Download Alexandria Bulletin - Alexandria Faculty of Medicine

El-Gharbawy.
Alexandria Bulletin
789
ANATOMY OF THE LIGAMENTOUS AND TENDINOUS STRUCTURES OF THE
POSTEROLATERAL CORNER OF THE KNEE: A PROPOSAL
FOR THEIR REPAIR
Ramadan M. El-Gharbawy
Anatomy Department, Faculty of Medicine, Alexandria University
ABSTRACT
Background: Knowledge of the anatomy and biomechanics of the posterolateral corner of the knee is required for
the proper evaluation of its posterolateral injuries and provides insight into the treatment of the resulting
posterolateral instability.
Objectives: To describe the gross anatomy of the ligamentous and tendinous structures of the posterolateral corner
of the knee and to provide a proposal for their repair.
Methods: Cadaveric study included dissection of ten preserved lower limbs.
Results: The three critical stabilizers of the posterolateral corner of the knee are the fibular collateral and
popliteofibular ligaments and the tendon of popliteus muscle. They resist varus angulation of the knee and
posterior translation and external rotation of the tibia. The fibular collateral ligament is the stabilizer in full
extension and the other two structures are responsible for the posterolateral stability in flexion. The lateral
intermuscular septum and the iliotibial tract could provide fibrous band suitable for the reconstruction of the three
stablizers of the posterolateral corner of the knee.
Key words: Fibular collateral ligament, popliteus tendon, popliteofibular ligament.
INTRODUCTION
Posterolateral knee injuries can be very
debilitating(1) and the resulting posterolateral knee
instability is a difficult clinical problem to diagnose
and treat.(2) There is an increased attention in the
reconstruction of the posterolateral corner of the
knee in the recent literature.(3) The current consensus
is that knowledge of the complex anatomy,
biomechanics and pertinent diagnostic tests of the
posterolateral corner of the knee is required for the
proper evaluation of its injuries and provides insight
into the treatment of the resulting posterolateral
instability.(1,4,5)
The posterolateral corner of the knee has been
described by several authors but there are still
controversies.(6) Little information is known about
the forces seen on the main individual structures
of the posterolateral corner of the knee to applied
loads. This information is needed to determine
which structures should be reconstructed and also
the relative strengths needed for the grafts used in
reconstruction.(7)
The fabellofibular, arcuate, fibular collateral and
popliteofibular ligaments and popliteus muscle are
currently considered the posterolateral supporting
structures of the knee.(6,8-10) The tendon of biceps
femoris muscle and the iliotibial tract are implicated
in the reconstruction process.(11-14)
The aim of the present study was to provide
detailed information of the morphological
characteristics of the ligamentous and tendinous
structures of the posterolateral corner of the knee;
both those acting as stabilizers and those involved in
their repair.
METHODS
Ten preserved lower limbs of adult male cadavers
Bull. Alex. Fac. Med. 42 No.3, 2006.
obtained from the dissecting room at the Anatomy
Department Alexandria Faculty of Medicine were
used in the present study.
The skin and superficial fascia on the
posterolateral aspect of each limb from midthigh
to midleg were raised. The deep fascia was
incised along the anterior limit of the iliotibial
tract and reflected posteriorly till its attachment
to the lateral intermuscular septum. The lateral
parts of the superior and inferior lateral genicular
blood vessels were identified. This was followed
by the dissection of the lateral intermuscular
septum and the identification of a fibrous band
belonging to the septum and separated from the
iliotibial tract either by the superior lateral
genicular artery or by one of its branches. The
deep fascia was raised from the back of the
lower thigh and upper leg and the dissection was
deepened down to the back of the knee. The
fabellofibular and the fibular collateral ligaments
were identified. The posterior part of the inferior
lateral genicular blood vessels was identified
followed by the removal of the fascia of popliteus
muscle to expose the arcuate ligament. Then the
fibular collateral ligament was detached from its
femoral attachment and so the fabellofibular
ligament from its fibular attachment. Lastly the
tendon of popliteus and the popliteofibular ligament
were identified.
The length, the width and the thickness of the
fabellofibular, fibular collateral, and popliteofibular
ligaments and the tendon of popliteus were
measured.The width of the biceps femoris tendon
and that of its anterior and posterior slips of insertion
were measured. Also the length, the width and the
thickness of fibrous band belonging to the lateral
intermuscular septum were measured. A German
Vernier Caliper with accuracy of 0.05 mm. was used
ISSN 1110-0834
790
Posterolateral Structures of the Knee.
in the measurements.The fibular collateral ligament
and the tendon of popliteus were detached and the
dimensions of the impressions of their attachments
were measured.(6)
RESULTS
Iliotibial Tract and the Lateral Intermuscular
Septum
The iliotibial tract on the lateral side of the knee
joint extended from the lateral border of the patella
to the anterior border of the biceps femoris tendon.
Above the knee the iliotibial tract was continuous
with the part of fascia lata covering vastus lateralis
muscle anteriorly and that covering the biceps
femoris muscle posteriorly (Fig. 1).
Laterally the lateral intermuscular septum was
attached to the iliotibial tract at its attachment
with the part of fascia lata covering the biceps
femoris (Fig. 2). Medially the septum was attached
to the linea aspera of the femur and the lateral
supracondylar line. The fleshy fibres of vastus
lateralis muscle arose from the anterior surface of
the lateral intermuscular septum. The fleshy fibres of
the short head of biceps femoris muscle arose from
the posterior surface of the lateral intermuscular
septum.
Just above the lateral femoral condyle the
medial part of the lateral intermuscular septum
lost its membranous texture and was replaced
by loosely felted fibrofatty tissue through which
branch of the superior lateral genicular artery
passed from the popliteal fossa to the anterolateral
aspect of the knee (Figs.2,3). The lateral part of
the lateral intermuscular septum was thickened
and formed cord-like fibrous band whose distal
end was attached to the lateral femoral condyle
just proximal to the attachment of the fibular
collateral ligament to the lateral femoral epicondyle
(Figs. 1,2,3). The proximal end of the band was
continuous with the iliotibial tract. This cord-like
fibrous band was separated from the overlying
iliotibial tract by loose fibrous tissue through which
either the superior lateral genicular artery or a
branch of it passed to ramify deep to the iliotibial
tract (Figs. 1,2,3).
