Lecture 10 Flashcards
Talus primary ossification center
- Center of talar body
- Appears by 6-7th fetal month
Talus secondary ossification center
- Not always present
- Posterior process
- Os Trigonum results if it does not fuse
Calcaneus ossification
- Consistently has 2 ossification centers
Calcaneus primary ossification center
- Center of calcaneus
- Appears 4-6th fetal month
Calcaneus secondary ossification center
- Calcaneal apophysis
- Contributes to calcaneal tuberosity and posterior surface
- Appears around age 6-8
- Fuses between 14-18
Cuboid ossification
- Single primary center
- Usually present at birth (9th month)
Navicular ossification
- Last foot bone to begin ossifiying
Navicular primary ossification center
- Appears at the center around age 3
Navicular secondary ossification center
- Not always present
- Forms medial bone
- Results in bipartite navicular if present and fails to fuse
Medial cuneiform primary ossification center
- Appears at the center around age 2
Medial cuneiform secondary ossification center
- Plantar in location
- Not always present
Intermediate cuneiform primary ossification center
- Appears at the center around age 3
Lateral cuneiform primary ossification center
- Appears at the center around age 1
1st metatarsal ossification
- 1⁰: appears in the shaft during 10th intrauterine week
- 2⁰: appears in the base around age 3 (proximal growth plate)
- Fuses ~ 18 years of age
2nd, 3rd, and 4th metatarsal ossification
- 1⁰: appears in the shaft during 9th intrauterine week
- 2⁰: appears at the head between 3 and 4 years of age (distal growth plate)
- Fuses ~ 18
5th metatarsal ossification
- 1⁰: appears in the shaft during the 10th intrauterine week
- 2⁰ : appears at the head between 3 and 4 years of age (distal growth plate)
- Fuses ~ 18
5th metatarsal secondary ossification
- Can be another 2⁰ in the styloid process
- Lack of fusion results in an os Vesalianum within the fibularis brevis tendon
Phalanges ossification
- Considered long bongs
- Develop by endochondral ossification
- Except for tufts of the distal phalanges (intramembranous ossification)
Phalanges primary ossification center
- Appears in the shaft of distal (9-12 intrauterine week)
- Proximal (11th – 15th intrauterine week)
- Middle (after 15th intrauterine week)
Phalanges secondary ossification center
- Appear in the base between ages 2-8 (age 3 is average)
- Fuse by age 18
1st MTPJ Sesamoid bones
- Begin ossification between years 7-8
- Medial sesamoid is usually larger than the lateral sesamoid of the 1st MTP joint
Tarsal bones present at birth
- Talus
- Cuboid
- Calcaneus
Tarsal bones present by 1 year of age
- Talus
- Cuboid
- Calcaneus
- Lateral cuneiform
Tarsal bones present by 2 years of age
- Talus
- Cuboid
- Calcaneus
- Lateral cuneiform
- Medial cuneiform
Tarsal bones present by 3 years of age
- Talus
- Cuboid
- Calcaneus
- Lateral cuneiform
- Medial cuneiform
- Intermediate cuneiform
- Navicular
Accessory ossicles are found within
- Tendons
- Joint capsules
- High pressure areas
Accessory ossicles
- Easily mistaken for fractures
- Some are derived from failure of union of 2ᵒ ossification center
- Usually asymptomatic
- Can become symptomatic
Symptomatic accessory ossicles usually invovle
- Fracture
- Dislocation
- Degeneration
- AVN
- Impingement
Accessory navicular (4-21%)
- Lack of fusion of a secondary ossification center of navicular tuberosity (type I and II)
Type I accessory navicular (os tibiale externum, os navicular secundum)
- Within posterior tibialis tendon at the insertion
- Proximal to navicular tuberosity
Type II accessory navicular (prehallux, bifurcate hallux)
