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Lower Extremity Anatomy II > Lecture 9 > Flashcards

Lecture 9 Flashcards

1
Q

Posterior tibial tendon dysfunction (insufficiency)

A
  • Most common cause of adult acquired pes planus
  • More common in females over 40
  • Caused by degeneration of the tibialis posterior tendong
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2
Q

Tibialis posterior

A
  • Primary foot inverter

- Primary dynamic stabilizer of the medial longitudinal

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3
Q

Tibialis posterior contraction

A
  • Elevates the arch and causes the midfoot/hindfoot to become more rigid
  • Increases efficiency of triceps surae during gait
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4
Q

Tibialis posterior pathway

A
  • Passes in groove on posterior aspect of medial malleolus
  • Poor blood supply in this area
  • Tendon splits into 3 components
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5
Q

3 components of tibialis posterior tendon

A
  • Main
  • Plantar
  • Recurrent
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6
Q

Main component of tibialis posterior tendon

A
  • Inserts on navicular tuberosity and medial cuneiform
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7
Q

Plantar component of tibialis posterior tendon

A
  • Inserts on the base of the 2nd-4th metatarsal, intermediate and lateral cuneiforms, cuboid
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8
Q

Recurrent component of tibialis posterior tendon

A
  • Inserts on sustentaculum tali
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9
Q

Degeneration of tibialis posterior may result from

A
  • Acute/traumatic rupture (less common)

- Tendinosis from repeated microtrauma (more common)

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10
Q

Degeneration of TP leads to

A
  • Loss of medial longitudinal arch
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11
Q

Overstress of TP leads to

A
  • Spring ligament failure (most important static stabilizer)

- Longer term can cause failure of deltoid

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12
Q

Long term TP degeneration can cause

A
  • Long term can cause collapse of the medial longitudinal arch
  • Joint degeneration
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13
Q

TP degeneration presentation

A
  • Pain in the medial hindfoot area (behind medial malleolus and along medial arc)
  • Changes foot appearance (arch height/positioning)
  • Too many toes sign and inability to stand on tip-toes
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14
Q

2 trabecular orientations from tibia

A
  • Posteriorly through talar body to the posterior calcaneus

- Anteriorly through talar body through the neck and head of talus

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15
Q

Trabeculae through talar body are oriented vertically

A
  • Through the neck/head transition to horizontal
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16
Q

Metatarsal bases, cuneiforms, cuboid, navicular trabeculae are oriented

A
  • Horizontally and transversely
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17
Q

Calcaneus trabeculae are oriented

A
  • Along lines of compression and tension
  • Most dense inferior to posterior facet and posterior to calcaneocuboid joint
  • Calcaneus is designed for bipedalism (balance and propulsion)
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18
Q

Neutral triangle of calcaneus

A
  • Visible area that contains fewer trabeculae
  • Inferior to lateral talar process
  • Reflects weight distribution
  • Cortical bone superior to the neutral triangle is dense
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19
Q

Neutral triangle of calcaneus is susceptible to

A
  • Fracture from axial loading
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20
Q

Bohler’s angle

A
  • Angle between 2 lines tangential to anterior and posterior calcaneus
  • Normal is 20-40⁰
  • < 20⁰ could indicate calcaneal fracture
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21
Q

Bohler’s angle boundaries

A
  • Anterior process to highest part of posterior facet

- Superior aspect of posterior calcaneal tuberosity to highest part of posterior facet

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22
Q

Angle of Gissane (“critical angle”)

A
  • Formed by the slopes of the calcaneal superior articular surface
  • Normal is 120-145⁰ (different normal)
  • > 145 could indicate fracture
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23
Q

Calcaneus intra-articular fracture (through posterior facet)

A
  • Intra-articular fracture line passes through neutral triangle
  • These occur due to axial loading (fall from height, MVA)
  • Lateral talar process acts like a wedge
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24
Q

Hallux sesamoid bones are paired ossicles located

A
  • Within the tendon of the medial and lateral heads of the FHB
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25
Q

Medial (tibial) sesamoid is usually larger than lateral (fibular)

A
  • Greater weight bearing

- More commonly injuried

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26
Q

Hallux sesamoid bones function

A
  • Fulcrums that increase leverage of flexor hallucis brevis
  • Weight bearing structures
    Protect metatarsal head and FHL tendon
27
Q

Hallux sesamoid bones begin ossification between years

A
  • 7 and 8
28
Q

Multipartite hallux sesamoid

A
  • Mostly medial sesamoid
  • Normal variant from multiple ossification centers
  • Bipartite is most common variant
  • When present, common to be bilateral
29
Q

Hallux abducto valgus (bunion)

A
  • Foot deformity that affects the 1st MTP joint

- Medial deviation of metatarsal (varus) and lateral deviation of hallux (valgus)

30
Q

Deformity of MTP joint in hallux abducto valgus allows the flexor/extensor tendons to

A
  • Bowstring, exerting a deforming force
  • Medial capsule/ligaments become stretched
  • Lateral capsule/lig become contracted
31
Q

Hallux abducto valgus (bunion) characteristics

A
  • Not just a transverse plane deformity
  • Met head produces the characteristic prominence
  • Less effective Windlass leads to metatarsalgia of lesser digits
  • F > M
32
Q

Weightbearing AP x-rays for hallux abducto valgus

A
  • Intermetatarsal angle
  • Hallux abductus angle (1st metatarsophalangeal angle)
  • Other x-rays exist
33
Q

Intermetatarsal angle

A
  • Angle between the lines through the shafts of the 1st and 2nd metatarsals on AP foot x-ray
  • Normal is less than 10ᵒ
34
Q

Hallux abductus angle (1st metatarsophalangeal angle)

A
  • Angle formed by a longitudinal bisecting line through the 1st met shaft and a longitudinal bisecting line through the proximal phalanx
  • Normal is less than 15⁰
35
Q

Morton’s neuroma (interdigital neuroma, interdigital neuritis, etc.)