This cord-like fibrous band was identified in
eight specimens (80%) in the present study. The
length of this cord-like fibrous band ranged
from 26.25 mm to 50.1 mm (mean 42.44±10.83
mm). Its width at its attachment to the iliotibial
tract ranged from 3.2 mm to 9.6 mm (mean
5.83±2.23 mm) while its width at its bony
attachment ranged from 2.8 mm to 9.35 mm (mean
4.84±2.0 mm). The thickness of this fibrous
band ranged from 1.4 mm to 3.15 mm (mean 1.93±
0.66 mm) (Table I). Harvesting a ribbon of
the iliotibial tract in line with this fibrous band
could potentially increase its length by many times
(Fig. 4).
Bull. Alex. Fac. Med. 42 No.3, 2006.
El-Gharbawy.
Fabellofibular Ligament
The fabellofibular ligament was identified in eight
specimens (80%). The ligament was ribbon-shaped
in six specimens (60%) (Figs. 5,6). In the other two
specimens (20%) the ligament was in the form
of a quadrilateral bar of fibrous tissue (Fig. 7).
Its proximal end was attached to the fabella
(Figs. 6,7,8). Its distal end was attached to the
fibular styloid process deep to the tendon of the
biceps femoris muscle (Figs. 5,8).
The length of the fabellofibular ligament ranged
from 22 mm to 45.6 mm (mean 33.34±8.95mm).
Its width at the fabellar side ranged from 5.35 mm
to 8.6 mm (mean 6.59±1.10 mm) and at the
fibular side ranged from 3.85 mm to 9.45 mm
(mean 5.71±2.13 mm). At the middle of the
ligament its width ranged from 4.1 mm to 6.15 mm
(mean 4.92±0.74 mm). The thickness of the
ligament at its middle ranged from 0.6 mm to 7.5
mm (mean 2.73±2.68 mm) (Table II).
Arcuate Ligament
In all specimens the fleshy fibres at the medial
two-thirds of the superolateral part of the popliteus
muscle at the level of the joint line were replaced by
fibrous membrane. At the posterior surface the fibres
of this fibrous membrane were either interwoven
with the fibres of the oblique popliteal ligament or
passed deep to it (Figs. 9,10). At its anterior surface
the fibres were attached to the posterior part of
lateral meniscus (Figs. 11,12).
The tendon of popliteus arose from the lateral
one-third of the superolateral part of the popliteus
muscle in all specimens (Figs. 9-11,13). The lateral
border of the fibrous membrane extended laterally
superficial to the popliteus tendon and was attached
to the fibular head at the root of the fibular
styloid process deep to the fabellofibular ligament
constituting the arcuate ligament (Figs. 9, 13).
Deep to the fabellofibular ligament this fibrous
membrane extended laterally to the fibular collateral
ligament to which it was attached. The inferior
lateral genicular blood vessels passed laterally
between the lower parts of the fabellofibular and
the arcuate ligaments then between the lower part of
the fibular collateral ligament and the joint capsule
(Fig. 5).
Fibular Collateral Ligament
The fibular collateral ligament was identified in all
specimens. The ligament lied obliquely deep to the
posterior part of the iliotibial tract. The ligament was
in the form of a cord-like fibrous band whose
femoral end was broader than its fibular end in eight
specimens (80%) (Fig. 14). In two specimens (20%)
the ligament was in the form of two fused fibrous
bands (Fig. 15).
The length of the fibular collateal ligament ranged
from 58.0 mm to 77.5 mm (meam 68.26±6.8 mm).
Its width at its femoral end ranged from 5.01 mm
El-Gharbawy.
Alexandria Bulletin
to 15.7 mm (mean 10.5±2.8 mm). Its width at
its fibular end ranged from 3.0 mm to 9.45 mm
(mean 5.78±1.96 mm). The thickness of the
ligament at its middle ranged from 1.7 mm to 3.0
mm (mean 2.31±0.42 mm) (Table III).
Proximally the fibular collateral ligament
was attached to the lateral femoral epicondyle
(Figs. 8,16). The shape of the impression of its
femoral attachment was oval in five specimens
(50%) (Figs. 17,18), rounded in two specimens
(20%) (Fig. 8) and triangular in three specimens
(30%) (Figs. 19,20). The longer diameters of the
oval-shaped impressions were vertical in three
specimens (Fig. 17) and horizontal in two specimens
(Fig. 18). The longer diameter ranged from 11.5 mm
to 13 mm (mean 12.37±0.61 mm). The shorter
diameter ranged from 7.6 mm to 12.3 mm (mean
9.09±1.85 mm). The diameters of the round-shaped
impressions were 9.7 mm and 11.6 mm. The
triangular impressions were nearly equilateral. The
length of its crura ranged from 8.7 mm to 16.5 mm
(mean 12.83±3.92 mm).
Distally the fibular collateral ligament was
attached to the anterosuperior part of the lateral
surface of the fibular head (Figs. 8,16,18). The shape
of the impression of its attachment was oval with the
longer diameter being vertical in six specimens
(60%) (Figs. 8,17,19), elongated in two specimens
(20%) (Fig. 20) and rounded in two specimens
(20%) (Fig. 18). The longer diameter of the ovalshaped impressions ranged from 9.25 mm to 14 mm
(mean 11.25±1.9 mm). The shorter diameter ranged
from 4.8 mm to 7.25 mm (mean 6.02±0.93 mm).
The diameters of the round-shaped impressions were
7.35 mm and 8.5 mm. The longer diameters of the
elongated impressions were 9.5 mm and 16.8 mm
and the shorter diameters were 4.8 mm and 7 mm.
To reach the site of its attachment to the fibular
head, the fibular collateral ligament passed between
two slips of the tendon of biceps femoris muscle.
One slip was flattened and attached to the anterior
border of the lateral surface of the fibular head
and this was refered to it in the present study as
the anterior slip. The other slip was bulky and
was attached to the upper surface of the fibular
head anteromedial to the fibular styloid process and
the adjacent part of the lateral surface of the fibular
head and it was refered to it as the posterior slip
(Figs. 18, 20).
Biceps Femoris Tendon
In the specimens of the present study the width of
the biceps femoris tendon just proximal to its
division into anterior and posterior slips ranged from
12.5 mm to 21.35 mm (mean 16.27±2.89 mm). The
width of the anterior slip of the tendon ranged from
8.6 mm to 20.03 mm (mean 14.83±3.96 mm). The
width of the posterior slip of the tendon ranged
from 11.8 mm to 23.0 mm (mean 17.54±3.69 mm)
(Table IV).
