The document discusses the kinesiology of the knee joint. It describes the anatomy and functions of the medial and lateral menisci, which act as shock absorbers within the knee. The cruciate ligaments (ACL and PCL) are discussed, with the ACL preventing anterior translation of the tibia and the PCL limiting posterior translation. Injuries commonly involve tears to the menisci from torsional forces on the knee, while ACL injuries often occur when rapidly changing directions or landing from a jump. The knee allows for flexion/extension in the sagittal plane and internal/external rotation when flexed, with the axis of rotation migrating through the ranges of motion.

1. Kinesiology of the Knee Joint 1
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2. Medial and
Lateral Menisci

3. • The medial and lateral menisci are crescent-
shaped, fibro cartilaginous structures located
within the knee joint.
• They transform the articular surfaces of the tibia
into shallow seats for the large femoral condyles.
Kinesiology of the Knee Joint
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4. Primary Functions of the Menisci
• Act as shock absorbers for the knee;
reduce friction and dissipate compressive forces
• Increase surface area of joint contact,
thereby reducing joint pressure
• Improve joint congruency
• Facilitate normal joint arthrokinematics
Kinesiology of the Knee Joint 4

6. • Coronary (meniscotibial) ligaments anchor the
external edge of each meniscus.
The transverse ligament connects the menisci
anteriorly.
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8. • Several muscles have secondary
attachments to the menisci.
• Part of the medial meniscus attaches to
the MCL.
• For this reason, excessive stress or
deformation of the MCL may also damage
the medial meniscus.
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9. Kinesiology of the Knee Joint 9

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11. • The primary role of the menisci is to absorb
and disperse the large compressive forces
transferred through the knee joint.
• These fibrocartilaginous structures,
are susceptible to injury from torsion or
“grinding” of the femoral condyles against the
tibia.
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12. Kinesiology of the Knee Joint 12

13. • Blood supply to the menisci is greatest near
the peripheral border.
• Injury to the outer one-third of the meniscus
may heal without surgery because of its
relatively good blood supply.
• The internal border is essentially avascular.
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16. Once injured, the menisci may not heal well.
This is especially true with the inner one-third of
the structure because of its poor blood supply:
• Inner one-third: Essentially avascular
• Middle one-third: Poor blood supply
• Outer one-third: Good blood supply
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19. MENISCI:
FUNCTIONAL CONSIDERATIONS
• The menisci reduce compressive stress
across the tibiofemoral joint.
• They stabilize the joint during motion,
lubricate the articular cartilage, provide
proprioception, and help guide the knee’s
arthrokinematics.
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20. • Compression forces at the knee reach 2.5 to 3
times the body weight when one is walking and
over 4 times the body weight when one ascends
stairs.
• The menisci nearly triple the area of joint
contact, thereby significantly reducing the
pressure.
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21. • With every step, the menisci deform
peripherally.
• The compression force is absorbed as
circumferential tension (hoop stress).
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22. Kinesiology of the Knee Joint 22

23. Kinesiology of the Knee Joint 23

24. MENISCI:
COMMON MECHANISMS OF INJURY
• Tears of the meniscus are the most common injury
of the knee.
• Meniscal tears are often associated with a forceful,
axial rotation of the femoral condyles over a partially
flexed and weight-bearing knee.
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25. Kinesiology of the Knee Joint 25

26. • The axial torsion within the compressed knee
can pinch and dislodge the meniscus.
• A dislodged or folded flap of meniscus (often
referred to as a “bucket-handle tear”) can
mechanically block knee movement.
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27. Kinesiology of the Knee Joint 27

28. • The medial meniscus is injured twice as
frequently as the lateral meniscus.
• Axial rotation with a valgus stress to the
knee can cause this.
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33. OSTEOKINEMATICS AT THE
TIBIOFEMORAL JOINT
Two degrees of freedom:
• Flexion & extension in the sagittal plane
• Provided the knee is slightly flexed,
internal and external rotation.
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34. Kinesiology of the Knee Joint 34

