The way a surgeon harvests the semitendinosus tendon during anterior cruciate ligament (ACL) reconstruction may shape how well the new ligament heals.
A recent prospective cohort study comparing 180 patients shows that leaving the distal tibial attachment intact significantly improves graft remodelling on MRI one year after surgery, reduces the rate of reoperation and shortens the time to return to sport. These findings position the attached semitendinosus (aST) technique as a notable refinement in ACL surgery, with direct consequences on graft healing quality and ACL graft structural integrity.
The information presented in this article is drawn from a peer-reviewed study led by Professor Cavaignac, titled Preserving the Semitendinosus Distal Attachment Is Associated With Improved Graft Remodeling After ACL Reconstruction.
Why graft remodelling matters after ACL reconstruction?
Graft remodelling is the biological process through which the transplanted tendon gradually transforms into a functional ligament. Its quality is one of the strongest prognostic factors for ACL reconstruction, influencing stability, durability and the risk of re-rupture.
On MRI, remodelling is measured using the signal-to-noise quotient (SNQ): the lower the value, the more mature and structurally sound the graft.
Attached vs free semitendinosus graft: what the study shows
The trial enrolled 180 patients, half receiving a standard free semitendinosus (ST) graft and half receiving an attached semitendinosus (aST) graft, in which the distal tibial insertion is preserved. The aST group demonstrated markedly better outcomes across several endpoints.
| Outcome at 1 year | aST group | ST group | p-value |
| Adjusted SNQ (MRI) | 1.18 | 3.88 | < .001 |
| Reoperation rate | 2.2% | 10% | .029 |
| Median Lysholm score | 99 | 95 | .004 |
| Mean time to return to sport | 248 days | 317 days | .002 |
No significant difference was found in tibial tunnel widening, Howell maturity grade, retear rate or IKDC score, suggesting that the benefit of preservation lies specifically in the biology of healing.
Clinical implications for return to sport after ACL reconstruction
Preserving the distal attachment appears to maintain a vascular and proprioceptive connection that supports faster maturation. For patients, this translates into:
- a quicker, more confident return to sport after ACL reconstruction (around 10 weeks earlier on average),
- a fivefold reduction in the need for further surgery,
- higher Lysholm scores, reflecting better day-to-day knee function.
This research adds meaningful evidence in favour of preserving the semitendinosus distal attachment to optimise graft healing quality. Readers interested in the methodology, statistical analysis and surgical detail are warmly invited to consult the complete study, as well as the other scientific publications by Professor Cavaignac on knee surgery. His careful, evidence-based work continues to offer valuable guidance to clinicians and patients alike.