A hamstring graft is one of three common ways to rebuild a torn anterior cruciate ligament (ACL), the ligament that stops your shin bone sliding forward and twisting under your thigh bone. For most people it works about as well as the alternatives. Graft rupture is uncommon with any of them, and trials that followed patients for around 15 years found similar results.[1,2]
The choice between grafts comes down to trade-offs. A hamstring graft causes less front-of-knee and kneeling pain than a patellar tendon graft, but it can leave some lasting weakness when you bend your knee.[3,4]
At a glance
- A hamstring graft uses one or two thin tendons from the back of your thigh to rebuild the torn ACL.
- Hamstring, patellar tendon and quadriceps tendon grafts have similar re-tear rates and long-term results.
- Hamstring grafts cause less kneeling and front-of-knee pain, but may leave mild hamstring weakness and a numb patch near the knee.
- Young people returning to pivoting sport have the highest risk of another injury, and an added procedure on the outer knee may lower it.
On this page
What is a hamstring graft, and which tendons are used?
How well does a hamstring graft work compared with other grafts?
What are the advantages of a hamstring graft?
What are the downsides and risks of a hamstring graft?
When might a different graft or an added procedure be considered?
What does recovery look like after hamstring ACL reconstruction?
What is a hamstring graft, and which tendons are used?
Your hamstrings are the muscles at the back of your thigh. Some of their tendons cross the inner side of the knee and attach to the top of the shin. For a hamstring graft, the surgeon takes one or two of the thinnest of these tendons, the semitendinosus and sometimes the gracilis, through a small cut on the inner shin just below the knee.
The tendons are folded into a thicker bundle, usually of three or four strands. This bundle is passed through tunnels drilled in the thigh bone and shin bone and fixed in place. Over the following months the graft heals into the bone and takes over the job of the torn ligament. Because the graft comes from your own body, it is called an autograft.
The two other common autografts are the patellar tendon (the middle third of the tendon below your kneecap, with a small block of bone at each end) and the quadriceps tendon (part of the tendon above your kneecap). Reconstruction is one option after an ACL tear, and some people manage with physiotherapy and strength training alone.
How well does a hamstring graft work compared with other grafts?
Graft rupture is uncommon whichever graft is used. A 2017 analysis pooled more than 47,000 reconstructions from trials, cohort studies and a national registry. Over an average of about five and a half years, roughly 3 in 100 grafts ruptured in both the hamstring and patellar tendon groups.[1] The statistics slightly favoured the patellar tendon, but the gap was small. About 235 people would need a patellar tendon graft instead of a hamstring graft to prevent one rupture. Knee looseness on examination was similar in both groups.
Longer follow-up shows the same picture. Six randomised trials that followed patients for an average of almost 15 years found no difference between hamstring and patellar tendon grafts in graft rupture, knee function or arthritis.[2] Trials comparing the quadriceps tendon with the other two grafts have also found similar failure rates, at least over the first two years.[5]
These figures are averages across thousands of people. Your own risk also depends on your age, your sport and when you return to it, which are covered below.
What are the advantages of a hamstring graft?
The main advantage is comfort at the front of the knee. Taking a patellar tendon graft can leave pain at the front of the knee and pain when kneeling. Across 21 randomised trials, the odds of these problems were about 69% lower with a hamstring graft than with a patellar tendon graft.[3] The same analysis found no difference between grafts in overall complications, further operations or revision surgery. This advantage counts for more if your work or sport involves a lot of kneeling. No bone is taken from the kneecap, so the kneecap is not weakened by the harvest.
There is no consistent evidence that a hamstring graft gets you back to sport sooner. In a 2025 review of 4,810 athletes, about 78% returned to sport after a hamstring graft and about 83% after a patellar tendon graft, a difference that was not statistically significant.[6]
What are the downsides and risks of a hamstring graft?
A hamstring graft has two specific trade-offs: some loss of hamstring strength, and a numb patch near the knee.
