The anterior cruciate ligament (ACL) is one of the main stabilizing ligaments of the knee. It stops the shinbone (tibia) from sliding forward on the thighbone (femur) and controls rotation when you plant, pivot or land. An ACL tear is one of the most common serious knee injuries in athletes. Dr. Andrew Dold, a board-certified, fellowship-trained sports medicine surgeon in Frisco, Texas, treats ACL tears in athletes of every level, from high school and weekend athletes to professionals.
- Most ACL tears happen without contact, during cutting, pivoting or landing
- A complete ACL tear does not usually heal on its own
- Not everyone needs surgery; it depends on your knee, your goals and any other injuries
- ACL reconstruction is usually same-day outpatient surgery
- Physical therapy typically starts within about a week of surgery
- Return to sport is based on strength and testing, not just the calendar
How do you tear your ACL?
Most ACL tears are non-contact injuries. In one study of 100 injured knees, 72% of ACL tears happened without contact.1 They happen when the foot is planted and the knee suddenly twists, changes direction, decelerates or lands awkwardly from a jump. This is why ACL tears are common in soccer, basketball, football, volleyball, rugby, lacrosse and skiing. A direct blow to the side of the knee can also tear the ACL, often along with other ligaments.
Female athletes tear their ACL more often than male athletes in the same sports; in a 13-year review of college soccer and basketball, ACL injury rates were significantly higher for women in both sports.2 Researchers think this is related to differences in landing mechanics, strength and anatomy. Injury-prevention programs that teach safer landing and cutting can lower the risk: combined research shows they cut the risk of ACL injury by about half.3
What does an ACL tear feel like?
- A pop felt or heard in the knee at the time of injury
- Swelling that develops within hours
- Pain, often making it hard to keep playing
- Loss of full range of motion
- A feeling that the knee is unstable or “gives way,” especially when turning or pivoting
After the first swelling settles, some people can walk fairly normally. That can be misleading: the knee may still give way with sports or quick turns, and each episode of giving way can damage the meniscus and cartilage.
Injuries that often come with an ACL tear
ACL tears are frequently combined with injuries to the meniscus, the MCL, the joint cartilage, or the posteromedial corner of the knee, a topic Dr. Dold has published on in the Journal of the American Academy of Orthopaedic Surgeons. Finding and treating these associated injuries is an important part of getting a good result.
How is an ACL tear diagnosed?
Dr. Dold starts with your history and a careful knee exam, including ligament stability tests such as the Lachman and pivot-shift tests. X-rays check for fractures. An MRI confirms the ACL tear and shows the meniscus, cartilage and other ligaments. Sometimes a more detailed look reveals injuries that were missed elsewhere:
Can an ACL tear heal without surgery?
A complete ACL tear does not usually heal back together on its own. That does not mean everyone needs surgery. Non-surgical treatment can be a reasonable choice for:
- People who do not play cutting or pivoting sports and are willing to adjust their activities
- Some partial ACL tears where the knee is still stable
- People whose knee does not give way during daily life after a focused rehab program
Non-surgical care focuses on physical therapy to restore motion and rebuild quadriceps and hamstring strength, and sometimes bracing for higher-risk activities. In a trial of 121 young, active adults with a new ACL tear, structured rehabilitation with the option of reconstruction later gave 2-year results similar to early reconstruction, and 36 of the 59 people in the rehabilitation group never needed surgery.4 The main risk of not reconstructing an unstable knee is repeated giving-way episodes, which can lead to meniscus tears and cartilage damage over time; in a study of 1,434 patients, cartilage and medial meniscus damage became more common the longer reconstruction was delayed.5 Dr. Dold will talk through the pros and cons for your situation.
ACL reconstruction surgery
For active people who want to return to cutting and pivoting sports, and for knees that keep giving way, ACL reconstruction is the standard treatment. The torn ligament is replaced with a tendon graft, passed through small tunnels in the femur and tibia and fixed in place. The surgery is done arthroscopically through small incisions, and it is typically performed as same-day outpatient surgery, so most patients go home the same day. Any meniscus or cartilage injuries are usually treated during the same operation. Whenever possible, Dr. Dold repairs a torn meniscus rather than removing it. For patients at higher risk of a re-tear, such as young athletes in pivoting sports, he may add a lateral extra-articular tenodesis (LET), a small reinforcing procedure on the outer side of the knee. In a randomized trial of young, high-risk patients, adding LET to a hamstring ACL reconstruction lowered the graft rupture rate from 11% to 4% at 2 years.6
Surgery is usually scheduled once the initial swelling has gone down and the knee has regained good motion. A short “prehab” program before surgery can help recovery afterward.
