Part of ACL reconstruction rehab
Hamstring vs patellar tendon graft: what each one changes about ACL rehab
Warning signs, and when to get help
What each graft is, and where it is taken from
An ACL reconstruction does not stitch the torn ligament back together. It replaces it with a graft, usually a piece of your own tendon, held in place by the fixation your surgeon used while your body rebuilds it into something more ligament like (NHS, OrthoInfo).
A hamstring graft is taken from one or two of the tendons that run down the back and the inner side of your thigh to the knee, the semitendinosus and usually the gracilis with it (Högberg and colleagues, 2026). A patellar tendon graft is taken from the middle of the tendon that runs from your kneecap down to your shin bone, usually with a small block of bone at each end, one from the kneecap and one from the shin. Both leave a second site in your leg that is healing at the same time as the knee, and that second site is where almost every difference between the two comes from.
So there are two healing jobs after this operation, not one. The graft inside the knee is being rebuilt, a process called ligamentization that takes months and that you cannot feel, and the place the tendon came from is also knitting back together. Biopsy studies in people confirm the graft goes through stages but do not agree on how long each stage takes (Claes and colleagues, 2011), which is part of why these programs run on tests rather than on how the knee feels. The first one governs when you can load the knee. The second governs which exercises get held back, and it is the one the rest of this page is about.
If your operation is still ahead and you are wondering what to ask, ACL reconstruction rehab sets out the whole program and where graft type changes it.
What does graft choice change about rehab?
The short answer: which exercise is held back, and which part of the knee is the slow one to recover.
After a hamstring graft, the exercises that make the hamstring pull against resistance are the ones that wait. The position on the main program is this, and it is the same here on purpose: start the hamstring curl and the bridges only when your surgeon or physio says you can, and expect the curl itself to wait, because the guidelines that give a date for bending the knee against resistance after this graft put it at week 6 for a held contraction and week 8 for a moving one (Briem and colleagues, 2026). Keep all added resistance off the hamstring, and read the 4 week mark as the point below which loading has been reported to tear the healing tendon rather than as the date you may start adding it: weight goes on at 12 weeks unless your own team gives you an earlier date. Stop a bridge or a curl if you feel a sudden sharp pain, a pull or a cramp at the back of the thigh.
The later dates are the ones people come looking for. Hopping and jumping have a later date again after this graft, at least 16 weeks unless your surgeon or physio clears them earlier, because the place the tendon came from is still rebuilding (Briem and colleagues, 2026). For the weighted version, expect it later than the rest of the single leg stage.
The same chart of the published guidelines shows some of the ones carrying hamstring graft advice holding flexor strengthening back for the first 6 to 8 weeks (Briem and colleagues, 2026), while a narrative review of hamstring harvest reads the same evidence as inconclusive between 4 and 12 weeks, with resisted work recommended only after 12 weeks (Högberg and colleagues, 2026). So unless your own team has given you an earlier date, treat 12 weeks as the point where weight gets added. Advice on the timing genuinely varies between teams, because the evidence is unclear: that same narrative review describes programs that loaded earlier without reported harm, which is why your own team's date comes first.
In practice that means the unweighted standing hamstring curl comes first, the standing hamstring curl with a weight comes later than you would expect, and the eccentric hamstring curl is a late addition that your physio introduces, not one you add yourself.
People read the hamstring hold as a ban on using the leg at all, so be clear about what is actually held back. It is the exercises that make the hamstring pull against resistance on its own, not every movement the muscle takes part in. The Aspetar guideline says a leg press may be started as early as 3 weeks after a hamstring graft, in a shallow range like a half squat, with pain at the front of the knee watched as the load goes up (Kotsifaki and colleagues, 2023), and the strengthening on both legs in the early stages carries on as usual. Your own team still sets your dates for all of it.
Expect the back of the thigh to be worked in more than one position once loading does start. The narrative review of hamstring harvest proposes loading the knee flexors across a range of hip and knee angles instead of in one seated position, bringing in eccentric work as the strengthening progresses, and testing strength with the hip bent and with the hip straight, because a seated test on its own can make the remaining deficit look smaller than it is (Högberg and colleagues, 2026). If your physio tests you lying face down as well as sitting, or has you doing hamstring work with the hip straight, that is why.