Hamstring strength. Removing tendons weakens knee bending, especially when the knee is bent deeply, as when you pull your heel towards your buttock. A review of 64 studies found that, on average, the operated leg had about 89% of the other leg’s bending strength at one year and about 92% at two years.[4] These figures are of low certainty because testing methods varied between studies. A small deficit can last. In a randomised trial that followed patients for 18 years, the hamstring group had about 11% less peak bending strength than the patellar tendon group, with no difference in knee function, stability or arthritis.[7] Rehabilitation includes progressive hamstring strengthening for this reason.
Numbness. A small skin nerve, the infrapatellar branch of the saphenous nerve, crosses the inner side of the knee near where the tendons are taken. Injury to it causes a numb or tingling patch below or beside the kneecap. In a review of 11 studies, this happened in about half of people when the cut ran up and down the leg, and in about a quarter when it ran across or at an angle.[8] In a randomised trial comparing incisions, the numb area shrank over six months and did not interfere with normal daily activities.[9]
General risks. As with any ACL reconstruction, other risks include infection, stiffness, blood clots, ongoing instability and re-tear of the graft. These apply whichever graft is used.
When might a different graft or an added procedure be considered?
Your age and sport have a large effect on the chance of another ACL injury. A review of 19 studies found that about 21% of people under 25 went on to injure either ACL again, rising to about 23% among young people who returned to sport.[10] That is close to 1 in 4.
For young people at high risk, an extra procedure may help. The STABILITY trial included 618 people aged 25 or younger who had a very loose knee, planned to return to pivoting sport, or had generally loose joints. All had a hamstring graft. Adding a lateral extra-articular tenodesis, a strip of tissue on the outer side of the knee that helps control twisting, reduced graft rupture over two years from 11% to 4%.[11] The added procedure caused a little more pain in the first three to six months, and function was similar by two years.
Other things your surgeon may weigh up include your work, how loose your knee is, any previous knee surgery and the size of your hamstring tendons. For some people a patellar tendon or quadriceps tendon graft is a better fit, and each has its own trade-offs.
What does recovery look like after hamstring ACL reconstruction?
Recovery follows a similar path whichever graft is used. A Dutch clinical guideline, based on a systematic review and expert consensus, recommends that rehabilitation continue for 9 to 12 months.[12] You move through each stage by meeting milestones in strength, hopping and movement quality, rather than by time alone. After a hamstring graft, hamstring strengthening is built up gradually because of the harvest.
Returning to pivoting sport too early raises the risk of another injury. In a study of 106 people who played pivoting sports, the re-injury rate fell by about half for each month that return to sport was delayed, up to nine months after surgery.[13] It was a small observational study, so it cannot prove cause and effect, but it supports waiting at least nine months and passing return-to-sport testing first.
Summary
A hamstring graft is a well-established option for ACL reconstruction, with re-tear rates and long-term results similar to patellar tendon and quadriceps tendon grafts. Its main advantage is less kneeling and front-of-knee pain. Its main trade-offs are some lasting hamstring weakness and a numb patch near the knee. If you are young and returning to pivoting sport, your risk of another injury is higher, and an added procedure on the outer knee or a different graft may be worth discussing. Whichever graft is used, plan on 9 to 12 months of rehabilitation before returning to pivoting sport.
References
Show all 15 referencesHide references
- Samuelsen B et al. 2017. Hamstring Autograft versus Patellar Tendon Autograft for ACL Reconstruction: Is There a Difference in Graft Failure Rate? A Meta-analysis of 47,613 Patients. Clinical Orthopaedics and Related Research.
- Gopinatth V et al. 2025. Long-term Results of Bone-Patellar Tendon-Bone Versus Hamstring Tendon Autograft for Primary Anterior Cruciate Ligament Reconstruction: A Meta-analysis of Randomized Controlled Trials. Orthopaedic Journal of Sports Medicine.
- Kunze K et al. 2023. Lower donor site morbidity with hamstring and quadriceps tendon autograft compared with bone-patellar tendon-bone autograft after anterior cruciate ligament reconstruction: a systematic review and network meta-analysis of randomized controlled trials. Knee Surgery, Sports Traumatology, Arthroscopy.
- Högberg J et al. 2024. Restoring Knee Flexor Strength Symmetry Requires 2 Years After ACL Reconstruction, But Does It Matter for Second ACL Injuries? A Systematic Review and Meta-analysis. Sports Medicine – Open.
