Lateral Tenodesis in ACL Reconstruction: Why, When and How?

Courtesy: Joao Espregueira Mendes, ISAKOS President, Porto, Portugal

Goals of ACL Reconstruction

• Ensure no pain, swelling, or instability.

• Restore range of motion, muscle strength, proprioception, kinematics, and stability.

• Prevent osteoarthritis if possible.

• Aim for a return to sports at the same level.

ACL Injuries in Football

• Not the most frequent injury but leads to the most absence days.

• Despite good results, a normal knee is not restored, and osteoarthritis risk remains.

• 15-20% of professional male football players suffer a second ACL injury.

• Young athletes face higher risks of re-injury, either on the same or contralateral knee.

Kinematic Abnormalities Post-ACL Reconstruction

• Walking and downhill running show altered tibial rotation.

• High-demand activities reveal instability.

• Over 50% of ACL-injured patients develop osteoarthritis within 20 years.

Unanswered Questions in ACL Injuries

• Why do some complete ACL ruptures show minimal pivot shift while others show severe instability?

• Why do some patients continue to experience pain and instability despite successful surgery?

• What factors contribute to failure in restoring normal biomechanics?

Risk Factors for ACL Injuries

• Include biomechanical, neuromuscular, environmental, anatomical, genetic, and hormonal factors.

• Focus on anatomical risk factors as they are relevant to orthopedic surgeons.

• Certain bone morphology traits increase ACL injury risk, graft failure, and secondary rupture.

Bone Morphology and ACL Risk

• Factors influencing ACL injury risk:

  • Intercondylar notch width and index.

  • Tibial slope.

  • Varus and valgus knee alignments.

  • Notch shape and femoral condyle width.

• Narrow intercondylar notch and increased tibial slope (>12-13°) correlate with higher ACL injury risk.

• Valgus alignment is associated with meniscal injuries and instability.

• Females have a greater Q-angle, possibly contributing to higher ACL injury rates.

Biomechanical Considerations

• ACL injuries often occur with valgus knee flexion and external rotation.

• Varus alignment increases forces on the ACL and graft.

• Opening wedge osteotomy must be carefully performed to avoid increasing tibial slope.

Femoral Condyle Morphology and Stability

• The flatter the lateral femoral condyle, the more stable the knee.

• A curved lateral condyle leads to increased instability.

• The “Porto Ratio” (XY/AB) below 0.8 is associated with a higher risk of ACL injury.

• Females have lower Porto Ratios, possibly explaining their increased ACL injury risk.

Measurement and Diagnosis of Instability

• Current clinical tests (Lachman, Pivot Shift) lack objective quantification.

• Developed a polyurethane testing device for 3D knee instability measurement.

• Allows precise evaluation of anterior translation, rotation, and overall laxity.

• Helps in decision-making for partial vs. full ACL reconstruction.

• Useful for assessing minor posterolateral or posteromedial instability.

• Identifies the “swing-gam” effect, where an ACL appears intact but is functionally deficient.

Bone Bruising and ACL Tears

• No correlation found between bone bruising and meniscal or cartilage injuries.

• Bone bruises contribute to prolonged pain but do not indicate instability.

Improving ACL Reconstruction Outcomes

• Role of Anterolateral Ligament (ALL) in rotational stability remains controversial.

• Studies show ALL reconstruction has limited impact on controlling rotation.

• Lateral extra-articular tenodesis (LET) is more effective than ALL reconstruction.

Lateral Extra-Articular Tenodesis (LET)

• Reduces ACL graft forces by up to 43%.

• Superior to ALL reconstruction for controlling rotation.

• Previous concerns about increased osteoarthritis risk have been addressed:

  • If performed in neutral foot rotation, no increase in osteoarthritis.

  • Improves post-op return to sport levels.

 

• Parker’s Study on ACL Reconstruction & Rotation Control:

  • Adding lateral tenodesis to ACL reconstruction improves channel widening and rotation control.

  • Conflicting studies:

    • 2020 study suggests reduced rupture risk in revision cases.

    • 2024 study disagrees but future studies may confirm rotational control benefits.

• Challenges in Young Populations:

  • High ACL rupture risk (20-25% globally).

  • Change in approach over the past 5-6 years:

    • Systematically adding lateral tenodesis to ACL reconstruction in young athletes.

• Current Indications for Lateral Tenodesis:

  • Explosive lateral pivot shift.

  • Significant rotational increase (>15mm) in the Porto Knee Testing Device.

  • Patients under 25 years old.

  • Bone morphology risks (e.g., poor ratio, hyperlaxity).

  • Revision ACL cases.

• Surgical Technique for Lateral Tenodesis:

  • Performed through a small (5cm) incision.

  • Uses a 1cm wide, 11cm long strip of the iliotibial band.

  • Two fixation techniques:

    • In immature athletes: Strip folded over itself to avoid damaging the growth plate.

    • In adults: Fixation above the femur for added stability.

• Role of External Rotation in ACL Injuries:

  • Internal rotation control is widely discussed, but external rotation is often overlooked.

  • Injury mechanisms involve external foot rotation and hip abduction.

  • Rotational forces put ACLs and grafts at high rupture risk if not controlled.

• Biomechanics of ACL Rupture:

  • Finite element studies show that:

    • External tibial rotation with high axial load stresses the anterior medial band first.

    • Stress then moves to the posterolateral region, leading to rupture.

• Modification in Lateral Tenodesis Technique:

  • Adjustment made to address both internal and external rotation control.

  • New technique involves:

    • Passing the graft below the lateral collateral ligament.

    • Redirecting the graft in front for simultaneous control of internal and external rotation.

  • Prospective studies are evaluating its effectiveness in reducing rupture risk, especially in young athletes.

• Objective Evidence of Improved Rotation Control:

  • Porto Knee Testing Device shows zero external rotation after modified lateral tenodesis.

  • Stress MRI confirms controlled external rotation from -3° to 0°.

• Key Takeaways:

  • ACL reconstruction results remain unsatisfactory regarding osteoarthritis, return to high-level sports, and biomechanics.

  • Bone morphology plays a crucial role:

    • Preventative programs should focus on high-risk populations.

    • Post-surgery bracing may help control rotation.

    • Lateral tenodesis can improve rotational stability.

  • Specific anatomical considerations:

    • Tibial slope >12°: Consider corrective osteotomy.

    • Abnormal P/T (patellar tendon) ratio: Factor into lateral tenodesis decisions.

  • Laxity should be objectively measured, not just categorized (1+, 2+, 3+).

  • ALL (anterolateral ligament) reconstruction is not the best option.

  • Lateral tenodesis effectively controls both internal and external tibial rotation.

  • Controlling rotational laxity can improve ACL reconstruction outcomes, especially in young athletes.