The best knee flexion angle for lateral extra-articular tenodesis graft fixation during anterior cruciate ligament reconstruction

Riccardo Compagnoni, Antonio Klasan, Alberto Grassi, Francesco Puglia, Stefano Zaffagnini, Pietro Simone Randelli, Jacques Menetrey: Optimal flexion angle for graft fixation in lateral extra—articular tenodesis combined with anterior cruciate ligament reconstruction: A systematic review. J Exp Orthop. 2025;12:e70312.

LET and ACL reconstruction: clarifying a critical technical detail

The Lemaire procedure and its modern iterations have solidified LET's role as a valuable adjunct to ACLR—especially for patients prone to rotational instability, such as young athletes or revision cases. LET serves to unload the intra-articular graft, limit internal tibial rotation, and improve postoperative stability.

The rationale for combining LET with ACLR lies in its ability to reinforce the anterolateral knee structures, offload the ACL graft, mitigate rotational laxity, and improve patient-reported outcomes and return-to-sport rates.

However, no consensus exists on the optimal knee flexion angle during LET graft fixation, a decision that may significantly impact functional recovery, graft integrity, and long-term outcomes.

We conducted a systematic review to address this knowledge gap, analyzing clinical outcomes across a range of fixation angles from 0° to 90°.

What the data show: 30° flexion leads the way

The review synthesized findings from 21 studies, representing over a thousand patients undergoing LET combined with ACLR. Fixation angles varied widely:

• 30° Fixation (10 studies): Most common. Consistently associated with improved pivot-shift control, enhanced knee stability, and better patient-reported outcomes.
• 45° (3 studies): Used primarily in revision cases, with mixed results.
• 60° (4 studies): Featured in the Stability 2 study and others. Shown to reduce anterior tibial translation in the short term but unclear long-term benefit.
• 90° (2 studies): Least commonly reported. Did not demonstrate superior outcomes.
• Other angles (0°, 20°): Explored in niche contexts like pediatric or isolated LET procedures.

LET graft fixation at 30° of knee flexion was by far the most common angle reported and interestingly the angle aligns closely with the peak anterolateral instability observed during pivot-shift testing (typically around 20–22°), supporting its biomechanical rationale. The findings are consistently favourable with the following advantages:

• Improved pivot-shift control, a clinical marker of rotational stability.
• Reduced anterior tibial translation, which decreases stress on the ACL graft.
• Enhanced patient-reported outcomes, including better scores on the Lysholm and IKDC scales.
• Lower re-injury and failure rates, particularly in paediatric and adolescent patients.

Why the angle matters for clinical practice

The lack of standardization around LET graft fixation angle introduces variability into ACLR outcomes. By highlighting the association between 30° fixation and improved stability, particularly in high-risk groups, this review suggests a practical target for surgeons aiming to optimize results.

The angle at which the graft is tensioned and fixed can influence rotational and sagittal stability, tibial alignment and screw-home mechanism, knee kinematics during gait and athletic activities, and potential overconstraint or underconstraint of the joint.

Fixing the LET graft at full extension or excessive flexion could theoretically lead to abnormal graft tension resulting in altered biomechanics, graft elongation, or compromised motion. Conversely, fixation at or near 30° may allow the graft to engage optimally at a biomechanical “sweet spot,” offering maximal rotational control without impairing the joint’s functional range.

As noted in the systematic review, pivot-shift kinematics peak at approximately 20.7°, making the 30° mark a pragmatic choice that mirrors the zone of maximal instability. In essence, this approach targets the flexion angle where LET's biomechanical contribution is needed most.

Moreover, the study underscores the need for individualized decision-making. Patient anatomy, activity level, and surgical context (e.g., primary vs. revision ACLR) may all inform the optimal angle in a given case.

Limitations and future directions

The review is limited by heterogeneity across studies and a predominance of Level III evidence. No formal meta-analysis was conducted due to inconsistent outcome reporting.

To move toward consensus, high-quality prospective studies are needed, ideally comparing fixation angles head-to-head with standardized LET techniques and long-term follow-up. Consensus statements or surgical guidelines could also help translate these findings into consistent practice.

Take-home messages

ACL reconstruction is a complex surgery that continues to evolve, particularly in how adjunctive procedures like LET are employed. The fixation angle of the LET graft, while often overlooked, is a technically important detail that can influence clinical success. Based on current evidence, 30° knee flexion appears to strike the best balance between biomechanical effectiveness and functional safety, but further research is required to standardize surgical protocols.

There is no one-size-fits-all angle so clinical judgment remains essential. LET augmentation during ACLR enhances rotational stability, especially in high-risk patients. As the orthopaedic community pushes for ever-better outcomes—whether it’s in elite athletes or weekend warriors—attention to such surgical nuances will remain key. 

For now, surgeons would be well-advised to consider 30° flexion as the go-to angle for LET graft fixation, which appears most consistently beneficial, aligning with biomechanical pivot-shift data, unless specific patient factors warrant deviation.