Vascularized vs Devascularized ACL Grafts: What the Evidence Shows

I touch on this in my broader guide to choosing an ACL graft, but it deserves its own explanation. It's one of the parts of ACL surgery I feel most strongly about, and the evidence for it has built up over 20+ years, from several different angles: anatomy, animal studies, MRI scans, and clinical trials. Here's that evidence, in the order it was built.

What "vascularized" means

Most ACL grafts are completely cut free from the body before being placed in the knee. They start out with no blood supply of their own, and the body has to grow new blood vessels into them from scratch. Only one technique reliably avoids this: a hamstring graft left attached at its natural attachment point on the shin bone (called the pes anserinus). Because it stays partly connected, it keeps some blood supply from day one. This is the technique I trained in directly during my fellowship in Bologna, under Professor Stefano Zaffagnini.

1. The anatomy behind it

In 2003, Zaffagnini's team dissected this attachment point and found something important: a real network of small blood vessels and nerves running into it.¹ That doesn't prove a graft heals better here — it just proves there's something worth testing. It set up two decades of research asking: does keeping this attachment actually change how a graft heals?

2. Why blood supply matters

Every ACL graft has to "come alive" inside the knee — a process called ligamentization. Normally, this happens in three stages: part of the graft first dies off, then new blood vessels grow in and repopulate it with cells, and finally it remodels into ligament-like tissue.² That first stage is the vulnerable one — the graft is at its weakest, right around the time patients are pushing into harder rehab. The idea behind an attached graft is simple: if it never fully loses its blood supply, maybe it can skip that weak, vulnerable stage altogether.

3. What animal studies showed

Because you can't biopsy a healing graft in a living patient, the first real tests were done in rabbits.

• Papachristou et al. (2007)³ compared attached and fully detached hamstring grafts. The detached grafts showed classic tissue die-off at 3 weeks before slowly recovering. The attached grafts stayed healthy from the start — no meaningful die-off phase at all.
• Liu et al. (2018)⁴ repeated this in a larger study (64 rabbits, tracked to 24 weeks) and added strength testing. Same pattern: attached grafts skipped the die-off phase, healed a stronger bond to bone, and were significantly stronger and stiffer by 12–24 weeks.

Two separate studies, same result: an attached graft heals faster and ends up stronger.

4. What human MRI scans showed

MRI can't see cell death directly, but it can measure how "settled" a healing graft looks — signal brightness, swelling, and fluid content are all markers of how mature a graft is.

• Ruffilli et al. (2016)⁷: attached grafts scored significantly better on a standard maturity scale at 6 months, with 90% reaching "good" healing versus 75% of detached grafts.
• Liu et al. (2018), human trial, 45 patients:⁵ detached grafts showed a clear rise-then-fall signal pattern (consistent with dying off, then healing). Attached grafts stayed calm and steady throughout.

• Grassi et al. (2020)⁶: attached grafts showed less swelling and better MRI maturity scores as early as 4 months, an advantage still visible at 18 months.
• Sinha et al. (2026)⁸, the most striking result yet: 79% of attached grafts were fully mature by 6 months, versus 0% of detached grafts. By the end of the study, 100% of attached grafts had fully matured, versus just 10% of detached grafts.

Four separate scans studies, four different research teams, all pointing the same way: attached grafts mature earlier and more predictably.

5. What this means for actual outcomes

Biology and scans only matter if patients feel the difference. This is where the evidence is more modest, and worth being honest about.

• Gupta et al. (2017)⁹, the largest trial (110 athletes, 2 years): attached grafts led to a tighter, more stable knee and a closer return to pre-injury sport level. The differences were real and statistically significant — but the authors themselves said they were too small to call "clinically meaningful" for any one patient.
• Ruffilli et al. (2016): despite the MRI advantage above, there was no meaningful difference in patient-reported outcomes by 2 years — both groups did well.
• Sinha et al. (2026): attached grafts scored significantly better on knee function and stability at 6 and 12 months.

So: two of three trials found a real clinical edge for attached grafts; one found the two approaches converge by two years. A better scan doesn't always translate into a proportionally bigger difference you'd feel.

The honest bottom line

Across anatomy, animal studies, and four human MRI studies, the evidence is consistent: a hamstring graft left attached at the pes anserinus heals faster and more predictably than a fully detached graft. That part is well established.

The clinical payoff is real, but smaller and less consistent — the trials are still modest in size (the largest is 110 patients), mostly from a handful of research centers, with limited long-term follow-up. We don't yet know if these early advantages still matter 10 years out.

My own take, having trained in this technique directly: preserving a graft's blood supply gives it a genuine head start, and in the right patient, that may support a more confident early rehab. It isn't a guarantee of a dramatically better outcome for any one person — and I think that's the honest way to describe where the evidence actually stands.

I've come to see the body's own capacity to heal, even under a surgeon's knife, as something worth quiet gratitude — a graft finding its way back to living tissue is a small reminder of how well we're made.

If you're weighing graft options, start with my broader guide to choosing a graft, and bring these questions to your surgeon.

References

1. Zaffagnini S, et al. Vascularity and neuroreceptors of the pes anserinus: anatomic study. Clin Anat. 2003.
2. Yao S, Fu BSC, Yung PSH. Graft healing after anterior cruciate ligament reconstruction (ACLR). Asia-Pac J Sports Med Arthrosc Rehabil Technol. 2021.
3. Papachristou G, et al. ACL reconstruction with semitendinosus tendon autograft without detachment of its tibial insertion: a histologic study in a rabbit model. Knee Surg Sports Traumatol Arthrosc. 2007.
4. Liu S, et al. Advantages of an Attached Semitendinosus Tendon Graft on Bone Tunnel Healing After Anterior Cruciate Ligament Reconstruction: A Rabbit Model. Am J Sports Med. 2018.
5. Liu S, et al. A randomized clinical trial to evaluate attached hamstring anterior cruciate ligament graft maturity with magnetic resonance imaging. Am J Sports Med. 2018.
6. Grassi A, et al. Hamstring grafts for anterior cruciate ligament reconstruction show better magnetic resonance features when tibial insertion is preserved. Knee Surg Sports Traumatol Arthrosc. 2020.
7. Ruffilli A, et al. Hamstring graft tibial insertion preservation versus detachment in anterior cruciate ligament reconstruction. Eur J Orthop Surg Traumatol. 2016.
8. Sinha S, et al. ACL reconstruction with attachment-sparing hamstring autograft results in earlier graft maturation and better short-term clinical outcome in comparison to free graft. Am J Sports Med. 2026.
9. Gupta R, et al. Outcome of hamstring autograft with preserved insertions compared with free hamstring autograft in anterior cruciate ligament surgery at 2-year follow-up. Arthroscopy. 2017.