Bull. Alex. Fac. Med. 42 No.3, 2006.
789
Tendon of Popliteus Muscle
The proximal part of the fleshy belly of the
popliteus muscle was ribbon-shaped. The popliteus
tendon arose from nearly the lateral one-third of the
proximal part of the muscle (Figs. 9-11,13). From
the remaining two-thirds and at the level of the joint
line, fibrous membrane arose and ascended where its
fibres were either interwoven with the fibres of the
oblique popliteal ligament or passed deep to it. The
deep surface of this fibrous membrane together with
some of the fleshy fibres were attached to the
posterior part of the periphery of the lateral
meniscus (Figs. 11,12).
The popliteus tendon was attached to the
anterior end of the groove for popliteus on the
lateral surface of the lateral femoral condyle in
nine specimens (90%). The impression of its
attachment was located anteroinferior to the
impression of the femoral attachment of the fibular
collateral ligament. In one specimen (10%) the
tendon was attached to the posterior end of the
groove.
The impression of attachment of the popliteus
tendon was oval-shaped in five specimens (50%),
rectangular in shape in four specimens (40%) and
elongated in shape in one specimen (10%). The
longer measurement of the impression was in the
direction of the groove in nine specimens (90%)
and across it in one specimen (10%). The longer
diameter of the oval-shaped impressions ranged
from 7.6 mm to 13.5 mm (mean 11.1±2.21 mm)
and the shorter diameter ranged from 4.0 mm to 8.2
mm (mean 6.27±1.87 mm). The length of the
rectangular-shaped impressions ranged from 11.0
mm to 14.3 mm (mean 12.89±1.57 mm) while their
breadth ranged from 6.45 mm to 9.5 mm (mean
8.01±1.35 mm). The measurements of the elongated
impression were 14.3 mm along the groove and 4.4
mm across it.
The length of the popliteus tendon ranged from
27.9 mm to 44.7 mm (mean 33.25±5.06 mm). The
width of the tendon at the belly side ranged from 6.8
mm to 14.55 mm (mean 10.29±2.23 mm). Its width
at the femoral side ranged from 10.0 mm to 14.25
mm (mean 11.64±1.48 mm). The thickness of the
tendon at its middle ranged from 2.2 mm to 4.5 mm
(mean 3.24± 0.92 mm) (Table V).
Popliteofibular Ligament
The inferolateral border of the popliteus tendon
was attached to the upper surface of the fibular
head deep to the biceps femoris tendon and the
arcuate ligament by a fibrous band. This band
constituted the popliteofibular ligament (Fig. 10). It
was quadrangular in shape and its length, measured
from the border of the popliteus tendon to the fibular
head, ranged from 7.35 mm to 14.4 mm (mean
11.13±1.82 mm). Its width ranged from 7.0 mm to
11.65 mm (mean 9.46±1.43 mm) (Table VI).
Posterolateral Structures of the Knee.
790
Comparison of the lengths, widths and thicknesses
of the fibular collateral ligament, fabellofibular
ligament, popliteus tendon and the fibrous band of
the lateral intermuscular septum revealed that the
El-Gharbawy.
measurements of the band are sometimes equal,
larger or lesser than those of the other three
structures (Table VII).
Table I. length, width and thickness of the cord-like fibrous band formed
by the lower end of the lateral intermuscular septum.
specimen
Length (mm)
I
III
IV
V
VI
VII
VIII
X
range
mean
41.85
50.10
26.25
43.95
27.50
50.00
57.20
42.70
26.25-50.10
42.44±10.83
Width (mm) at the
proximal end
8.40
4.85
4.90
3.20
6.80
4.95
9.60
3.95
3.20-9.60
5.83±2.23
Width (mm) at the
distal end
3.70
5.25
3.35
2.80
4.80
9.35
4.65
4.85
2.80-9.35
4.84±2.01
Thickness (mm) at
the middle
1.70
3.15
2.80
1.45
1.40
1.55
1.75
1.65
1.40-3.15
1.93±0.66
Table II. Length, width and thickness of the fabellofibular ligament.
specimen
II
IV
V
VI
VII
VIII
IX
X
range
mean
Length
(mm)
40.00
45.60
37.15
39.70
34.60
23.15
22.00
24.55
22.0-45.6
33.34±8.95
Width(mm) at
the fabellar end
5.47
5.35
6.65
6.90
6.20
6.00
7.60
8.60
5.35-8.6
6.59±1.10
Width(mm)at
the fibular end
3.85
5.00
4.25
4.80
4.90
8.75
4.70
9.45
3.85-9.45
5.71±2.13
Width(mm) at
its middle
4.15
4.45
4.80
4.10
4.75
5.15
5.80
6.15
4.1-6.15
4.92±0.74
Thickness (mm) at
its middle
2.00
1.10
1.20
0.60
6.45
7.50
1.05
1.95
0.6-7.5
2.73±2.68
Table III. Length, width and thickness of the fibular collateral ligament.
Specimen
I
II
III
IV
V
VI
VII
VIII
IX
X
range
mean
Length
(mm)
58.00
66.35
68.85
77.50
64.30
76.60
70.00
75.15
66.70
59.15
58.0-77.5
68.26±6.80
Width at the
femoral end (mm)
5.01
9.65
10.60
15.70
12.45
11.90
11.90
9.50
8.65
9.65
5.01-15.7
10.50±2.80
Bull. Alex. Fac. Med. 42 No.3, 2006.
Width at the
fibular end (mm)
3.00
6.60
5.10
9.45
4.50
7.50
5.20
7.00
3.35
6.05
3.0-9.45
5.78±1.96
Thickness at the
middle (mm)
3.00
2.30
2.70
2.30
1.70
2.10
2.80
2.20
2.15
1.80
1.7-3.0
2.31±0.42
Alexandria Bulletin
El-Gharbawy.
