Presentation on theme: "ACL Reconstruction: The Anatomic Approach"— Presentation transcript:
1ACL Reconstruction: The Anatomic Approach Steven P. Brantley, MDSpero G. Karas, MDHead Team Physician- Atlanta FalconsTeam Physician- Georgia Tech BaseballAssociate Professor of OrthopaedicsDirector, Orthopaedic Sports Medicine FellowshipEmory Healthcare Sports Medicine
2Background ACL is second most commonly injured ligament in the knee ACL rupture is estimated to occur in 1 in 3000 people in the U.S.Resulting in an estimated 100,000 reconstructions a year6th most common orthopaedic procedure performed in the U.S.
3ACL AnatomyACL origin: posterior aspect of the medial surface of the lateral femoral condyleIt courses anteriorly and medially to insert on the tibial plateau in an area medial to the insertion of the anterior horn of the lateral meniscus and anterolateral to the the anterior tibial spine
4ACL Anatomy 1o blood supply from the middle geniculate artery Its osseous attachments provide little to its vascularityInnervation from the posterior articular nerve
5ACL’s Two Bundles ACL Consist of 2 bundles Anteromedial (AM) bundle Originates more proximally and posteriorly.Inserts anteriorly and medial.Posterolateral (PL) bundle
6Two BundlesAM and PL bundle tension different depending on the position of the knee:90o flexion: the AM bundle taut while the PL bundle relaxed.Full extension: the PL bundle tensed and the AM bundle relaxedGirgis et al, CORR 1975PLAM
9ACL BiomechanicsThe ACL functions to resist anterior translation of the tibia on the femurAM bundleProvides 85% of resistance to the anterior drawer in 90o of flexionResists tibial rotationPL bundleHelps provide varus-valgus stability when the knee is in full extension.
10ACL InjuriesThe majority of ACL injuries occur from non-contact injuriesPivot shift injuryOccurs as individual decelerates and try to change directions abruptly or lands from a jumpFemales are 6 times more likely to suffer an ACL tear as their male counterparts
12Goals of ACL Reconstruction To provide a stable and pain-free knee under physiologic loadsTo provide an expedient return to previous level of function
13Goal of ACL Reconstruction To help prevent future injury to the meniscus and cartilageTo help prevent future degenerative arthritis- ?
14ACL ReconstructionJones et al in 1963 JBJS was 1st to describe modern technique of ACL reconstruction.Used Patellar tendon attached distally to reconstruct ACL in 12 patients.
15ACL ReconstructionDespite advances in surgical technique and rehabilitation protocols, there are still failures of ACLROnly 78% of athletes in the WNBA have been able to return to sport after undergoing ACL reconstruction.Namdari S et al, Physician and Sports Med, 2011
16Risk of ACL ReinjuryThe rates of re-tearing after ACL reconstruction ranges from 3-30% in the literatureBiggest Risk Factor:RTP < 7 months- 15.3%RTP > 7 months- 5.2%Laboute et al Ann Phys Med Rehab, 2010
17Traditional ACL Reconstruction Traditional ACL reconstructions placed femoral tunnel in a vertical non-anatomic position.Reconstructed primarily the AM bundle but not the PM.Picture Courtesy Dr. Freddie Fu.
18Traditional ACL Reconstuction With AM bundle reconstructed anterior translation controlled- negative Lachman’s Exam.Not very good rotatory stability- continued pivot shift.
19Abnormal MechanicsTashman et al in AJSM 2004 demonstrated abnormal external rotation of the tibia and limb adduction during running activities in patient who had underwent nonanatomical ACL reconstruction.Woo et al in JBJS 2002 illustrated in cadavers that a conventional single bundle ACL was successful in restoring anterior translation control, but was ineffective at restoring the native ACL’s rotatory stability.
20Double Bundle ACL Reconstruction Attempts to restore both the AM and PL bundle of ACLRestore both anterior translation and rotatory control
21Double BundleYagi et al in AJSM 2002 demonstrated in cadeveric studies that double bundle ACL reconstruction restored anterior translation and rotatory control significantly closer to that of the native ACL than did a single bundle reconstruction.Had 97% and 91% of the in situ forces of the intact ACL for controlling anterior tibial translation and rotation compared to 89% and 66% for the single bundle non-anatomic reconstruction.
22Double Bundle ACL- Is it the Answer? Technically more difficultLimited in graft selectionMay over constrain the knee, Markolf et al in JBJS 2008
24Single Bundle Anatomical ACL Reconstruction Places bone tunnels in correct anatomical positions in hopes of restoring knee mechanics closer to natural ACLImproves rotatory stability
25Anatomic Reconstruction Pictures Courtesy of Dr. Freddie Fu
26Bone TunnelsTunnels are drilled independently to allow for anatomic positioning of tunnelsAllows for a more oblique graft in the coronal and sagittal planeThis orientation better prevents pivot shift
27Bone TunnelsTraditional ACL reconstruction uses a trans-tibial approach to drill the femoral tunnelThis places tibial tunnel too posterior in order to drill in the anatomic femoral positionStrauss et al in AJSM 2011 demonstrated in a cadaveric study that it is not possible to drill an anatomic femoral tunnel through an anatomic tibial tunnel positionPlaced femoral tunnel too superior and posterior to anatomic position
32Tunnel PositionLoh et al in Arthroscopy 2003 looked at knee stability in a cadaveric model comparing ACL reconstruction with either the femoral tunnel in the 11 o’clock or 10 o’clock position.Demonstrated that the 10 o’clock position was more effective in resisting rotatory loads.No difference between the two positions in preventing anterior tibial translation.
33Anatomic ACL Reconstruction: Single vs. Double Bundle Kondo E et al in AJSM 2011 performed a biomechanical study comparing anterior translation and pivot shift stability in double bundle, anatomic single bundle, and trans-tibial ACL reconstructionThe double bundle and anatomic single bundle ACL reconstructions demonstrated significantly improved rotational stability compared to the nonanatomic reconstructionNo difference biomechanically detected between the anatomic double and single bundle reconstruction
34Anatomic Reconstuction vs Non-Anatomic Sadoghi P et al in Athroscopy 2011 compared clinical outcomes of patient who underwent either anatomic or non-anatomic single bundle ACL reconstructionFound that anatomic ACL reconstruction had significantly improved outcomes in clinical scores and rotatory stability when compared to non-anatomic reconstruction
35Conclusion Rotatory control a key to restoring function Non-anatomic “vertical” ACL reconstruction does not restore the rotatory stability of the native ACLSingle-bundle anatomic ACL reconstruction decreases the pivot shift phenomenon and more closely mimics native ACL biomechanics