After a patellar tendon graft, nothing is held back at the back of the thigh and the problem moves to the front. What needs protecting instead is the harvest site itself. The tendon and the bone it was taken from are weaker for a while where the graft came out, which is where a patellar tendon can tear or a kneecap can break (OrthoInfo), so kneeling straight down onto that site and falling onto the front of the knee are the two things to keep away from. Ask your surgeon how long that applies to you, because the answer depends on how much tendon and bone was taken and on how your knee is healing.
Pain at the front of the knee is common and pain on kneeling is often more common too (OrthoInfo), the front of the thigh is usually slower to switch on properly, and full straightening needs watching: the pooled trial data found a statistically significant loss of extension range with this graft (Mohtadi and colleagues, 2011). That makes quad sets and the terminal knee extension the two to be fussy about, and it makes anterior knee pain something to report rather than push through. The Aspetar guideline asks clinicians to adjust the load when it appears. In the first weeks your physio may also spend time on how freely the kneecap itself moves: in the scoping review's chart of published guidelines, the advice written for this harvest site is aimed at a stiff kneecap and pain at the front of the knee, and progressive kneecap mobilizing is one of the things it names (Briem and colleagues, 2026).
There is one exercise where the graft really does change the timing, and it runs the opposite way round from what most people guess. Straightening the knee against a weight at the ankle, sitting down, was tested in a trial that randomized 68 patients to start it at week 4 or week 12. The people with a hamstring graft who started at week 4 ended up with slightly looser knees than both the hamstring graft late group and the patellar tendon early group, and patellar tendon grafts showed no such difference (Heijne and Werner, 2007). The authors said their results could not determine the right starting time. Some teams hold that exercise back after a hamstring graft because of it, and that is a reasonable reading, not a rule.
The same trial is the clearest evidence for the point this whole section rests on: which muscle stays weak followed the graft rather than the exercise timing. Both hamstring graft groups still had less hamstring strength at 7 months than before their operation, whichever week they started, and the patellar tendon group that started early was the only one whose thigh strength had not got back to where it was (Heijne and Werner, 2007).
A meniscus or cartilage repair done in the same operation overrides all of this. If one was, get your surgeon's go-ahead before deep or loaded bending, before kneeling, and before any hopping or twisting, because those limits often run for months after a repair and are lifted later than the ones on walking.
Donor site symptoms, and what settles
Expect symptoms where the tendon was taken. They differ depending on which graft you had, and most of them fade slowly instead of stopping on a particular week.
After a hamstring graft, the back of the thigh is often tight, tender and oddly weak feeling for the first weeks, and some people get cramping when it is first loaded. The harvested tendons do grow back in most people, in roughly 70 to 86% of cases, but the muscle they belong to is changed by the harvest: it can be smaller, the tendon longer, the junction between muscle and tendon sitting higher up the thigh, and those changes can still be there years later (Högberg and colleagues, 2026). That range covers both tendons together, and they do not fare the same: one review inside it found regrowth in about 79% of semitendinosus tendons against about 43% of gracilis tendons, and regrowth looks less likely with older age and in people who smoke (Högberg and colleagues, 2026). That is why the back of the thigh gets its own attention for months, not weeks.
The narrative review of what harvesting the tendon does describes consequences for the muscle itself and for function, and it reports that the timing of knee flexor strengthening is unclear. That review, reading the scoping review's chart of the published guidelines, puts dynamic flexor loading as something to avoid in the first 4 weeks, unsettled between 4 and 12 weeks and recommended after 12, with isometric knee bending started from week 6 (Högberg and colleagues, 2026, reading Briem and colleagues, 2026). The chart itself shows some guidelines beginning resisted knee bending at week 8, so the weeks between those two numbers are where teams differ, not a stretch where nothing happens at the back of the thigh. The symptom to report rather than train through is a sudden sharp pain at the back of the thigh during loaded work, because the same review cites case reports of exactly that after aggressive loading in the first 3 to 4 weeks.
After a patellar tendon graft, the front of the knee is the sore area and kneeling is the activity most people notice it with. A patch of numb skin next to a scar is common after both grafts, not this one alone, because small skin nerves run across the places the cuts are made. OrthoInfo describes numbness of the outer part of the upper leg next to the incision as not uncommon, and says it may be temporary or permanent.
