OTR 704 2.6 Knee, Ankle, & Foot

What structure is shown?

Femur

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Femoral head

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Neck of the femur

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Greater trochanter

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Lesser trochanter

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Linea aspera

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Medial epicondyle

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Lateral epicondyle

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Medial condyle

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Lateral condyle

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Intercondylar fossa

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Patella

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Apex

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Medial and lateral facets

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Tibia

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Medial condyle

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Lateral condyle

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Tibial tuberosity

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Medial malleolus

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Fibula

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Fibular head

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Lateral malleolus

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Tarsals

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Talus

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Calcaneus

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Cuboid

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Navicular

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Medial cuneiform

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Intermediate cuneiform

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Lateral cuneiform

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Metatarsals

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Proximal phalanges

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Middle phalanges

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Distal phalanges

Bones of the lower extremity

• Femur

• Tibia & fibula

• Patella

• Bones of the foot — tarsals, metatarsals, & phalanges

Femur

Structural support for the thigh

• Muscle attachments at bony landmarks: medial and lateral epicondyles, medial and lateral condyles, intercondylar fossa

Tibia

Primary weight-bearing bone of the lower leg; direct link between the knee & ankle

• Muscle attachments at bony landmarks: tibial plateau, medial and lateral condyles, tibial tuberosity, medial malleolus

Fibula

Bone of the lower leg that bears little weight

• Muscle attachments at bone landmarks: head of fibula, lateral malleolus

Patella

Sesamoid bone embedded in the quadriceps tendon; stabilizes the anterior knee

• Bony landmarks: apex, medial & lateral facets

Bones of the foot

• Tarsals (7) — talus, calcanceous, navicular, cuboid, cuneiforms (medial, intermediate, lateral)

• Metatarsals (5) — 1st metatarsal sesamoid bones

• Phalanges — proximal, middle, and distal

Arches of the foot

• Lateral longitudinal — pinky toe to heel

• Medial longitudinal — great toe to heel

• Transverse — just proximal to toes

Atypical high arch

Aka pes cavus; excessive supination/inversion or genu varus

Low/flatter arch

Aka pes planus; excessive pronation/eversion or genu valgus

Hallux valgus

Great toe turned laterally toward the other toes (bunion)

Claw toes

Extended MTP, flexed PIP & DIP

Hammer toes

Extended MTP, flexed PIP, & extended DIP

Joints of the LE

Joints of the LE are designed to absorb & withstand compressive forces during weight-bearing activities

• Tibiofemoral (knee) joint

• Patellofemoral joint

• Tibiofibular joint

• Talocrural joint (ankle joint #1)

• Subtalar and transverse tarsal joints (ankle joint #2)

• Intertarsal joints

• Metatarsophalangeal (MTP) joints

• Interphalangeal (IP) joints

Tibiofemoral joint

Knee joint; a biaxial, hinge joint

• Supports the weight of the trunk & upper body

• Movements: flexion/extension and internal/external rotation

• Screw-home mechanisms — “locks” & “unlocks” the knee

Knee rotation (screw-home mechanism)

• “Locks” the knee in closed-pack position for maximal stability; femoral condyles with tibial fossas

  • Tibia rotates laterally and femur rotates medially in full extension

• Reverse movements “unlocks” the knee

  • Requires activation of the popliteus muscle to medially rotate the tibia (and lateral rotation of the femur)

Tibiofemoral joint supporting structures

• Anterior & posterior cruciate ligaments (ACL & PCL) — prevents anterior/posterior translation of the tibia

• Medial & lateral collateral ligaments (MCL & LCL) — prevents medial/lateral translation of the tibia

• Medial & lateral meniscus — cushions & increases surface area

Why are women more susceptible to injuries to the supporting structures of the knee?

Strength programs often lead to muscle imbalance for women, with strong quadriceps muscles and weak hamstrings; also due to anatomical differences (e.g., greater angle from pelvis/hip to knee)

Knee varus

Disruption (injury or laxity) of LCL causes the knee position to be altered in the frontal plane

• Inward angulation of the tibia

• Lateral shift of the knee complex

• Genus varus/varum = bow-leggedness

Knee valgus

Disruption (injury or laxity) of MCL causes the knee position to be altered in the frontal plane

• Outward angulation of the tibia

• Medial shift of the knee complex

• Genus valgus/valgum = knock-kneed

Genu recurvatum

Hyperextension of the knee

Tibial torsion (knee rotation)