Which graft is right for ACL surgery?
This is one of the most common questions patients ask Dr. Dold, and he has written about it in depth in ACL surgery: choosing a graft The main options are:
| Graft | What it is | Key points |
|---|---|---|
| Patellar tendon (bone-tendon-bone, BTB) autograft | The middle third of your own patellar tendon, with a small bone block at each end | Dr. Dold’s preferred graft for most young, active patients. In a registry of nearly 46,000 reconstructions, it had a lower risk of revision surgery than hamstring grafts.7 More kneeling and front-of-knee pain in the early years. Watch Dr. Dold’s BTB technique video |
| Hamstring autograft | Two of your own hamstring tendons | Smaller incision and less kneeling pain early on; a higher revision risk than patellar tendon grafts in large registries7 |
| Quadriceps tendon autograft | Part of your own quadriceps tendon | An increasingly used option with a large, strong graft |
| Allograft (donor tissue) | Tendon from a tissue donor | No harvest from your own knee, but a significantly higher failure rate in young, active patients (about 5 times the odds of re-tear compared with a patellar tendon autograft in one large study8). Can be a good option for patients over about 40. |
In young, active patients, the evidence strongly supports using your own tissue (an autograft) rather than donor tissue. Between the autograft options, long-term functional results are similar in most studies (one randomized trial found comparable results 15 years after patellar tendon and hamstring reconstructions9), so the choice is individualized. Dr. Dold and his patients decide together after discussing the pros and cons of each.
Watch Dr. Dold: ACL reconstruction videos
ACL surgery recovery timeline
Every recovery is different, and Dr. Dold gives each patient a specific plan. As a general guide:
| Time after surgery | Typical focus |
|---|---|
| First 2 weeks | Control swelling and pain, get the knee fully straight, activate the quadriceps, walk with full weight as comfortable using crutches for support for about 1–2 weeks, and a brace for a few weeks. Outpatient physical therapy usually starts within about a week. |
| Weeks 2–6 | Restore range of motion, wean off crutches, normalize walking |
| Months 2–3 | Build strength and balance; stationary bike and other low-impact exercise |
| Months 3–4 | Start a gradual running progression once strength and motion allow |
| Months 4–9 | Agility, jumping and cutting drills, progressing as strength and control allow |
| About 9 months and beyond | Sport-specific training and return-to-sport testing. Return to cutting and pivoting sports is usually not before about 9 months, and only after passing strength and functional tests. |
Returning to sport too early is one of the biggest risk factors for re-injury: in one study, the re-injury rate fell by about half for each month return to sport was delayed, up to 9 months after surgery, and patients who failed return-to-sport tests had far more re-injuries.10 So readiness is judged by testing, not just by the date.
Complications
ACL reconstruction is generally safe and effective, but every surgery carries risks, including stiffness, infection, blood clots, pain at the graft harvest site, graft re-tear and later arthritis. Dr. Dold reviews these in detail before surgery.
Watch Dr. Dold explain ACL tears
Some of these videos show real surgery, so some viewers may prefer not to watch.
More videos on Dr. Dold’s YouTube channel.
What the research shows
The ACL is one of the most studied ligaments in the body. Here is what major trials and reviews add.
Surgery or rehabilitation first?
Two well-known randomized trials reached different conclusions. In the Swedish KANON trial, starting with rehabilitation (with surgery later if needed) gave results similar to early reconstruction at 5 years, and some ACLs even showed signs of healing on MRI. In the Dutch COMPARE trial, early reconstruction gave better knee function and sports participation at 2 years. Together, these support a personalized decision based on your sport, instability and goals.
Graft choice and extra stability
Patellar tendon, hamstring and quadriceps tendon grafts have similar failure rates and outcomes in recent meta-analyses; quadriceps tendon grafts tend to cause less pain at the harvest site. In young, high-risk athletes, the STABILITY trial found that adding a lateral extra-articular tenodesis lowered graft rupture, and long-term data suggest it may also reduce arthritis.
Return to sport and reinjury
Nearly 1 in 4 young athletes who return to high-level sport have a second ACL injury. Guidelines recommend criterion-based rehabilitation and objective strength and hop testing before return, and psychological readiness also matters.
Prevention and long-term health
Exercise-based prevention programs reduce ACL injuries, particularly in young female athletes, who are at higher risk. ACL injury raises the long-term risk of knee arthritis regardless of treatment, which is another reason prevention matters.