Neither of those is the same as the warning signs. A sudden loss of your ability to straighten the knee or lift the straight leg, especially after a pop or a stumble, or a dip or gap you can feel just above or below the kneecap, is a same day call, and it is on the list at the foot of this page because the tendon or the kneecap near where a graft was taken can rarely tear or break.
If pain at the front of your knee is the dominant problem months later, patellar tendinopathy covers that tendon in its own right, and knee pain when squatting covers the movement that provokes it. For the back of the thigh, hamstring strain and hamstring tendinopathy are the two that describe its own problems, although a harvested tendon is not the same thing as either and your physio is the one to tell the difference.
Is one graft stronger or safer?
On the outcomes most people care about, the trials say the two are broadly similar, and the differences that do show up are in the detail, not in the headline.
The Cochrane review pooled 19 randomized or quasi-randomized trials in 1,597 young to middle aged adults. It found no significant difference between patellar tendon and hamstring grafts in single leg hop testing, in return to activity, in Tegner and Lysholm scores, in IKDC scores, in re-rupture, or in patient reported outcomes. Where it did find differences: patellar tendon grafts gave more stable knees on all the static stability tests, and came with more problems at the front of the knee, particularly kneeling. Patellar tendon grafts showed a statistically significant loss of extension range with a trend toward reduced extension strength, and hamstring grafts a trend toward reduced flexion range with a statistically significant loss of flexion strength (Mohtadi and colleagues, 2011).
There are limits on how far that can be read. Many of the included trials were judged at high risk of bias, mainly over randomization, blinding and incomplete outcome assessment. The reviewers said there was insufficient evidence to draw firm conclusions about long term function, and that the long term data were too limited to say anything about osteoarthritis. And they noted that the clinical importance of those range of motion losses is unclear, which is a reminder that a statistically significant difference on a goniometer is not automatically something you would notice.
The population matters too. The review only accepted trials in skeletally mature adults, so it describes young to middle aged people whose bones had finished growing, which is not the same as a 55 year old having a revision, or someone whose meniscus was repaired at the same time. In a child or teenager still growing, graft choice is decided on different grounds again, because the growth plates sit close to where the tunnels and the fixation go and OrthoInfo names growth plate injury as a risk of reconstruction at that age.
The AAOS guideline recommendation on which of your own tendons to use is written for skeletally mature patients only, and the guideline makes no recommendation about which autograft to use in a knee that is still growing (Brophy and Lowry, 2023). Nothing here is a guide to that decision. A pooled result from trials describes the average of a group that may not include anyone much like you.
The age of that evidence matters as well. The Cochrane searches ran to April 2008, so the trials in it predate much of what is done now. The most recent pooled look at young athletes, 30 studies and 5,871 people, 1,684 with a patellar tendon graft and 4,187 with a hamstring graft, reported a return to sport rate of 73.8% and a re-rupture rate of 4.2% across the whole group.
Patellar tendon grafts came out with higher return to sport, higher return to the preinjury level and a lower re-rupture rate, and none of those differences reached statistical significance (Mocini and colleagues, 2026). Newer data, same answer: a direction some surgeons weigh when they operate on a young athlete, not a result that decides the question. This is one of the places surgeons do differ, and that is a difference of judgement rather than one of them being wrong.
The guideline that sits over all of this does separate the two grafts, and how it does that is the part to read closely. The American Academy of Orthopaedic Surgeons guideline on managing ACL injuries says that when an ACL reconstruction is done with your own tissue, in a patient whose bones have finished growing, surgeons may favor a bone-patellar tendon-bone graft to reduce the risk of graft failure or infection, or a hamstring graft to reduce the risk of pain at the front of the knee or on kneeling. Its strength of recommendation is Moderate, which the guideline defines as meaning the benefits exceed the potential harm while the quality or applicability of the evidence is not as strong, and that grade was reached by downgrading (Brophy and Lowry, 2023).
The recommendation points both ways at once, and which way it points for you depends on which risk you and your surgeon would rather spend. So this is not the same statement as the trials finding no significant difference, and both statements can hold: the trials asked whether average outcomes differed and could not show that they did, while the guideline asks what a surgeon should do with one specific risk in mind. Graft failure and infection on one side, pain at the front of the knee and kneeling on the other, is the clearest summary of this whole page.
Does graft choice change when you run or go back to sport?