A
  • Compression neuropathy of the common plantar digital nerve
  • Not a true neuroma
  • F > M
36
Q

Morton’s neuroma is most commonly located

A
  • Between 3rds and 4th metatarsal (3rd webspace)
37
Q

Neuropathic pain in the distribution of a common digital nerve (Morton’s neuroma)

A
  • Intermittent pain most commonly on the plantar forefoot, also in plantar toes and dorsal webspace
  • Pain free intervals
  • Sharp burning pain, sometimes numbness
38
Q

Morton’s neuroma may be caused by

A
  • Repetitive irritation of the nerve that leads to perineural fibrosis
  • This is believed to disrupt the nerves and arteries
39
Q

Nerve irritation associated with Morton’s neuroma may be caused by

A
  • Compressed or stretched against the deep transverse metatarsal ligament
  • Repetitive toe dorsiflexion, tight narrow shoes, tight gastro-soleus complex
40
Q

Morton’s neuroma presentation

A
  • Patients describe abnormal forefoot sensations (burning or an ache)
  • Feels like they are walking on a pebble
  • Sensory abnormalities in affected nerve distribution
  • Pain with passive/active toe dorsiflexion
41
Q

Squeeze test (used for Morton’s neuroma)

A
  • Squeezing of the metatarsal heads while palpating the interspace may elicit pain
  • Also may elicit a click (Mulder’s click) with the pain
42
Q

Morton’s neuroma dx made clinically

A
  • US or MRI can confirm if needed
43
Q

Morton’s neuroma conservative treatment

A
  • Change footwear
  • Metatarsal padding
  • Mobilization/manipulation
  • Injections
  • Etc.
44
Q

Surgical treatment for Morton’s neuroma required if

A
  • Conservative treatment fails
  • Neurectomy
  • Cut through deep transverse metatarsal ligament
45
Q

Plantar skin thickness

A
  • Thick overall

- Thickest at the heel, lateral plantar margin, met heads

46
Q

Plantar epidermis

A
  • Keratinzed stratified squamous epithelium
47
Q

Keratinocyte

A
  • Major cell type of plantar epidermis
48
Q

Melanocytes

A
  • Not numerous on plantar skin

- Produce little melanin

49
Q

Langerhan’s cells

A
  • Immunological function
50
Q

Merkel’s cells

A
  • Mechanorecteptors
51
Q

Plantar dermis contains

A
  • Fibroblasts
  • Collagen
  • Nerves
  • Arteries & veins
  • Lymph vessels
52
Q

Plantar dermis vasculature

A
  • Nourishes the avascular epidermis
53
Q

Plantar dermis layers

A
  • More superficial papillary layer of loose connective tissue
  • Deeper reticular layer of denser connective tissue
54
Q

Plantar skin color

A
  • Yellow-golden from carotene in the subcutaneous fat

- Pink color from oxygemoglobin found in the highly vascular plantar dermis

55
Q

Plantar vs. dorsal skin

A
  • More fixed than dorsal (dorsal is more mobile)
  • Dorsal doesn’t require as big as an incision
  • Plantar is more resistant to abrasion
  • Plantar lacks hair follicles and sebaceous glands
  • Plantar has large amounts of eccrine sweat glands
  • Plantar has numerous flexion creases
  • Cleavage lines (Langer lines)
56
Q

Cleavage lines (Langer lines)

A
  • Run longitudinal in a proximal to distal orientation
57
Q

Arterial supply to the plantar skin

A
  • Found within the subdermal plexus

- Vessels to the skin perforate through the deep fascia from deeper branches

58
Q

Plantar subcutaneous tissue characteristics

A
  • Thin in the arch area
  • Fat pads
  • Shock absorption, energy dissipation and dispersion
    protect from stress generated during locomotion
59
Q

Fat pads located

A
  • Heel: ~ 2cm thick
  • MTP joint (ball of foot)
  • Distal phalanges
60
Q

Heel fat pad

A
  • Specialized adipose-based structure formed by fibrous septa and connective tissue
  • Creates chambers that retain adipose tissue
  • Globules of fat encapsulated by fibroelastic strands of tissue
61
Q

Fat pad at ball of foot

A
  • Subcutaneous tissue at the ball of the foot is maintained by a system of intersecting ligaments and bands
  • Also provide protection and cushion to neurovascular structures between metatarsals
62
Q

Fat pads can undergo atrophy (thinning) or loss of anchorage

A
  • Descreased ability to disperse forces leading to pain

- Heel fat pad atrophy is a common cause of heel pain

63
Q

Calcaneofibular ligament with anterior talofibular ligament

A
  • Forms 105ᵒ angle

Lower Extremity Anatomy II (9 decks)

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