery later if the knee stays unstable):

• In the KANON trial of young active adults, the two strategies produced similar patient-reported outcomes at 2, 5 and 11 years, and about half of the rehabilitation group never needed reconstruction.
• In the Dutch COMPARE trial, early reconstruction gave slightly better scores at 2 years, though the difference was not clinically meaningful, and half of the rehabilitation group went on to have surgery.
• In the UK ACL SNNAP trial of patients with ongoing instability months after injury, reconstruction gave better knee scores than continued rehabilitation.
• An MRI follow-up from KANON found signs of ACL healing in about a third of patients assigned to rehabilitation, which was associated with better outcomes.

In practice, reconstruction is generally recommended if your knee gives way in daily life or sport, if you plan to return to cutting, pivoting or jumping sports, if you have a repairable meniscus tear, or if you have other ligament injuries. Patients with lower demands, or who prefer to try rehabilitation first, can often do well without surgery. A delay to try rehabilitation does not appear to harm outcomes in adults, but repeated giving-way episodes can damage the meniscus and cartilage.

Graft choices

The graft becomes your new ACL. Each option has trade-offs:

• Bone–patellar tendon–bone (BTB) autograft: bone-to-bone healing and a slightly lower graft rupture rate in large registry and meta-analysis data, with more kneeling pain and front-of-knee discomfort.
• Hamstring tendon autograft: smaller incision and less kneeling pain; a meta-analysis of over 47,000 reconstructions found graft rupture rates were low and nearly identical (about 2.8%) to BTB, with a statistically small difference.
• Quadriceps tendon autograft: meta-analyses report graft survival and function comparable to BTB and hamstring grafts, with less harvest-site pain.
• Allograft (donor tissue): avoids a harvest site and can suit older or lower-demand patients and revision or multi-ligament surgery. In young athletes autograft is generally preferred, and irradiated allografts have shown poorer stability than autografts.

Dr. Dold chooses the graft with you based on your age, sport, anatomy, prior surgery and preferences.

Lateral extra-articular tenodesis (LET) and anterolateral procedures

Some knees have extra rotational looseness (a high-grade pivot shift). In the STABILITY trial of 618 patients aged 14 to 25 at high risk of failure, adding a lateral extra-articular tenodesis to a hamstring ACL reconstruction reduced graft rupture from 11% to 4% at two years, with slightly more pain in the first few months. Meta-analyses support considering LET or anterolateral ligament reconstruction for high-risk patients, such as young athletes in pivoting sports, those with generalized ligament laxity, high-grade pivot shift, or revision surgery. One long-term trial of an older LET technique raised a possible increase in lateral compartment arthritis, so the procedure is used selectively.

ACL repair and newer techniques

Repairing the patient’s own torn ACL instead of replacing it has been revisited for certain tears close to the bone. A systematic review found reconstruction had better survival than repair across available studies. The bridge-enhanced ACL repair (BEAR) technique showed results comparable to reconstruction at two years in one randomized trial; longer-term data are still being gathered. Dr. Dold can discuss whether your tear pattern makes you a candidate.

Risk of re-tear and who is at higher risk

A meta-analysis found an overall second ACL injury rate of about 15% (either knee), rising to about 23% in athletes under 25 who return to sport. In one large series, the highest graft rupture rate (about 28%) was in males under 18. A large meta-analysis of risk factors identified younger age, return to high-level sport, higher activity level, increased posterior tibial slope, high-grade knee laxity and family history as factors associated with revision or re-rupture. These are the patients in whom graft choice, LET and careful return-to-sport testing matter most.

Recovery and rehabilitation

ACL reconstruction is usually an outpatient procedure. Rehabilitation guidelines recommend a prehabilitation phase before surgery to restore motion and reduce swelling, followed by criterion-based phases after surgery:

• Weeks 0–6: full extension, swelling control, quadriceps activation, weight-bearing as tolerated in most cases
• Months 2–4: strength and balance, stationary bike, progression toward running when criteria are met
• Months 4–9: running, agility, jumping and sport-specific training
• About 9 months or later: return to cutting and pivoting sport after passing strength and hop testing

Blood flow restriction training has been shown in randomized trials and reviews to help preserve muscle and improve strength after ACL reconstruction. If you also had a meniscus repair, early bending and weight-bearing may be limited. See our meniscus repair page.

