The hip joint is a ball-and-socket synovial joint located between the acetabulum of the pelvis and the head of the femur. It is stabilized by strong ligaments like the iliofemoral, pubofemoral, and ischiofemoral ligaments. The hip joint allows for flexion, extension, abduction, adduction, and rotation of the lower limb and is innervated by nerves from the lumbar plexus. Dislocations or fractures of the femoral neck can impair stability and mobility of the hip joint.

1. THE HIP JOINT
Dr M Idris Siddiqui

2. Hip Joint
• Hip Joint is a synovial joint which is
ball and socket type, that is located
between:
• Hip bone’ s acetabulum and
• Head part of femur.
• This is considered as biggest ball and
socket joint in the body.

4. Articulating Surfaces
acetabulum
• The acetabulum is a cup-like depression located on
the inferolateral aspect of the pelvis. Its cavity is
deepened by the presence of a fibrocartilaginous
collar – the acetabular labrum.
• The acetabulum (Latin acetabulum = vinegar cup)
presents 3 features:
– A horseshoe-shaped lunate surface,
– Acetabular notch, and
– Acetabular fossa.
• Out of these, only lunate surface is articular and covered by an
articular cartilage.

6. Articulating Surfaces
Head of femur
• The head of femur is hemispherical, and
fits completely into the concavity of the
acetabulum.
• Both the acetabulum and head of femur
are covered by articular hyaline cartilage
which is thicker at the places of weight
bearing(with the exception of a small pit-
the fovea capitis for ligamentum teres)

7. CAPSULE OF HIP JOINT
• The capsular ligament is a powerful.
• On the hip bone, it is connected 5-6 millimeter
beyond the acetabular margin, outer aspect of the
acetabular labrum and transverse acetabular
ligament.
• On the femur, it is connected anteriorly to the
intertrochanteric line and posteriorly 1 cm in front
of (medial to) the intertrochanteric crest.
• The capsule is thicker anterosuperiorly.
Posteroinferiorly it is thin and loosely connected.

9. CAPSULE OF HIP JOINT
• The capsule is made up 2 types of fibres-
inner circular fibres and outer longitudinal
fibres.
• The inner circular fibres create collar around
the femoral neck (zona orbicularis). These
fibres are not directly connected to the
bones.
• The outer longitudinal fibres are represented
along the neck toward the head to create the
retinacula

10. The synovial membrane
• The synovial membrane lines:
• Inner aspect of the fibrous capsule,
–The intracapsular portion of the femoral neck,
–Glenoid labrum (both surfaces),
–Transverse acetabular ligament,
–Ligamentum teres, and
–Fat in the acetabular fossa.
• It is thin on the deep surface of the
iliofemoral ligament where it is compressed
against the head.

11. Ligaments
• The ligaments of the hip joint act to increase stability.
• Joint capsule itself is a powerful ligament .
• The ligaments of the hip joint can be divided into two
groups – intracapsular and extracapsular:
Intracapsular
• Ligament of head of femur. It is a relatively small
structure, which runs from the acetabular fossa to the
fovea of the femur.
– It encloses a branch of the obturator artery (artery to head
of femur), a minor source of arterial supply to the hip joint.
• Transverse acetabular ligament.
• Acetabular labrum.

12. Ligaments
Extracapsular
• There are three main extracapsular
ligaments, continuous with the outer
surface of the hip joint capsule:
1. Iliofemoral ligament
2. Pubofemoral
3. Ischiofemoral.

14. ILIOFEMORAL LIGAMENT
• The iliofemoral ligament is inverted Y-shaped ligament, which is
located anteriorly and closely combined with the capsule.
• Its apex is connected to the lower half of the anterior inferior iliac
spine and area between it and above acetabular margin.
• Its base is connected to the intertrochanteric line. This ligament
includes 3 parts-
– A Lateral thick group of oblique fibres,
– A medial thick group of vertical fibres, and
– A large central thin portion.
• Iliofemoral ligament prevents the trunk from falling backwards in
the standing position.
– It prevents hyperextension of the hip joint. It is the strongest of
the three ligaments.

15. PUBOFEMORAL LIGAMENT
• It spans between the superior pubic rami and the
intertrochanteric line of the femur, reinforcing the
capsule anteriorly and inferiorly.
• The pubofemoral ligament is a triangular ligament
– Base above i.e. iliopubic eminence, superior pubic ramus,
and obturator crest.
– Apex i.e. intertrochanteric line of the femur below.
• It is located inferomedially and supports the joint on
this particular aspect.
• Inferiorly it combines with all the anteroinferior part
of the capsule and medial group of the iliofemoral
ligament.
– It has a triangular shape, and prevents excessive abduction and extension.

16. ISCHIOFEMORAL LIGAMENT
1. It spans between the body of the ischium and the
greater trochanter of the femur, reinforcing the
capsule posteriorly.
2. The ischiofemoral ligament is comparatively feeble
and supports the capsule posteriorly.
3. Above it isconnected to the ischium posteroinferior
to the acetabulum.
– From ischium its fibres spiral behind the femoral neck to
be connected into the greater trochanter deep to the
iliofemoral ligament.
– It prevents hyperextension and holds the femoral head in the
acetabulum.

18. Ligamentum teres /foveal ligament
(Round ligament of head of femur)
• This ligament is also termed ligamentum teres of the
head of femur. It is a flat triangular ligament with apex
connected to the fovea of the head, and its base to the
Transverse acetabular ligament.
• The ligamentum teres is a round ligament that
connects the femoral head with the acetabulum. The
ligament contains a blood vessel, originated from the
acetabular branches of the obturator and medial
circumflex femoral arteries which contribute the blood
supply of the femoral head during childhood.
– Transverse acetabular ligament. It is ensheathed by a conical
reflection of the synovial membrane.

20. ACETABULAR LABRUM
• Acetabular labrum is a fibrocartilaginous
rim connected to the acetabular margin.
• It is triangular in cross section.
• The labrum not only deepens the
acetabulum (socket) but takes the head
of femur softly to hold it in position.

