Both grafts perform equally well long-term — so why does choice still matter?

Patients often arrive at a graft consultation asking whether the patellar tendon option is stronger or more reliable. The short answer, drawn from the best available long-term data, is that it makes less difference than most people expect. A 2025 meta-analysis pooling six randomised controlled trials (n=495, mean follow-up 14.6 years) found no statistically significant differences between bone-patellar tendon-bone (BPTB) and hamstring tendon autografts in graft rupture rate, revision rate, Lysholm functional score, Tegner activity score, or KT-1000 laxity measurements. An earlier review of 19 RCTs involving 1,597 adults reached the same conclusion at shorter follow-up periods. By the most rigorous measures available, both grafts hold up comparably over time.

One finding is worth raising clearly in any pre-operative conversation: both graft types are associated with significantly greater osteoarthritis progression in the reconstructed knee compared with the contralateral, uninjured knee — with a relative risk of 3.64 (p<0.0001) — and neither graft confers an advantage here. This is not a reason to avoid reconstruction, but it informs realistic expectations about long-term joint health.

Equivalence at the population level, however, does not mean the two options are interchangeable for every individual. Patient anatomy, sport and activity demands, tolerance for specific donor-site effects, and surgeon experience all shift the balance in ways that the aggregate data cannot capture. Some subgroups — including younger female athletes and those returning to high-contact pivoting sport — lack dedicated long-term RCT data that would confirm the same equivalence holds for them specifically. The practical question, therefore, is not which graft performs better overall, but which is the better fit for a particular patient's circumstances.

How each graft is harvested and fixed

Knowing what happens in theatre helps make sense of why the two grafts have different recovery timelines — and why fixation biology has historically driven graft preference in high-demand athletes.

Bone-patellar tendon-bone (BPTB)

The surgeon takes the central third of the patellar tendon, leaving a strip roughly 10 mm wide. Crucially, a small block of bone is taken with it at each end — one from the lower pole of the patella, the other from the tibial tuberosity just below the knee. These bone plugs are then press-fitted and secured inside the femoral and tibial tunnels drilled during the arthroscopic procedure. Because the plugs sit bone-against-bone inside the tunnels, they heal by the same biological mechanism as a fracture: direct bony union. This process is generally considered reliable by around six weeks, giving the reconstructed ligament early structural security.

Hamstring tendon autograft

Here, one or two hamstring tendons — most commonly the semitendinosus, sometimes combined with the gracilis — are harvested through a small incision below the knee. The tendons are folded and bundled to create a multi-strand construct, but there are no bone plugs. Instead, the graft is held in place using cortical suspensory buttons (small metal implants anchored to the outer cortex of the femur or tibia) or aperture interference screws. Over the following months the tendon slowly remodels into a structure that resembles a ligament — a process called ligamentisation. This is simply the body gradually converting the tendon tissue into something functionally closer to the original ACL; it takes longer than bone-to-bone healing, which traditionally informed the more cautious early rehabilitation approach.

Modern hamstring fixation devices have substantially narrowed the historical concern about graft 'slippage' or early laxity: improved suspensory systems and larger-diameter graft constructs mean the early stability gap between the two techniques is considerably smaller than it once was.

Both procedures are performed arthroscopically; the open portion of each operation is limited to the harvest incision, which is positioned and sized differently for each graft.

Retear risk in young, high-demand athletes

The most practically significant difference between the two grafts — and the one that drives graft selection in elite sport — emerges in retear risk data rather than functional scores.

The MOON Knee Group's prospective registry, tracking over 3,500 ACL reconstructions across seven US institutions, consistently identifies patellar tendon autograft as carrying the lowest average retear risk among graft options. This advantage is most consequential for patients under 22 competing in pivoting or contact sports — the subgroup where a retear carries the heaviest burden: a second major surgery, a longer recovery, and cumulative cartilage exposure. It is worth noting that the six-RCT meta-analysis cited earlier showed a relative risk of 0.88 favouring BPTB for rupture (meaning roughly 12% fewer ruptures in the BPTB group), but with a p-value of 0.70 this did not reach statistical significance in that dataset. The MOON registry's directional signal, drawn from a far larger real-world cohort, provides the stronger practical signal for this subgroup.

Real-world clinical behaviour aligns with that data: a 2024 survey found 97% of NFL team physicians use BPTB exclusively for primary ACL reconstruction. That figure reflects expert preference shaped by years of registry observation, not a controlled trial.

The absolute retear difference — framed as the number of additional retears per 100 patients with one graft versus the other — varies across cohorts and study populations, which is precisely why the conversation is best had individually with the operating surgeon, who can apply current figures to a patient's specific risk profile.