789
Table IV. Widths of the biceps femoris tendon (BFT) and its anterior
(AS) and posterior (PS) slips.
specimen
I
II
III
IV
V
VI
VII
VIII
IX
X
range
mean
BFT(mm)
16.45
12.50
14.90
13.40
14.10
15.55
19.65
15.70
19.10
21.35
12.5-21.35
16.27±2.89
AS (mm)
20.03
16.25
17.50
13.70
8.60
12.00
14.90
9.30
19.75
16.25
8.6-20.03
14.83±3.96
PS (mm)
17.50
17.54
23.00
16.30
16.00
11.80
14.70
22.85
20.55
18.30
11.8-23.0
17.54±3.69
Table V. Length, width and thickness of the popliteus tendon
Specimen
I
II
III
IV
V
VI
VII
VIII
IX
X
range
mean
Length
(mm)
28.20
35.85
33.55
35.20
44.70
35.30
32.40
27.90
28.25
31.15
27.9-44.7
33.25±5.06
Width at the muscle
belly side (mm)
6.80
9.45
12.20
14.55
8.55
8.50
9.45
10.65
12.00
10.75
6.8-14.55
10.29±2.23
Width at the
femoral side (mm)
10.40
10.10
12.20
12.00
13.65
12.20
10.00
14.25
10.55
11.05
10.0-14.25
11.64±1.48
Thickness at its
middle (mm)
2.40
2.20
4.50
2.45
3.35
2.80
2.30
4.15
3.95
4.30
2.2-4.5
3.24±0.92
Table VI. length and width of the popliteofibular ligament.
Specimen
I
II
III
IV
V
VI
VII
VIII
IX
X
range
mean
Length(mm)
11.20
11.25
11.15
14.40
12.90
11.20
9.90
10.80
7.35
11.15
7.35-14.4
11.13±1.82
Width(mm)
9.00
11.25
11.65
7.00
8.10
8.80
9.95
9.55
10.50
8.80
7.0-11.65
9.46±1.43
Table VII. length, width at the femoral end (WFE), width at the other end (WOE) and thickness at the middle (TM)
of the fibular collateral ligament (FCL), fabellofibular ligament (FFL), popliteus tendon (PT)
and the fibrous band of the lateral intermuscular septum (FB).
structure
FCL
FFL
PT
FB
Length (mm)
68.26±6.8
33.34±8.95
33.25±5.06
42.44±1083
Bull. Alex. Fac. Med. 42 No.3, 2006.
WFE (mm)
10.5±2.8
6.6±1.1
11.64±1.48
4.84±2.01
WOE (mm)
5.78±1.96
5.71±2.13
10.29±2.23
5.83±2.23
TM (mm)
2.31±0.42
2.73±2.68
3.24±0.92
1.93±0.66
790
Posterolateral Structures of the Knee.
Fig 1. A photograph of the lateral aspect of the left knee of
an adult male cadaver showing the biceps femoris (bf) and
vastus lateralis (vl) muscles separated from the lateral
intermuscular septum. The lower lateral part of the septum
is in the form of a thickened fibrous band (fb) attached
(arrow) to the lateral femoral condyle just proximal to the
attachment (arrowhead) of the fibular collateral ligament
(fcl) to the lateral femoral epicondyle. The superior lateral
genicular artery (slg) passes between the fibrous band of
the lateral intermuscular septum and the iliotibial tract (itt)
which is rotated and retracted. Note the inferior lateral
genicular artery (ilg) and the deep suprapatellar bursa of
the knee joint (b).
Fig 3. A photograph of the posterolateral aspect of the
right knee of an adult male cadaver showing the cord-like
fibrous band (fb) of the lateral intermuscular septum
attached (arrow) to the lateral femoral condyle just
proximal to the attachment (black arrowhead) of the fibular
collateral ligament (fcl) to the lateral femoral epicondyle.
The branches of the superior lateral genicular artery (slg)
pass medial (white arrow) and lateral (white arrowhead) to
the fibrous band from the popliteal fossa to the front of the
knee. Note the fabellofibular ligament (ffl) and the lateral
head of gastrocnemius (lg), biceps femoris (bf) and vastus
lateralis (vl) muscles.
Bull. Alex. Fac. Med. 42 No.3, 2006.
El-Gharbawy.
Fig 2. A photograph of the posterolateral aspect of the left
knee of the adult male cadaver in Fig. (1) showing the
lower part of the lateral intermuscular septum (lis) after
separation and retraction of the biceps femoris muscle (bf).
Laterally the septum is attached to the deep surface of the
iliotibial tract (itt). The medial part of the septum above the
lateral femoral condyle is in the form of a loosely felted
membrane (removed here) through which branch (black
arrow) of the superior lateral genicular artery (slg) passes.
The lateral part of the septum is in the form of a thick
fibrous band (fb) and is attached (green arrow) to the
lateral femoral condyle just proximal to the attacment
(arrowhead) of the fibular collateral ligament (fcl) to the
lateral femoral epicondyle.
Fig 4. A photograph of the posterolateral aspect of the
lower part of the right thigh of an adult male cadaver
showing the iliotibial tract (itt) reflected posteriorly to
expose its deep surface and the anterior surface of the
lateral intermuscular septum (lis) which here is detached
from the femur. The fibrous band (fb) of the lateral
intermuscular septum could be potentially lengthened by a
corresponding part of the iliotibial tract along to the
attachment of the tract with the septum (arrowheads). Note
the superior lateral genicular artery (slg), vastus lateralis
muscle (vl) and the lateral femoral condyle (lfc).
El-Gharbawy.
Alexandria Bulletin
789
Fig 5. A photograph of the posterolateral aspect of the
right knee of the adult male cadaver in Fig. (3) showing the
ribbon-shaped fabellofibular ligament (ffl) extending from
the lateral head of gastrocnemius muscle (lg) to the fibular
styloid process (arrowhead) deep to the tendon of the
biceps femoris muscle (bf). The inferior lateral genicular
artery (ilg) arises from the popliteal artery (pa) and passes
laterally on the fascia (f) of popliteus muscle (p) deep to
the lower part of the fabellofibular ligament and then
between the fibular collateral ligament (fcl) and the
capsule of the knee joint (c). Note soleus muscle (sm).
Fig 6. A photograph of the posterolateral aspect of the
right knee of the adult male cadaver in Figs. (3,5) showing
the ribbon-shaped fabellofibular ligament (ffl) attached to
the fabella (f). Note the lateral femoral condyle (*),
plantaris muscle (pl), lateral (lg) and medial (mg) heads of
gastrocnemius muscle, biceps femoris muscle (bf), tendon
of popliteus muscle (pt) and the popliteal artery (pa).