21. TRANSVERSE ACETABULAR LIGAMENT

22. TRANSVERSE ACETABULAR LIGAMENT
• It is a part of acetabular labrum,
which bridges the acetabular notch.
• It is devoid of cartilage cells.
• The acetabular notch so becomes
converted in the foramen which
carries the acetabular vessels and
nerves to the hip joint.

23. SOLIDITY OF THE HIP JOINT
• The firmness of the hip joint is supplied by the
following factors which help prevent its
dislocation:
• Depth of the acetabulum and narrowing of its
mouth by the acetabular labrum.
• 3 powerful ligaments (iliofemoral, pubofemoral,
and ischiofemoral) reinforcing the capsule of the
joint.
• Strength of the surrounding muscles, example,
gluteus medius, gluteus minimus, etc.
• Length and obliquity of the neck of femur.

24. RELATIONSHIPS

25. ANTERIORLY Tendon of iliopsoas divided from joint by a synovial
bursa, pectineus (lateral part), straight head of rectus
femoris.
Femoral nerve in the groove between the iliacus and the
psoas.
Femoral artery in front of the psoas tendon.
Femoral vein in front of the pectineus.
POSTERIORLY Piriformis, obturator externus, obturator internus, superior
and inferior gemelli, quadratus femoris, and gluteus
maximus.
Superior gluteal nerve and vessels above the piriformis.
Inferior gluteal nerve and vessels below the piriformis.
Sciatic nerve, posterior cutaneous nerve of the thigh, and
nerve to quadratus femoris.
SUPERIORLY Reflected head of rectus femoris medially.
Gluteus minimus, gluteus medius, and gluteus maximus
laterally.
INFERIORLY Pectineus.
Obturator externus.

26. BURSAE AROUND THE HIP JOINT

27. BURSAE AROUND THE HIP JOINT
• These are 7 in number:
• 4 under glutens maximus,
• Between gluteus maximus and smooth area of the ilium being
located between the posterior curved line and the outer lip of
the iliac crest.
• Between gluteus maximus and lower part of the outer aspect of the
higher trochanter (trochanteric bursa).
• Between gluteus maximus and ischial tuberosity (ischial bursa).
• Between the tendon of gluteus maximus and vastus
lateralis (gluteofemoral bursa).
• 1 under gluteus medius, 1 under gluteus minimus,
• 1 under psoas tendon as under:
– i.e. between the iliopubic eminence and the psoas tendon.
It’s termed subpsoas bursa.

28. ARTERIAL SUPPLY
• The arterial supply of the head and neck of the femur
medically really essential. It is originated from the
following three sources:
1. Acetabular branches of the obturator artery and the
medial circumflex femoral arteries. These arteries get
to the head via the round ligament of the head.
2. Retinacular vessels (the main source) originate from
the medial circumflex femoral artery, run along the
neck of the femur via the retinaculum of the capsule.
3. Nutrient artery of the femur supplies few branches to
the neck and head of femur

29. Arterial Supply
• The arterial supply to the hip joint is largely via the medial
and lateral circumflex femoral arteries – branches of the
profunda femoris artery (deep femoral artery).
– These anastomose at the base of the femoral neck to form a ring,
from which smaller arteries arise to supply the hip joint itself.
• The medial circumflex femoral artery is responsible for the
majority of the arterial supply via Retinacular vessels (the
lateral circumflex femoral artery has to penetrate through the
thick iliofemoral ligament).
– Damage to the medial circumflex femoral artery can result
in avascular necrosis of the femoral head.
• The artery to head of femur (acetabular branches of
obturator artery) and the superior/inferior gluteal arteries
provide some additional supply.

30. NERVE SUPPLY
The hip joint is supplied by the following nerves:
The hip joint is innervated primarily by
the sciatic, femoral and obturator nerves.
• 4 spinal nerves (L2, L3, L4, L5) control the
movements of the hip joints as below:
– L2 and L3 modulate flexion, adduction, and medial
rotation.
– L4 and L5 modulate extension, abduction, and lateral
rotation.
• These same nerves innervate the knee, which
explains why pain can be referred to the knee from
the hip and vice versa

33. Flexion Iliopsoas , rectus femoris, and sartorius and also
by the adductor muscles
Extension
(a backward movement
of the flexed thigh)
Gluteus maximus and the hamstring muscles
Abduction Gluteus medius and minimus, assisted by the
sartorius, tensor fasciae latae, and piriformis
Adduction Adductor longus and brevis and the adductor
fibers of the adductor magnus. These muscles are
assisted by the pectineus and the gracilis
Lateral rotation Piriformis , obturator internus and externus,
superior and inferior gemelli, and quadratus
femoris, assisted by the gluteus maximus
Medial rotation Anterior fibers of the gluteus medius and gluteus
minimus and the tensor fasciae latae
Circumduction
(combination of all movements)
Note: The extensor group of muscles is more powerful than the flexor group, and the lateral
rotators are more powerful than the medial rotators.

34. DISLOCATION OF THE HIP JOINT
• (a) Congenital dislocation: The congenital dislocation
of the hip joint is much more common than every
other joint within the body. It happens because of
two reasons:
• The joint capsule is loose at birth.
• Hypoplasia of the acetabulum and femoral head: In
this state, the head of femur slips upward into
the gluteal region since the upper margin of the
acetabulum is developmentally deficient.
• Medically, it presents as:
– Inability of the newborn to abduct the thigh.
– Affected limb is shorter in length and externally rotated.
– Asymmetry of skin folds of the thighs.
– Lurchinggait with positive Trendelenburg’s hint

35. Stabilising Factors
• The primary function of the hip joint is to weight-bear. There are a
number of factors that act to increase stability of the joint.
1. The first structure is the acetabulum. It is deep, and
encompasses nearly all of the head of the femur.
2. There is a horseshoe shaped fibrocartilaginous ring around the
acetabulum which increases its depth, known as the acetabular
labrum. The increase in depth provides a larger articular surface.
3. The iliofemoral, pubofemoral and ischiofemoral ligaments are
very strong, and along with the thickened joint capsule, provide a
large degree of stability. These ligaments have a unique spiral
orientation; this causes them to become tighter when the joint is
extended.
4. In addition, the muscles and ligaments work in a reciprocal
fashion at the hip joint:
– Anteriorly, where the ligaments are strongest, the medial flexors
(located anteriorly) are fewer and weaker.
– Posteriorly, where the ligaments are weakest, the medial rotators are
greater in number and stronger .

