Content uploaded by Andy Williams
Author content
All content in this area was uploaded by Andy Williams on Jun 20, 2020
Content may be subject to copyright.
The Role of the Anterolateral
Structures and the ACL in
Controlling Laxity of the Intact
and ACL-Deficient Knee:
Letter to the Editor
DOI: 10.1177/0363546516638069
Dear Editor:
We read with significant interest the article by Kittl
et al
10
on the role of the anterolateral structures in control-
ling laxity of the intact and anterior cruciate ligament
(ACL)–deficient knee. We congratulate the authors on
this interesting study, which contributes further to our
understanding of the role of these anatomic structures.
However, we would like to bring up some important
questions and remarks related to this paper. First, has
the dissection technique utilized in this study been previ-
ously validated? How did the authors confirm that they
were isolating the deep iliotibial band (ITB) from the
superficial ITB? Similarly, the isolation of the anterolat-
eral ligament (ALL) performed in this study has never, to
our knowledge, been performed in this way. How did the
authors ensure that the deep capsule-osseous layer and
the ALL were completely separated in their entirety?
Was histologic analysis subsequently performed to ensure
that each structure tested was as described?
The ALL described in the article and illustrated in Fig-
ure 3 is visually quite different from the structure
described in previous publications.
1-5,19
The ALL depicted
in Figure 3 of this article appears significantly smaller,
with an attachment that appears to be adjacent to the joint
line of the tibia, above the tibial landmarks previously
described. Furthermore, the anatomic depiction lacks the
fanlike insertion on the tibia that has been widely pub-
lished.
1-5,19
In addition, Figure 2B of the Kittl et al
10
article
demonstrates the knee after resection of the capsule-osse-
ous layer of the ITB, prior to isolation of the ALL, yet there
does not appear to be any distinguishable structure
remaining, certainly not the presence of a robust ALL.
We know that the dissection technique utilized contrib-
utes significantly to the interpretation of the characteristics
of these anterolateral structures, specifically the ALL,
1,3-5
and that this interpretation also alters the biomechanical
characteristics of these structures.
9,14
Areviewofarticles
by Kaplan
7,8
and Terry et al
17,18
reveals the historical chal-
lenge in defining these structures. It is interesting, how-
ever, that Terry et al
17
describe the capsule-osseous layer
of the deep ITB as a structure ‘‘whose proximal origin is con-
tinuous with fascia covering the plantaris and lateral gas-
trocnemius and whose tibial insertion is just posterior to the
Gerdy tubercle.’’ Furthermore, Terry et al
17
describe this
structure as acting as if it is ‘‘an anterolateral ligament of
the knee’’ (Figure 1
18
). We postulate that perhaps the
‘‘deep capsulo-osseous layer of the ITB’’ referenced by Terry
et al
17
and the ALL of the knee are generally the same
structure, just dissected with different techniques.
Current literature clearly demonstrates that directly
underneath the ‘‘superficial’’ ITB lies the ALL, as demon-
strated not only by the dissection technique from Daggett
et al
2
but also by magnetic resonance imaging studies show-
ing that the ALL runs inferior to the ITB with no other dis-
tinguishable structure between them.
6,11
Additionally, we
know that this structure is histologically an extracapsular
ligament
4,19
and is involved in rotational control of the
knee.
13,15,16
The correlation between the ALL and the ‘‘cap-
sulo-osseous layer of the ITB’’ as described by Terry et al
17
is
further supported by biomechanical findings. When the
findings of this study by Kittl et al
10
are compared with
those of other studies examining the role of the ALL in
internal rotation control of the tibia,
13,15,16
the results are
quite similar if one considers the structures to be the
same. Regardless of name, we are now all in agreement
that an anatomic structure, deep to the superficial ITB
that inserts posterior to the Gerdy tubercle, plays a signifi-
cant role in controlling internal rotation of the knee.