Return to sport: timing and testing

In the Delaware-Oslo cohort, the re-injury rate fell by 51% for each month return to sport was delayed up to 9 months after surgery, and patients who failed objective return-to-sport criteria had much higher re-injury rates. In professional athletes, not meeting all discharge criteria before returning to team training was associated with a fourfold higher graft rupture risk. Across studies, about 81% of patients return to some sport, 65% to their pre-injury level, and 55% to competitive sport. Fear of re-injury is a common reason people do not return, so psychological readiness is part of the plan.

Long-term outlook and arthritis

An ACL tear increases the long-term risk of knee arthritis, which is present in roughly a third of reconstructed knees over the long term. Pooled data show reconstruction does not by itself prevent arthritis compared with non-surgical care; meniscus damage is a major driver, and removing the meniscus at the time of ACL surgery is strongly associated with later arthritis. Protecting the meniscus, by repairing it when possible and preventing repeated giving-way, is a central goal.

Children and teenagers

In growing children, reviews have found that non-operative care of complete ACL tears is associated with more meniscus and cartilage damage, while surgical stabilization gives good stability and function. Physeal-sparing and transphyseal techniques are both used, with a low overall rate of growth disturbance (about 2.6% in one review). Re-tear is a larger concern than growth disturbance in this age group.

Preventing ACL injuries

Neuromuscular injury-prevention programs that include plyometric exercises reduced ACL injury risk by about 60% in a meta-analysis of cluster randomized trials. Female athletes have roughly 1.5 times the risk of male athletes in adolescent sports. Prevention training is also recommended after reconstruction to protect both knees.

Watch Dr. Dold: ACL reconstruction

Some of these videos show real surgery, so some viewers may prefer not to watch.

More videos on Dr. Dold’s YouTube channel.

What patients say

Patient reviews in their own words. Individual results vary. Read more patient reviews.

Why see Dr. Dold

Dr. Dold is a fellowship-trained orthopedic sports medicine surgeon who has cared for athletes at every level, from youth and high school to professional sports. He bases each ACL plan on your goals and your risk profile, including whether surgery is needed, which graft fits you, whether an added lateral procedure is warranted, and objective testing before return to sport. Read more in our ACL surgery questions and knee arthroscopy pages.

