Surgical Reconstruction Issues



Immediate ACL reconstruction

Early v delayed ACL reconstruction

Repair v Reconstruction

Graft choices



Single versus double bundle

Anterolateral ligament (ALL) reconstruction / Extra-articular tenodesis

Trans-tibial v anteromedial drilling

Position of knee during tibial fixation

Tunnel placement


Immediate ACL Reconstruction




Does early ACL reconstruction in the acute injury period increase risk of stiffness?




Deabate et al Am J Sports Med 2020

- meta-analysis of 8 RCTs

- 3 with 3 week cut off, 5 with 10 week cut off

- no evidence of increased risk of stiffness, complications, or poorer outcomes


Early versus delayed ACL reconstruction




Does delayed ACL reconstruction or long wait to surgery result in increased injury?




Prodomidis et al Am J Sports Med 2020

- systematic review and meta-analysis of timing of ACLR and meniscal tears

- meta-analysis of 5 RCTS demonstrated surgery > 3 and > 6 months after injury associated with increased medial meniscal tears



Repair versus Reconstruction




Early after ACL injury

Suture repair +/- internal splint +/- scaffold




Murray et al Am J Sports Med 2020

- RCT of 100 patients average age 17

- injury < 45 days, midsubstance tear

- suture repair + scaffold

- no difference in laxity or functional outcome

- 14% repair v 6% reconstruction required revision at 2 years


Graft Choices




Bone patella tendon bone

Hamstring tendons



Patella tendon





- risk of patella fracture

- increased anterior knee pain compared to hamstring / quadriceps


ACL BPTB Patella Fracture APACL BPTP Patella Fracture LateralACL BPTB Patella ORIF APACL BPTB Patella ORiF Lateral





- less PFJ pain compared with patella tendon



- some weakness of hamstrings which may be important in some athletes (sprinters)





- reduced AKP compared with patella tendon

- potentially thicker graft compared to hamstring


Revision Results


Persson et al Am J Sports Med 2014

- Norwegian ACL registry of 12,600 patients

- at mean follow up of 5 years, revision rate 4.2%

- revision rate patella tendon 2.1%

- revision rate hamstring 5.1%

- in 15 - 19 age group, 5 year revision rate 9.5% (HS) v 3.5% (PT)

- > 30 age group, 5 year revision rate 2.1% (HS) v 1.2% (PT)


Lind et al KSSTA 2020

- Danish ACL registry, revision rate at 2 years

- revision rate quadriceps tendon 4.7%

- revision rate hamstring tendon 2.3%

- revision rate patella tendon 1.5%


Tiplady et al AJSM 2023

- NZ ACL registry

- 1200 young women between 15 and 20

- hamstring graft failure 7.7%

- BPTB graft failure 1%


Anterior knee pain


Marques et al Orthop J Sports Med 2020

- 438 patients, overall incidence of 6%

- 10% in PT, 3% in HS group

- risk increased by extension deficit (24% v 5%)






No donor site morbidity





Older patient




Disease transmission 


Slower incorporation

Increased failure rate




Zeng et al Arthroscopy 2016

- meta-analysis of 9 RCTs autograft v allograft

- increased failures rates and poorer outcomes for irradiated allograft

- no difference for non irradiated allograft






No donor site morbidity








Tulloch et al KSSTA 2019

- 55 cases single surgeon LARS at mean follow up 7 years

- 33% mechanical failure

- 40% secondary surgery

- giant cell synovitis seen at arthroscopy


Single v Double Bundle




Anatomically reproduce both bundles of ACL

? increase stability




Technically difficult




Mascarenhas et al Arthroscopy 2016

- systematic review of meta-analysis

- improved stability in AP planes and rotational

- no difference in clinical outcomes or retear


Anterolateral ligament reconstruction / Extra-articular tenodesis




Injury to ALL at time of ACL injury

Contributes to rotational instability




Kunz et al Arthroscopy 2021

- meta-analysis

- addition of ALL / LET improves pivot shift


Getgood et al Am J Sports Med 2020

- RCT of hamstring ACL +/- LET

- 600 patients, grade 2 pivot, ligamentous lax, < 25

- addition of LET / ALL reduced clinical failure and re-rupture


Pinheiro et al Am J Sports Med 2023

- ACLR in 200 elite male professional soccer players

- 53% played at least one season at pre-injury performance

- 30% pre-injury performance at 2 years

- 22% pre-injury performance at 5 years

- LET doubled chance of return to play

- age > 25 and chondral defects poor prognosis


Trans-tibial v anteromedial portal drilling





- drill tibial tunnel

- insert guide through tibial tunnel to drill femoral tunnel

- tunnels more vertical

- tibial tunnel position dictates femoral tunnel position


Anteromedial portal drilling

- drill femoral tunnel through anteromedial portal

- anatomic ACL reconstruction

- allows femoral tunnel position at anatomic site of ACL insertion

- less vertical graft

- potentially more stable knee




Loucas et al Orthop J Sports Med

- systematic review

- anteromedial drilling associated with improved AP and rotational stability

- anteromedial drilling associated with improved clinical outcome scores


Knee position during graft fixation




Secure ACL graft on tibial side at full extension

- don't lose knee extension

- graft potentially not as tight


Secure ACL graft on tibial side at 30 degrees of flexion

- graft will tighten as go to full extension, potentially more stable knee

- can limit patient's ability to achieve full extension




Chahal et al Arthroscopy 2021

- RCT of patella tendon fixation at 0 versus 30 degrees

- 169 patients

- no difference in reoperation, knee extension loss, stability or functional outcome