36. REFERRED PAIN OF THE HIP JOINT
• In diseases of the hip joint like
tuberculosis, the pain is referred
to the knee joint due to the
common nerve supply of these
two joints.

37. FRACTURES OF THE NECK OF THE
FEMUR
• These fractures are generally
common in people of more
than 60 years of age notably in
females because their femoral
necks become weak and fragile
as a result of osteoporosis.
• The fractures of the neck of
femur are of 4 types:
• Subcapital (near the head).
• Cervical (in the middle).
• Basal (near the trochanters).
• Pretrochanteric fracture (just
distal to 2 trochanters).

38. Hip Joint Stability and Trendelenburg's Sign
• The stability of the hip joint when a person stands on
one leg with the foot of the opposite leg raised above
the ground depends on three factors:
– The gluteus medius and minimus must be functioning
normally.
– The head of the femur must be located normally within the
acetabulum.
– The neck of the femur must be intact and must have a
normal angle with the shaft of the femur.
• If any one of these factors is defective, then the pelvis
will sink downward on the opposite, unsupported side.
The patient is then said to exhibit a positive
Trendelenburg's sign

41. Knee joint
Dr M Idris Siddiqui

43. Knee joint
• The knee joint is a synovial joint,
the largest in the body and most
complex joint.
• It is a modified hinge joint.
– In addition to flexion and extension a small amount of
rotation of the leg is possible in the flexed position of the
knee.
• It is a compound joint that includes two condylar
joints between the femur and the tibia and a sellar
(saddle) joint between the patella.
1. Lateral femorotibial joint
2. Medial femorotibial joint
3. Femoropetellar joint

44. Articulating surfaces
• Tibiofemoral:
–The medial condyles of the femur
–The lateral condyles of the femur
– Articulating with the tibial condyles.
• Patellofemoral:
–The anterior and distal part of the
femur articulating with the patella.

47. Lower end of the femur
• Lateral Condyle
• It is stouter and more powerful in relation to the medial
condyle.(outer is strouter, inner is thinner)
• Its medial surface creates the lateral boundary of
intercondylar fossa.
– A groove below and behind the lateral epicondyle gives
connection to popliteus in its anterior part.
• Medial Condyle
– Its lateral surface creates medial boundary of intercondylar fossa.
– About 1 cm is longer than medial codyle of the femur.
• The patellar surface of the lower end of femur V-shaped &
saddle-shaped. Its lateral portion is wider and extends to a
higher level in relation to the medial portion,
corresponding to articular outermost layer of the patella.

48. Intercondylar Fossa (Notch)
• It is a deep notch, which divides 2 condyles
posteriorly.
• It is restricted posteriorly above by intercondylar
path.
• It presents medial and lateral walls and floor.
– Medial wall of the fossa gives attachments to the upper end of
posterior cruciate ligament in its anteroinferior part.
– Lateral wall of the fossa gives connection to the upper end of
anterior cruciate ligament in its posterosuperior part.
– Mnemonic: LAMP = Lateral condyle gives connection to Anterior
cruciate ligament and Medial condyle to Posteriorcruciate ligament

49. SUPERIOR SURFACE OF THE TIBIA
• The upper end of the tibia is markedly
expanded from side to side, to form two large
condyles which overhang the posterior
surface of the shaft.
• The upper end includes:
–(a) A medial condyle,
–(b) A lateral condyle,
–(c) An intercondylar area,

51. Upper End
of the tibia

54. Tibial plateau
•The condyles form a flat surface,
known as the tibial plateau.
•This structure articulates with the
femoral condyles to form the
major articulation of the knee
joint.

55. The tibial condyles
• Medial condyle(two main feature):
– Surface on the medial condyle is oval (long axis
anteroposterior) in conformity with the medial femoral
condyle and meniscus.
– The peripheral flattened part is covered by the
fibrocartilaginous plate, the medial meniscus.
• Lateral condyle(two main feature):
– The lateral surface is a little smaller and more nearly
circular, in conformity with the lateral femoral condyle
and meniscus.
• It has a smaller facet for the head of fibula.
– It is separated from the femur by the lateral meniscus.

56. Posterior Surface of the patella
• The large articular area is divided mainly by a
vertical ridge into a bigger lateral and a
smaller medial area to fit with the mutual
articular surfaces of the femur.
• The vertical ridge itself takes up the groove on
the patellar surface of femoral lower end.
• Larger lateral articular area is located in
contact with the lateral femoral condyle.

58. Intercondylar Area
• 1. It is the rough area on the superior surface of the
upper end of tibia between the articular surfaces of 2
condyles.
• 2. The middle of intercondylar area is narrow and
marked by an elevation referred to as intercondylar
eminence.
– This consists of two tubercles and a roughened area.
– This area is the main site of attachment for the ligaments and
the menisci of the knee joint.
– The tibial intercondylar tubercles fit into the intercondylar
fossa of the femur.
• 3. From before backwards, the intercondylar area gives
attachments to 6 structures.
• Cont.

59. The condyles form a flat surface,
known as the tibial plateau.
This structure articulates with the femoral condyles

60. The intercondylar area
gives attachments to 6 structures.
From before backwards
Intercondylar eminence
• Mnemonic: Medical College London, London Medical College.
1. Anterior horn of Medial meniscus.
2. Anterior Cruciate ligament.
3. Anterior horn of Lateral meniscus.
4. Posterior horn of Lateral meniscus.
5. Posterior horn of Medial meniscus.
6. Posterior Cruciate ligament.

61. Joint capsule
• The joint capsule consists of the external fibrous
layer and the internal synovial membrane.
• The fibrous layer is thin, except for the thickened
parts that make up the intrinsic ligaments of the
knee.
• It encapsulates the knee joint while at the same
time making adjustment for the important
structures.
• It is attached about 0.5-1 cm beyond the articular
margins on femur and tibia both.