Not the gates themselves. Possibly which gate is slow for you.
The first run is decided by criteria rather than by a date, and the criteria are the same whichever graft was used: a knee that straightens fully and bends at least 95% as far as the other one, no more than a trace of swelling, thigh strength and a jump measure each more than 80% of the other leg, and pain free hopping on the spot on one leg. Most of the studies the Aspetar guideline reviewed also set a minimum of about 12 weeks after surgery. ACL return to running goes through all of that.
Where the graft can show is in which criterion holds you up. Thigh strength is one of the gates, and the front of the thigh is the slower recovery after a patellar tendon graft, so that is the item worth testing early and often. Hamstring strength is also tested before a return to sport, and after a hamstring graft it is loaded later, so there is less time to build it. ACL return to sport testing sets out the battery and who runs it.
The overall arc does not change. Rehab after an ACL reconstruction carries on for 9 to 12 months (van Melick and colleagues, 2016), and in the Grindem study of 106 people playing pivoting sports the rate of injuring the knee again fell by about half for each month the return was delayed, up to 9 months (Grindem and colleagues, 2016). That is the same for both grafts. For how the exercises are staged, see ACL rehab exercises by phase.
Who chooses the graft, and on what
Your surgeon, with you, and it is one of the decisions where saying what your week actually looks like changes the answer.
This page does not recommend a graft and should not be read as leaning toward one. The reason is not politeness. It is that the evidence separates them on particular risks rather than on how well people end up doing, graft failure and infection on one side and pain at the front of the knee and on kneeling on the other (Brophy and Lowry, 2023), so the choice turns on things that are specific to you and to the person operating: what your knee looks like inside, whether anything else needs repairing, whether this is a first reconstruction or a revision, what you need to be able to do afterward, and what your surgeon has the most experience with. That last one is a legitimate factor and not a cop out.
Raise two things before the decision is made, because they are the ones most often missed. If your job, your sport or your religious practice involves a lot of kneeling, say so, because kneeling discomfort is the symptom most consistently linked to a patellar tendon graft. And if you already have a hamstring problem, or your sport is heavily hamstring dependent, say that too.
Then ask three questions and write the answers down: which graft, why that one for my knee, and what does it change about the first 3 months. If the answer to the third is vague, ask your physio the same question, because it is their plan it changes.
A quadriceps tendon graft or a donor graft, in short
Both exist, both are used, and neither is in most of the evidence above.
The quadriceps tendon, above the kneecap, is one of the autograft options OrthoInfo lists. It groups the harvest site risks at the front of the knee as failure of the straightening mechanism: a broken kneecap after either a patellar tendon or a quadriceps tendon graft, and a torn patellar tendon after a patellar tendon graft, both from the tissue being weakened where the graft was taken. Our warning sign for a sudden loss of straightening covers that, and the parent program carries the same line. Hopping and jumping have a date attached to that harvest site as well: at least 16 weeks after surgery unless your surgeon or physio has cleared them earlier, because the place the tendon was taken from is still rebuilding (Briem and colleagues, 2026). The Cochrane review compared patellar tendon with hamstring only, so it does not tell you how a quadriceps tendon graft compares with either.
A donor graft, called an allograft, avoids taking tissue from your own leg, and this is the one place the guideline is firm about graft choice. The AAOS guideline says that in an ACL reconstruction, surgeons should prefer a graft from your own body to a donor one, because that improves outcomes and brings the rate of graft failure down, and it points particularly at young or active patients. It grades that Strong, its highest level, which it defines as meaning practitioners should follow it unless a clear and compelling rationale for an alternative approach is present (Brophy and Lowry, 2023). So a donor graft is not a tidier version of the same operation. Its own wording, particularly in young and or active patients, also tells you where that concern is strongest, which is part of why a surgeon may weigh it differently for an older or less active knee, or for a knee that needs more than one graft at once.
OrthoInfo lists patellar, Achilles, semitendinosus, gracilis and posterior tibialis tendons among the options, and is direct about the trade-off: despite careful screening and processing, a donor graft carries a risk of passing on a virus, including HIV and hepatitis C. The figure it gives is about the donor, not about you, and it is worth reading precisely: the chance of a bone allograft coming from an HIV infected donor is calculated at less than 1 in 1 million. It also reports deaths linked to bacterial infection from allograft tissue where the tissue was taken or sterilized improperly. Those are the facts as that page states them. What they mean for a particular knee, and why a surgeon might still choose it, is a conversation with the surgeon.