Frequently asked questions

Research cited on this page

1. Frobell RB, Roos EM, Roos HP, et al. A randomized trial of treatment for acute anterior cruciate ligament tears. N Engl J Med. 2010;363(4):331-42. PubMed
   KANON trial: rehabilitation plus early reconstruction did not outperform rehabilitation with optional delayed reconstruction at 2 years; the delayed strategy substantially reduced reconstructions.
2. Frobell RB, Roos HP, Roos EM, et al. Treatment for acute anterior cruciate ligament tear: five year outcome of randomised trial. BMJ. 2013;346:f232. PubMed
   KANON 5-year results: no difference in outcomes; 51% of the optional-delay group had reconstruction.
3. Lohmander LS, Roemer FW, Frobell RB, et al. Treatment for Acute Anterior Cruciate Ligament Tear in Young Active Adults. NEJM Evid. 2023;2(8):EVIDoa2200287. PubMed
   KANON 11-year results: no differences in patient-reported outcomes between the two strategies.
4. Reijman M, Eggerding V, van Es E, et al. Early surgical reconstruction versus rehabilitation with elective delayed reconstruction for patients with anterior cruciate ligament rupture: COMPARE randomised controlled trial. BMJ. 2021;372:n375. PubMed
   COMPARE trial: early reconstruction gave slightly better (not clinically relevant) 2-year scores; 50% of the rehabilitation group later had reconstruction.
5. Beard DJ, Davies L, Cook JA, et al. Comparison of surgical or non-surgical management for non-acute anterior cruciate ligament injury: the ACL SNNAP RCT. Health Technol Assess. 2024;28(27):1-97. PubMed
   ACL SNNAP trial: in non-acute ACL-deficient patients, reconstruction gave better knee scores at 18 months than rehabilitation; 41% of the rehabilitation group later had surgery.
6. Monk AP, Davies LJ, Hopewell S, et al. Surgical versus conservative interventions for treating anterior cruciate ligament injuries. Cochrane Database Syst Rev. 2016;4(4):CD011166. PubMed
   Cochrane review: low-quality evidence of no difference in function between surgery and rehabilitation at 2 and 5 years; many rehabilitation patients later chose reconstruction.
7. Krause M, Freudenthaler F, Frosch KH, et al. Operative Versus Conservative Treatment of Anterior Cruciate Ligament Rupture. Dtsch Arztebl Int. 2018;115(51-52):855-862. PubMed
   Systematic review: randomized evidence cannot definitively show which approach yields better function; observational studies trend toward surgery for stability.
8. Saueressig T, Braun T, Steglich N, et al. Primary surgery versus primary rehabilitation for treating anterior cruciate ligament injuries: a living systematic review and meta-analysis. Br J Sports Med. 2022;56(21):1241-1251. PubMed
   Meta-analysis: low-certainty evidence that primary rehabilitation with optional surgery gives similar outcomes to early reconstruction.
9. Filbay SR, Roemer FW, Lohmander LS, et al. Evidence of ACL healing on MRI following ACL rupture treated with rehabilitation alone may be associated with better patient-reported outcomes: a secondary analysis from the KANON trial. Br J Sports Med. 2023;57(2):91-98. PubMed
   KANON MRI follow-up: ACL healing seen in 30% of patients randomized to rehabilitation and associated with better outcomes.
10. Filbay SR, Bullock G, Russell S, et al. No Difference in Return-to-Sport Rate or Activity Level in People with Anterior Cruciate Ligament (ACL) Injury Managed with ACL Reconstruction or Rehabilitation Alone: A Systematic Review and Meta-Analysis. Sports Med. 2025;55(9):2191-2205. PubMed
    Systematic review: no difference in return-to-sport rates or activity levels between reconstruction and rehabilitation alone, with high risk of bias in most studies.
11. Mistry H, Metcalfe A, Colquitt J, et al. Autograft or allograft for reconstruction of anterior cruciate ligament: a health economics perspective. Knee Surg Sports Traumatol Arthrosc. 2019;27(6):1782-1790. PubMed
    Systematic review and cost analysis: autograft and allograft are both effective (failure about 6% vs 7%); autograft is usually first choice on cost.
12. Zeng C, Gao SG, Li H, et al. Autograft Versus Allograft in Anterior Cruciate Ligament Reconstruction: A Meta-analysis of Randomized Controlled Trials and Systematic Review of Overlapping Systematic Reviews. Arthroscopy. 2016;32(1):153-63.e18. PubMed