Fig 7. A photograph of the posterolateral aspect of the
right knee of an adult male cadaver showing the
fabellofibular ligament (ffl) is in the form of a thick
quadrilateral bar of fibrous tissue attached to the fabella
(f). The fibular collateral ligament (fcl) is detached from its
site of attachment (arrowheads) on the lateral femoral
epicondyle and it is retracted. The arcuate ligament (al) is
detached from the fibular head and retracted. The tendon
of popliteus muscle (pt) is attached to the anterior end of
the groove for popliteus (gp) on the lateral surface of the
lateral femoral condyle (*) anteroinferior to the impression
of attachment of the fibular collateral ligament. Note the
biceps femoris (bf), plantaris (pl), and lateral head of
gastrocnemius (lg) muscles.
Fig 8. A photograph of the posterolateral aspect of the
right knee of the adult male cadaver in Fig. (4) showing the
fabellofibular ligament (ffl) detached from its site of
attachment (arrowheads) on the fibular styloid process (fs).
The proximal end of the ligament is attached to the fabella
(f). The round-shaped femoral (black arrow) and the ovalshaped fibular (white arrow) impressions of the fibular
collateral ligament are also shown. In this specimen the
inferior lateral genicular artery is lacking and its territory is
supplied by the superior lateral genicular artery (slg).
Bull. Alex. Fac. Med. 42 No.3, 2006.
790
Posterolateral Structures of the Knee.
El-Gharbawy.
Fig 9. A photograph of the posterior aspect of the left
popliteus muscle (p), biceps femoris tendon (bf), part of
soleus muscle (s), and semimembranosus tendon (st). The
fleshy fibres at the medial two-thirds of the superolateral
part of popliteus muscle are replaced by fibrous membrane
(fm) that passes deep to the oblique popliteal ligament
(opl). The tendon of popliteus (pt) arises from the lateral
one-third of the superolateral part of popliteus muscle. The
lateral border of the fibrous membrane extends laterally
superficial to the popliteus tendon and is attached to the
fibular head (fh) constituting the arcuate ligament (al).
Fig 10. A photograph of the posterolateral aspect of the
left knee of the adult male cadaver in Figs. (1,2) showing
the popliteus tendon (pt) arising from the lateral one-third
of the superolateral part of popliteus muscle (p). The fleshy
fibres on the medial two-thirds of the superolateral
part attach to a fibrous membrane (fm) that passes deep to
and blends with the oblique popliteal ligament (opl). At the
side of the muscle belly the inferolateral border
(arrowhead) of popliteus tendon is attached to the fibular
head (black arrow) deep to the biceps femoris tendon (bf)
by the popliteofibular ligament (pf). Note the plantaris (pl)
and lateral head of gastrocnemius (lg) muscles and the
popliteal (pa) and inferior lateral genicular (ilg) arteries.
Fig 11. A photograph of the anterior surface of the
popliteus muscle (p) in Fig. (9) showing the popliteus
tendon (pt) arising from the lateral one-third of the fleshy
fibres of the superolateral part of the muscle. The fleshy
fibres of the medial two-thirds are attached (arrow) to the
posterior part of the lateral meniscus (lm). Note the cut
surface of the fibular head (fh) and the part of the soleus
muscle (s) attached to it.
Fig 12. A photograph of the posterolateral aspect of the left
knee of an adult male cadaver showing the popliteus
tendon (pt) detached from its attachment site (arrowheads)
and retracted to show the attachment of the fleshy fibres of
popliteus (arrow) to the posterior part of the lateral
meniscus (lm). Note the lateral femoral (*) and tibial (tc)
condyles.
Bull. Alex. Fac. Med. 42 No.3, 2006.
El-Gharbawy.
Alexandria Bulletin
789
Fig 13. A photograph of the posterolateral aspect of the left
knee of the adult male cadaver in Fig. (12) showing the
tendon of popliteus (pt) arising from the lateral one-third of
the superolateral part of the popliteus muscle (p) and
passing deep to the arcuate ligament (al) to reach the site of
its femoral attachment. The arcuate ligament extends from
the fibrous membrane (fm) to the fibular head (fh). Note
that the fleshy fibres of the medial two-thirds of the
superolateral part of popliteus muscle attach to this fibrous
membrane.
Fig 14. A photograph showing six fibular collateral
ligaments. The ligaments are in the form of cord-like
fibrous bands. The femoral ends (fe) of the ligaments are
broader than their fibular ends (fi).
Fig 15. A photograph of the posterolateral aspect of the left
knee of an adult male cadaver showing the fibular
collateral ligament (fcl) is in the form of two fused fibrous
bands at its femoral end. At the fibular end of the ligament
the two bands separate. One band (arrow) is attached to the
lateral tibial condyle (*) just distal to the margin of its
articular surface. The other band (arrowheads) passes
between the anterior (as) and posterior (ps) slips of the
biceps femoris tendon (bf) to the fibular head.
Fig 16. A photograph of the lateral aspect of the right
knee of the adult male cadaver in Figs. (4,8) showing the
fibular collateral ligament (fcl) attached proximally to the
lateral femoral epicondyle (*). Distally the ligament is
attached (green arrow) to the lateral surface of the fibular
head (fh) between the sites of attachment of the anterior
(arrowheads) and posterior (black arrows) slips of the
biceps femoris muscle (removed). The fabellofibular
ligament (ffl) is in the form of a thick quadrilateral bar of
fibrous tissue. Note the lateral head of gastrocnemius
muscle (lg) and the superior lateral genicular artery (slg).
Bull. Alex. Fac. Med. 42 No.3, 2006.
790
Posterolateral Structures of the Knee.
Fig 17. A photograph of the lateral aspect of the right knee
of an adult male cadaver showing the femoral
(arrowheads) and fibular (arrows) impressions of the
fibular collateral ligament. Both impressions are ovalshaped and vertical. The anterior slip (as) of the biceps
femoris (bf) tendon is cut and retracted from the posterior
slip (ps) to uncover the fibular impression. Note the lateral
femoral condyle (*).
Fig 19. A photograph of the lateral aspect of the left knee
of the adult male cadaver in Fig. (15) showing the femoral
and fibular impressions of the fibular collateral ligament
(fcl) which is detached and retracted anteriorly. The
femoral impression (arrowheads) is in the form of an
equilateral triangle. The fibular impression (arrows) is
vertical oval-shaped. The popliteus tendon (pt) is attached
just inferior to the femoral impression of the fibular
collateral ligament. The anterior slip (as) of the biceps
femoris tendon (bf) is detached and retracted posteriorly to
uncover the fibular impression.