If something feels wrong at any point after your operation, whichever graft you had, ACL surgery complications sorts the warning signs by how fast to act.
This page is education rather than advice about your own knee. Your surgeon chose or will choose your graft, your physiotherapist sets your program around it, and nothing here overrides either.
Related exercise programs
Warning signs
Get emergency help now
- Emergency: sudden, severe pain in your lower leg that is much worse than you would expect, especially with a tight bandage or brace on the leg. It may come with a tight, swollen leg, pain that gets worse when the muscle is stretched, numbness, pins and needles or weakness. Call emergency services or go to an emergency department straight away, and do not drive yourself. This can be acute compartment syndrome, which needs urgent surgery.
- Emergency: since your operation, you suddenly become short of breath, you get chest pain or pain in your upper back that may be worse when you breathe in, you cough up blood, your heart is beating very fast, or you faint. Call emergency services straight away, even if your leg looks normal. These can be signs of a blood clot in the lungs (pulmonary embolism).
Get help today
- Same day: a calf or thigh that is newly swollen or getting more swollen, warm, tender, red or darker than usual, has swollen veins that are sore to touch, or has a throbbing or cramping pain that does not fit your injury or condition, or that feels different from normal muscle soreness after exercise. This can be a sign of a blood clot (deep vein thrombosis), especially after surgery, an injury, time in a cast or boot, a long trip or a spell of being much less mobile than usual. Get medical advice the same day. If you are also short of breath or have chest pain, call emergency services.
- Same day: since your operation, your wound is oozing, leaking or has pus coming out of it, or its edges start to come apart, or your knee is tender, swollen, painful or red and it is not getting better or is getting worse, or you have a high temperature or feel hot and cold or shivery. Redness can be harder to see on brown or black skin. Contact your surgical team the same day, or get urgent medical advice if you cannot reach them. These can be signs of an infection in the wound or the knee joint. If you feel very unwell, go to an emergency department. If you have a very high or very low temperature, shivering you cannot control, you are breathing very fast or finding it hard to breathe, you are confused or your speech is slurred, your skin, lips or tongue look blue, gray, pale or blotchy (on brown or black skin this can be easier to see on the palms of the hands or soles of the feet), or you have a rash that does not fade when you press it, call emergency services, as this can be sepsis.
- Same day: your knee swells up quickly over a few hours and feels tight and full, with more pain than the day before, and there was no fall, twist or pop to explain it. This can happen while your temperature is normal and the wound looks fine. Contact your surgical team the same day, or get assessed the same day at urgent care or an emergency department if you cannot reach them. Bleeding into the joint and an early infection inside the joint can both look like this from the outside, and a knee that is hot to touch, or a temperature alongside it, makes an infection more likely. Do not wait for a call back if either is there. If you feel very unwell, go to an emergency department.
- Same day: your knee gives way, or you feel a pop, a shift or a twist inside it, and it swells up within a few hours or is very painful. Keep your weight off it and contact your surgical team, or get assessed the same day at urgent care or an emergency department. A fall or a twist can damage the new ligament (graft) or a meniscus repair. If the knee looks out of shape, or your foot turns numb, cold or pale, go to an emergency department straight away, and do not drive yourself. If the knee only feels a little unsteady now and then, with no swelling or pain, it is not an emergency, but tell your physio or surgeon in the next few days.
- Same day: the knee is locked, which means it is stuck bent and you cannot straighten it, even after gently trying to move it, or it suddenly will not bend or straighten as far as it did before. Contact your surgical team, or get assessed the same day at urgent care or an emergency department. A torn piece of meniscus can get caught in the joint and block it. This is different from the slow, gradual stiffness of the early weeks.
- Same day: you suddenly cannot straighten your knee by yourself or lift your leg straight when you could before, often after a pop, a fall or a stumble, or you notice a dip or a gap just above or below your kneecap. Keep your weight off it and contact your surgical team, or get assessed the same day at urgent care or an emergency department. After a patellar tendon or quadriceps tendon graft, the tendon or the kneecap near where the graft was taken can rarely tear or break.
