Kinesiology of the Lower Limb-Knee Joint-Session 3

1. Kinesiology of
the Knee Joint
Presented by : Zinat Ashnagar, PT, PhD
Assistant Professor, Tehran University of Medical
Sciences
https://orcid.org/0000-0001-5515-2130
Zinatashnagar@gmail.com

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Anteromedial fibers: Tibial attachment: extracapsular
fibers with the synovial sheath
Posterolateral fibers: Femoral Condyle attachment:
Intracapsular without synovial sheath
ACL

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Nearly 70% of all sport-related ACL injuries occur
during non-contact or minimal contact situations.
Many of these non-contact injuries occur when an
individual is landing from a jump or quickly
decelerates during a change of direction such as
when “cutting” to the left or the right over a planted
lower extremity..

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Research strongly suggests that three
biomechanical factors that, when combined,
put the ACL at high risk for injury:
(1) Strong activation of the quadriceps muscle over a
slightly flexed or fully extended knee,
(2) Marked “valgus collapse” of the knee
(3) Excessive external rotation of the knee (often this
occurs as excessive internal rotation of the femur
relative to a fixed tibia).

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11. • Women are two to eight times more likely
to have an ACL injury than men.
• It has been proposed that this is due to
differences in physical conditioning,
muscular strength, and neuromuscular
control.
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13. • Other hypothesized causes of this gender-
related difference in ACL injury rates
include pelvis and lower extremity (leg)
alignment, increased ligamentous laxity,
and the effects of estrogen on ligament
properties.
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Evidence indicates that weakness (and, equally
important, poor control) of the hip abductors and
external rotators contributes to “valgus collapse” of
the knee.
Clinicians who work on ACL prevention programs
with athletes often incorporate strengthening and
neuromuscular reeducation techniques for the
abductors and external rotators of the hip to help
dynamically control the position of the knee.

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The medial and lateral collateral ligaments
strengthen the medial and lateral sides of the
capsule of the knee.
These ligaments are the primary frontal plane
stabilizers of the knee.
Medial and Lateral Collateral Ligaments

16. • (MCL)A flat, broad structure that crosses
the medial aspect of the joint.
• Spans medial side of the knee between
the medial epicondyle of the femur and the
proximal medial tibia.
• Superficial part
• Deep part
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The medial (tibial) collateral ligament

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23. • The primary function of the MCL is to resist
valgus-producing forces.
• Some fibers of the MCL attach to the medial
meniscus of the knee;
•Therefore, injury to the MCL may involve injury
to the medial meniscus as well.
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25. • A round, strong cord that runs nearly vertical
between the lateral epicondyle of the femur
and the head of the fibula.
• Does NOT attach to the lateral meniscus.
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The lateral (fibular) collateral ligament

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32. • The MCL provides resistance against valgus
(abduction) force.
• The lateral collateral ligament provides
resistance against varus (adduction) force.
• Produce a general stabilizing tension for the
knee throughout the sagittal plane range of
motion.
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MEDIAL AND LATERAL COLLATERAL
LIGAMENTS