Bull. Alex. Fac. Med. 42 No.3, 2006.
El-Gharbawy.
Fig 18. A photograph of the lateral aspect of the left
knee of an adult male cadaver showing an oval-shaped
horizontal femoral (arrowheads) and rounded fibular
(arrows) impressions of the fibular collateral ligament. The
popliteus tendon (pt) is detached and retracted from its
impression (pi) which is rectangular in shape and is located
at the anterior end of the groove for popliteus (*)
anteroinferior to the femoral impression of the fibular
collateral ligament. Note the biceps femoris tendon (bf)
with its anterior (as) and posterior (ps) slips.
Fig. (20): A photograph of the lateral aspect of the left
knee of an adult male cadaver showing a triangular femoral
impression (arrowheads) at the lateral femoral epicondyle
and an elongated fibular impression (white arrows) of the
fibular collateral ligament (detached and removed). The
biceps femoris tendon divides into anterior (as) and
posterior (ps) slips for the passage of the fibular collateral
ligament. The fabellofibular ligament (ffl) is attached to
the fabella (f) which glides on the lateral femoral condyle
(*). Note the inferior lateral genicular artery (ilg).
El-Gharbawy.
Alexandria Bulletin
DISCUSSION
In the present study the fabellofibular ligament
was identified in 8 (80%) specimens. Sudasna and
Harnsiriwattanagit(15) found the ligament in 34
(68%) specimens. Kim et al.(16) reported it in 21
(42.1%) of the dissected knees and Diamantopoulos
et al.(6) reported it in 4 (40%) specimens. This varied
incidence might be due to racial difference and it
needs to be researched.
In the current study the fabellofibular ligament
was in the form of a thin ribbon-shaped band in 6
(60%) specimens and was in the form of a thick
fibrous cord in two (20%) specimens. A relation
between the thickness of the ligament and the
morphological characteristics of the fabella present
could not be noticed. These results disagree with
Minowa et al.(10) who reported a strong correlation
between the morphological and even the histological
characteristics of the fabella and the thickness of the
fabellofibular ligament in the Japanese. They found
a thick fabellofibular ligament in 38.1% (40/105) of
knees with a hard fabella and in 82.8% (24/29) of
knees with a bony fabella.
To date, the fabellofibular ligament is not
considered as one of the major stabilizers of the
posterolateral corner of the knee.(3,17) However, the
present study showed that the ligament was
intermediate in thickness (2.73±2.68 mm) between
the fibular collateral ligament (2.31±0.42 mm) and
the popliteus tendon (3.24±0.92) which are two of
the three critical stabilizers of the posterolateral
corner of the knee.(3,17) Minowa et al.(10) ascribed a
possible function, common for the fabellofibular and
the arcuate ligaments, which is fixation of the
popliteal tendon on the joint capsule and lateral
meniscus rather than direct stabilization against
rotation stress.
The present study showed that the fibrous
membrane into which the medial two-thirds of
fibres of the superolateral part of the popliteus
muscle and its lateral extension, the arcuate
ligament, could be looked upon as a peculiar
arrangement of the joint capsule rather than a
ligament critical for joint stabilization. This view is
supported by the current belief that the arcuate
ligament is not among the structures critical for the
posterolateral stability of the knee.(3,17) The function
ascribed for the arcuate ligament is that ascribed for
the fabellofibular one and so a negative correlation
between the thicknesses of both ligaments is
reported.(10)
However, There is another view for both the
fabellofibular and arcuate ligaments in the
literature(18) that deserves mention and that might
serve to resolve the debate. This view describes an
arcuate popliteal ligament as "a Y-shaped thickening
of posterior capsular fibres. The stem of the Y is
attached to the head of the fibula. The medial limb
arches over the tendon of popliteus to the posterior
Bull. Alex. Fac. Med. 42 No.3, 2006.
789
edge of the tibial intercondylar area. Some popliteus
muscle fibres are attached to it. The lateral limb
ascends to the lateral femoral condyle". It is obvious
that this arcuate popliteal ligament comprises both
the fabellofibular and arcuate ligaments in the
present study and the stem of the Y in this view
corresponds to the attachments of both ligaments to
the fibular styloid process. This could explain the
negative correlations between the thicknesses of
both ligaments and the common function ascribed
for them.(10)
The fibular collateral ligament was in the form of
cord-like fibrous band in 80% of the specimens of
the present study. This agree with the standard
discription of the ligament in the anatomical
textbooks.(18-20) However, in the remaining 20% of
the specimens the ligament was in the form of
two bands that were fused at their femoral ends.
At the fibular end one band was attached to
the tibial condyle and the other band was attached
to the fibular head in the classical way. This
arrangement might prove the possibility of fixing
the graft to the tibial condyle instead of the fibular
head on reconstructing the fibular collateral
ligament. These results coincide with those of
Diamantopoulos et al.(6) who were able to confirm
by microsurgical dissection an anatomic variation of
the fibular collateral ligament in 20% of their knees.
The femoral end of the fibular collateral ligament
was attached to the lateral femoral epicondyle in all
specimens of the present study. This agree with what
is published by many authors.(18-20) However,
Meister et al.(21) stated that the center of the femoral
attachment site of the fibular collateral ligament was
3.7 mm posterior to the ridge of the lateral femoral
epicondyle, not at its apex and Brinkman et al.(22)
reported that the fibular collateral ligament was
attached posterior (4.6 mm, sd 2) and proximal
(1.3mm sd 3.6) to the lateral epicondyle of the
femur. The shape of femoral impression of the
fibular collateral ligament in this study varied from
oval vertical, oval horizontal, rounded to triangular
and its recorded dimensions were double or triple
the distances reported by those authors. So despite
the distances mentioned between the point of the
epicondyle and the center of the attachment site it is
absolutely right to consider the ligament attached to
the epicondyle.
The present work showed that the fibular end of
the fibular collateral ligament was attached to the
anterosuperior part of the lateral surface of the
fibular head in 80% of the specimens. To reach
its insertion site the fibular end of the ligament
passed deep to the biceps femoris tendon and
between its anterior and posterior slips. These results
agree with the standard discription in the anatomical
textbooks.(18-20) In the remaining 20% one of the two
bands forming the ligament was inserted in the
classical way while the other was inserted into the
790
Posterolateral Structures of the Knee.
lateral tibial condyle.