ACL repair
Newer repair techniques, including bridge-enhanced repair, have shown promising early results in selected patients, but younger patients have had higher revision rates after repair than after reconstruction.
What patients say
Patient reviews in their own words. Individual results vary. Read more patient reviews.
Why see Dr. Dold
- Board certified by the American Board of Orthopaedic Surgery, with subspecialty certification in Sports Medicine
- Sports medicine and arthroscopy fellowship at NYU Langone / Hospital for Joint Diseases; orthopedic residency at the University of Toronto
- Fellow of the American College of Surgeons (FACS), the American Academy of Orthopaedic Surgeons (FAAOS), the American Orthopaedic Association (FAOA) and the Royal College of Surgeons of Canada (FRCSC)
- Published research on knee ligament and meniscus surgery, including The Posteromedial Corner of the Knee (JAAOS, 2017) and transtibial meniscal root repair (KSSTA, 2017)
- Team physician and surgical consultant to Rugby Canada; has cared for professional and Olympic athletes from the NFL, NBA, NHL, MLS, PGA Tour, Major League Rugby and USA Gymnastics
- D Magazine Best Doctors (Collin County), 2019–2026 · Rated 4.9 on Google
Frequently asked questions
Can an ACL tear heal on its own?
A complete ACL tear does not usually heal back together on its own. Some people, especially those who do not play cutting or pivoting sports, do well with physical therapy alone. Partial tears and stable knees may also be treated without surgery.
What does a torn ACL feel like?
Most people feel or hear a pop, followed by swelling within hours, pain, and a feeling that the knee is unstable or gives way, especially when turning.
Can you walk with a torn ACL?
Often yes, once the swelling settles. But the knee may still give way with sports or quick turns, and repeated giving way can damage the meniscus and cartilage, so it should be evaluated.
Do I need surgery for a torn ACL?
Not always. Surgery is usually recommended for active people who want to return to cutting and pivoting sports, and for knees that keep giving way. Dr. Dold will help you decide based on your knee, your goals and any other injuries.
Is ACL surgery outpatient?
Yes. ACL reconstruction is typically performed as same-day outpatient surgery, and most patients go home the same day.
When does physical therapy start after ACL surgery?
Outpatient physical therapy usually starts within about a week of surgery.
How long does it take to recover from ACL surgery?
Most people walk without crutches within a few weeks and begin running at around 3 to 4 months. Return to cutting and pivoting sports is usually not before about 9 months, and only after passing strength and functional testing.
Which graft is right for ACL reconstruction?
In young, active patients the evidence strongly favors using your own tissue (autograft) over donor tissue. Patellar tendon, hamstring and quadriceps tendon autografts each have pros and cons, and the choice is individualized.
What is the difference between ACL repair and ACL reconstruction?
Reconstruction replaces the torn ligament with a tendon graft and is the standard treatment. Repair stitches the ligament back and is only an option for select tears near the bone; current guidelines favor reconstruction because of lower revision rates.
How long should I wait to have ACL surgery?
Surgery is usually done once the initial swelling has gone down and you have regained good knee motion, often within a few weeks of injury. Waiting too long with an unstable knee can risk further meniscus and cartilage damage.
Research cited on this page
- Boden BP, Dean GS, Feagin JA Jr, Garrett WE Jr. Mechanisms of anterior cruciate ligament injury. Orthopedics. 2000;23(6):573-578. PubMed
- Agel J, Arendt EA, Bershadsky B. Anterior cruciate ligament injury in National Collegiate Athletic Association basketball and soccer: a 13-year review. Am J Sports Med. 2005;33(4):524-530. PubMed
- Webster KE, Hewett TE. Meta-analysis of meta-analyses of anterior cruciate ligament injury reduction training programs. J Orthop Res. 2018;36(10):2696-2708. PubMed
- 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):331-342. PubMed
- Ralles S, Agel J, Obermeier M, Tompkins M. Incidence of secondary intra-articular injuries with time to anterior cruciate ligament reconstruction. Am J Sports Med. 2015;43(6):1373-1379. PubMed
- 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
- Gifstad T, Foss OA, Engebretsen L, et al. Lower risk of revision with patellar tendon autografts compared with hamstring autografts: a registry study based on 45,998 primary ACL reconstructions in Scandinavia. Am J Sports Med. 2014;42(10):2319-2328. PubMed
- Kaeding CC, Pedroza AD, Reinke EK, et al. Risk factors and predictors of subsequent ACL injury in either knee after ACL reconstruction: prospective analysis of 2488 primary ACL reconstructions from the MOON cohort. Am J Sports Med. 2015;43(7):1583-1590. PubMed
- Webster KE, Feller JA, Hartnett N, et al. Comparison of patellar tendon and hamstring tendon anterior cruciate ligament reconstruction: a 15-year follow-up of a randomized controlled trial. Am J Sports Med. 2016;44(1):83-90. PubMed