62. Joint capsule attachments
• On femoral side
• It is deficient anteriorly, where it is replaced by the
quadriceps femoris, the patella and the ligamentum patellae.
• Posteriorly , it is attached to the intercondylar line
• Laterally , it encloses the origin of the popliteus.
• On tibial side
• Anteriorly descends along the margins of the condyles to
tibial tuberiosity, where it is deficient.
• Posteriorly, it is attached to the intercondylar ridge which
limits the attachment of the posterior cruciate ligament
• Posterolaterally, there is a gap behind the lateral condyle for
passage of the tendon of the popliteus.

63. The capsule is strengthened by
• The capsular ligament is weak but is
strengthened by:
–Anteriorly – medial and lateral patellar retinacula
which are extensions from the vastus medialis
and lateralis
–Laterally by the iliotibial tract
–Medially by expansions from the tendons of the
Sartorius and semimembranosus
–Posteriorly, by the oblique popliteal ligament

64. Gaps in capsule of knee joint
• The capsule has two constant gaps:
1. One for the superapatellar bursa
2. Another for the exit of the tendon of
the popliteus.
–Sometimes there are gaps that
communicate with the bursae deep to
the medial head of the gastrocnemius ,
and deep to the semimembranosus.

66. The synovial membrane
• The synovial membrane of the knee joint lines the capsule,
except posteriorly where it is reflected forwards by the
cruciate ligaments, forming a common covering for both
ligaments.
• In front, it is absent from the patella. Above the patella, it is
prolonged upwards for 5 cm or more as the
suprapatellar bursa. Below the patella, it covers the deep
surface of the infrapatellar pad of fat, which separates it from
the patellar ligament.
• A median fold, the infrapatellar synovial fold, extends
backwards from the fat pad to the intercondylar fossa of the
femur. An alar fold diverges on each side from the median
fold to reach the lateral edges of the patella.
• *The synovial membrane does not cover the surfaces of the menisci.
RJL page 139

68. Connecting strucures
• Extracapsular(Capsule of knee joint):
– Medial (tibial) collateral ligament
– Lateral (fibular) collateral ligament
– Ligametum patellae
– Oblique popliteal ligament
• Intracapsular ligament:
– Anterior Cruciate Ligament
– Posterior Cruciate Ligament
– Medial Meniscus
– Lateral Meniscus

69. The cruciate ligaments of the knee
• There are the anterior cruciate ligament (ACL)
and the posterior cruciate ligament (PCL).
• These ligaments are two strong, rounded
bands that extend from the head of
the tibia to the intercondyloid notch of
the femur.
• The ACL is lateral and the PCL is medial.
• The PCL is larger and stronger than the ACL.
• These form a cross arrangement(X) as these
are named as.

71. Cruciate Ligaments
Anterior Cruciate Ligament Posterior Cruciate Ligament
Lies outside the synovial cavity of the joint but
inside the knee joint capsule.
Lies outside the synovial cavity but within the
fibrous joint capsule.
Arises from the anterior intercondylar area of
the tibia and passes upward, backward, and
laterally to insert into the medial surface of the
lateral femoral condyle.
Arises from the posterior intercondylar area of
the tibia and passes upward, forward, and
medially to insert into the lateral surface of the
medial femoral condyle.
Prevents forward sliding of the tibia on the
femur (or posterior displacement of the femur
on the tibia) and prevents hyperextension of
the knee joint.
Prevents backward sliding of the tibia on the
femur (or anterior displacement of the femur
on the tibia) and limits hyperflexion of the
knee.
Is slightly longer than the posterior cruciate
ligament.
Is shorter, straighter, and stronger than the
anterior cruciate ligament.
Is taut during extension of the knee and is lax
during flexion. (The small, more anterior
band is taut during flexion.)
Is taut during fl exion of the knee and is lax
during extension. (The small posterior band is
lax during flexion and taut during extension.)
*Anterior Cruciate Ligamentm may be torn when the knee is hyperextended.

73. Menisci
• Menisci (semilunar cartilages) are
flattened crescent-shaped discs inside
the knee joint (one medial, one lateral),
wedged between the articular surfaces
(condyles) of the femur and the tibia and
thickest at the periphery.
–Medial meniscus
–Lateral meniscus

74. Meniscus
• Each meniscus has:
• Two ends, both attached to the tibia
• Two borders – Outer border is thick, convex and
fixed to the fibrous capsule, inner border is thin,
concave and free.
• Two surfaces – The upper surface is concave for
articulation with the femur. The lower surface is flat
and rests on the peripheral two thirds of the tibial
condyle. The peripheral thick part is vascular. The
inner part is avascular and is nourished by synovial
fluid.

75. Medial Meniscus Lateral Meniscus
Lies outside the synovial cavity but
within the joint capsule.*
Lies outside the synovial cavity but
within the joint capsule.*
C -shaped (i.e., forms a semicircle)
and is attached to the medial
collateral ligament and
interarticular area of the tibia.
Nearly circular, acts as a cushion,
and facilitates lubrication.
Acts as a cushion or shock
absorber and lubricates the
articular surfaces by distributing
synovial fluid in a windshield-
wiper manner.
Separated laterally from the
fibular (or lateral) collateral
ligament by the tendon of the
popliteal muscle and aids in
forming a more stable base for the
articulation of the femoral
condyle.
Transverse Ligament
■ Binds the anterior horns (ends) of the lateral and medial semilunar cartilages (menisci).
*The synovial membrane does not cover the surfaces of the menisci. RJL page 139

77. Movements of the minisci
• Minisci are moved passively by displacement
between tibial & femoral condyles.
• Minisci are moved actively as a result of their
attachments to muscles and ligaments.
• Minisci are pushed anteriorly as knee extends.
• Minisci are pushed posteriorly during flexion.
• During axial rotation minisci follow movements of
femoral conyles.

78. Extracapsular Ligaments
Medial (Tibial)
Collateral
Ligament
Is a broad band that extends from the medial femoral
epicondyle to the medial tibial condyle.
■ Is firmly attached to the medial meniscus, and its
attachment is of clinical significance because injury to the
ligament results in concomitant damage to the medial
meniscus.
■ Prevents medial displacement of the two long bones and
thus abduction of the leg at the knee.
■ Becomes taut on extension and thus limits extension
and abduction of the leg.
Lateral (Fibular)
Collateral
Ligament
Is a rounded cord that is separated from the lateral
meniscus by the tendon of the popliteus muscle and also
from the capsule of the joint.
■ Extends between the lateral femoral epicondyle and the
head of the fi bula.
■ Becomes taut on extension and limits extension and
adduction of the leg.
Cont.

