One of my talks at Delhi Arthroscopy Club....... this presentation provides a insight regarding the conceptual evolution in tunnel placement during ACL reconstruction.

1. EVOLUTION OF TUNNEL PLACEMENT
IN ANTERIOR CRUCIATE LIGAMENT
RECONSTRUCTION:
FROM ISOMETRIC TO ANATOMIC
Dr Dhananjaya Sabat
Assistant Professor
Maulana Azad Medical College & SushrutaTrauma Center, New
Delhi

2. Tunnel placement is the most
important factor for successful
result: WHY?
Marchant BG, Noyes FR, Westin SDB, Fleckenstein C. Prevalence of Nonanatomical
Graft Placement in a Series of Failed Anterior Cruciate Ligament Reconstructions.
Am J Sports Med October 2010 vol. 38 no. 10 1987-1996
• 88% nonanatomic graft placement
• 61% of the grafts were entirely on the intercondylar
femoral roof
• 35% extended posterior to the ACL tibial attachment.
• Transtibial technique had been used in 83%:
significantly increased vertical orientation of graft
In this series comprising 112 revision ACLR

3. Zantop T, Kubo S, Petersen W, Musahl V, Fu FH. Current Techniques in
Anatomic Anterior Cruciate Ligament Reconstruction. Arthroscopy: The Journal
of Arthroscopic and Related Surgery. 2007,23,9:938-947
• 20 panelist worldwide.
• Femoral AM bundle tunnel
placement : consistent among
the panelists.
• Femoral PL bundle placement:
greater variance in tunnel
placement.
• 50% -Transtibial AM bundle
tunnel
• 55% use aimers
• 55% do AM tunnel drilling first

4. ISOMETRIC CONCEPT
Concept : full range of knee can be achieved w/o
causing long-term ligament deformation.
Authors tried to define the isometric point…..
But:
 Isometry can not exist because, during ROM, there
is no one point on femur that maintains a fixed
distance from a single point on tibia
 Elongation always will occur

5. ISOMETRIC TIBIAL TUNNEL
 Tibial aimer fixed at 550 is seated on the
debrided stump of the ACL.
 Center of tunnel is at 7 mm anterior to
the PCL notch/ posterior fovea /
retroeminentia ridge; in line with the
posterior border of the anterior horn of
lateral meniscus
 Outside entry: 4 cm from tibial joint
line, 2cm medial to tibial tubercle
Morgan CD, KalmanVR, Grawl DM. Definitive landmarks for
reproducible tibial tunnel placement in anterior cruciate
ligament reconstruction. Arthroscopy 1995;11:275-288
Jackson DW, Gasser SI.Tibial tunnel placement in ACL
reconstruction. Arthroscopy 1994;10:124-131

6. ISOMETRIC FEMORAL TUNNEL
 Transtibial technique
 Center of tunnel at “over the top”
position
 6-8 mm anterior to the true back wall; i.e.
extreme posterior cortex; at the junction
of the roof and the lateral wall of the
femoral intercondylar notch, resulting in
a 1-2mm proximal cortical margin (back
wall thickness).
Morgan CD, KalmanVR, Grawl DM. Definitive landmarks for
reproducible tibial tunnel placement in anterior cruciate
ligament reconstruction. Arthroscopy 1995;11:275-288
McGuire DA, Hendricks SD, Grinstead GL. Use of an endoscopic
aimer for femoral tunnel placement in anterior cruciate
ligament reconstruction. Arthroscopy 1996;12:26-31.
Hardin G, Bach B, Bush-Joseph C, Farr J. Endoscopic single
incision ACL reconstruction using patellar tendon autograft:
surgical technique. Am J Knee Surg1992;5:144-155.

7.  Which bundle regions of ACL are most isometric
 Graft placed as closely as possible to centers of
tibial & femoral attachments of AM bundle results in
least amount of strain (least change in length of ACL
during complete ROM of knee)
 Many surgeons feel that it is more important to
replace the more non-isometric PL bundle
Focus shifted……
Penner DA, Daniel DM, Wood P, Mishra D. An in vitro study of anterior cruciate ligament
graft placement and isometry. Am J Sports Med June 1988 vol. 16 no. 3 238-243

8. Anatomic or Isometric???
A femoral tunnel position inside the anatomical
footprint of the ACL results in knee kinematics
closer to the intact knee than does a tunnel
position located for best graft isometry
MusahlV, Plakseychuk A,VanScyoc A, SasakiT, Debski RE, McMahon PJ, Fu FH.
Varying FemoralTunnels Between the Anatomical Footprint and Isometric
PositionsEffect on Kinematics of the Anterior Cruciate Ligament–Reconstructed
Knee. AJSM(2005),33,5,712-8

9. Anatomic ACLR better restores anterior
translational as well as rotational stability.
ZavrasTD, Race A, Amis AA.The effect of femoral attachment location on anterior
cruciate ligament reconstruction: graft tension patterns and restoration of
normal anterior-posterior laxity patterns. KSSTA 2005;13:92-100.