Furthermore, while the authors found a significant con-
tribution of the ‘‘superficial’’ ITB to stability of the knee, we
believe that these laboratory findings do not translate clin-
ically. In the setting of acute ACL tear, one rarely encoun-
ters an injury to the ITB. Additionally, although the
authors found the different structures contributing to rota-
tion at varying degrees of flexion, physiologic motion of the
knee in its entirety is what is important, and this motion is
limited internal rotation toward knee extension (ie, 15°)
with significantly more physiologic rotation in deeper
degrees of knee flexion (ie, 90°).
12
Figure 1. The capsulo-osseous layer of the iliotibial band as
described by Terry et al
17
demonstrates significant similarity
to the anterolateral ligament as described by Claes et al.
1
(Reprinted with permission from Terry et al.
17
Ó1986, Amer-
ican Orthopaedic Society for Sports Medicine.)
The American Journal of Sports Medicine, Vol. 44, No. 4
Ó2016 The Author(s)
NP14
In conclusion, we believe that the findings in this study
could be biased because of the dissection technique chosen,
thus preventing a reasonable conclusion from being
reached. We agree with the comment by Terry et al
17
that ‘‘the functional anatomy of the iliotibial tract is com-
plex.’’ Regardless of nomenclature, we do agree with the
authors that the anterolateral structures play a significant
role in rotational control of the knee, and they should
remain a focus of study to improve our clinical and func-
tional results after pivot shift–type injuries.
Matt Daggett, DO, MBA
Kansas City, Missouri, USA
Steven Claes, MD
Lubbeek, Belgium
Camilo P. Helito, MD
Sa˜o Paulo, Brazil
Pierre Imbert, MD
Saint-Raphae¨l, France
Edoardo Monaco, MD
Rome, Italy
Christian Lutz, MD
Strasbourg, France
Bertrand Sonnery-Cottet, MD
Lyon, France
Address correspondence to Matt Daggett, DO, MBA (email:
matthewdaggett@gmail.com).
One or more of the authors has declared the following potential
conflict of interest or source of funding: S.C., E.M., and B.S-C. are
all consultants with Arthrex Inc.
REFERENCES
1. Claes S, Vereecke E, Maes M, Victor J, Verdonk P, Bellemans J.
Anatomy of the anterolateral ligament of the knee. J Anat. 2013;
223:321-328.
2. Daggett M, Busch K, Sonnery Cottet B. Surgical dissection of the
anterolateral ligament. Arthrosc Tech. In press.
3. Daggett M, Ockuly A, Cullen M, et al. Femoral origin of the anterolat-
eral ligament: an anatomic analysis [published online December 22,
2015]. Arthroscopy. doi:10.1016/j.arthro.2015.10.006.
4. Dodds AL, Halewood C, Gupte CM, Williams A, Amis AA. The antero-
lateral ligament: anatomy, length changes and association with the
Segond fracture. Bone Joint J. 2014;96(3):325-331.
5. Helito CP, Demange MK, Bonadio MB, et al. Anatomy and histology of
the knee anterolateral ligament. Orthop J Sports Med. 2013;1(7):
2325967113513546.
6. Helito CP, Demange MK, Helito PV, et al. Evaluation of the anterolat-
eral ligament of the knee by means of magnetic resonance examina-
tion. Rev Bras Ortop. 2015;50(2):214-219.
7. Kaplan EB. Factors responsible for stability of the knee joint. Bull
Hosp Joint Dis. 1957;18:51-59.
8. Kaplan EB. Surgical approach to the lateral (peroneal) side of the
knee joint. Surg Gynecol Obstet. 1957;104:346-356.
9. Kennedy MI, Claes S, Fuso FA, et al. The anterolateral ligament: an
anatomic, radiographic, and biomechanical analysis. Am J Sports
Med. 2015;43(7):1606-1615.
10. Kittl C, El-Daou H, Athwal K, et al. The role of the anterolateral struc-
tures and the ACL in controlling laxity of the intact and ACL-deficient
knee. Am J Sports Med. 2016;44(2):345-354.