79. Extracapsular Ligaments
Patellar Ligament (Tendon) Is a strong flattened fibrous band that is the
continuation of the quadriceps femoris tendon. Its
portion may be used for repair of the anterior cruciate
ligament.
■ Extends from the apex of the patella to the tuberosity
of the tibia.
Arcuate Popliteal Ligament Arises from the head of the fibula, arches superiorly
and medially over the tendon of the popliteus muscle
on the back of the knee joint, and fuses with the
articular capsule.
Oblique Popliteal Ligament Is an oblique expansion of the semimembranosus
tendon and passes upward obliquely across the
posterior surface of the knee joint from the medial
condyle of the tibia.
■ Resists hyperextension of the leg and lateral rotation
during the fi nal phase of extension.
Popliteus Tendon Arises as a strong cord-like tendon from the lateral
aspect of the lateral femoral condyle and runs between
the lateral meniscus and the capsule of the knee joint
deep to the fibular collateral ligament.

84. Relations
Anteriorly The prepatellar bursa
Posteriorly The popliteal vessels;
Tibial and common peroneal nerves;
Lymph nodes; and
The muscles that form the boundaries of the
popliteal fossa, namely, the semimembranosus,
the semitendinosus, the biceps femoris, the two
heads of the gastrocnemius, and the plantaris
Medially Sartorius, gracilis, and semitendinosus muscles
Laterally Biceps femoris and common peroneal nerve

87. Locking mechanism
• When standing, the knee joint is 'locked'.
• One component of the locking mechanism is a change in
the shape and size of the femoral surfaces that articulate
with the tibia:
– The joint surfaces become larger and more stable in
extension.
• Another component of the locking mechanism is
medial rotation of the femur on the tibia during
extension.
• Medial rotation and full extension tighten all the
associated ligaments.
• Another feature that keeps the knee extended
when standing is that the body's center of gravity
is positioned along a vertical line that passes
anterior to the knee joint.
• The popliteus muscle unlocks the knee by
initiating lateral rotation of the femur on the tibia.

88. Bursae around knee joint

89. Bursae Locations Comments
Suprapatellar
Between femur and tendon of
quadriceps femoris
Held in position by articularis genu
muscles; communicates freely with
(superior extension of) synovial
cavity of knee joint
Popliteus
Between tendon of popliteus and lateral
condyle of tibia
Opens into synovial cavity of knee
joint inferior to lateral meniscus
Anserine
Separates tendons of sartorius, gracilis,
and semitendinosus from tibia and tibial
collateral ligament
Area where tendons of these
muscles attach to tibia; resembles a
goose's foot (L. pes anserinus)
Gastrocnemius
Deep to proximal attachment of tendon
of medial head of gastrocnemius
An extension of synovial cavity of
knee joint
Semimembranosus
Between medial head of gastrocnemius
and semimembranosus tendon
Related to distal attachment of
semimembranosus
Subcutaneous
prepatellar
Between skin and anterior surface of
patella
Allows free movement of skin over
patella during movements of leg
Subcutaneous
infrapatellar
Between skin and tibial tuberosity Helps knee withstand pressure
when kneeling
Deep infrapatellar
Between patellar ligament and anterior
surface of tibia
Separated from knee joint by
infrapatellar fat pad
Bursae around knee joint

92. Blood Supply of Knee Joint
The knee joint is supplied by
the anastomosis around it which is
formed by contribution from
•Five genicular branches of the popliteal
artery
•Descending genicular branch of the
femoral artery
•Descending branch of
the lateral circumflex femoral artery
•Two recurrent branches of the anterior
tibial artery
•Circumflex fibular branch of the posterior
tibial artery.
The anastomosis supplies the
patella, the femoral and tibial
condyles, bone marrow, articular
capsule, and synovial membrane.

94. The venous system of the knee joint
• The venous system of the knee joint is
primarily composed of the popliteal and
femoral veins. These veins simply run with
their corresponding arteries and drain
deoxygenated blood from the
arterial anastomosis..

95. Nerve Supply of Knee Joint
• Femoral nerve, through its branches to the vasti,
especially the vastus medialis.
• Sciatic nerve, through the genicular branches of the
tibial and common peroneal nerves.
• Obturator nerve through its posterior division.
• Infrapatellar branch of the saphenous nerve provides
cutaneous sensation to the medial anterior aspect of
the knee.
• Peripatellar plexus is composed of branches from
anterior cutaneous branches of the femoral nerve and
the lateral femoral cutaneous nerve to provide
cutaneous sensation to the rest of the knee

96. Lymphatic drainage of Knee joint
• The lymphatic drainage of knee
joint is to popliteal nodes.
• Most of the lymph vessels
accompany the genicular arteries.
• The popliteal nodes drain into the
inguinal group of lymph node

97. Stability of Knee Joint
• Structurally, the knee is a week joint because the
articular surfaces are not congruent. The tibial condyles
are too small and shallow to hold the large, convex,
femoral condyles in place. The femoropatellar
articulation is not inherently stable because shallow
articular surfaces, and because of the outward
angulation between the long axis of thigh and of the
leg.
• Stability to the joint is imparted by
– Cruciate ligaments – maintain anteroposterior stability.
– Collateral ligament – maintain side to side stability.
– Caspule thickenings as note before
– Iliotibial tract plays an important role in stabilizing the knee.
– Patellar retinacula

99. The Ankle Joint
also known as the Talocrural Joint
Dr M Idris Siddiqui

104. The ankle joint
• The ankle joint is a hinged synovial joint.
• It connects:
with
The distal ends of the tibia and fibula
The proximal end of the talus

105. Articulating Surfaces
–Trochlea of Talus
–Malleolar(lateral & medial)
Mortis formed by Tibia &
Fibula
–Lateral & Medial Malleolus

106. The ankle joint
• Proximal articular outermost layer of the ankle
joint is made by the articular facets of the:
– Lower end of tibia consisting of its medial malleolus.
– Lateral malleolus.
– Inferior transverse tibiofibular ligament.
• These 3 together create a deep tibiofibular socket
(also termed “tibiofibular mortise”).
• Distal articular outermost layer of the ankle joint is
composed by:
– The articular facets on the upper, medial, and lateral
aspects of the body of the talus.