35. • The healthy knee moves from 130 to 150
degrees of flexion to about 5 to 10
degrees beyond the 0-degree (straight)
position.
• The axis of rotation for flexion and
extension is not fixed, but migrates within
the femoral condyles.
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36. Instantaneous Axis of Rotation
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37. Kinesiology of the Knee Joint 37

38. • The curved path of the axis is known as an
“evolute”.
• With maximal effort, internal torque varies
across the range of motion.
• External devices attached to the knee
rotate about a fixed axis of rotation.
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39. • A hinged orthosis can cause rubbing or
abrasion against the skin.
• Goniometric measurements are more
difficult.
• Place the device as close as possible to the
“average” axis of rotation.
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40. • Internal and external rotation of the knee
occurs about a vertical or longitudinal axis
of rotation.
• This motion is called axial rotation.
• The freedom of axial rotation increases
with greater knee flexion.
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41. • A knee flexed to 90 degrees can perform
about 40 to 45 degrees of axial rotation.
• External rotation generally exceeds
internal rotation by a ratio of nearly 2:1.
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43. • Internal and external (axial) rotation of the right knee.
• A, Tibial-on-femoral (knee) rotation.
• In this case the direction of the knee rotation (internal or
external) is the same as the motion of the tibia; the femur
is stationary.
• B, Femoral-on-tibial rotation. In this case the tibia is
stationary and the femur is rotating.
• The direction of the knee rotation (external or internal) is
the opposite of the motion of the moving femur: external
rotation of the knee occurs by internal rotation of the
femur;
• internal rotation of the knee occurs by external rotation of
the femur.
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44. • Once the knee is in full extension, axial
rotation is maximally restricted.
• The naming of axial rotation is based on
the position of the tibial tuberosity relative
to the anterior distal femur.
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45. • External rotation of the knee is when the
tibial tuberosity is located lateral to the
anterior distal femur.
• This does not stipulate whether the tibia or
femur is the moving bone.
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46. ARTHROKINEMATICS AT THE
TIBIOFEMORAL JOINT:
INTERNAL AND EXTERNAL (AXIAL)
ROTATION OF THE KNEE
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47. • The knee must be flexed to maximize
independent axial rotation between the
tibia and femur.
• The arthrokinematics involve a spin
between the menisci and the articular
surfaces of the tibia and femur.
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48. ARTHROKINEMATICS AT THE TIBIOFEMORAL JOINT:
EXTENSION OF THE KNEE
Tibial-on-femoral extension
• The articular surface of the tibia rolls and
slides anteriorly on the femoral condyles.
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50. • Femoral-on-tibial extension
• Standing up from a deep squat position.
• The femoral condyles simultaneously roll
anterior and slide posterior on the articular
surface of the tibia.
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51. ARTHROKINEMATICS AT THE TIBIOFEMORAL
JOINT: “SCREW-HOME” ROTATION KNEE
• Locking the knee in full extension requires
about 10 degrees of external rotation.
• It is referred to as “screw-home”rotation.
• It is a conjunct rotation.
• As it nears full extension, the knee rotates
externally about 10 to 15 degrees.
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52. • The shape of the articular surfaces of the
tibiofemoral joint necessitates that flexion
and extension are accompanied by slight
automatic rotational movements.
• This automatic rotation—defined by the
position of the tibia relative to the femur—
assists in locking the knee, the so-called
screw-home mechanism.
Kinesiology of the Knee Joint 52

53. • This locking mechanism can occur by
rotation of the tibia on the femur or by
rotation of the femur over a fixed tibia.
• In either case, this rotation helps lock the
knee into extension.
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54. • It is mechanically linked to the flexion and
extension kinematics and cannot be
performed independently.
• The combined external rotation and
extension maximizes the overall contact
area.
• This increases congruence and favors
stability.
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55. Kinesiology of the Knee Joint 55