11. Kosy JD, Mandalia VI, Anaspure R. Characterization of the anatomy
of the anterolateral ligament of the knee using magnetic resonance
imaging. Skeletal Radiol. 2015;44(11):1647-1653.
12. Lutz C, Sonnery-Cottet B, Niglis L, Freychet B, Clavert P, Imbert P.
Behavior of the anterolateral structures of the knee during internal
rotation. Orthop Traumatol Surg Res. 2015;101(5):523-528.
13. Monaco E, Ferretti A, Labianca L, et al. Navigated knee kinematics
after tear of the ACL and its secondary restraint. Knee Surg Sports
Traumatol Arthrosc. 2012;20:870-877.
14. Parsons EM, Gee AO, Spiekerman C, Cavanagh PR. The biomechan-
ical function of the anterolateral ligament of the knee. Am J Sports
Med. 2015;43(3):669-674.
15. Rasmussen MT, Nitri M, Williams BT, et al. An in vitro robotic assess-
ment of the anterolateral ligament, part 1: secondary role of the ante-
rolateral ligament in the setting of an anterior cruciate ligament injury.
Am J Sports Med. 2016;44(3):585-592.
16. Sonnery-Cottet B, Lutz C, Daggett M, et al. The involvement of the ante-
rolateral ligament in rotational control of the knee [published online Feb-
ruary 10, 2016]. Am J Sports Med. doi:10.1177/0363546515625282.
17. Terry GC, Hughston JC, Norwood LA. The anatomy of the iliopatellar
band and iliotibial tract. Am J Sports Med. 1986;14:39-45.
18. Terry GC, Norwood LA, Hughston JC, Caldwell KM. How iliotibial
tract injuries of the knee combine with acute anterior cruciate liga-
ment tears to influence abnormal anterior tibial displacement. Am J
Sports Med. 1993;21:55-60.
19. Vincent J-P, Magnussen RA, Gezmez F, et al. The anterolateral liga-
ment of the human knee: an anatomic and histologic study. Knee
Surg Sports Traumatol Arthrosc. 2012;20:147-152.
The Role of the Anterolateral
Structures and the ACL in
Controlling Laxity of the Intact
and ACL-Deficient Knee:
Response
DOI: 10.1177/0363546516638070
Authors’ Response:
We thank Daggett and colleagues for their insightful
comments and their interest in our article regarding the
role of the anterolateral structures in controlling knee lax-
ity. In light of the recent anatomic development, we are
most grateful to have the opportunity to clarify a number
of points from our work.
Before answering the concerns raised regarding our dis-
section routine, we feel that it is very important to eluci-
date our anatomic point of view. In an examination of
some recent publications of the anterolateral ligament
(ALL), it seems as though other important anatomic struc-
tures have not received sufficient attention. It was not only
Terry et al
11
who described the deep fibers of the iliotibial
tract (ITT) to be important in controlling the anterior sub-
luxation of the lateral tibial plateau but also Mu¨ ller,
9
Lobenhoffer et al,
7
and Hassler and Jakob.
4
Terry et al
11,13
were the first to associate the deep ITT
fibers (namely, the capsulo-osseous layer) with the term
AJSM Vol. 44, No. 4, 2016 Letter to the Editor NP15
anterolateral ligament, followed by Vieira et al
14
in 2007.
Confusion may have arisen from the use of different names
in the literature: Mu¨ ller, ligamentum femorotibiale ante-
rius; Lobenhoffer, retrograde fiber bundle; and Hassler
and Jakob, ligamentum tractotibiale. These terms have
all been applied to what may be described as the femoral
attachment of fibrous structures, which are effectively
a distal prolongation of the lateral intermuscular septum
and which include the Kaplan fibers. All the cited studies
found a femoral insertion site at the linea aspera around
the distal termination of the intermuscular septum and
a tibial insertion site either posterior to the Gerdy tubercle
or directly at it. Conversely, the description of the femoral
insertion site of the ALL varies widely among authors.