107. Articulating Surfaces
• The body of the talus fits snugly into the mortise
formed by the bones of the leg.
• The body of talus presents 3 articular surfaces:
– Superior pulley-shaped articular surface (trochlear
surface).
• Articulate the inferior aspect of the lower end of tibia
– Medial comma-shaped articular surface.
• Articulates the lateral aspect of medial malleolus
– Lateral triangular articular surface.
• Articulates the medial aspect of lateral malleolus
• The wedge shaped body of the talus fits into the
socket above.

108. The socket
–The socket is provided flexibility by
•The tibiofibular ligaments,
•The flexibility of the fibula,
•Slight movements of the fibula at
the superior tibiofibular joint

109. SOLIDITY OF THE ANKLE JOINT
• The trochlear surface on the superior aspect of
the body of talus is wider in front than behind.
• During dorsiflexion, ankle joint of the anterior
wider part of the trochlea moves posteriorly and
fits correctly into the tibiofibular mortise, thus
joint is stable.
• During plantar flexion, the narrow posterior part
of the trochlea doesn’t fit correctly in the
tibiofibular mortise, thus the joint is unstable
during plantar flexion.

110. VARIABLES KEEPING THE SOLIDITY OF
THE ANKLE JOINT
• Close interlocking of its articular surfaces.
• Strong, medial, and lateral collateral
ligaments.
• Deepening of tibiofibular socket posteriorly by
the inferior transverse tibiofibular ligament.
• Tendons (4 in front and 5 behind) crossing the
ankle joint.
• Other ligaments of the joint.

111. Stability of Ankle Joint
• Ankle joint is a strong joint made stable by
–Close interlocking of the articular surfaces
–Strong collateral ligaments on the sides
–The tendons that cross the joint (four in front,
and five behind)
• The depth of the superior articular socket is
contributed to
• The downward projection of
the medial and lateral malleoli,
• Transverse tibiofibular ligament.

112. Factors tend to displace the tibia and fibula forwards
• Anatomically, two factors tend to displace the tibia
and fibula forwards over the talus
– The forward pull of tendons passes from the leg to the foot.
– Pull of gravity. When standing line of gravity falls in front of
ankle joint.
• But following factors are responsible for prevention of
displacement:
– The talus is wedge shaped, being wider anteriorly.
– The posterior border of the lower end of the tibia is
prolonged downwards.
– Ligamentous structures

113. LIGAMENTS
• The essential ligaments of ankle joint
are:
1. Capsular ligament.
2. Medial and lateral collateral
ligaments.

114. Joint Capsule
• The articular capsule surrounds the joints, and is attached,
– Above , to the borders of the articular surfaces of the tibia and
malleoli; and
– Below , to the talus around its upper articular surface.
• Anteriorly:
– The joint capsule is a broad, thin, fibrous layer.
• Posteriorly:
– The fibres are thin and run mainly transversely blending with the
transverse ligament.
• Laterally:
– The capsule is thickened, and attaches to the hollow on the
medial surface of the lateral malleolus.
• The synovial membrane extends superiorly between Tibia & Fibula as far as
the Interosseous Tibiofibular Ligament.

115. FIBROUS CAPSULE
• The joint capsule is thin in front and behind to
enable hinge movements and thick on either side
where it combines with the collateral ligaments.
• It encompasses the joint entirely. It is connected to
the articular margins of the joint all around with
two exceptions:
– Posterosuperiorly it is connected to the inferior
transverse tibiofibular ligament.
– Anteroinferiorly it is connected to the dorsum of the
neck of talus at some distance from the trochlear
surface.

116. The synovial membrane
• The synovial membrane lines the
inner surface of the joint capsule, but
ends at the periphery of the articular
cartilages.
–A small synovial process goes upward
into the inferior tibiofibular
syndesmosis.

117. Medial Ligament
• The medial ligament (or deltoid ligament) is attached
to the medial malleolus (a bony prominence projecting
from the medial aspect of the distal tibia).
• It consists of an apex attached to tip and margins of
medial malleolus and a base which fan out attaching
to: (3 tarsal bones)
– The talus,
– The Calcaneus
– The Navicular bones.
• The primary action of the medial ligament is to
resist over-eversion of the foot

119. DELTOID OR MEDIAL LIGAMENT
• The deltoid ligament is an extremely triangular ligament on the
medial side of the ankle compensating the shortness of medial
malleolus.
• It splits into 2 parts:
• Superficial and deep.
– Above, both the parts have a common connection to the apex and
margins of the medial malleolus.
– Below, the connection of superficial and deep parts differs.
• Superficial part: Its fibres are split into 3 parts:
• Anterior :
– Anterior fibres (tibionavicular) are connected to the tuberosity of navicular bone and the
medial
• Middle :
– Middle fibres (tibiocalcanean) are connected to the entire length of sustentaculum tali.
• Posterior:
– Posterior fibres (posterior tibiotalar) to the medial tubercle and adjoining part of the
medial surface of talus.
• Deep part (anterior tibiotalar) is connected to the anterior part of
the medial surface of talus.

120. The lateral ligament
• The lateral ligament is composed of 3 parts:
• Anterior talofibular – (poor flat band) spans between the
lateral malleolus and lateral aspect of the talus.
• Posterior talofibular – (powerful band)spans between the
lateral malleolus and the posterior aspect of the talus.
• Calcaneofibular – (long rounded cord) spans between the
lateral malleolus and the calcaneus
• Superficially, the deltoid ligament is crossed by the tendons
of tibialis posterior and flexor digitorum longus on the other
hand lateral ligament is crossed superficially by the tendons
of peroneus longus and brevis.
• It resists over-inversion of the foot

124. LIGAMENT DESCRIPTION PROXIMAL
ATTACHMENT
DISTAL
ATTACHMENT
ROLE
Anterior
Talofibular
Ligament
(ATFL)
Flat Weak Band that
extends Anteriomedially.
Most commonly damaged
ligament of the ankle.
Lateral
Malleolus
Neck of Talus •Restrain anterior
displacement of the
talus in respect to the
fibula and tibia.
•Resists Inversion in
planterflexion.
Posterior
Talofibular
Ligament
(PTFL)
Thick, fairly strong band
that runs horizontally
medially.
This ligament is under
greater strain in full
dorsiflexion of ankle.
Rarely injured because
bony stability protects
ligaments when ankle in
dorsiflexion.
Malleolar Fossa
of Fibula
Lateral
Tubercle of
Talus
Forms the back wall of
the recipient socket for
the talus' trochlea.
Resists posterior
displacement of the
talus.
Calcaneofibular
Ligament (CFL)
Round cord that passes
posterioinferiorly
Tip of Lateral
Malleolus
Lateral
Surface of
Calcaneus
•Aids Talofibular
stability during
Dorsiflexion.
•Restrain inversion of
the calcaneus with
respect to the fibula.
Prevent Talar tilt into
Inversion.

