Your surgeon offers you three main ACL graft choices: hamstring tendon, patellar tendon (BPTB), or quadriceps tendon. They're not equivalent. The choice affects your rehab, your re-tear risk, your strength recovery curve, and what kind of donor-site pain you carry. Here's what the choice actually means from a physio's point of view.
What an ACL graft is, plainly
When you tear your ACL, the ligament can't be sewn back together reliably. Instead, the surgeon takes a piece of tendon from elsewhere in your body (or, less commonly, from a donor) and uses that tendon to rebuild the ligament. They drill tunnels through your thigh bone and shin bone, thread the new graft through, and fix it at each end. Over the next 12 to 18 months that tendon biologically reshapes itself into something that behaves like a ligament. This process is called ligamentisation.
The choice of which tendon to use is the "graft type" decision. The three common options in Australia are hamstring, patellar tendon, and quadriceps tendon. Each has trade-offs.
Hamstring tendon graft (semitendinosus/gracilis)
This is the most common graft in Australia. The surgeon takes the semitendinosus tendon (one of your inner hamstrings), often combined with the gracilis, and uses that.
Pros: Smaller incision, less anterior knee pain post-op, generally easier to kneel on later in life. Good strength to weight characteristics.
Cons: Hamstring strength deficits that can persist for years if rehab is undercooked. Slightly higher re-tear rate in young athletes (under 25) compared to BPTB in some studies. Some athletes report ongoing sense of hamstring "weakness" or cramping.
Rehab implications: Hamstring rehab is the priority through months 2 to 6. Nordic curls, Romanian deadlifts and isolated hamstring loading have to be programmed deliberately. If you've had a hamstring graft and your physio isn't testing hamstring strength specifically, that's a gap.
Patellar tendon graft (BPTB, bone-patellar tendon-bone)
The "gold standard" for high-level athletes for many years. The surgeon takes the middle third of your patellar tendon (the tendon connecting your kneecap to your shin) along with small bone plugs at each end.
Pros: Bone-to-bone healing at the tunnel ends, which is faster and stronger initial fixation. Historically lower re-tear rates in young pivoting athletes. Many elite contact-sport athletes still choose BPTB for this reason.
Cons: Anterior knee pain (kneecap-area discomfort) post-op, which can persist. Difficulty kneeling for years. Risk of patellar tendinopathy. Slightly higher rate of patella fracture (rare but real).
Rehab implications: Quad inhibition is severe in the first 6 weeks. Patellar tendon loading needs to be progressive. Kneeling-based exercises get reintroduced cautiously, sometimes never fully. Patients in jobs requiring kneeling (tradies, tilers, gardeners) need to factor this in.
Quadriceps tendon graft
Becoming more popular over the last 5 to 10 years. The surgeon takes a strip from the quadriceps tendon just above the kneecap.
Pros: Large, strong graft. Less donor-site pain than BPTB. Less hamstring weakness than hamstring graft. Increasingly competitive re-tear rates in athletic populations. Particularly useful in revision surgery (when an ACL has been done before).
Cons: Quad weakness early post-op can be more severe than other grafts, because you've literally cut into the muscle that drives knee extension. Newer technique, so long-term outcome data is less mature than hamstring or BPTB.
Rehab implications: Aggressive quad activation in the first 2 weeks is non-negotiable. NMES (electrical muscle stimulation) is more often indicated. Open-chain knee extension is often introduced later than with other grafts because of the donor-site healing.
Allograft (donor tendon)
Less common in Australia. Tissue from a deceased donor. Used most often in older patients or revision cases where autograft tissue has already been used.
Pros: No donor-site morbidity (no other part of your body has been operated on).
Cons: Slower ligamentisation, higher re-tear rate in young active patients (which is why it's rarely used in under-30 athletes). Small infection risk.
Re-tear rates: the honest comparison
Across the literature, in young athletes returning to cutting and pivoting sport, re-tear rates broadly track like this: BPTB and quad tendon around 8 to 12 percent, hamstring around 12 to 18 percent, allograft 20 percent or higher. These are rough averages. The single biggest variable in re-tear risk is not which graft you got, it's whether you completed objective return-to-sport criteria before going back. A well-rehabbed hamstring will outperform an undercooked BPTB every time.
The graft choice is a surgical decision. The re-tear risk is a rehab decision. Don't confuse the two.
Which graft should you choose?
That conversation happens between you and your orthopaedic surgeon, and it depends on your sport, your age, whether you can tolerate kneeling, whether you've had a previous ACL, and the surgeon's preference. As physios we don't make this decision. What we do is build a rehab programme that accounts for whatever graft you've got, target the specific weaknesses that graft creates, and get you to objective return-to-sport criteria regardless of which tendon ended up in your knee.
What to bring to your physio
When you start ACL rehab with us, bring your surgical notes if you can. We want to know: graft type, fixation method (screws, suspensory buttons), any meniscus or cartilage work done at the same time, and any specific weight-bearing or range-of-motion restrictions your surgeon has set. Those details shape the first 12 weeks of your rehab. If you don't have the notes, we can request them from your surgeon's rooms.