    Meta-analysis: autograft gave better function and stability than irradiated allograft, with no difference versus non-irradiated allograft.
13. Wang HD, Zhu YB, Wang TR, et al. Irradiated allograft versus autograft for anterior cruciate ligament reconstruction: A meta-analysis and systematic review of prospective studies. Int J Surg. 2018;49:45-55. PubMed
    Meta-analysis: irradiated allografts had poorer stability and subjective scores than autografts in primary reconstruction.
14. Samuelsen BT, Webster KE, Johnson NR, et al. Hamstring Autograft versus Patellar Tendon Autograft for ACL Reconstruction: Is There a Difference in Graft Failure Rate? A Meta-analysis of 47,613 Patients. Clin Orthop Relat Res. 2017;475(10):2459-2468. PubMed
    Meta-analysis of 47,070 reconstructions: graft rupture 2.80% with BTB vs 2.84% with hamstring; statistically lower with BTB but small in absolute terms.
15. Mouarbes D, Menetrey J, Marot V, et al. Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis of Outcomes for Quadriceps Tendon Autograft Versus Bone-Patellar Tendon-Bone and Hamstring-Tendon Autografts. Am J Sports Med. 2019;47(14):3531-3540. PubMed
    Meta-analysis: quadriceps tendon autograft had outcomes and graft survival comparable to BTB and hamstring, with less harvest-site pain than BTB.
16. Dai W, Leng X, Wang J, et al. Quadriceps Tendon Autograft Versus Bone-Patellar Tendon-Bone and Hamstring Tendon Autografts for Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis. Am J Sports Med. 2022;50(12):3425-3439. PubMed
    Meta-analysis: quadriceps tendon autograft had comparable graft survival and function with lower donor-site morbidity.
17. Connors JP, Cusano A, Saleet J, et al. Return to Sport and Graft Failure Rates After Primary Anterior Cruciate Ligament Reconstruction With a Bone-Patellar Tendon-Bone Versus Hamstring Tendon Autograft: A Systematic Review and Meta-analysis. Am J Sports Med. 2025;53(8):1996-2006. PubMed
    Systematic review: BTB and hamstring autografts had similar return-to-sport and re-rupture rates.
18. White T, Castro M, Antonio L, et al. Quadriceps, hamstring and patella tendon autografts for primary anterior cruciate ligament reconstruction demonstrate similar clinical outcomes, including graft failure, joint laxity and complications: A systematic review with meta-analysis of randomised controlled trials. Knee Surg Sports Traumatol Arthrosc. 2026;34(5):1631-1646. PubMed
    Systematic review: quadriceps tendon autografts had similar failure, laxity and patient-reported outcomes to hamstring and BTB grafts.
19. Getgood AMJ, Bryant DM, Litchfield R, et al. Lateral Extra-articular Tenodesis Reduces Failure of Hamstring Tendon Autograft Anterior Cruciate Ligament Reconstruction: 2-Year Outcomes From the STABILITY Study Randomized Clinical Trial. Am J Sports Med. 2020;48(2):285-297. PubMed
    STABILITY trial (618 patients aged 14–25): adding LET reduced graft rupture from 11% to 4% at 2 years.
20. Firth AD, Bryant DM, Litchfield R, et al. Predictors of Graft Failure in Young Active Patients Undergoing Hamstring Autograft Anterior Cruciate Ligament Reconstruction With or Without a Lateral Extra-articular Tenodesis: The Stability Experience. Am J Sports Med. 2022;50(2):384-395. PubMed
    STABILITY secondary analysis: LET was protective against graft rupture; younger age and greater posterior tibial slope increased risk.
21. Onggo JR, Rasaratnam HK, Nambiar M, et al. Anterior Cruciate Ligament Reconstruction Alone Versus With Lateral Extra-articular Tenodesis With Minimum 2-Year Follow-up: A Meta-analysis and Systematic Review of Randomized Controlled Trials. Am J Sports Med. 2022;50(4):1137-1145. PubMed
    Meta-analysis: lateral extra-articular procedures improve rotational stability and reduce graft re-rupture in primary reconstruction.
22. Castoldi M, Magnussen RA, Gunst S, et al. A Randomized Controlled Trial of Bone-Patellar Tendon-Bone Anterior Cruciate Ligament Reconstruction With and Without Lateral Extra-articular Tenodesis: 19-Year Clinical and Radiological Follow-up. Am J Sports Med. 2020;48(7):1665-1672. PubMed