125. LIGAMENTS DESCRIPTION PROXIMAL
ATTACHMENT
DISTAL
ATTACHMENT
ROLE
Anterior
Tibiotalar
Ligament
Medial
Malleolus
Head of Talus Reinforces
Ankle Joint.
Control
Plantarflexion &
Eversion
Posterior
Tibiotalar
Ligament
Talus
Posteriorly
Control
Dorsiflexion
Tibionavicular
Ligament
Forms most
anterior part of
the Deltoid
Ligament
Dorsomedial
Aspect of
Navicular
Reinforces
Ankle Joint
Tibiocalcaneal
Ligament
Very thin
ligament
Sustentaculum
Tali
Reinforces
Ankle Joint

126. The Ankle ‘Ring’
• The ankle joint and associated ligaments can be
visualised as a ring in the coronal plane:
• The upper part of the ring is formed by the articular
surfaces of the tibia and fibula.
• The lower part of the ring is formed by the subtalar
joint (between the talus and the calcaneus).
• The sides of the ring are formed by the medial and
lateral ligaments.
• A ring, when broken, usually breaks in two places (the
best way of illustrating with is with a polo mint – it is
very difficult to break one side without breaking the
other).

127. RELATIONS OF THE ANKLE JOINT
• Anterior: Anteriorly from medial to lateral side the ankle joint is related to
these structures:
– Tibialis anterior.
– Extensor Hallucis longus.
– Anterior tibial Artery.
– Deep peroneal Nerve.
– Extensor Digitorum longus.
– Peroneus tertius.
• Mnemonic: The Himalayas Are Not Dry Tablelands.
• Posterior: Posteriorly from medial to lateral side the ankle joint is related to
these structures:
– Tibialis posterior.
– Flexion Digitorum longus.
– Posterio r tibial Artery.
– Posterio r tibial N erve.
– Flexor Hallucis longus.
• Mnemonic: The Doctors Are Not Here.

129. POSTERIOR COMPARTMENT (SUPERFICIAL)
MUSCLE ACTION PROXIMAL
ATTACHMENT
DISTAL
ATTACHMENT
INNERVATION
Gastrocnemius Plantarflexion when
Knee Extended
Flexion Knee
Raises Heel during
Walking
Lateral Head: Lateral
Aspect of Lateral
Femoral Condyle
Medial Head: Popliteal
Surface of Femur
Superior to Medial
Femoral Condyle
Posterior Surface
Calcaneus via
Calcaneal Tendon
(Achilles Tendon)
Tibial Nerve
S1-S2
Soleus Plantarflexion
Steadies Leg on Foot
Posterior Aspect of
Head Fibula
Superior ¼ Posterior
Surface Tibia
Soleal Line & Medial
Border Tibia
Plantaris Weakly Assists
Gastrocnemius in
Plantarflexion
Inferior end Lateral
Supracondylar Line of
Femur
Oblique Popliteal
Ligament

130. POSTERIOR COMPARTMENT (DEEP)
MUSCLE ACTION PROXIMAL
ATTACHMENT
DISTAL
ATTACHMENT
INNERVATION
Tibialis Posterior Plantarflexion
Inversion
Supports Medial
Longitudinal Arch
Interosseous
Membrane
Posterior Surface
Tibia inferior to
Soleal Line
Posterior Surface
Fibula
Navicular Tuberosity
Cuneiform
Cuboid
Bases of Metatarsals
2-4
Tibial Nerve
L4-L5
Flexor Digitorum
Longus
Plantarflexion
Flexion Lateral Four
Digits
Supports
Longitudinal Arch
Medial Part Posterior
Surface
Tibia inferior to
Soleal Line
Broad Tendon to
Fibula
Base Distal
Phalanges Digits 2-4
Tibial Nerve
S2-S3
Flexor Hallucis
Longus
Weak Plantarflexion
Flexion Big Toe at all
Joints
Supports Medial
Longitudinal Arch
Inferior 2/3 Posterior
Surface Fibula
Inferior Part
Interosseous
Membrane
Base Distal Phalanx
of Big Toe

131. LATERAL COMPARTMENT
MUSCLE ACTION PROXIMAL
ATTACHMENT
DISTAL
ATTACHMENT
INNERVATION
Peroneus Brevis Weak
Plantarflexion
Eversion
Inferior 2/3 of
Lateral Surface
Fibula
Dorsal Surface
Tuberosity of
Base
5th Metatarsal
Superficial
Peroneal Nerve
(Superficial
Fibular Nerve)
L5 - S2Peroneus
Longus
Weak
Plantarflexion
Eversion
Supports
Transverse Arch
Head &
Superior 2/3
of Lateral
Surface Fibula
Base 1st
Metatarsal
Medial Cuniform

