Lecture 9 Flashcards
Posterior tibial tendon dysfunction (insufficiency)
- Most common cause of adult acquired pes planus
- More common in females over 40
- Caused by degeneration of the tibialis posterior tendong
Tibialis posterior
- Primary foot inverter
- Primary dynamic stabilizer of the medial longitudinal
Tibialis posterior contraction
- Elevates the arch and causes the midfoot/hindfoot to become more rigid
- Increases efficiency of triceps surae during gait
Tibialis posterior pathway
- Passes in groove on posterior aspect of medial malleolus
- Poor blood supply in this area
- Tendon splits into 3 components
3 components of tibialis posterior tendon
- Main
- Plantar
- Recurrent
Main component of tibialis posterior tendon
- Inserts on navicular tuberosity and medial cuneiform
Plantar component of tibialis posterior tendon
- Inserts on the base of the 2nd-4th metatarsal, intermediate and lateral cuneiforms, cuboid
Recurrent component of tibialis posterior tendon
- Inserts on sustentaculum tali
Degeneration of tibialis posterior may result from
- Acute/traumatic rupture (less common)
- Tendinosis from repeated microtrauma (more common)
Degeneration of TP leads to
- Loss of medial longitudinal arch
Overstress of TP leads to
- Spring ligament failure (most important static stabilizer)
- Longer term can cause failure of deltoid
Long term TP degeneration can cause
- Long term can cause collapse of the medial longitudinal arch
- Joint degeneration
TP degeneration presentation
- 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
2 trabecular orientations from tibia
- Posteriorly through talar body to the posterior calcaneus
- Anteriorly through talar body through the neck and head of talus
Trabeculae through talar body are oriented vertically
- Through the neck/head transition to horizontal
Metatarsal bases, cuneiforms, cuboid, navicular trabeculae are oriented
- Horizontally and transversely
Calcaneus trabeculae are oriented
- 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)
Neutral triangle of calcaneus
- Visible area that contains fewer trabeculae
- Inferior to lateral talar process
- Reflects weight distribution
- Cortical bone superior to the neutral triangle is dense
Neutral triangle of calcaneus is susceptible to
- Fracture from axial loading
Bohler’s angle
- Angle between 2 lines tangential to anterior and posterior calcaneus
- Normal is 20-40⁰
- < 20⁰ could indicate calcaneal fracture
Bohler’s angle boundaries
- Anterior process to highest part of posterior facet
- Superior aspect of posterior calcaneal tuberosity to highest part of posterior facet
Angle of Gissane (“critical angle”)
- Formed by the slopes of the calcaneal superior articular surface
- Normal is 120-145⁰ (different normal)
- > 145 could indicate fracture
Calcaneus intra-articular fracture (through posterior facet)
- 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
Hallux sesamoid bones are paired ossicles located
- Within the tendon of the medial and lateral heads of the FHB
Medial (tibial) sesamoid is usually larger than lateral (fibular)
- Greater weight bearing
- More commonly injuried
Hallux sesamoid bones function
- Fulcrums that increase leverage of flexor hallucis brevis
- Weight bearing structures
Protect metatarsal head and FHL tendon
Hallux sesamoid bones begin ossification between years
- 7 and 8
Multipartite hallux sesamoid
- Mostly medial sesamoid
- Normal variant from multiple ossification centers
- Bipartite is most common variant
- When present, common to be bilateral
Hallux abducto valgus (bunion)
- Foot deformity that affects the 1st MTP joint
- Medial deviation of metatarsal (varus) and lateral deviation of hallux (valgus)
Deformity of MTP joint in hallux abducto valgus allows the flexor/extensor tendons to
- Bowstring, exerting a deforming force
- Medial capsule/ligaments become stretched
- Lateral capsule/lig become contracted
Hallux abducto valgus (bunion) characteristics
- Not just a transverse plane deformity
- Met head produces the characteristic prominence
- Less effective Windlass leads to metatarsalgia of lesser digits
- F > M
Weightbearing AP x-rays for hallux abducto valgus
- Intermetatarsal angle
- Hallux abductus angle (1st metatarsophalangeal angle)
- Other x-rays exist
Intermetatarsal angle
- Angle between the lines through the shafts of the 1st and 2nd metatarsals on AP foot x-ray
- Normal is less than 10ᵒ
Hallux abductus angle (1st metatarsophalangeal angle)
- 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
Morton’s neuroma (interdigital neuroma, interdigital neuritis, etc.)
- Compression neuropathy of the common plantar digital nerve
- Not a true neuroma
- F > M
Morton’s neuroma is most commonly located
- Between 3rds and 4th metatarsal (3rd webspace)
Neuropathic pain in the distribution of a common digital nerve (Morton’s neuroma)
- Intermittent pain most commonly on the plantar forefoot, also in plantar toes and dorsal webspace
- Pain free intervals
- Sharp burning pain, sometimes numbness
Morton’s neuroma may be caused by
- Repetitive irritation of the nerve that leads to perineural fibrosis
- This is believed to disrupt the nerves and arteries
Nerve irritation associated with Morton’s neuroma may be caused by
- Compressed or stretched against the deep transverse metatarsal ligament
- Repetitive toe dorsiflexion, tight narrow shoes, tight gastro-soleus complex
Morton’s neuroma presentation
- 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
Squeeze test (used for Morton’s neuroma)
- Squeezing of the metatarsal heads while palpating the interspace may elicit pain
- Also may elicit a click (Mulder’s click) with the pain
Morton’s neuroma dx made clinically
- US or MRI can confirm if needed
Morton’s neuroma conservative treatment
- Change footwear
- Metatarsal padding
- Mobilization/manipulation
- Injections
- Etc.
Surgical treatment for Morton’s neuroma required if
- Conservative treatment fails
- Neurectomy
- Cut through deep transverse metatarsal ligament
Plantar skin thickness
- Thick overall
- Thickest at the heel, lateral plantar margin, met heads
Plantar epidermis
- Keratinzed stratified squamous epithelium
Keratinocyte
- Major cell type of plantar epidermis
Melanocytes
- Not numerous on plantar skin
- Produce little melanin
Langerhan’s cells
- Immunological function
Merkel’s cells
- Mechanorecteptors
Plantar dermis contains
- Fibroblasts
- Collagen
- Nerves
- Arteries & veins
- Lymph vessels
Plantar dermis vasculature
- Nourishes the avascular epidermis
Plantar dermis layers
- More superficial papillary layer of loose connective tissue
- Deeper reticular layer of denser connective tissue
Plantar skin color
- Yellow-golden from carotene in the subcutaneous fat
- Pink color from oxygemoglobin found in the highly vascular plantar dermis
Plantar vs. dorsal skin
- 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)
Cleavage lines (Langer lines)
- Run longitudinal in a proximal to distal orientation
Arterial supply to the plantar skin
- Found within the subdermal plexus
- Vessels to the skin perforate through the deep fascia from deeper branches
Plantar subcutaneous tissue characteristics
- Thin in the arch area
- Fat pads
- Shock absorption, energy dissipation and dispersion
protect from stress generated during locomotion
Fat pads located
- Heel: ~ 2cm thick
- MTP joint (ball of foot)
- Distal phalanges
Heel fat pad
- 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
Fat pad at ball of foot
- 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
Fat pads can undergo atrophy (thinning) or loss of anchorage
- Descreased ability to disperse forces leading to pain
- Heel fat pad atrophy is a common cause of heel pain
Calcaneofibular ligament with anterior talofibular ligament
- Forms 105ᵒ angle