33. • The collateral ligaments become taut at full
extension.
• This increased tension in the stretched ligaments is
useful for locking the extended knee while
standing—a mechanism that allows a person to
periodically rest the quadriceps.
• However, increased tension in the ligaments does
increase the likeliness of injury.
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39. The “Terrible Triad”
• The “terrible triad” describes the simultaneous injury of
the anterior cruciate ligament, medial collateral ligament,
and medial meniscus.
• Most often this injury occurs as a result of large
rotational and valgus-producing forces to the nearly or fully
extended knee, when the foot is firmly planted on the
ground.
• It is interesting to note that there is a triad of forces
(rotation, valgus, and extension) that produce injury to the
“terrible triad” of knee structures.
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46. PATELLOFEMORAL JOINT
• The patellofemoral joint is the interface
between the articular side of the patella
and the intercondylar (trochlear) groove of
the femur.
• The quadriceps muscle, the fit of the joint
surfaces, and passive restraint from
retinacular fibers and capsule all help to
stabilize this joint.
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47. • Abnormal kinematics of this joint can lead to
anterior knee pain and degeneration of the joint.
• As the knee flexes and extends, a sliding motion
occurs between the articular surfaces of the
patella and intercondylar groove.
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48. PATELLOFEMORAL JOINT KINEMATICS
• The patella typically dislocates laterally.
• There is an overall lateral line of force of the
quadriceps muscle.
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49. POINT OF MAXIMAL CONTACT OF PATELLA ON
FEMUR DURING EXTENSION
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50. POINT OF MAXIMAL CONTACT OF PATELLA ON
FEMUR DURING EXTENSION
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51. PATH OF CONTACT OF PATELLA ON
INTERCONDYLAR GROOVE
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53. INNERVATION OF THE MUSCLES
• The quadriceps femoris is innervated by the
femoral nerve (one nerve for the knee’s sole
extensor group).
• The flexors and rotators are innervated by
several nerves from both the lumbar and sacral
plexus, but primarily the tibial portion of the
sciatic nerve.
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54. SENSORY INNERVATION OF THE KNEE
• Sensory innervation of the knee and
associated ligaments is supplied primarily
by spinal nerve roots from L3 to L5.
• The posterior tibial nerve is the largest
afferent supply of the knee.
• The obturator and femoral nerve also supply
some afferent innervation to the knee.
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55. MUSCULAR FUNCTION AT THE KNEE
• Muscles of the knee are described as two
groups:
–Knee extensors (quadriceps femoris)
–Knee flexor-rotators
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56. ACTIONS & INNERVATIONS OF MUSCLES THAT
CROSS THE KNEE
Muscle Action Innervation Plexus
Sartorius Hip flexion,
external rotation,
and abduction
Knee flexion and
internal rotation
Femoral nerve Lumbar
Gracilis Hip flexion and
abduction
Knee flexion and
internal rotation
Obturator nerve Lumbar
Quadriceps
Rectus Femoris
Vastus Group
Knee extension
and hip flexion
Knee extension
Femoral nerve Lumbar
Popliteus Knee flexion and
internal rotation
Tibial nerve Sacral
Semimembranosus Hip extension
Knee flexion and
internal rotation
Sciatic nerve
(tibial portion)
Sacral
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57. ACTIONS & INNERVATIONS OF MUSCLES THAT CROSS
THE KNEE
Muscle Action Innervation Plexus
Semitendanosus Hip extension
Knee flexion and
internal rotation
Sciatic nerve (tibial
portion)
Sacral
Biceps femoris
(short head)
Knee flexion and
external rotation
Sciatic nerve
(common fibular
portion)
Sacral
Biceps femoris
(long head)
Hip extension
Knee flexion and
external rotation
Sciatic nerve (tibial
portion)
Sacral
Gastrocnemius Knee flexion
Ankle plantar
flexion
Tibial nerve Sacral
Plantaris Knee flexion
Ankle plantar
flexion
Tibial nerve Sacral
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58. EXTENSORS OF THE KNEE
•Quadriceps femoris
– Rectus femoris
– Vastus lateralis
– Vastus medialis
– Vastus intermedius
• Contraction of the vastus group produces
about 80% of the extension torque at the
knee.
• They only extend the knee.
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59. QUADRICEPS CROSS-SECTION
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60. QUADRICEPS FEMORIS:
ANATOMIC CONSIDERATIONS
• Contraction of the rectus femoris produces about
20% of the extension torque at the knee. The rectus
femoris muscle extends the knee and flexes the hip.
• The inferior fibers of the vastus medialis exert an
oblique pull on the patella that help to stabilize it as it
tracks through the intercondylar groove.
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61. QUADRICEPS FEMORIS:
FUNCTIONAL CONSIDERATIONS
• The knee extensor muscles produce a
torque that is about two thirds greater than
that produced by the knee flexor muscles.
• Isometric activation – stabilizes and protects
the knee
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62. Concentric activation
• Accelerates the tibia or femur toward knee
extension.
• Used in raising the body’s center of mass
during uphill running, jumping, or standing
from a seated position.
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63. Eccentric activation
• Controls the rate of descent of the body’s
center of mass during sitting and
squatting.
• Provides shock absorption at the knee.
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64. EXTERNAL (FLEXION) TORQUES
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66. EXTERNAL TORQUE DEMANDS AGAINST
QUADRICEPS
• During tibial-on-femoral knee extension, the
external moment arm of the weight of the
lower leg increases from 90 to 0 degrees of
knee flexion.
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68. • During femoral-on-tibial knee extension (as
in rising from a squat position), the external
moment arm of the upper body weight
decreases from 90 to o degrees of knee
flexion.
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71. • Maximal knee extension (internal) torque
typically occurs between 45 and 70 degrees
of knee flexion, with less torque produced
at the near extremes of Flex and Ext.
• The internal moment arm used by
quadriceps is greatest between about 60
and 20 degrees of knee flex.
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INTERNAL TORQUE