    19-year randomized follow-up: no difference in patient-reported outcomes with or without an older LET technique; possible increase in lateral compartment arthritis.
23. Zhao D, Pan JK, Lin FZ, et al. Risk Factors for Revision or Rerupture After Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis. Am J Sports Med. 2023;51(11):3053-3075. PubMed
    Meta-analysis of 629,120 patients: younger age, male sex, family history, higher tibial slope, high-grade laxity and return to high activity were associated with revision or re-rupture.
24. Wiggins AJ, Grandhi RK, Schneider DK, et al. Risk of Secondary Injury in Younger Athletes After Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis. Am J Sports Med. 2016;44(7):1861-76. PubMed
    Meta-analysis: overall second ACL injury rate 15%; about 23% in athletes under 25 who return to sport.
25. Webster KE, Feller JA. Exploring the High Reinjury Rate in Younger Patients Undergoing Anterior Cruciate Ligament Reconstruction. Am J Sports Med. 2016;44(11):2827-2832. PubMed
    Cohort study: graft rupture in 18% of young patients; highest (28%) in males under 18; most within the first 2 years.
26. Ardern CL, Taylor NF, Feller JA, et al. Fifty-five per cent return to competitive sport following anterior cruciate ligament reconstruction surgery: an updated systematic review and meta-analysis including aspects of physical functioning and contextual factors. Br J Sports Med. 2014;48(21):1543-52. PubMed
    Meta-analysis of 7,556 patients: 81% returned to any sport, 65% to pre-injury level and 55% to competitive sport.
27. Ardern CL, Webster KE, Taylor NF, et al. Return to sport following anterior cruciate ligament reconstruction surgery: a systematic review and meta-analysis of the state of play. Br J Sports Med. 2011;45(7):596-606. PubMed
    Meta-analysis: return to competitive sport is relatively low despite good knee function, suggesting psychological factors contribute.
28. Webster KE, Feller JA, Whitehead TS, et al. Return to Sport in the Younger Patient With Anterior Cruciate Ligament Reconstruction. Orthop J Sports Med. 2017;5(4):2325967117703399. PubMed
    Cohort study: 76% of young patients returned to their pre-injury sport; fear of re-injury was a common reason for not returning.
29. Grindem H, Snyder-Mackler L, Moksnes H, et al. Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: the Delaware-Oslo ACL cohort study. Br J Sports Med. 2016;50(13):804-8. PubMed
    Delaware-Oslo cohort: re-injury rate fell 51% for each month return to sport was delayed up to 9 months; passing return-to-sport criteria was associated with fewer re-injuries.
30. Kyritsis P, Bahr R, Landreau P, et al. Likelihood of ACL graft rupture: not meeting six clinical discharge criteria before return to sport is associated with a four times greater risk of rupture. Br J Sports Med. 2016;50(15):946-51. PubMed
    Professional athletes: not meeting all six discharge criteria before returning to team training was associated with a fourfold higher graft rupture risk.
31. van Melick N, van Cingel RE, Brooijmans F, et al. Evidence-based clinical practice update: practice guidelines for anterior cruciate ligament rehabilitation based on a systematic review and multidisciplinary consensus. Br J Sports Med. 2016;50(24):1506-1515. PubMed
    Clinical practice guideline: rehabilitation should include prehabilitation and three criterion-based postoperative phases with strength and hop testing.
32. Kotsifaki R, Korakakis V, King E, et al. Aspetar clinical practice guideline on rehabilitation after anterior cruciate ligament reconstruction. Br J Sports Med. 2023;57(9):500-514. PubMed
    Aspetar clinical practice guideline on rehabilitation after ACL reconstruction: return to running and training are key milestones.
33. Kruse LM, Gray B, Wright RW. Rehabilitation after anterior cruciate ligament reconstruction: a systematic review. J Bone Joint Surg Am. 2012;94(19):1737-48. PubMed
    Systematic review: new rehabilitation modalities should not replace motion, strengthening and functional exercises; accelerated rehabilitation does not appear harmful.
34. Jack RA, Lambert BS, Hedt CA, et al. Blood Flow Restriction Therapy Preserves Lower Extremity Bone and Muscle Mass After ACL Reconstruction. Sports Health. 2023;15(3):361-371. PubMed