56. • The most important factor is the shape of the
medial femoral condyle.
• The articular surface of the medial femoral
condyle curves about 30 degrees laterally, as
it approaches the trochlear groove.
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57. Kinesiology of the Knee Joint 57

58. • The articular surface of the medial condyle extends
farther anteriorly than the lateral condyle, the tibia is
obliged to follow the laterally curves path into full
tibia-on femoral extension.
• During femoral on tibial extension, the femur follows
the medially curves path on the tibia.
• In either case, the result is external rotation of the
knee at full ext.
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59. ARTHROKINEMATICS AT THE TIBIOFEMORAL
JOINT: FLEXION OF THE KNEE
• For a knee that is fully extended to be
unlocked, it must first internally rotate
slightly.
• This internal rotation is achieved by the
popliteus muscle.
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62. Kinesiology of the Knee Joint 62

63. • Cruciate, meaning cross-shaped,
describes the spatial relation of the
anterior and posterior cruciate ligaments
as they cross within the intercondylar
notch of the femur.
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64. • The cruciate ligaments are intracapsular and
covered by extensive synovial lining.
• Together, they resist the extremes of all knee
movements.
• The provide most of the resistance to anterior
and posterior shear forces.
• They contain mechanoreceptors and
contribute to proprioceptive feedback.
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65. Kinesiology of the Knee Joint 65

66. ANTERIOR CRUCIATE LIGAMENT: ANATOMY
AND FUNCTION
• The anterior cruciate ligament (ACL)
attaches along an impression on the anterior
intercondylar area of the tibial plateau.
• It runs obliquely in a posterior, superior, and
lateral direction.
Kinesiology of the Knee Joint 66

67. • The fibers become increasingly taut as the
knee approaches and reaches full
extension.
• The quadriceps is referred to as an “ACL
antagonist” because contraction of the
quadriceps stretches (or antagonizes)
most fibers of the ACL.
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68. ANTERIOR CRUCIATE LIGAMENT:
COMMON MECHANISMS OF INJURY
• The ACL is the most frequently totally ruptured
ligament of the knee.
• Approximately half of all ACL injuries occur in
persons between the ages of 15 and 25.
• Landing from a jump quickly and forcefully
decelerating, cutting, or pivoting over a single
planted limb
• Hyperextension of the knee while the foot is
planted firmly on the ground
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72. • An ACL tear can happen when you
change direction rapidly, slow down when
running, land after a jump, or receive a
direct blow to your knee.
• Athletes who participate in high demand
sports like soccer, skiing and basketball
are sports where ACL knee injuries can
happen.
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73. Knee Joint 73

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75. Knee Joint 75

76. POSTERIOR CRUCIATE LIGAMENT:
ANATOMY AND FUNCTION
• The posterior cruciate ligament (PCL)
attaches from the posterior intercondylar area
of the tibia to the lateral side of the medial
femoral condyle.
• The PCL is slightly thicker than the ACL.
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Knee Joint

77. • The “posterior drawer” test evaluates the
integrity of the PCL.
• The PCL limits the extent of anterior
translation of the femur relative to the fixed
lower leg.
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79. POSTERIOR CRUCIATE LIGAMENT: COMMON
MECHANISMS OF INJURY
• Most PCL injuries are associated with high
energy trauma such as an automobile
accident or contact sports.
• Falling over a fully flexed knee with the
ankle plantar flexed
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Knee Joint

80. • Injuries to the posterior cruciate ligament
are less common.
• It can be injured during a direct blow to the
tibia when the knee is bent, or when the
knee is over-straightened.
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81. • “Dashboard” injury – the knee of a
passenger in an automobile strikes the
dashboard subsequent to a front-end
collision, driving the tibia posterior relative
to the femur.
• Often after a PCL injury the proximal tibia
sags posterior relative to the femur when
the lower leg is subjected to the pull of
gravity.
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82. 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."
82Kinesiology of the Lower Limb

83. Kinesiology of the Knee Joint 83
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