- patients fixed in full extension had increased activity scores and less pain


Tunnel Placement


1.  Intra-operative tunnels


Isometricity does not exist

- no point on femur that maintains fixed distance from point on tibia

- up to 3 mm elongation acceptable

- graft should tighten with increased extension


A. Tibial tunnel 


Sagittal plane

- 7 mm anterior to PCL & central

- posterior 1/2 ACL footprint


Coronal plane

- 2/3 way towards medial tibial spine from anterior horn of lateral meniscus


Tunnel angle

- usually 55o

- reduce angle to shorten tunnel if have short graft


B. Femoral tunnel 


More vertical placement of tunnel

- increased AP stability

- less rotational stability / pivot shift


Coronal plane

- 2 o'clock rather than 1 (right knee)

- 10 o'clock rather than 11 (left knee)


Sagittal plane

- want to be posterior

- identify back wall in flexion

- want 2mm of back wall behind tunnel


2.  X-ray assessment


Lateral x-ray


Femoral tunnel

- intersection of line posterior femoral cortex and Blumensaat's line


Tibial tunnel

- posterior to Blumensaat's line in full extension

- parallel to Blumensaat's line


ACL Reconstruction Femoral Tunnels SagittalACL Reconstruction Sagittal Tibial Tunnel


Pinczewski JBJS Br 2008

- 200 patients followed up over 7 years


1.  Posterior femoral tunnel placement

- 86% along Blumensaat's line 


2. Anterior tibia tunnel placement

- 48% along tibial plateau

- parallel to Blumensaat's


ACL Reconstruction Sagittal Tunnel Measurement


AP Xray


1.  Medial tibial tunnel placement

- 46% (towards medial)


2.  Lateral femoral tunnel placement

- 42% from lateral LFC


3.  Graft inclination

- 19o


ACL Reconstruction AP Tunnel MeasurementsACL Reconstruction Graft Inclination Measurement


11% rupture rate over 7 years

- associated with posterior tibial tunnel placement


Good rotational stability

- 19o inclination in coronal plane

- avoid too vertical orientation


3.  Incorrect tunnel positions


Tibial Tunnel


A.  Anterior tibial tunnel

- impingement / limits extension / cyclops lesion


B. Posterior tibial tunnel

- impinge on PCL

- extension strain in extension


C.  Lateral tibial tunnel

- impinges on lateral wall femoral condyle


Femoral Tunnel


A.  Anterior Femoral Tunnel

- limits flexion

- increased strain in flexion / stretches graft

- increases risk of failure


B.  Posterior Femoral Tunnel

- excessive strain in extension


C.  Vertical Graft


Fu etal Arthroscopy 2003

- cadaver study of graft in 10 v 11 o'clock position

- demonstrated increased rotational instability in 11 o'clock


Options for drilling femur


1.   Trans - tibial 


Traditional techique

- drill tibial tunnel first

- place guide up tibial tunnel onto femur


ACL Transtibial Tunnel



- cannot damage MFC


Potential disadvantage

- tibial tunnel sets position of femoral tunnel

- tends to make the graft more vertical



- drill femur with knee at 90o


2.  Anteromedial portal



- allows separation of femoral from tibial tunnel

- can place femoral tunnel lower on femoral wall


ACL Anteromedial Femoral Tunnel



- places drills and reamers close to MFC

- must be careful not to damage cartilage



- must hyperflex knee

- or femoral tunnel may exit in PFJ


Femoral Tunnel Back wall blow-out




Cannot use RCI screw to secure femoral side


Avoid by


1. Using posterior offset femoral guide

- divide tunnel size required in half and add 2

- 6mm for 7.5 mm hamstring tunnel

- 7mm for 10 mm BPTB tunnel


2.  Appropriate knee flexion when drilling femoral tunnel 

- hyperflexing knee if using AM portal

- 90o of flexion if using transtibial technique




1.   Endo-button 

- don't need back wall for fixation


2.  Redrill tunnel 

- change angle by flexing knee +++

- get in good bone stock


3.  Fix in over the top position

- pass graft around back of femoral condyle using curved hemostat

- may need medial parapatella approach

- lateral approach to femur

- fix to femur with screw / staple

- can pass around lateral intermuscular septum and LCL




ACL Large Notch OsteophyteACL Post Notchplasty



- smaller notch increases risk of re-rupture / stretching by causing graft impingement

- more necessary with larger grafts i.e. BPTB

- required if presence of notch osteophytes



- notchplasty can lateralise

- important to only debride anterior portion of notch

- do not debride lateral wall or will lateralise the femoral graft



- trial with guide wire / reamer / chondrotome / graft

- check for lateral wall impingement

- check for roof impingement

- notchplasty as required


Graft Fixation


Graft fixation is weakest link first 6-12 weeks

- BPTB 6-10 weeks to incorporate

- HS 12 weeks (bone grows into tendon resembling Sharpey's fibres)


After 12 weeks the weak link is the graft




Aperture Fixation


Interference screw

- metal / bioabsorbable


Suspensory Fixation





ACL Transfix Pin


Fauno et al Arthroscopy 2005

- compared transfix and endobutton

- demonstrated increased tunnel widening with fixation away from joint i.e endobutton





- biomechanical studies in tibia with hamstring

- line to line screw size less strong than tunnel diameter + 1



- probably more important than diameter in hamstring

- has been demonstrated than increasing length increases fixation

- increase number of threads available for fixation



- important with bone block

- must keep divergence below 200


Central / eccentric placement

- no significant difference


Metal v bioabsorbable


Mascarenhas Arthroscopy 2015

- meta-analysis

- no difference in outcome

- increased knee effusion, femoral tunnel widening, and screw breakage with bioabsorbable