- Same day: a leg or foot that is getting weaker, for example your foot drags, catches on the ground or slaps down when you walk (foot drop). Get medical advice the same day. If the weakness is getting worse by the hour, go to an emergency department.
- Same day: new numbness, tingling or burning in your lower leg or foot, beyond the numb patch of skin near your scars. Contact your surgical team or get medical advice the same day. If it started after a fall or an injury, or your foot or toes turn cold, pale, blue or gray, call emergency services or go to an emergency department straight away, and do not drive yourself.
Book an appointment
- Within a few days: your knee still will not straighten as far as the other one, or bend as far as your physio expects, and it is not improving from week to week, or it is slowly losing movement it had. This is not an emergency, but contact your physio or surgeon within the next few days. Tell them if the knee feels blocked right at the end of straightening, or clunks or hurts there, rather than simply feeling tight, and tell them if it stops short of straight in the months after your operation. A small lump of scar tissue at the front of the knee (a cyclops lesion) can block the last few degrees, and when it does it usually shows up 3 to 6 months after surgery. It is uncommon, most surgeons treat it first with rehab aimed at straightening, and a short keyhole operation to remove it is kept for a knee that stays stuck (D'Ambrosi and colleagues, 2026). Stretching harder is not the answer either way. Getting the knee fully straight is one of the first aims of rehab.
Common questions
Which ACL graft is better, hamstring or patellar tendon?
The research does not settle it, which is why surgeons differ and why this page will not pick one for you. The Cochrane review of 19 randomized and quasi-randomized trials, 1,597 young to middle aged adults, found no significant difference between the two grafts in single leg hop testing, return to activity, Tegner and Lysholm scores, IKDC scores, re-rupture or patient reported outcomes. It did find differences in the detail: patellar tendon grafts produced more stable knees on the static stability tests, and more problems at the front of the knee, especially with kneeling. Patellar tendon grafts showed a statistically significant loss of extension range, and hamstring grafts a statistically significant loss of flexion strength. The reviewers rated many of the trials at high risk of bias and said there was not enough evidence for firm conclusions about long term function (Mohtadi and colleagues, 2011). The AAOS guideline goes further than the trials and names the trade-off as a recommendation: in a patient whose bones have finished growing, surgeons may favor a bone-patellar tendon-bone graft to reduce the risk of graft failure or infection, or a hamstring graft to reduce the risk of pain at the front of the knee or on kneeling, at Moderate strength (Brophy and Lowry, 2023). That still is not a winner, because it points in both directions. It does tell you what the choice is actually being made about.
Does a hamstring graft weaken the hamstring?
There is a measurable effect at the harvest site. The harvested tendons grow back in roughly 70 to 86% of cases, and even then the muscle is left altered: smaller, with a longer tendon and the join between muscle and tendon sitting higher up the thigh, and those changes can persist for years (Högberg and colleagues, 2026). The same review notes that one test position is not enough to judge the recovery, because a seated test can make the deficit look smaller than it is, so strength is better checked with the hip bent and with the hip straight. What that means for you in practice is less about weakness you will notice walking and more about how the back of the thigh is trained later. Resisted hamstring work is held back early while the site heals, then built deliberately, and the strength tests before a return to sport include the hamstring for that reason. Tell your physio about any pulling, cramping or sharp pain at the back of the thigh when loaded work starts, because the same review cites case reports of sudden sharp pain after aggressive loading in the first 3 to 4 weeks.
Why does the front of my knee hurt after a patellar tendon graft?
Because that is where the graft came from. OrthoInfo says pain at the front of the knee is common after a patellar tendon graft, and that pain when kneeling is often more common too. The Cochrane review found the same pattern pooled across trials: more anterior knee problems with a patellar tendon graft, especially on kneeling (Mohtadi and colleagues, 2011). The Aspetar guideline asks clinicians to adjust the load when anterior knee pain appears rather than to push through it, so this is worth reporting rather than enduring. Pain that is settling week by week is the expected course. Pain that is building, or a sudden loss of your ability to straighten the knee against gravity, is in the warning signs on this page instead.
Can I kneel again after an ACL graft?