The present work revealed that the femoral
impressions of the fibular collateral ligament were
larger than its fibular impressions in spite of the fact
that both attachments must have equal strengths. The
lesser strength of the fibular attachment is probably
compansated by the holding action of the biceps
femoris tendon on the fibular end of the fibular
collateral ligament. This fact must be taken into
consideration in planning the width of the grafts that
will be used for the reconstruction of the ligament if
it is not going to be fixed under the biceps femoris
tendon.
The collected evidence from the obtained results
suggests that the femoral impression of the fibular
collateral ligament is anterosuperior to its fibular
impression in full extension of the knee a position in
which the ligament is tightened. In this position the
ligament could act as a critical static stabilizer
of the posterolateral corner of the knee. It can resist
varus angulation of the knee, posterior translation
of the tibia and its external rotation. Sugita and
Amis(23) reported that the fibular collateral ligament
slackened significantly with knee flexion and
became vertical at 70 degrees of knee flexion and
was thus poorly oriented to withstand tibial external
rotation. So there must be a posterolateral stabilizer
other than the fibular collateral ligament for the
flexed knee. This posterolateral stablizer of the
flexed knee is provided by the popliteus muscle with
its tendon and the popliteofibular ligament.
The length of the fibular collateal ligament in the
present study (68.26± 6.8 mm) nearly coincides with
that reported by Meister et al.(21) (mean 66 mm).
However, the thickness of the ligament at its middle
(2.31 ± 0.42 mm) in the present study disagrees with
that reported by the same authors(21) (mean 3.4 mm).
The tendon of popliteus was attached at the
anterior end of the popliteal groove anteroinferior to
the femoral impression of the fibular collateral
ligament in 90% of the specimens of the present
study. These results are in agreement with those
published by other authors.(18-20) The popliteofibular
ligament was present in all the specimens. These
results coincide with those reported by several
authors.(19,24,25)
The tendon of popliteus passed obliquely
superolateral and anteriorly inside the capsule deep
to the fibular collateral ligament to reach its site of
attachment. The popliteofibular ligament was in the
form of a quadrilateral fibrous band that extended
from the inferolateral border of the popliteus tendon
to the fibular head deep to the fibular styloid
process. Needless to say that the isometric point of
the lateral femoral condyle lies between the femoral
impression of the fibular collateral ligament and the
attachment site of the tendon of popliteus. On
flexion of the knee with a fixed tibia the femur
rotates laterally by the action of popliteus to unlock
Bull. Alex. Fac. Med. 42 No.3, 2006.
El-Gharbawy.
the knee. This rotation changes the direction of the
popliteus tendon into superolateral instead of
superolateral and anterior. At the same time the
attachment site of the tendon moves forward and
upward and the femoral impression of the fibular
collateral ligament moves backward and downward.
The result will be straightening of the angle between
the tendon of popliteus and the popliteofibular
ligament and the two structures form straight tight
fibrous cord on the lateral aspect of the flexed knee
that can resist varus angulation, posterior translation
of the tibia and its external rotation. As already
mentioned in the flexed position the fibular
collateral ligament is slackened and is ineffective as
a posterolateral stabilzer.This hypothesis gets
support from the results of other workers.(23)
The results of the present research pave the road
to propose a plan for the reconstruction of the
critical stabilizers of the posterolateral corner. The
fibular collateral ligament was present deep to the
posterior border of the iliotibial tract and at its
junction with the fascia lata covering the biceps
femoris tendon. This situation is ideal for using the
fibrous band of the lateral intermuscular septum for
the reconstruction of the ligament. The band's length
can be potentially increased, several times, by
excising longitudinal ribbon of the posterior border
of the iliotibial tract of suitable length and width and
which is continuous with the proximal end of the
band. The proximal end of the ribbon could be
passed through a tunnel deep to the iliotibial tract
to reach the fibular head where it could be fixed.
At the fibular head the band could be passed
through a bony tunnel drilled into the fibular head
then to be stitched to the deep surface of the
biceps femoris tendon. On doing so, the attachment
of the fibrous band to the lateral femoral condyle
just proximal to the attachment of the femoral end of
the fibular collateral ligament will serve as the
femoral attachment of the reconstructed ligament.
The thickness of the fibrous band and that of the
iliotibial tract are suitable as a graft and this
thickness could even be doubled by excizing a
ribbon of the iliotibial tract of double-width and
folding it on itself.
The tendon of popliteus and the popliteofibular
ligament, the other two critical stabilizers of the
posterolateral knee, could be reconstructed at the
same time with the fibular collateral ligament. In this
case a Y-shaped ribbon is prepared. The stem of the
Y will be the fibrous band of the lateral
intermuscular septum which is attached to the lateral
femoral condyle just proximal to the femoral
impression of the fibular collateral ligament. The Y
will has a longer limb which will be prepared from
the posterior border of the iliotibial tract above the
attachment of the fibrous band to it. The shorter limb
of the Y will be prepared from the posterior border
of the iliotibial tract below its attachment with the
El-Gharbawy.
Alexandria Bulletin
fibrous band.
The longer limb of the Y-shaped graft is passed
through the bony tunnel drilled into the fibular head.
Then this longer limb after its fixation to the head is
passed inside the joint capsule to meet the shorter
limb of the Y-shaped graft which is pushed into the
capsule through an opening into its superolateral
part. Inside the capsule the two limbs are fixed
together and to the stump of the popliteus tendon in
a fashion similar to their original pattern.
This technique of reconstruction has many
advantages. First, the operator has already one end
of the graft well fixed in the proper site and no
need for drilling hole in the lateral femoral condyle,
preparation of bone plug and fixation screws.
Second, the arc of rotation of the graft is great
without jeopardizing its blood supply. Third, the
technique provides a homotropic repair. Therefore
on using it in the reconstruction of chronic injuries
one could expect the results that he gains from the
primary anatomical repair in acute rupture of the
ligaments.
The technique of reconstruction of the posterolateral stabilizers of the knee which is proposed by
the present work needs to be tested both in cadaveric
and clinical studies. Theoritically it seems to be
superior to the other reconstruction techniques using
grafts prepared from biceps femoris tendon.(12,14)
Achilis tendon,(3) semitendinosus tendon(26) and
patellar ligament.(27)
REFERENCES
1. LaPrade RF, Wentorf F. Diagnosis and treatment
of posterolateral knee injuries. Clin Orthop Relat
Res. 2002 Sep;(402): 110-21.
