ACL Reconstruction: Techniques and Avoiding Pitfalls

Timothy Hosea, MD

University Orthopaedic Associates

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Liberally “borrowed” images from the internet

Questions to be Answered

• What is the unique anatomy and function of the Anterior Cruciate Ligament (ACL) and how do today’s reconstruction techniques attempt to recreate it?

• What is the history of ACL reconstruction and its evolution?

• What is a current technique of an ACL reconstruction and what is its rationale?

• What are possible technical complications associated with the reconstruction?

• What are my personal preferences in reconstructing the ACL?

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Of course: Based on Current Literature

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What is our Goal?

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• To restore normal knee kinematics

– Possible source of osteoarthritis if lost (Carmont, 2011)

• Provide a pain free stable knee

• To provide an expedient return to previous level of function

Timing of ACL Surgery

• Time interval is not as important as the condition of the knee at the time of surgery

• Elective procedure (Shelbourne, AJSM, 1991) – Full ROM

– Minimal effusion

– Minimal pain

– Mentally prepared for the reconstruction and rehab

• AVOID ARTHROFIBROSIS AT ALL COSTS – Cosgarea, 1995; Shelbourne, 1997; Magit,2007

ACL function

• Anterior translation of the tibia with respect to the femur

• Prevent anterio-lateral rotation

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Embryology 45 Days gestation

Bechler, Hosea 1991

ACL Double bundle

• Anterior Medial Bundle

– Anterior stability

– Taut in flexion

• Posterior Lateral Bundle

– Rotational stability

– Taut in extension

ACL Anatomy Double Bundle

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Kopf, Fu 2012

ACL Reconstruction Techniques

• Until the 1970s, there was a significant controversy about the functional importance of the ACL

• 1970s: ACL repair – Not universally successful

• Early 1980s: Repair with augmentation

• Complete replacement of the ACL with a graft – Clancy: Bone Patella Tendon Bone (vascularized)

• JBJS, 1982

ACL Techniques

• 1990s Transtibial Technique

• Non anatomic

• Quick reproducible

• Femoral tunnel drilled with offset guide through the tibial tunnel.

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ACL Technique

• 2000s

– Anatomically placed tunnels better restore normal knee kinematics

• Tashman, 2004, 2007

– Non anatomic transtibial techniques result in high percentage of OA

• Biau, 2007; Fithian, 2005; Simon, 2015

– Postulated that initial trauma (articular cartilage damage) and tunnel placement may contribute to the onset of OA

• Kopf, Fu, 2012

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ACL Technique

• Double Bundle – Attempts to reproduce the

normal ACL anatomy • Fu etal

– Superior anterior and rotational stability • Clinical implications still unknown

• NIH clinical trails in progress

– Not indicated: • Small, native ACL (<14 mm)

• Open physes

• Narrow notch (<13 mm)

• Severe bone bruising

• Multiple ligament injuries – Fu, 2012

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Vyas, Fu 2010

ACL Technique

• Anatomic single bundle – Awareness of the

importance of anatomic placement • Increased failure of an ACL

reconstruction with non anatomic placement

– Anatomic tibial tunnel placement

– Femoral tunnel placed independent of the tibial tunnel

• Double bundle issues – Increased operating time

• Double the number of tunnels

• Complexity of passing and securing the 2 grafts

• Possibility of large bony voids in the lateral femoral condyle if revision necessary

• 6% rerupture rate – (Carmont, 2011)

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ACL technique

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Kopf, Fu 2012

Technical Aspects of ACL Reconstruction

• Position of the ACL graft is the most critical surgical variable

– Direct effect on knee biomechanics and clinical outcome

Graft Options

• Bone Patella Bone • Hamstring

• Allograft

• Advantages – Lower rate of graft failure

– Sufficient strength

– Bone plug to bone tunnel fixation

• Disadvantages – Increased anterior knee pain

– Small risk patella fractures • Freedman, Bach, 2003

Frank, JBJS, 1997

Graft Options

• Bone Patella Bone

• Hamstring • Allograft

• Advantages

– Adequate strength – Little donor morbidity

• Disadvantages – Higher rate of graft failure

• Freedman, Bach 2003 • Gifstad, 2014

– Increased laxity , functionally similar • Feller, 2002

Graft Pearl

• Size matters

– Hamstring < 8mm

• Increased failure rate – Magnussen, 2012

Surgical Technique

Femoral Notchplasty

• Femoral notch stenosis associated with ACL tears

– LaPrade, 1994, Souryal, 1988

• Increased visualization of the ACL footprint and the posterior condylar wall

Tibial Tunnel Site

• Tibial insertion:

–15 mm behind anterior border of articular surface

–Medial to attachment of anterior horn of lateral meniscus

Insertion sites

• Femoral attachment:

– Posteriorlateral aspect of the intercondylar notch on lateral femoral condyle

Femoral Tunnel Placement

Non Anatomic Single Bundle Vertical Graft

Anatomic Single Bundle

Passing the Graft

Graft Fixation

• Fixation is the weak link during the early stages of healing

• Fixation Goal

– Obtain biologic incorporation of the graft at the anatomic attachment of the ACL and restore the transition from soft tissue to fibrocartilage to calcified cartilage to bone

Fixation Choices

• Interference Screw – Most popular

– Avoid divergence away from bone plug • Divergence >15 deg

decrease in pullout strength

• Clinical studies: few failures

– Blunted screw threads for soft tissue grafts

– Bioabsorbable screws

Fixation Choices

• Endobutton

• Screw and washer

• Cross pin fixation

• Rigid Fix

Anatomic ACL Reconstruction

Poor Surgical Technique

• Vertical tunnels: poor rotational control

Non-anatomic Single Bundle

Poor Surgical Technique

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• Anterior femoral tunnel: Graft failure in flexion

Epiphyseal sparring ACL

reconstruction

Kocher, 2006, 2007

Graft Healing

• BPTB grafts: – Heal by bone plug incorporation and resembled the normal

insertion of the normal ACL

• Hamstring grafts: – Heal by fibrils of the graft penetrating the bone directly and

result in the a fibrous insertion of the tendon

• Allografts: – Slower rate of incorporation

– Greater decrease in structural properties

– Prolonged inflammatory response

Bone Tunnel Widening

• More frequent with allograft and hamstring reconstruction – Associated with accelerated,

brace free rehabilitation protocol (Vadala, 2007)

– Associated with fixation points not close to the joint (Fauno, 2005)

• No study confirms that tunnel widening has an adverse effect on ACL results – Revision is more difficult

ACL Complications

• 60-80% are surgical / technical errors – Femoral tunnel

placement

– Fixation failure or mismatch

– Untreated or unrecognized secondary insufficiencies • Morgan, 2012

Summary: ACL Reconstruction

• Anatomic tunnel placement

• Gold Standard Graft

– B-PT-B

• Hamstring graft with open growth plates or patellofemoral issues

– Semitendinosis

– Gracilis

• Always repair the meniscus