10. 10 O’ Clock / 11 O’ Clock !!!!
The 10 o’clock position more effectively resists
rotatory loads when compared with the 11 o’clock
position as evidenced by smaller ATT and higher in
situ force
Loh JC, FukudaY, Tsuda E, Richard J. Knee Stability and Graft Function Following
Anterior Cruciate Ligament Reconstruction: Comparison Between 11 O’clock and 10
O’clock FemoralTunnel Placement. Arthroscopy:The Journal of Arthroscopic and
Related Surgery,Vol 19, No 3 (March), 2003: pp 297-304
The clock concept is easy to use. However, it is
inaccurate in describing the location of femoral tunnel
placement and lead to non-anatomic tunnel position

11. Jonsson H, Riklund-Ahlstrom K, Lind J. Positive pivot shift after
ACL reconstruction predicts later osteoarthritis: 63 patients
followed 5-9 years after surgery. Acta Orthop Scand 2004;
75:594-599.
ANATOMIC
ACLR
BETTER
ROTATIONAL
STABILITY
? DECREASED
RISK OF
OSTEOARTHRITIS

13.  PALMER (1938) - first to describe two
bundles, AM & PL
 Two distinct functional bundles with unique
insertion sites demonstrated in
fetal, cadaveric and arthroscopic studies.
Each bundle is named after its tibial insertion
site- AM & PL
The AM and PL bundles differ in their
length, width, and insertion area
INTRA_
ARTICULAR
LENGTH
INSERTION
AREA ON
FEMUR
INSERTIO
N AREA ON
TIBIA
AM BUNDLE 28-38 mm 44 mm sq 67 mm sq
PL BUNDLE 18-20 mm 40 mm sq 52 mm sq

14. Yasuda K et al
P. Colombet et al. 2006
Zhao J
TIBIAL ATTACHMENT
More variable

15. Arthroscopically Useful Landmarks for
Identifying ACL Tibial Footprint
A> anterior margin of PCL
ACL CENTER AM CENTER PL CENTER
Iriuchishima et al.2010 23. 4 mm 12. 3 mm
Purnell et al.2008 16.5 ± 2 mm (12.7-19.1 mm)
Heming et al.2007 15.0 mm
Colombet et al.2006 17.5 ± 1.7 mm
Edwards et al.2007 15.2 mm (range, 11-18 mm) 17 .2 mm (13-19
mm)
10 .1 mm (8-13
mm)
Hutchinson and
Bae2001
10.4 ± 2.4 mm; posterior
border - 6.7 ±1.2 mm anterior
to PCL
Cuomo et al.2006 Anterior border 22.3 mm (16-
27 mm) ; posterior border 6.2
mm (2-8 mm)

16. B> lateral Meniscus
Zantop et
al.2008
From center of anterior insertion of lateral meniscus;AM center is 2.7 ±0.5
mm posterior and 5.2 0.7 mm medial , PL center is 11.2 ±1.2 mm posterior
and 4.1 0.6 mm medial
Siebold et
al.2008
Posterior horn of lateral meniscus is adjacent to posterior border of PL
footprint; centrum of PL footprint is 5 mm anterior
C> Tibial spine
Luites et
al.2007
Centrum of AM bundle is one-fourth interspinous distance from ML
intercondylar eminence; PL bundle centrum is 4 mm more lateral,
approximately halfway between spines; tibial footprint centrum as a whole is
two-fifths ML (interspinous distance)

17. ANTERIOR HORN OF LATERAL MENISCUS:
IS IT A GOOD LANDMARK?
NO

18. The center of theACL tibial
attachment was 9.12 ± 1.54 mm
behind the posterior edge of
the intermeniscal ligament.
The center of the ACL tibial
attachment was 5.3 ± 1.14 mm
anterior from a projected line
from the peak of the medial
tibial spine
Ferretti M, Doca D, Ingham SM, Cohen M, Fu FH. Bony
and soft tissue landmarks of the ACL tibial insertion
site: an anatomical study . KSSTA 2011

19. RADIOGRAPHIC METHOD
 The lateral knee radiograph method
 Amis and Jakob line (1998): line parallel to the
medial tibial plateau.
 Stäubli and Rauschning (1994) : line is
perpendicular to the tibial axis
 Both lines yield similar results
 AM center at 1/3rd of the AP distance along either
line, PL center is at 40 - 50% of the AP distance
along either line.