132. ANTERIOR COMPARTMENT
MUSCLE ACTION PROXIMAL
ATTACHMENT
DISTAL
ATTACHMENT
INNERVATION
Tibialis Anterior Dorsiflexion
Inversion
Supports Medial
Longitudinal Arch
Lateral Condyle Tibia
Superior ½ Lateral
Surface Tibia
Interosseous Membrane
Medial & Inferior
Surfaces
Medial Cuniform
Base of 1st
Metatarsal
Deep Peroneal
Nerve
(Deep Fibular
Nerve)
L4-L5
Extensor
Digitorum
Longus
Dorsiflexion
Extends Lateral
Four Digits
Lateral Condyle Tibia
Superior ¾ Anterior
Surface
Interosseous Membrane
Middle & Distal
Phalanges of Lateral
Four Digits
Deep Peroneal
Nerve
(Deep Fibular
Nerve)
L5-S1
Extensor Hallucis
Longus
Dorsiflexion
Extends Big Toe
Middle Part Anterior
Surface Fibula
Interosseous Membrane
Dorsal Aspect of
Base Distal
Phalanx of Big Toe
Peroneus Tertius Dorsiflexion
Aids Eversion
Inferior 1/3 Anterior
Surface Fibula
Interosseous Membrane
Dorsum Base 5th
Metatarsal

133. ARTERIAL & NERVE SUPPLY
• ARTERIAL SUPPLY
• It is by the malleolar branches of anterior
tibial, posterior tibial, and peroneal arteries.
• NERVE SUPPLY
• It is by the branches of deep peroneal and
tibial nerves. (The segmental innervations is
by L4, L5; S1, S2 spinal sections).

134. Movements
Movements Principal muscles Accessory muscles
Dorsiflexion Tibialis anterior
1.Extensor
digitorum longus.
2.Extensor hallucis
longus.
3.Peroneus tertius.
Plantar flexion
1.Gastrocnemius.
2.Soleus.
1.Plantaris.
2.Tibialis posterior.
3.Flexor hallucis
longus.
4.Flexor digitorum
longus.
•The ankle joint is stable in dorsiflexion and shaky in plantar flexion.
•The dorsiflexion is restrained by the L4, L5 spinal segments and plantar flexion by the
S1, S2 spinal sections.

135. ANKLE SPRAINS
• The excessive stretches and/or tearing of ligaments of
the ankle joint is named the ankle sprain. The ankle
sprains are normally caused by the falls from height or
spins of ankle.
• When the plantar-flexed foot is excessively inverted,
the anterior and posterior talofibular and
calcaneofibular ligaments are stretched and torn. The
anterior talofibular ligament is most commonly torn.
• When the plantar-flexed foot is excessively everted, the
deltoid ligament isn’t torn; instead there’s an avulsion
fracture of medial malleolus.
• The inversion sprains are much more common than
eversion sprains.

136. DISLOCATION OF THE ANKLE
• The dislocations of ankle joint are
uncommon because it is a quite stable
joint because of tibiofibular mortise.
• Nevertheless, whenever dislocation takes
place it is constantly escorted by the
fracture of one of the malleoli

137. POTT’S FRACTURE
(FRACTURE DISLOCATION OF THE ANKLE)
• It takes place when the foot is caught in the rabbit
hole and everted forcibly.
– Oblique fracture of the lateral malleolus because of
internal rotation of the tibia.
– Transverse fracture of the medial malleolus as a result
of pull by powerful deltoid ligament.
– Fracture of the posterior margin of the lower end of
tibia (third malleolus) because it’s carried forward.
• These phases are also referred to as first, 2nd, and
third degree of Pott’s fracture, respectively. The
third degree of Potts fracture is also termed
trimalleolar fracture.

138. OPTIMUM POSITION OF THE ANKLE
• The optimum position of the ankle is
one where ankle joint is in slight
plantar flexion.
• understanding of position is
important for using plaster cast in
the ankle region

141. SUBTALAR JOINT
Dr M Idris Siddiqui

142. The subtalar joint
• There are just two joints between
the talus and calcanean:
–Posterior talocalcanean joint and
–Anterior talocalcaneonavicular joint.
• The posterior talocalcanean joint is
frequently designated as subtalar
joint.

143. The subtalar joint
• The subtalar joint is an articulation
between two of the tarsal bones in
the foot – the talus and calcaneus.
• The joint is classed structurally as
a synovial joint, and functionally as
a plane synovial joint.

145. Articulating Surfaces
• The subtalar joint is formed between two of the
tarsal bones:
• Inferior surface of the body of the talus
– The posterior talar articular surface.
• Superior surface of the calcaneus
– The posterior calcaneal articular facet.
• As is typical for a synovial joint, these surfaces are
covered by articular cartilage.

147. Stability
• The subtalar joint is enclosed by a joint capsule,
which is lined internally by synovial membrane and
strengthened externally by a fibrous layer.
• The capsule is also supported by three ligaments:
– Posterior talocalcaneal ligament
– Medial talocalcaneal ligament
– Lateral talocalcaneal ligament

148. Additional ligaments
• An additional ligament – the interosseous
talocalcaneal ligament – acts to bind the talus
and calcaneus together.
– It lies within the sinus tarsi (a small cavity between
the talus and calcaneus), and is particularly strong;
providing the majority of the ligamentous stability to
the joint.
• The cervical ligament is lateral to sinus tarsi. It
goes upward and medially from upper surface of
the calcaneum to the tubercle on the inferolateral
aspect of the neck of talus. It becomes tight in
inversion.

149. Movements
• The subtalar joint is formed on an oblique axis and
is therefore the chief site within the foot for
generation of eversion and inversion movements.
This movement is produced by the muscles of the
lateral compartment of the leg. and tibialis anterior
muscle respectively.
• The nature of the articulating surface means that
the subtalar joint has no role in plantar or
dorsiflexion of the foot.

150. Neurovascular Supply
• The subtalar joint receives supply from two
arteries and two nerves. Arterial supply comes
from the posterior
tibial and peronealarteries.
• Innervation to the plantar aspect of the joint is
supplied by the medial or lateral plantar
nerve, whereas the dorsal aspect of the joint
is supplied by the deep peoneal nerve

151. Calcaneal Fracture
• The calcaneus is often fractured in a ‘crush‘ type injury.
The most common mechanism of damage is falling
onto the heel from a height – the talus is driven into
the calcaneus. The bone can break into several pieces,
known as a comminuted fracture. Upon x-ray imaging,
the calcaneus will appear shorter and wider.
• A calcaneal fracture can cause chronic problems, even
after treatment. The subtalar joint is usually disrupted,
causing the joint to become arthritic. The patient will
experience pain upon inversion and eversion – which
can make walking on uneven ground particularly
painful