Usually, and it often takes longer and feels stranger after a patellar tendon graft. Kneeling discomfort is the symptom most consistently reported more often with that graft, both on OrthoInfo and in the pooled trial data (Mohtadi and colleagues, 2011). Timing is not ours to give: if a meniscus or cartilage was repaired in the same operation, kneeling and deep bending are held until your surgeon lifts the limit, and those limits often run for months and are lifted later than the ones on walking. Ask your surgeon directly about kneeling if your job or your prayer practice needs it, and ask early, because it is one of the few questions where the answer can influence which graft is used.
Does graft choice change the ACL recovery timeline?
It changes the order of some things rather than the length of the whole. Rehab after an ACL reconstruction carries on for 9 to 12 months whichever graft was used (van Melick and colleagues, 2016), and the gates between stages are tests rather than dates. What the graft changes is which test is slow for you: a patellar tendon graft tends to make the front of the thigh and full straightening the limiting items, and a hamstring graft puts resisted hamstring loading behind a hold of at least 4 weeks, with 12 weeks the default point at which weight is added unless your own team gives you an earlier date (Briem and colleagues, 2026; Högberg and colleagues, 2026). Both of those can move an individual date without moving the overall span. Your surgeon's protocol is the one that counts.
What about a quadriceps tendon graft or a donor graft?
Both are used, and neither was in the comparison most of the evidence on this page comes from. The Cochrane review compared patellar tendon with hamstring only, so it does not answer the quadriceps tendon question at all (Mohtadi and colleagues, 2011). On donor grafts the AAOS guideline is firm: it asks surgeons to prefer a graft from your own body over a donor one, for better outcomes and a lower rate of graft failure, particularly in young or active patients, graded Strong (Brophy and Lowry, 2023). That is a reason to ask why an allograft is being proposed, not a reason to refuse one, because there are knees where a surgeon has good grounds for it. OrthoInfo lists the quadriceps tendon among the autograft options and names a broken kneecap at the harvest site as a possible complication of it, the same complication it lists for a patellar tendon graft. It lists donor grafts including patellar, Achilles, semitendinosus, gracilis and posterior tibialis tendons, with a risk of passing on a virus such as HIV or hepatitis C despite screening and processing, and with deaths linked to bacterial infection from tissue that was taken or sterilized improperly. If your surgeon has proposed one of these, ask why for your knee specifically, and ask what it changes about the first 3 months.
References
- Mohtadi NG, Chan DS, Dainty KN, Whelan DB. Patellar tendon versus hamstring tendon autograft for anterior cruciate ligament rupture in adults. Cochrane Database of Systematic Reviews. 2011;(9):CD005960. https://doi.org/10.1002/14651858.CD005960.pub2
- Brophy RH, Lowry KJ. American Academy of Orthopaedic Surgeons Clinical Practice Guideline Summary: Management of Anterior Cruciate Ligament Injuries. Journal of the American Academy of Orthopaedic Surgeons. 2023;31(11):531-537. https://doi.org/10.5435/JAAOS-D-22-01020
- Mocini F, Corona K, Mercurio M, et al. Return to Sport After ACL Reconstruction: Hamstring Tendons vs Patellar Tendon A Systematic Review and Meta-analysis. Sports Medicine and Arthroscopy Review. 2026. https://doi.org/10.1097/JSA.0000000000000457
- Högberg J, Wernbom M, Hamrin Senorski E. Can we rebuild what has been taken? A narrative review of biological and functional consequences of hamstring tendon harvest in ACL surgery. Science Progress. 2026;109(3):00368504261461371. https://doi.org/10.1177/00368504261461371
- Briem K, Zebis MK, Haraldsson BÞ, Bencke J, Fernandes L. Rehabilitation guidelines after autograft anterior cruciate ligament reconstruction need more graft-specific exercise recommendations: A scoping review. Knee Surgery, Sports Traumatology, Arthroscopy. 2026;34(1):83-101. https://doi.org/10.1002/ksa.12666
- Heijne A, Werner S. Early versus late start of open kinetic chain quadriceps exercises after ACL reconstruction with patellar tendon or hamstring grafts: a prospective randomized outcome study. Knee Surgery, Sports Traumatology, Arthroscopy. 2007;15(4):402-414. https://doi.org/10.1007/s00167-006-0246-z
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Written and checked by the PocketPhysio editorial team. Last updated 2026-10-24.
This page is general education, not a diagnosis or a personal treatment plan. See a physiotherapist or doctor for advice about your own situation.