Originally, it was reported to be anterior and distal to
the lateral femoral epicondyle, and a conjunction to the lat-
eral meniscus was described. These characteristics cer-
tainly do not match the descriptions of the capsulo-
osseous layer of the ITT. Thus, in accordance with Claes
et al,
1
we believe that the original ALL ‘‘is clearly distinct
from the ITB, and both its deep layer and its capsulo-
osseous layer should not be confused with the ALL.’’
Some later descriptions of the ALL,
2,3,6
however, postu-
late different insertion sites related to the lateral femoral
epicondyle, and it remains unclear whether this ‘‘ligamen-
tous’’ structure is a capsular thickening or an extracapsu-
lar structure. Based on the pictures in recent anatomic
and biomechanical publications,
2,6,10
it may be possible
that the anterolateral knee capsule (which has a connection
to the lateral meniscus) and fibers of the capsulo-osseous
ITT layer have been collectively described as this ‘‘robust’’
ALL, having a fanlike tibial insertion site posterior to the
Gerdy tubercle (Figure 1). This, of course, raises an impor-
tant question: why the original terms (capsulo-osseous
layer, midthird capsular ligament) have been neither
maintained nor adopted. Thus, it seems that the orthopae-
dic community is lacking a consistent terminology for the
anterolateral side of the knee. Some studies may also
have been affected by the use of embalmed cadaver speci-
mens.
1,2
This preservation method has been shown to be
unsuitable for the specific layer-by-layer dissection of the
lateral side of the knee (Terry et al
11
; P. Lobenhoffer, per-
sonal communication, 2015). Therefore, one should be cau-
tious when interpreting anatomic studies using this
embalming technique.
The present study, however, addressed these layered
anatomic structures using fresh-frozen cadaver specimens.
At least 15 cadaver knee specimens were dissected prior to
this study, and the anatomic structures and their insertion
sites were evaluated. It was easy to separate the superfi-
cial layer of the ITT from the deep/capsulo-osseous layer,
as they have completely different insertion sites. All fibers
of the superficial layer of the ITT inserting at the Gerdy
tubercle were resected, and when these fibers were fol-
lowed proximally, there was no insertion site at the meta-
physis of the femur. As such, they could be completely
removed. The superficial layer, which was covering the
capsulo-osseous layer, was then peeled off, leaving the
more-posterior fibers in place. The next step included
resection of the biceps femoris, with all its arms inserting
at different locations. Terry and LaPrade
12
described an
anatomic structure called the biceps femoris capsulo-osse-
ous confluens, which connects the biceps femoris tendon
with the capsulo-osseous layer. This resection confirmed
the presence of the capsulo-osseous layer without any
superficial fibers left on it. This dissection technique was
adopted and slightly modified from that of Mu¨ ller.
8
The capsulo-osseous layer of the ITT was then resected,
to identify the proximal attachments at the linea aspera,
and followed distally. Once freed from its proximal attach-
ment, this structure was not adherent with its underlying
structures and could be easily followed to its distal inser-
tion site at the area posterior to the Gerdy tubercle.
Thus, this structure formed a direct link from the linea
aspera of the femur to the tibia, just posterior to the Gerdy
tubercle. There was absolutely no doubt that the capsulo-
osseous layer was completely separated from its underly-
ing structures. Once these 2 layers had been removed,
a large drop in torque was observed in all 16 knees, imply-
ing a potent role of the ITT in controlling internal tibial
rotation.
Owing to the aforementioned inconsistencies in the
descriptions of the ALL, it was necessary to divide the
next step into 2 separate cuts. A 4-Nm internal rotational
torque was applied to identify the tense fibers running
obliquely over the lateral collateral ligament (LCL). These
were cut representing all ALLs described running superfi-
cial to the LCL. The remaining structure, named the mid-
third capsular ligament in the early 1970s, was then cut.