- Connected to navicular tuberosity by cartilaginous bridge
- Often bilateral
- Large, located near navicular tuberosity
Type III accessory navicular
- Prominent navicular tuberosity (cornuate navicular
- A fused type II
Os supranaviculare (1-3.5%)
- Also called Piries bone, os talonavicular dorsale
- Located proximal dorsal aspect of navicular
Os Peroneum (20-70%)
- Located within the tendon of peroneus longus (lateral to fibular sulcus/groove of cuboid, lateral to cuboid)
- Commonly bilateral
- Can cause degeneration of peroneus longus tendon
- Can form joint with cuboid tuberosity
Os Vesalinum (0.1-1%)
- Found within tendon of peroneus brevis at insertion on styloid process of 5th metatarsal
- Unfused secondary ossification center
- Seen on AP and medial oblique xray
Os Trigonum (7-25%)
- Located posterior to talus
- Lack of fusion of secondary ossification center of the lateral tubercle
- Can cause posterior impingement and tenosynovitis of FHL
Os sustentaculi (0.3-1%)
- Located on posterior aspect of sustentaculum tali
Os calcaneum secundarius (~1%)
- Located at anterior process of calcaneus
- Can mimic bifurcate ligament avulsion fracture
Os subtibiale (rare)
- Near posterior colliculus of medial malleolus
Os Supratalare/os astraglus (~1%)
- Located dorsal to neck of talus
Os Intercuneiforme (1-2%)
- Located between cuneiforms dorsally
- Usually between medial and intermediate
Os Intermetatarseum (~4-5%)
- Between bases of metatarsals
- Most common between 1st and 2nd; 4th and 5th
- Can form a synovial joint with neighboring bone or fuse to them
Accessory sesamoid bones
- Most common at the IPJ of the hallux and the MTPJ of the 5th digit
Ankle joint innervation
- Deep fibular nerve
- Accessory deep fibular when present
- Tibial nerve
- Saphenous nerve
- Sural nerve
Subtalar joint innervation
- Tibial nerve
- Lateral dorsal cutaneous (sural)
- Medial plantar
- Deep fibular
- Accessory deep fibular when present
Talocalcaneonavicular joint innervation
- Medial plantar
- Deep fibular
Calcaneoucuboid joint innervation
- Lateral plantar
- Sural
- Deep fibular
- Accessory deep fibular when present
Cuneocuboid and cuboidonavicular joint innervation
- Lateral plantar
- Deep fibular
1st and 2nd cuneonavicular, medial intercuneiform, cuneometatarsal 1-2 innervation
- Deep fibular
- Plantar side: Medial plantar
3rd cuneonavicular, 3rd cuneometatatarsal, lateral intercuneiform innervation
- Deep fibular
- Lateral plantar
Cuboid, metatarsal 4,5 innervation
- Sural
- Superficial fibular
- LPN
Dorsal innervation of intermetatarsal joint
- Deep fibular nerve
Plantar innervation of intermetatarsal joint
- Deep branch of lateral plantar (between 2nd/3rd and 3rd/4th met bases)
- Superficial branch of LPN (between 4th/5th met base)
MTP joint and IP joint innervation
- Branches from the dorsal and plantar digital nerves that pass by the joint
- 2-4th MTP joints can also receive innervation from deep branch of LPN
Talocrural in OPEN kinetic chain
- Roll and slide in opposite directions
- Calcaneus and foot moving on talus
Talocrural joint in CLOSED kinetic chain
- Roll and slide of mortise on the trochlea
- Talus, forefoot is fixed, calcaneus is mostly fixed
Pronation in OPEN kinetic chain involves
- Dorsiflexion
- Abduction
- Eversion
Supination in OPEN kinetic chain involves
- Plantarflexion
- Adduction
- Inversion
Pronation in CLOSED kinetic chain involves
- Plantarflexion (talus)
- Adduction (talus)
- Eversion (calcaneus)
- Tibia internal rotation
Supination in CLOSED kinetic chain involves
- Dorsiflexion (talus)
- Abduction (talus)
- Inversion (calcaneus)
- Tibia external rotation
