ACL reconstruction (quadrupled semitendinosus autograft) + LET/ALL augmentation (allograft): 2-year biological, failure-mode and training outlook. This one is made for me, but useful if you want a rough idea of where you stand. Change the surgery date 👇 and see where you are in your own timeline. It works best on Desktop with an oldkool mouse or touchpad. Most praise goes to these fine lads. Important: Surgeon/physio protocol overrides everything. Not medical advice.
Swipe sideways to see the full 2-year timeline - bars, dots and milestones have details.
Clinical benchmarks, diameter margins, and construct gating factors at a glance.
Tissue Benchmark
The new graft tissue alone holds about 2,422 N at implantation - roughly 112% of a healthy native ACL (2,160 N). The "twice as strong / 200%" claims refer to high-end reports (up to ~4,500 N), not the typical graft.
Diameter Margin
| Diameter | Mean | SD | Weakest |
|---|---|---|---|
| 6 mm | 2,359 N | +/- 474 | 1,567 N |
| 7 mm | 3,263 N | +/- 677 | 2,288 N |
| 8 mm | 3,908 N | +/- 556 | 2,874 N |
| 9 mm | 4,360 N | +/- 606 | 3,720 N |
Different graft, different study (Boniello 2015): looped semitendinosus+gracilis allografts (n=44), not this page's quadrupled autograft. Read the trend: spread is wide, and values often fall well below 4,000 N. Clinical note: autografts ≤8 mm show higher early failure rates in some patients.
Clinical Gate
Day 0: ~20% (screw holds ~300-500 N)
Wk 4-8: 10-25% (nadir / revascularization)
6 Mo: ~45-70% (tunnel integrated)
2 Yr: ~50-65% plateau
What actually limits loading is the construct: graft + bone tunnels + fixation screws. On day zero it is fixation-limited; it dips during weeks 4-8 as the graft remodels. The reassuring number is not the gating number.
Quotations from the abstracts of the studies this timeline draws on. Follow the links for the full papers. Please keep in mind that my medical training is limited.
"In the younger specimens, linear stiffness (242 +/- 28 N/mm) and ultimate load (2160 +/- 157 N) values found when the femur-ACL-tibia complex was tested in the anatomical orientation were higher than those reported previously in the literature."
Woo SL, et al. "Tensile properties of the human femur-anterior cruciate ligament-tibia complex." Am J Sports Med 1991;19(3):217-25. PMID 1867330
"The maximum load to failure (tensile strength) of the HT graft has been reported by multiple studies to be higher than that of the native ACL, with 2,422 N being the commonly-cited value, and other estimates ranging as high as 4,500 N."
Banovetz MT, et al. "Biomechanical considerations for graft choice in anterior cruciate ligament reconstruction." Ann Jt 2023;8:17. PMC10929340
"All grafts at time zero failed by pullout from the bone tunnel, whereas grafts at 6 and 9 weeks failed intraligamentously at the screw insertion site. [...] At 52 weeks, tensile stress of the reconstruction equaled 63.8% and 47.3% of the Achilles tendon graft at time zero and the native ACL, respectively."
Weiler A, et al. "Tendon healing in a bone tunnel. Part I." Arthroscopy 2002;18(2):113-23. PMID 11830804
"The mean load to failure was 2,359 +/- 474 N, 3,263 +/- 677 N, 3,908 +/- 556 N, and 4,360 +/- 606 N for the 6-, 7-, 8-, and 9-mm grafts, respectively. [...] hamstring grafts may not be nearly as strong as previously appreciated."
Boniello MR, et al. "Impact of Hamstring Graft Diameter on Tendon Strength." Arthroscopy 2015;31(6):1084-90. PMID 25703286
"Graft cellularity was evident at 28 W and continued to increase through 132 W as the tendon ossified at sites of bone contact. [...] At 132 W, implants fully replaced by newly remodeled bone."
Cole BJ, et al. "ACL reconstruction in a translational model in sheep using biointegrative mineral fiber reinforced screws." Sci Rep 2024. PMID 39521891
The week-by-week ranges, phase bars, milestones and gating window on this page mirror the healing model assembled in the rehab repository (healing/graft-healing-biology.md, frozen 2026-09-12), which also carries the full bibliography: clinical-education summaries of the three-phase healing model (Clinical Tree; Banff Sport Medicine; Dr Dan Cohen) and the skeletally immature sheep series (5%, 15.2%, 41.2%, 69% at wk 3/6/12/24) behind the panel-1 markers. Allograft (ALL) curves track the same cascade shifted 2-4 weeks later; that offset is inferred from general allograft data, not from ALL-specific studies.
Built by one guy, one laptop, and multiple reconstructed ACLs. Ex-wanna-be-pro cyclist turned hobby engineer; this timeline started as a personal rehab cheat sheet and got out of hand. Deaf in the left ear, which explains the occasional one-sided opinion.