- White T et al. 2025. 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 Surgery, Sports Traumatology, Arthroscopy.
- Connors JP et al. 2025. 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. The American Journal of Sports Medicine.
- Popović M et al. 2024. Reduced Knee Flexion Strength 18 Years After ACL Reconstruction With Hamstring Tendon Versus Patellar Tendon. The American Journal of Sports Medicine.
- Pękala P et al. 2017. Risk of iatrogenic injury to the infrapatellar branch of the saphenous nerve during hamstring tendon harvesting: A meta-analysis. Muscle & Nerve.
- Sabat D et al. 2013. Nerve injury during hamstring graft harvest: a prospective comparative study of three different incisions. Knee Surgery, Sports Traumatology, Arthroscopy.
- Wiggins AJ et al. 2016. Risk of Secondary Injury in Younger Athletes After Anterior Cruciate Ligament Reconstruction. The American Journal of Sports Medicine.
- Getgood A et al. 2020. Lateral Extra-articular Tenodesis Reduces Failure of Hamstring Tendon Autograft Anterior Cruciate Ligament Reconstruction: 2-Year Outcomes From the STABILITY Study Randomized Clinical Trial. The American Journal of Sports Medicine.
- van Melick N et al. 2016. Evidence-based clinical practice update: practice guidelines for anterior cruciate ligament rehabilitation based on a systematic review and multidisciplinary consensus. British Journal of Sports Medicine.
- Grindem H et al. 2016. Simple decision rules reduce reinjury risk after anterior cruciate ligament reconstruction. British Journal of Sports Medicine.
- Choudhary A et al. 2026. Hamstring muscle strength recovery remains incomplete at 2 years after harvest for ACL reconstruction and does not correlate with radiological tendon regeneration at 6 months: A prospective study. Knee Surgery, Sports Traumatology, Arthroscopy.
- Sharma A et al. 2016. Does Gracilis Preservation Matter in Anterior Cruciate Ligament Reconstruction? A Systematic Review. Arthroscopy: The Journal of Arthroscopic and Related Surgery.
Frequently Asked Questions
Do the hamstring tendons grow back after being harvested?
Often, at least partly. In one study of 48 people, MRI scans six months after surgery showed complete regrowth of tendon tissue in half and none in about 3 in 10.[14] Strength recovery was similar whether or not the tendon regrew, and bending strength reached about 84% of the other leg at two years. Ongoing hamstring exercise still matters, even when the tendon regrows.
Does the type of graft affect my risk of arthritis later?
Current evidence suggests not. In trials that followed people for about 15 years, arthritis progressed at a similar rate after hamstring and patellar tendon grafts.[2] However, reconstructed knees were about 3.6 times as likely to show arthritis progression as the person’s other knee, whichever graft was used.
Will I get back to my previous level of sport?
Many people do, but not everyone. Across studies of athletes, about 80% returned to some sport and about 55% returned to their pre-injury level, with no significant difference between hamstring and patellar tendon grafts.[6] Whether you return to your previous level depends on your knee, your rehabilitation and your own goals.
Does it matter whether one or two hamstring tendons are taken?
Sometimes only the semitendinosus tendon is used, and sometimes the gracilis is taken as well to make a thicker graft. A review of 12 studies found that taking both tendons caused slightly more weakness when the knee is bent deeply (about 4% in standard strength testing, and up to about 14% at 105 to 110 degrees of bending).[15] There was no difference in knee stability or patient-reported outcomes, so the choice depends mainly on how thick a graft is needed.
Wondering which ACL graft would suit your knee?
Dr Vishal Pai’s practice includes sports knee surgery such as ACL reconstruction. If you have an ACL injury, a consultation is a chance to discuss whether reconstruction is right for you and, if so, which graft may suit your age, sport and work.
Written by Dr Vishal Pai
Vishal is an experienced knee surgeon based in Bayside, Melbourne. He consults at Sandringham Orthopaedic Specialists and operates at The Avenue Hospital and Calvary Holmesglen Private Hospital. His practice focuses on sports knee surgery, including ACL reconstruction and meniscal repair, as well as robotic knee replacement.