
The Scientific Basis for Arthroscopic Double Bundle Anterior Cruciate Ligament (ACL) Reconstruction
Restoration of knee stability in order to:
- preserve meniscus & articular cartilage
- slow degeneration
- diminish pain
- enhance function
Failure Rate of Single Bundle ACL Recon
- 10 – 20 % failure (Harner et al)
- Evaluation and treatment of recurrent instability after anterior cruciate ligament. Instructional Course Lecture 2001
Clinical Results after One-bundle ACL Reconstruction
- Single Bundle ACLR
- Greatly improved over the past 20 years
- The current standard
- However, many Orthopaedic surgeons have not been completely satisfied by the clinical results, because:
- IKDC “A” rate is about 70%
- The “A-rank” knee does not mean the “normal” knee
- The Pivot-shift is not sufficiently controlled
- Patients feel some uncomfortable or unstable sensation during their athletic activities
Single Bundle ACL -Biomechanics
- Studied the effectiveness of single bundle ACL Reconstruction using Hamstring and Patellar tendon
- Address anterior tibial translation
- But poorly address combined rotational stability
- Savio Woo et al, JBJS(Am) 84:2002
Tibiofemoral kinematics following successful ACL reconstruction using Dynamic MRI
- 10 successful ACL recon with hamstring autograft (Lysholm score average 98/100) who returned to normal daily and sporting activities were scanned
- Contralateral normal knees as control
- Persistent anterior subluxation of lateral tibial plateau in all positions of flexion in ACL reconstructed group (p<0.003)
- Logan, AJSM 2004
Excessive Tibial Rotation During High-Demand Activities Is Not Restored by ACL Reconstruction
- Studied the effectiveness of single bundle ACL Reconstruction using Hamstring and Patellar tendon
- Address anterior tibial translation
- But poorly address combined rotational stability
- Savio Woo et al, JBJS(Am) 84:2002

Rotatory Stability
- 2 or 10 o’clock femoral tunnel position of a single-bundle ACL reconstruction improved rotatory stability when compared with the 1 or 11 o’clock position
- However, neither the 10 o’clock nor the 11 o’clock tunnel position could restore the kinematics and the in situ forces of the intact knee
- Loh et al, Arthroscopy 2003
Biomechanical Criticism of Single Bundle ACLR
- Biomechanical studies with cadaver knees
1-B ACLR cannot completely restore the normal anterior laxity
1-B ACLR has no effect on the rotatory instability
Woo et al: JBJS, 84A:907, 2002
Yagi, et al: AJSM, 30: 660, 2002 - Kinematic analyses with patients
1-B ACLR cannot improve the rotatory instability during walking or running, independent of the graft (BTB, Hamstring, etc)
Georgoulis et al: AJSM, 31: 75, 2003
Ristanis et al: Arthroscopy, 21: 1323, 2005
Chouliaras et al: AJSM, 35:189, 2007
Tashman et al: Clin Orthop, 454: 66, 2007




Native ACL -Biomechanics
- Distribution of in situ forces in the ACL in response to rotatory loads
- Anterior Tibial Load
Force in PLB was highest at full extension and decreased with flexion
Force in AMB was lower than PLB at full extension
But increased with increasing flexion
Reaching a maximum at 60o flexion
Then decreasing at 90o flexion - Combined Rotatory Load
Force in PLB was higher at 15o and lower at 30o flexion
Force in AMB was similar at 15o and 30o of flexionGabriel MT, SL Woo et al JOR 2004


Intra-operative evaluation



Conclusion
Biomechanically, the anatomic 2-B ACLR can restore the knee significantly closer to the intact knee than the 1-B ACLR
Clinically, the anatomic 2-B procedures appear to restore better knee stability than the 1-B procedures in ACLR with the hamstring tendon graft, although there remain some controversies
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