72. The high torque potential of the quadriceps
within this arc of motion is used during many
functional activities that incorporate femoral-
on-tibial kinematics such as ascending a
high step, rising from a chair, or holding a
partial squat position while participating in
sports, such as basketball or speed skating.
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73. • Note the rapid decline of internal the rapid
decline potential as the knee angles
approaches full Ext.
• Of interest, the external torque applied
against the knee during femoral on tibial
Ext also declines rapidly during the same
ROM.
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75. There appears to be a general biomechanical
match in the internal torque potential of the
quadriceps and the external torques applied
against the quadriceps during the last
degrees of complete femoral on tibial knee
Ext.
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76. • This match account for the popularity of
“closed kinematic chain” exercises that
focus on applying resistance to the
quadriceps while the upright person
moves the body through this arc of femoral
on tibial knee Ext.
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77. QUADRICEPS WEAKNESS:
PATHOMECHANICS OF “EXTENSOR LAG”
• People with significant weakness of the
quadriceps often have difficulty completing
the full range of tibial-on-femoral extension
of the knee.
• They fail to produce the last 15 to 20
degrees of extension. This is referred to as
“extensor lag”.
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78. • Swelling or effusion of the knee increases
the likelihood of an extensor lag.
• Swelling increases intra-articular pressure.
• Passive resistance from hamstring muscles
can also limit full knee extension.
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79. FUNCTIONAL ROLE OF THE PATELLA
• The patella acts as a “spacer” between the
femur and the quadriceps muscle, which
increases the internal moment arm of the
knee extensor mechanism.
• The patella augments the extension torque
at the knee.
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80. USE OF PATELLA TO INCREASE THE INTERNAL
MOMENT ARM
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81. PATELLOFEMORAL JOINT KINETICS
• The patellofemoral joint is exposed to high
magnitudes of compression force.
– 1.3 times body weight during walking on level
surfaces
– 2.6 times body weight during performance of a
straight leg raise
– 3.3 times body weight during climbing of stairs
– 7.8 times body weight during deep knee bends
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82. • TWO INTERRELATED FACTORS ASSOCIATED
WITH JOINT COMPRESSION FORCE ON THE
PATELLOFEMORAL JOINT
1. Force within the quadriceps muscle
2. Knee flexion angle
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83. COMPRESSION FORCE WITHIN THE PATELLOFEMORAL
JOINT
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84. • The knee flexion angle influences the
amount of force experienced at the joint.
• Both the compression force and the area of
articular contact on the patellofemoral joint
increase with knee flexion, reaching a
maximum between 60 and 90 degrees.
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85. • Having the area of joint contact greatest at positions
that are generally associated with the largest
muscular-based compression force naturally protects
the joint against stress-induced cartilage
degeneration.
• This mechanism allows most healthy and normally
aligned patellofemoral joints to tolerate large
compression forces over a life time.
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87. FACTORS AFFECTING THE TRACKING OF THE
PATELLA ACROSS THE PATELLOFEMORAL JOINT
• If the patellofemoral joint has less than optimal
congruity, it can lead to abnormal “tracking” of
the patella.
• The patellofemoral joint is then subjected to
higher joint contact stress, increasing the risk
of degenerative lesions and pain.
• This can lead to patellofemoral pain syndrome
and osteoarthritis.
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88. • Excessive tension in the iliotibial band or
lateral patellar retinacular fibers can add to
the natural lateral pull of the patella.
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90. References
• Mansfield PJ, Neumann DA. Essentials of Kinesiology for the Physical
Therapist Assistant E-Book. Elsevier Health Sciences; 2018 Oct 23.
• Neumann DA. Kinesiology of the musculoskeletal system; Foundation for
rehabilitation. Mosby & Elsevier. 2010.
• Wise CH. Orthopaedic manual physical therapy from art to evidence. FA
Davis; 2015 Apr 10.
• https://vdocuments.mx/kinesiology-of-the-musculoskeletal-system-dr-
michael-p-gillespie.html
• PPT "KINESIOLOGY OF THE MUSCULOSKELETAL SYSTEM Dr. Michael
P. Gillespie."
90Kinesiology of the Lower Limb