2. Laprade RF, Wentorf FA, Olson EJ, Carlson CS.
An in Vivo Injury Model of Posterolateral Knee
Instability. Am J Sports Med. 2006 Mar 27; (Epub
ahead of print).
3. Sekiya JK, Kurtz CA. Posterolateral corner
reconstruction of the knee: surgical technique
utilizing a bifid Achilles tendon allograft and a
double femoral tunnel. Arthroscopy. 2005 Nov;
21(11): 1400.
4. Veltri DM, Warren RF. Anatomy, biomechanics,
and physical findings in posterolateral knee
instability. Clin Sports Med. 1994 Jul; 13(3): 599614.
5. Covey DC. Injuries of the posterolateral corner of
the knee. J Bone Joint Surg Am. 2001 Jan; 83-A
(1): 106-18.
6. Diamantopoulos A, Tokis A, Tzurbakis M,
Patsopoulos I, Georgoulis A. The posterolateral
corner of the knee: evaluation under microsurgical
dissection. Arthroscopy. 2005 Jul; 21(7): 826-33.
7. La Prade RF, Tso A, Wentorf FA. Force
measurements on the fibular collateral ligament,
popliteofibular ligament, and popliteus tendon to
applied loads. Am J Sports Med. 2004 Oct-Nov;
Bull. Alex. Fac. Med. 42 No.3, 2006.
789
32 (7): 1695-701.
8. De Maeseneer M, Shahabpour M, Vanderdood K,
De Ridder F, Van Roy F, Osteaux M.
Posterolateral supporting structures of the knee:
findings on anatomic dissection, anatomic
slices and MR images. Eur Radiol. 2001; 11 (11):
2170-7.
9. La Prade RF, Lv TV, Wentorf FA, Engebretsen L.
The posterolateral attachments of the knee: a
qualitative and quantitative morphologic analysis
of the fibular collateral ligament, popliteus
tendon, popliteofibular ligament, and lateral
gastrocnemius tendon. Am J Sports Med. 2003;
Nov-Dec; 31(6): 854-60.
10. Minowa T, Murakami G, Kura H, Suzuki D,
Han SH, Yamashita T. Does the fabella contribute
to the reinforcement of the posterolateral corner
of the knee by inducing the development of
associated ligaments? J Orthop Sci. 2004; 9(1):
59-65.
11. Boszotta H, Helperstorfer W, Jusner A,
Hoffmann K. Physiopathology of the knee joint
after distal iliotibial band transfer. Arch Orthop
Trauma Surg. 1992; 111(4): 213-9.
12. Wascher DC, Grauer JD, Markoff KL. Biceps
tendon tenodesis for posterolateral instability of
the knee. An in vitro study. Am J Sports Med.
1993 May-Jun; 21(3): 400-6.
13. Pavlovich RI, Nafarrate EB. Trivalent
reconstruction for posterolateral and lateral knee
instability. Arthroscopy. 2002 Jan; 18(1): E1.
14. Zhao J, He Y, Wang J. Anatomical
reconstruction of knee posterolateral complex with
the tendon of the long head of biceps femoris. Am
J Sports Med. 2006 May 30; (Epub ahead of
print).
15. Sudasna S, Harnsiriwattanagit K. The
ligamentous structures of the posterolateral aspect
of the knee. Bull Hosp Jt Dis Orthop Inst. 1990
Sprig; 50(1): 35-40.
16. Kim YC, Chung IH, Yoo WK, Suh JS, Kim SJ,
Park CI. Anatomy and magnetic resonance
imaging of the posterolateral structures of the
knee. Clin Anat. 1997; 10(6): 397-404.
17. LaPrade RF, Johansen S, Wentorf FA,
Engebretsen L, Esterberg JL, Tso A. An analysis
of an anatomical posterolateral knee reconstruction: an in vitro biomechanical study and
development of a surgical techinque. Am J Sports
Med. 2004 Sep; 32(6): 1405-14.
18. Sinnatamby CS. Last's Anatomy, Regional
and Applied. 10th ed., Churchill- Livingstone,
Edinburgh, 1999: 132-3.
19. Standring S. Gray's Anatomy: The Anatomical
Basis of Clinical Practice. 39th ed., Elsevier
Churchill Livingstone, London, 2005: 1479-80.
20. Romanes GJ. Cunningham's Manual of Practical
Anatomy. 15th ed., Mass Publishing Co., Egypt,
1997: Vol. (1): 216.
790
Posterolateral Structures of the Knee.
21. Meister BR, Michael SP, Moyer RA, Kelly JD,
Schneck CD. Anatomy and kinematics of the
lateral collateral ligament of the knee. Am J Sports
Med. 2000 Nov-Dec; 28(6): 869-78.
22. Brinkman JM, Schwering PJ, Blankevoort L,
Koolos JG, Luites J, Wymenga AB. The insertion
geometry of the posterolateral corner of the knee.
J Bone Joint Surg Br. 2005 Oct; 87(10): 1364-8.
23. Sugita T, Amis AA. Anatomic and biochemical
study of the lateral collateral and popliteofibular
ligaments. Am J Sports Med. 2001 Jul-Aug;
29(4): 466-72.
24. Veltri DM, Deng XH, Torzilli PA,
Maynard MJ, Warren RF. The role of the
popliteofibular ligament in stability of the human
knee. A biochemical study. Am J Sports Med.
Bull. Alex. Fac. Med. 42 No.3, 2006.
El-Gharbawy.
1996 Jan-Feb; 24(1): 19-27.
25. Maynard MJ, Deng X, Wickiewicz TL,
Warren RF. The popliteofibular ligament.
Rediscovery of a key element in posterolateral
stability. Am J Sports Med. 1996 May-Jun; 24 (3):
311-6.
26. Buzzi R, Aglietti P, Vena LM, Giron F. Lateral
collateral ligament reconstruction using a semitendinosus graft. Knee Surg Sports Traumatol
Arthrosc. 2004 Jan; 12(1): 36-42.
27. Latimer HA, Tibone JE, EIAttrache NS,
McMahon PJ. Reconstruction of the lateral
collateral ligament of the knee with patellar
tendon allograft. Report of a new techinque in
combined ligament injuries. Am J Sports Med.
1998 Sep-Oct; 26(5): 656-62.