5
This last cut exposed the surface of the lateral femoral con-
dyle, lateral meniscus, and rim of the tibial plateau as far
Figure 1. The lateral aspect of a left knee: distal to the left,
proximal to the right. The anterolateral ligament complex
(ALL) is grasped by the forceps close to the femoral attach-
ment, which is 6 to 10 mm proximal and posterior to the lateral
epicondyle. The ALL complex passes over the lateral (fibular)
collateral ligament and fans out to wrap over the anterolateral
rim of the tibial plateau. This exposure followed a longitudinal
incision of the posterior edge of the iliotibial tract and anterior
reflection of the resulting flap (in upper forceps), with sharp
dissection posterior to the Gerdy tubercle, exposing/clarifying
the ALL and the lateral collateral ligament.
NP16 Letter to the Editor The American Journal of Sports Medicine
posteriorly as the LCL, so no fibers could have been left
intact across the area identified as being the ALL in all
studies that we had seen. These 2 structures directly
deep to the ITT, whatever one may consider the ALL,
had no significant contribution in controlling internal tib-
ial rotation in this robotic setup. A histologic analysis of
the resected structures was not necessary, because every
structure could be identified macroscopically.
By a fortunate coincidence, the senior signatory of the
letter from Daggett et al, Bertrand Sonnery-Cottet, had
arranged to visit our laboratory, and so we took the opportu-
nity to dissect some knees together. We found that we were
largely in agreement about the anatomy of the ALL: its
course—passing over the LCL; its attachments—posterior/
proximal to the lateral epicondyle and midway between
the Gerdy tubercle and the head of the fibula; and how it
was tightened by tibial internal rotation (see Figure 1).
We also saw that the internal rotation laxity increased
when the ALL had been transected.
How, then, to explain our difference of opinion regard-
ing the importance of the ALL as a restraint of tibial inter-
nal rotation laxity? We believe that this difference has
arisen because of our differing methods of study, both ana-
tomic and biomechanical. Anatomically, the structure
defined as the ALL complex in Figure 1 is bulkier than
the relatively flimsy ALL that had been described at the
time when our cutting study started,
1,3
which had no con-
nection to the ITT. Some fibers seen here would have been
defined as belonging to the deep capsulo-osseous layer of
the ITT in our study—which dissected them from the
underlying ALL by separating the layers proximal to
distal—whereas the preparation in the picture was dis-
sected posterior to the ITT and left the distal attachment
around the rim of the tibia. Most biomechanical studies
have been based on observations of changes of laxity
when the ALL was cut, whereas our study moved the tibia
by a fixed amount and measured the reduction of force and/
or torque needed after a structure was cut. While changes
of laxity are observed during clinical examination and are
familiar to surgeons, it is the measurement of changes of
load needed to displace the tibia that is necessary to dis-
cover the primary and secondary restraints. Use of that
method found that the ITT resisted much more of the tibial
internal rotation torque than the ALL.
CONCLUSION
The confusion surrounding the anatomy of the anterolat-
eral side of the knee suggests an urgent need for a consis-
tent terminology for these structures, including older
descriptions of the deep fibers of the ITT and the joint cap-
sule. It seems that some interpretations of the ALL may
describe a structure complex that includes fibers from dif-
ferent anatomic structures. The ALL complex may be
found crossing the anterolateral aspect of the knee just
proximal/posterior to the lateral epicondyle, over the
LCL, and down to the rim of the tibia posterior to the
Gerdy tubercle and anterior to the head of the fibula.
Finally, there is no doubt that it is best to study the anat-
omy by dissecting knees together! We all learned a lot from
each other when Bertrand visited us in London, and we
have formed a friendly partnership now and are planning
to do some experiments on lateral extra-articular soft tis-
sue reconstructions together—une vraie entente cordiale!
Christoph Kittl, MD
Hadi El-Daou, PhD
Kiron K. Athwal, MEng
Chinmay M. Gupte, PhD, FRCS
London, UK
Andreas Weiler, MD, PhD
Berlin, Germany
Andy Williams, FRCS
Andrew A. Amis, FREng, DSc(Eng)
London, UK
Address correspondence to Andrew A. Amis, FREng, DSc(Eng)
(email: a.amis@imperial.ac.uk).