20. AP distance wrt AP depth of tibia: AM – 25% (21.1-
29.5), PL- 46.4% ( 40.1-51.5)
ML distance wrt ML width of tibia: AM – 50.5%
(44.1-54.7), PL – 52.4 (49.5- 56.1)
Forsythe B, Kopf S, Wong AK, Martins CAQ, Anderst W, Tashman S, Fu FH. The location of
femoral and tibial tunnels in anatomical double bundle anterior cruciate ligamnet
reconstruction analyzed by three dimensional computed tomography models. JBJS
Am.2010;92:1418-26

21. FEMORAL ATTACHMENT
More consistent
P. Colombet et al. 2006

22. The AM and
PL bundles
change from
being parallel
in extension to
crossing in
flexion

23. Arthroscopically Useful Landmarks for
Identifying ACL Femoral Footprint
Arthroscopic landmarks are less useful:
 parallax, which occurs when viewing with an 30 degree
arthroscopic camera
 variability in the size of diverse femora
Useful landmarks:
 femoral ACL stump (Footprint)
 Resident’s ridge
Better visualization through
 AM portal
 70 degree scope

24. Two osseous landmarks: the lateral intercondylar ridge and the
lateral bifurcate ridge.
When the knee is in 90· of flexion, the lateral intercondylar
ridge runs through the entire ACL footprint with no ACL fibers
attaching superior to this ridge. The lateral bifurcate ridge runs
almost perpendicular to the lateral intercondylar ridge and
separates the AM and PL bundle femoral insertion sites.

25. Ruler Method “Mid Bundle
Reconstruction”
 In the absence of consistent intra-operative visualisation or
landmarks
 The centre of the ACL insertion lies at a point 50% along a
line drawn from the proximal articular cartilage border and
the distal articular cartilage parallel to the tibial surface,
with the knee at 90 degree
Validation of a new technique to determine midbundle femoral tunnel position in
anterior cruciate ligament reconstruction using 3-dimensional computed
tomography analysis. Bird JH, Carmont MR, Dhillon M, Smith N, Brown C,
Thompson P, SpaldingT. Arthroscopy. 2011 Sep;27(9):1259-67.

26. RADIOGRAPHIC METHOD
 Bernard and Hertel method: the centrum as % distance
along the Blumensaat line (from proximal and posterior to distal and
anterior) by % distance along a line perpendicular to the Blumensaat line
(from proximal and anterior to distal and posterior).
 Mochizuki method
 Edward method
 Takahashi method
The mean ratio between the AP femur
measurement and the center of the
ACL femoral attachment -74 to 80%.
Jenny JY , Ciobanu E, Philippe Clavert P, Jaeger JH, Kahn JL,
Kempf JF. Anatomic attachment of the ACL. Comparison
between radiological and CT analysis . Knee Surg Sports
Traumatol Arthrosc (2011) 19:806–810

27. By quadrant method:
AM Bundle PL bundle
Parallel to
Blumensaat
Perpendicular
to
Blumensaat
Parallel to
Blumensaat
Perpendicular
to
Blumensaat
Forsythe et al 21.7 % 33.2% 35.1% 55.3%
Zantop et al 18.5% 22.3% 29.3% 53.6%

28. In summary…
 ACL center: 43% of the proximal-to-distal
length of the lateral, femoral intercondylar notch
wall and femoral socket radius + 2.5 mm
anterior to the posterior articular margin.
 AM center: 29.5% of the proximal-to-distal
length of the lateral, femoral intercondylar notch
wall.
 PL center : 50% of the proximal-to-distal
length of the lateral, femoral intercondylar notch
wall.
 From posterior to anterior, the AM bundle appears
slightly anterior to the PL bundle, and both bundles
appear socket radius + 2.5 mm anterior to
the posterior cartilage margin.
Kaseta MK, DeFrate LE, Charnock BL, Sullivan RT, Garrett WE. Reconstruction technique affects
femoral tunnel placement in ACL reconstruction. Clin Orthop Relat Res 2008;466: 1467-1474.