    Randomized trial: blood flow restriction therapy preserved leg muscle and bone mass for up to 12 weeks after reconstruction.
35. Gopinatth V, Garcia JR, Reid IK, et al. Blood Flow Restriction Enhances Recovery After Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis of Randomized Controlled Trials. Arthroscopy. 2025;41(4):1048-1060. PubMed
    Systematic review: blood flow restriction after reconstruction improved pain, IKDC scores and strength.
36. Webster KE, Hewett TE. Anterior Cruciate Ligament Injury and Knee Osteoarthritis: An Umbrella Systematic Review and Meta-analysis. Clin J Sport Med. 2022;32(2):145-152. PubMed
    Meta-analysis: ACL injury markedly increases knee arthritis risk, present in about a third of reconstructed patients long term; surgery does not reduce arthritis prevalence compared with nonsurgical care.
37. Magnussen RA, Mansour AA, Carey JL, et al. Meniscus status at anterior cruciate ligament reconstruction associated with radiographic signs of osteoarthritis at 5- to 10-year follow-up: a systematic review. J Knee Surg. 2009;22(4):347-57. PubMed
    Systematic review: meniscus status at reconstruction affects arthritis risk; virtually all patients with complete meniscectomy developed radiographic arthritis.
38. Vavken P, Murray MM. Treating anterior cruciate ligament tears in skeletally immature patients. Arthroscopy. 2011;27(5):704-16. PubMed
    Systematic review: in skeletally immature patients, conservative care was associated with poor outcomes and secondary meniscus and cartilage damage; surgical stabilization gave good stability and function.
39. Longo UG, Ciuffreda M, Casciaro C, et al. Anterior cruciate ligament reconstruction in skeletally immature patients : a systematic review. Bone Joint J. 2017;99-B(8):1053-1060. PubMed
    Systematic review: overall growth disturbance after pediatric ACL reconstruction was 2.6%, with no difference between transphyseal and physeal-sparing techniques.
40. Wong SE, Feeley BT, Pandya NK. Complications After Pediatric ACL Reconstruction: A Meta-analysis. J Pediatr Orthop. 2019;39(8):e566-e571. PubMed
    Meta-analysis: growth disturbance can occur with any technique; re-rupture is a more frequent problem in children and teens.
41. Nwachukwu BU, Patel BH, Lu Y, et al. Anterior Cruciate Ligament Repair Outcomes: An Updated Systematic Review of Recent Literature. Arthroscopy. 2019;35(7):2233-2247. PubMed
    Systematic review: reconstruction had better survivorship and patient-perceived improvement than ACL repair.
42. Murray MM, Fleming BC, Badger GJ, et al. Bridge-Enhanced Anterior Cruciate Ligament Repair Is Not Inferior to Autograft Anterior Cruciate Ligament Reconstruction at 2 Years: Results of a Prospective Randomized Clinical Trial. Am J Sports Med. 2020;48(6):1305-1315. PubMed
    Randomized trial: bridge-enhanced ACL repair (BEAR) was noninferior to autograft reconstruction for patient-reported outcomes and laxity at 2 years.
43. Al Attar WSA, Bakhsh JM, Khaledi EH, et al. Injury prevention programs that include plyometric exercises reduce the incidence of anterior cruciate ligament injury: a systematic review of cluster randomised trials. J Physiother. 2022;68(4):255-261. PubMed
    Meta-analysis of cluster randomized trials: prevention programs with plyometric exercises reduced ACL injury risk by 60%.
44. Arundale AJH, Bizzini M, Giordano A, et al. Exercise-Based Knee and Anterior Cruciate Ligament Injury Prevention. J Orthop Sports Phys Ther. 2018;48(9):A1-A42. PubMed
    Clinical practice guideline: exercise-based knee and ACL injury prevention programs are recommended for athletes.
45. Bram JT, Magee LC, Mehta NN, et al. Anterior Cruciate Ligament Injury Incidence in Adolescent Athletes: A Systematic Review and Meta-analysis. Am J Sports Med. 2021;49(7):1962-1972. PubMed
    Meta-analysis: female adolescent athletes were about 1.5 times as likely as males to sustain an ACL injury.

Medically reviewed by Andrew P. Dold, MD, FAOA, FAAOS, FACS, FRCSC. Last reviewed October 2026. This page is general information, not medical advice. Your own diagnosis and treatment plan depend on your exam and imaging.