One or more of the authors has declared the following potential
conflict of interest or source of funding: The study discussed here
was supported by a Research Fellowship grant from Smith &
Nephew (Endoscopy) Co and a grant from the AGA (Society for
Arthroscopy and Joint Surgery), which supported C.K. The
Engineering and Physical Sciences Research Council and
Wellcome Trust–funded Centre of Excellence for the application of
technology for the treatment of osteoarthritis at Imperial College
London provided the robot and supported H.E.-D. Newcastle
Healthcare Charity supported K.K.A. All support was paid to
a research account of Imperial College London.
REFERENCES
1. Claes S, Vereecke E, Maes M, Victor J, Verdonk P, Bellemans J.
Anatomy of the anterolateral ligament of the knee. J Anat.
2013;223:321-328.
2. Daggett M, Ockuly AC, Cullen M, et al. Femoral origin of the antero-
lateral ligament: an anatomic analysis [published online December
22, 2015]. Arthroscopy. doi:10.1016/j.arthro.2015.10.006.
3. Dodds A, Halewood C, Gupte C, Williams A, Amis A. The anterolat-
eral ligament: anatomy, length changes and association with the
Segond fracture. Bone Joint J. 2014;96(3):325-331.
4. Hassler H, Jakob RP. Ein beitrag zur ursache der anterolateralen
instabilita
¨t des kniegelenkes: eine studie an 20 leichenknien unter
besonderer beru
¨cksichtigung des tractus iliotibialis [On the cause
of the anterolateral instability of the knee joint. A study on 20 cadaver
knee joints with special regard to the tractus iliotibialis (author’s
transl)]. Arch Orthop Traumat Surg. 1981;98:45-50.
5. Hughston J, Andrews J, Cross M, Moschi A. Classification of knee
ligament instabilities, part II: the lateral compartment. J Bone Joint
Surg Am. 1976;58(2):173-179.
6. Kennedy MI, Claes S, Fuso FAF, et al. The anterolateral ligament: an
anatomic, radiographic, and biomechanical analysis. Am J Sports
Med. 2015;43(7):1606-1615.
7. Lobenhoffer P, Posel P, Witt S, Piehler J, Wirth CJ. Distal femoral fixa-
tion of the iliotibial tract. Arch Orthop Traumat Surg. 1987;106:285-290.
8. Mu
¨ller W. Anatomy of the Knee [DVD]. Luxembourg, Belgium;
ESSKA; 2006.
9. Mu
¨ller W. The Knee: Form, Function and Ligament Reconstruction.
Berlin, Germany: Springer; 1983.
10. Sonnery-Cottet B, Lutz C, Daggett M, et al. The involvement of the
anterolateral ligament in rotational control of the knee [published
AJSM Vol. 44, No. 4, 2016 Letter to the Editor NP17
online February 10, 2016]. Am J Sports Med. doi:10.1177/
0363546515625282.
11. Terry GC, Hughston JC, Norwood LA. The anatomy of the iliopatellar
band and iliotibial tract. Am J Sports Med. 1986;14:39-45.
12. Terry GC, LaPrade RF. The biceps femoris muscle complex at the knee:
its anatomy and injury patterns associated with acute anterolateral-
anteromedial rotatory instability. Am J Sports Med. 1996;24(1):2-8.
13. Terry GC, Norwood LA, Hughston JC, Caldwell KM. How iliotibial
tract injuries of the knee combine with acute anterior cruciate liga-
ment tears to influence abnormal anterior tibial displacement. Am J
Sports Med. 1993;21:55-60.
14. Vieira ELC, Vieira EA
´, da Silva RT, dos Santos Berlfein PA, Abdalla
RJ, Cohen M. An anatomic study of the iliotibial tract. Arthroscopy.
2007;23(3):269-274.
For reprints and permission queries, please visit SAGE’s Web site at http://www.sagepub.com/journalsPermissions.nav.
NP18 Letter to the Editor The American Journal of Sports Medicine