- 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):804-808. PubMed
- 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
At 5 years, the KANON randomized trial found initial rehabilitation with optional later reconstruction gave results similar to early reconstruction in young active adults. - 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
The COMPARE randomized trial found early reconstruction gave better self-reported knee function and sports participation at 2 years than rehabilitation with optional later surgery. - Eggerding V, Reijman M, Meuffels DE, et al. ACL reconstruction for all is not cost-effective after acute ACL rupture. Br J Sports Med. 2022;56(1):24-28. PubMed
In the same trial, routine early reconstruction was not considered cost-effective for a standard ACL population. - 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
In the KANON trial, MRI signs of ACL healing appeared in about 1 in 3 patients treated first with rehabilitation and were linked to favorable outcomes. - 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
A review of randomized trials could not definitively say whether surgery or rehabilitation gives better function after ACL rupture. - 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
Across adolescent sports, female athletes were about 1.5 times as likely as male athletes to tear the ACL. - Crossley KM, Patterson BE, Culvenor AG, et al. Making football safer for women: a systematic review and meta-analysis of injury prevention programmes in 11 773 female football (soccer) players. Br J Sports Med. 2020;54(18):1089-1098. PubMed
In women’s soccer, exercise-based prevention programs reduced ACL injuries by about 45%. - Magaña-Ramírez M, Gallardo-Gómez D, Álvarez-Barbosa F, et al. What exercise programme is the most appropriate to mitigate anterior cruciate ligament injury risk in football (soccer) players? A systematic review and network meta-analysis. J Sci Med Sport. 2024;27(4):234-242. PubMed
A 2024 review supported structured warm-up programs such as FIFA 11+ and Knäkontroll for reducing injuries. - 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
A meta-analysis found quadriceps tendon autografts had similar survival and function to patellar tendon and hamstring grafts, with less donor-site pain. - 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
A 2026 review again found similar failure rates and outcomes across quadriceps, hamstring and patellar tendon grafts, with lower donor-site problems for quadriceps tendon. - 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
In the STABILITY trial, adding a lateral extra-articular tenodesis, using a larger graft and avoiding high tibial slope were linked to fewer graft ruptures. - 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
A meta-analysis found extra-articular procedures improved rotational stability and reduced graft re-ruptures in primary ACL reconstruction. - Gkekas NK, Stamiris D, Koutalos AA, et al. Combining ACL Reconstruction with Lateral Extra-Articular Tenodesis Reduces Long-Term Osteoarthritis Risk Versus Isolated ACL Reconstruction: A Systematic Review and Meta-Analysis. J Bone Joint Surg Am. 2026;108(3):193-201. PubMed
A 2026 meta-analysis found adding a lateral tenodesis reduced the long-term risk of moderate-to-severe arthritis, especially on the outer side of the knee. - 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
Nearly 1 in 4 young athletes who return to high-level sport after ACL reconstruction have a second ACL injury. - 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
Evidence-based guidelines recommend criterion-based rehabilitation and a battery of strength and hop tests before return to sport. - Nedder VJ, Raju AG, Moyal AJ, et al. Impact of Psychological Factors on Rehabilitation After Anterior Cruciate Ligament Reconstruction: A Systematic Review. Sports Health. 2025;17(2):291-298. PubMed
Fear of reinjury and low psychological readiness were linked to worse return-to-sport outcomes after ACL reconstruction. - 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
ACL injury markedly increases the long-term risk of knee arthritis, which develops in roughly a third of knees over time. - 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
A randomized trial found bridge-enhanced ACL repair (BEAR) gave non-inferior outcomes to reconstruction at 2 years in young active patients. - Rilk S, Goodhart GC, van der List JP, et al. Anterior cruciate ligament primary repair revision rates are increased in skeletally mature patients under the age of 21 compared to reconstruction, while adults (>21 years) show no significant difference: A systematic review and meta-analysis. Knee Surg Sports Traumatol Arthrosc. 2025;33(1):29-58. PubMed
Primary ACL repair in patients 21 or younger carried up to six times the revision risk of reconstruction, while adults had no significant difference.
Medically reviewed by Andrew P. Dold, MD, FAOA, FAAOS, FACS, FRCSC. Last reviewed October 2026. This page is general information, not medical advice. Individual results vary.
