Courtesy: Joao Espregueira Mendes, ISAKOS President, Porto, Portugal
Goals of ACL Reconstruction
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Ensure no pain, swelling, or instability.
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Restore range of motion, muscle strength, proprioception, kinematics, and stability.
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Prevent osteoarthritis if possible.
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Aim for a return to sports at the same level.
ACL Injuries in Football
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Not the most frequent injury but leads to the most absence days.
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Despite good results, a normal knee is not restored, and osteoarthritis risk remains.
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15-20% of professional male football players suffer a second ACL injury.
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Young athletes face higher risks of re-injury, either on the same or contralateral knee.
Kinematic Abnormalities Post-ACL Reconstruction
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Walking and downhill running show altered tibial rotation.
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High-demand activities reveal instability.
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Over 50% of ACL-injured patients develop osteoarthritis within 20 years.
Unanswered Questions in ACL Injuries
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Why do some complete ACL ruptures show minimal pivot shift while others show severe instability?
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Why do some patients continue to experience pain and instability despite successful surgery?
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What factors contribute to failure in restoring normal biomechanics?
Risk Factors for ACL Injuries
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Include biomechanical, neuromuscular, environmental, anatomical, genetic, and hormonal factors.
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Focus on anatomical risk factors as they are relevant to orthopedic surgeons.
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Certain bone morphology traits increase ACL injury risk, graft failure, and secondary rupture.
Bone Morphology and ACL Risk
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Factors influencing ACL injury risk:
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Intercondylar notch width and index.
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Tibial slope.
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Varus and valgus knee alignments.
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Notch shape and femoral condyle width.
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Narrow intercondylar notch and increased tibial slope (>12-13°) correlate with higher ACL injury risk.
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Valgus alignment is associated with meniscal injuries and instability.
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Females have a greater Q-angle, possibly contributing to higher ACL injury rates.
Biomechanical Considerations
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ACL injuries often occur with valgus knee flexion and external rotation.
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Varus alignment increases forces on the ACL and graft.
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Opening wedge osteotomy must be carefully performed to avoid increasing tibial slope.
Femoral Condyle Morphology and Stability
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The flatter the lateral femoral condyle, the more stable the knee.
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A curved lateral condyle leads to increased instability.
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The “Porto Ratio” (XY/AB) below 0.8 is associated with a higher risk of ACL injury.
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Females have lower Porto Ratios, possibly explaining their increased ACL injury risk.
Measurement and Diagnosis of Instability
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Current clinical tests (Lachman, Pivot Shift) lack objective quantification.
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Developed a polyurethane testing device for 3D knee instability measurement.
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Allows precise evaluation of anterior translation, rotation, and overall laxity.
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Helps in decision-making for partial vs. full ACL reconstruction.
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Useful for assessing minor posterolateral or posteromedial instability.
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Identifies the “swing-gam” effect, where an ACL appears intact but is functionally deficient.
Bone Bruising and ACL Tears
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No correlation found between bone bruising and meniscal or cartilage injuries.
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Bone bruises contribute to prolonged pain but do not indicate instability.
Improving ACL Reconstruction Outcomes
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Role of Anterolateral Ligament (ALL) in rotational stability remains controversial.
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Studies show ALL reconstruction has limited impact on controlling rotation.
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Lateral extra-articular tenodesis (LET) is more effective than ALL reconstruction.
Lateral Extra-Articular Tenodesis (LET)
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Reduces ACL graft forces by up to 43%.
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Superior to ALL reconstruction for controlling rotation.
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Previous concerns about increased osteoarthritis risk have been addressed:
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If performed in neutral foot rotation, no increase in osteoarthritis.
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Improves post-op return to sport levels.
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Parker’s Study on ACL Reconstruction & Rotation Control:
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Adding lateral tenodesis to ACL reconstruction improves channel widening and rotation control.
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Conflicting studies:
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2020 study suggests reduced rupture risk in revision cases.
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2024 study disagrees but future studies may confirm rotational control benefits.
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Challenges in Young Populations:
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High ACL rupture risk (20-25% globally).
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Change in approach over the past 5-6 years:
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Systematically adding lateral tenodesis to ACL reconstruction in young athletes.
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Current Indications for Lateral Tenodesis:
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Explosive lateral pivot shift.
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Significant rotational increase (>15mm) in the Porto Knee Testing Device.
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Patients under 25 years old.
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Bone morphology risks (e.g., poor ratio, hyperlaxity).
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Revision ACL cases.
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Surgical Technique for Lateral Tenodesis:
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Performed through a small (5cm) incision.
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Uses a 1cm wide, 11cm long strip of the iliotibial band.
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Two fixation techniques:
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In immature athletes: Strip folded over itself to avoid damaging the growth plate.
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In adults: Fixation above the femur for added stability.
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Role of External Rotation in ACL Injuries:
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Internal rotation control is widely discussed, but external rotation is often overlooked.
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Injury mechanisms involve external foot rotation and hip abduction.
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Rotational forces put ACLs and grafts at high rupture risk if not controlled.
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Biomechanics of ACL Rupture:
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Finite element studies show that:
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External tibial rotation with high axial load stresses the anterior medial band first.
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Stress then moves to the posterolateral region, leading to rupture.
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Modification in Lateral Tenodesis Technique:
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Adjustment made to address both internal and external rotation control.
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New technique involves:
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Passing the graft below the lateral collateral ligament.
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Redirecting the graft in front for simultaneous control of internal and external rotation.
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Prospective studies are evaluating its effectiveness in reducing rupture risk, especially in young athletes.
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Objective Evidence of Improved Rotation Control:
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Porto Knee Testing Device shows zero external rotation after modified lateral tenodesis.
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Stress MRI confirms controlled external rotation from -3° to 0°.
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Key Takeaways:
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ACL reconstruction results remain unsatisfactory regarding osteoarthritis, return to high-level sports, and biomechanics.
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Bone morphology plays a crucial role:
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Preventative programs should focus on high-risk populations.
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Post-surgery bracing may help control rotation.
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Lateral tenodesis can improve rotational stability.
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Specific anatomical considerations:
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Tibial slope >12°: Consider corrective osteotomy.
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Abnormal P/T (patellar tendon) ratio: Factor into lateral tenodesis decisions.
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Laxity should be objectively measured, not just categorized (1+, 2+, 3+).
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ALL (anterolateral ligament) reconstruction is not the best option.
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Lateral tenodesis effectively controls both internal and external tibial rotation.
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Controlling rotational laxity can improve ACL reconstruction outcomes, especially in young athletes.
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