One genuine evidence gap deserves honest acknowledgement: no head-to-head RCT has followed a specifically young-female cohort to long-term outcomes. Some observational data suggests hamstring grafts may carry a slightly higher retear risk in this group, but this evidence is not yet definitive. For these patients in particular, the choice warrants a direct conversation rather than a default.

Which patients suit each graft — a practical decision-aid

For many patients, the practical dividing line is not retear statistics alone but lifestyle — specifically, whether the knee will need to bear prolonged or repeated kneeling after surgery. Leading with that question often clarifies the decision more quickly than any outcome score.

When BPTB tends to be the stronger fit

Under-22 athletes returning to football, rugby, basketball, or other pivoting and contact sports represent the clearest BPTB indication; the retear-risk evidence underpinning this is set out in the preceding section. Beyond that profile, BPTB is also generally preferred where early graft security carries particular weight — for instance, athletes competing at a level where a second injury would be professionally significant.

Certain patients are steered away from BPTB regardless of sport. Skeletally immature individuals carry a risk of growth-plate disturbance at the patellar and tibial harvest sites. Those with pre-existing anterior knee pain or patellar tendinopathy may worsen those symptoms if the central third of the tendon is removed. And anyone whose occupation or regular activity involves frequent kneeling — tradespeople, wrestlers, or individuals whose religious practice includes floor-level prayer — faces a meaningful risk of persistent kneeling discomfort at the harvest site.

When hamstring autograft tends to suit better

Hamstring graft is favoured for patients with kneeling-dependent lifestyles, for smaller-framed individuals in whom patellar tendon width may not yield a graft of sufficient diameter (something assessed on preoperative imaging before a plan is confirmed), and for athletes whose sport does not depend on maximal hamstring output. The smaller incision and generally lower early anterior knee pain are also weighed by patients prioritising comfort in the early recovery period.

One caveat worth naming: some observational data suggests a slightly higher retear signal with hamstring grafts specifically in young female athletes, though this evidence is not yet definitive — making a direct individual discussion with the operating surgeon particularly important in that group.

A third option, the quadriceps tendon autograft, is an emerging alternative with a growing evidence base, though its comparison with BPTB and hamstring grafts falls outside the scope of this article.

Donor-site trade-offs both options carry

Every graft harvest leaves a gap in tissue and a set of donor-site symptoms the patient carries through recovery — independent of how well the reconstruction itself performs.

BPTB donor site

Anterior knee pain is the most consistently reported complaint. Most patients experience some discomfort on kneeling or when pressing the knee against a hard surface during the first year, and a proportion carry persistent kneeling sensitivity beyond that. Numbness around the incision and clicking at the harvest site are also recognised, usually temporary but occasionally lasting. Patellar fracture through the harvest point is rare yet documented, and surgical technique is directed at minimising this risk.

Hamstring donor site

Harvest measurably reduces peak hamstring torque and knee flexion strength — a deficit that some studies suggest can persist at two years post-surgery. For most recreational patients this imposes no significant functional limitation, but for sprint-dominant athletes or cyclists where posterior-chain power is central to performance, it is a genuine trade-off rather than a minor footnote.

The role of rehabilitation

Across observational data, rehab fidelity — progressive loading, neuromuscular retraining, and objective return-to-sport testing — consistently appears as a stronger predictor of outcome than graft material. That is not a consolation for the trade-offs named above; it is a separate, honest statement about where outcome variance largely sits once graft choice is made. Return to full pivoting sport typically takes nine to twelve months regardless of which graft is used, determined by graft maturation and neuromuscular readiness rather than by the calendar.

Getting the right assessment before deciding

Graft choice should not be finalised before the operating surgeon has reviewed the full picture: an MRI to confirm the ACL tear and identify any concomitant meniscal or cartilage pathology, patellar tendon dimensions (a narrow tendon may make BPTB impractical regardless of preference), patient age, sport level, occupation, and the donor-site trade-offs each option carries for that individual. General information — including this article — can sharpen the questions to ask; it cannot substitute for that conversation.

A biomechanical baseline before surgery also has practical value. Objective movement and load data, of the kind gathered through MAI Motion® gait analysis available at Lincolnshire Knee, can document pre-operative function and later serve as a reference point for return-to-sport decisions — a role rehabilitation teams often find useful when the calendar-based targets covered in the previous section give way to performance-based ones.

Lincolnshire Knee is part of the MSK Doctors group and offers consultant-led assessments without a GP referral at Sleaford NG34 and Grantham NG31. Appointments can be arranged at lincolnshireknee.co.uk.