Tibia rotates relative to the femur; approximately 20-25° normal

• Improper positioning (sitting) can create more torsion

Medial tibial torsion

Knees anterior & inward; feet lateral → can lead to increased valgus

Lateral tibial torsion

Knees anterior & outward; feet medial → can lead to increased varus

Patellofemoral joint

Gliding articulation between the femur and patella

• Knee flexion causes the patella to glide inferiorly and laterally

• Knee extension causes the patella to glide superiorly and medially

Tibiofemoral joints

Proximal AND distal articulations between the tibia & fibula; very slight movement, contribute primarily to ankle stability

Talocrural joint

Ankle joint #1; articulation between the superior talus and medial & lateral malleoli of the tibia/fibula

• Uniaxial, hinge joint

• Movements = dorsiflexion/plantar flexion

• Closed-pack position = maximal dorsiflexion

Subtalar and transverse tarsal joint

Ankle joint #2; subtalar is between inferior talus & calcaneus and transverse tarsal is between hindfoot & midfoot tarsals

• Movements = inversion/eversion

• Functionally important for navigation of uneven terrain, balance

Intertarsal joints

Articulation between tarsal bones and between tarsals and metatarsals

Metatarsophalangeal (MTP) joints

Ellipsoid joint; allows for flexion/extension and some abduction/adduction

Interphalangeal (IP) joints

Hinge joints; allows for flexion/extension

Plantar fascia

Connects calcaneus to base of toes and supports arches of the foot

• Primary shock absorber during walking/running (weight-bearing)

• Inflammation → plantar fasciitis

Semimembranosus action

Flexion & internal (medial) rotation of the knee; extension & internal rotation (assists) of the hip; tilts pelvis posteriorly

**Hamstring

Semimembranosus origin

Ischial tuberosity

Semimembranosus insertion

Posterior aspect of medial condyle of tibia

Semimembranosus innervation

Sciatic (tibial branch) L4 & L5, S1 & S2

Semitendinosus action

Flexion & internal (medial) rotation of the knee; extension & internal rotation (assists) of the hip; tilts pelvis posteriorly

**Hamstring

Semitendinosus origin

Ischial tuberosity

Semitendinosus insertion

Proximal, medial shaft of the tibia at the per anserinus tendon

Semitendinosus innervation

Sciatic (tibial branch) L4 & L5, S1 & S2

Biceps femoris action

Flexion & external (lateral) rotation of the knee; extension & external rotation (assists) of the hip; tilts pelvis posteriorly

**Hamstring

Biceps femoris origin

Long head: ischial tuberosity

Short head: lateral lip of linea aspera

Biceps femoris insertion

Head of the fibula

Biceps femoris innervation

Long head: Sciatic (tibial branch), L5, S1 to S3

Short head: Sciatic (fibular branch), L5, S1 & S2

Popliteus action

Internal (medial) rotation of the knee (“unlocks” the knee); assists in knee flexion

Popliteus origin

Lateral condyle of the femur

Popliteus insertion

Proximal, posterior aspect of tibia

Popliteus innervation

Tibial L4 & L5, S1

Quadriceps femoris group action

All: Extension of the knee

Rectus femoris: flexion of the hip

**Rectus femoris; vastus medialis, intermedius, & lateralis

Rectus femoris origin

Anterior inferior iliac spine (AIIS)

Vastus medialis origin

Medial lip of linea aspera

Vastus intermedius origin

Anterior & lateral shaft of the femur

Vastus lateralis origin

Lateral lip of linea aspera, gluteal tuberosity, & greater trochanter

Quadriceps femoris group insertion

Tibial tuberosity (via the patella & patellar ligament)

Quadriceps femoris group innervation

Femoral L2 to L4

Tibialis anterior action

Inversion of the foot; dorsiflexion of the ankle

Tibialis anterior origin

Lateral condyle of the tibia; proximal, lateral surface of the tibia; interosseous membrane

Tibialis anterior insertion

Medial cuneiform & base of the 1^st metatarsal

Tibialis anterior innervation

Deep fibular L4 & L5, S1

Extensor hallucis longus action

Extension of the 1^st toe, dorsiflexion of the ankle, inversion of the foot

Extensor hallucis longus innervation

Deep fibular L4 & L5, S1

Extensor digitorum longus action

Extension of the 2^nd through 5^th toes, dorsiflexion of the ankle, eversion of the foot

Extensor digitorum longus innervation

Deep fibular L4 & L5, S1

Gastrocnemius action

Flexion of the knee, plantar flexion of the ankle

Gastrocnemius origin

Condyles of the femur, posterior surfaces

Gastrocnemius insertion

Calcaneus via calcaneal tendon

Gastrocnemius innervation

Tibial S1 & S2