NORMAL ANATOMY Ossification Ossification center 1° vs. 2° Age at ossification Age at fusion Talus head 1° 7 months gestational age 13-15 yo body 2° 7 months gestational age 13-15 yo Calcaneus body 1° 6 months gestational age 13-15 yo tuberosity 2° 9 yo 13-15 yo Navicular 1° 7 months gestational age 13-15 yo Cuboid 1° birtth 13-15 yo Lateral cuneiform 1° 1 yo 13-15 yo Middle cuneiform 1° 4 yo 13-15 yo Medial cuneiform 1° 3 yo 13-15 yo Metatarsals shaft 1° 9 weeks gestational age birth epiphysis 2° 5-8 yo 14-18 yo Phalanges body 1° 10 weeks gestational age 14-18 yo epiphysis 2° 2-3 yo 14-18 yo Osteology & Attachments Superior view Inferior view Medial view Lateral view Columns Medial 1st metatarsal medial cuneiform navicular talus Middle 2nd + 3rd metatarsals middle + lateral cuneiforms navicular talus Lateral 4th + 5th metatarsals cuboid calcaneus Joints Lisfranc divides forefoot + midfoot Chopart divides midfoot + hindfoot RADIOGRAPHIC VIEWS AP view Positioning patient supine knee flexed + foot flat on plate beam aim at base of 3rd metatarsal + 10° cephalad Indications hallux valgus = used to determine angle Critique symmetrical concavity of 1st metatarsal shaft + intermetatarsal spaces alignment of 2nd metatarsal with medial cuneiform superimposition of 2nd-5th metatarsal bases increased with ER (also aids visualization of navicular tuberosity) open tarsometatarsal + navicular-cuneiform + medial-middle cuneiform joints Lateral view Positioning patient lateral decubitus on ipsilateral side foot dorsiflexed 90° beam aim at base of 3rd metatarsal Critique superimposition of metatarsals visualization of talocalcaneal joint Oblique view Positioning patient supine knee flexed + foot IR 45° beam aim at base of 3rd metatarsal Indications cuboid joint space Critique superimposition of base of 1st + 2nd metatarsals no superimposition of base of 3rd-5th metatarsals overrotation leads to superimposition of 5th metatarsal base + 4th metatarsal tuberosity underrotation leads to superimposition of 4th + 5th metatarsal base visualization of 5th metatarsal tuberosity + tarsal sinus open joints around cuboid Tangential view Positioning METHOD PATIENT BEAM Lewis prone toes dorsiflexed + ball of foot perpendicular to plate 1st MTP joint n/a Holly seated vs. supine ankle neutral + toes dorsiflexed 75° 1st MT n/a Causton lateral decubitus on contralateral side knee flexed + foot in lateral position 1st MTP joint 40° cephalad Indications metatarsal heads sesamoid bones = Lewis view preferred over Holly view (Holly view tends to produce more magnification) Critique Lewis/Holly no superimposition of sesamoids + metatarsals Causton slight superimposition of sesamoid bones Weightbearing view Positioning VIEW PATIENT BEAM AP erect on plate base of 3rd MT 10° cephalad Lateral erect with plate between feet base of 3rd MT n/a Indications AP assess integrity of transverse arch lisfranc injury lateral assess integrity of longitudinal arch NORMAL FINDINGS Normal variants accessory navicular enlargement of plantar medial aspect classification type 1 = sesamoid bone in tibialis posterior insertion type 2 = separate accessory bone attached to native navicular via synchondrosis type 3 = complete bony enlargement apophysis of proximal 5th metatarsal oriented longitudinally parallel to the shaft important to differentiate from fracture, which is oriented transversely bipartite medial cuneiform anatomical variant where there are 2 ossification centers may cause medial cuneiform to be larger than normal medial cuneiform "E" sign seen on lateral view CLINICAL PEARLS Ottawa foot rules XRs are indicated if any of the following criteria are met TTP over navicular TTP over base of 5th MT inability to bear weight, i.e. ambulate >4 steps Midfoot stress fractures Type Mechanism of Injury Findings Longitudinal (41%) force through metatarsal heads on plantarflexed foot leads to compression of midfoot between metatarsals and talus • vertical fracture = cuneiforms/navicular Medial (30%) inversion leads to adduction of midfoot on hindfoot • flake fracture = dorsal talus/navvicular, lateral calcaneus, cuboid • dislocation = midfoot, isolated talonavicular, medial swivel (talonavicular joint dislocation + subtalar joint subluxation + intact calcaneocuboid joint) Lateral (17%) lateral force to forefoot leads to cuboid being crushed between 4th/5th metatarsal bases and calcaneus • nutcracker fracture = comminuted cuboid and navicular avulsion • lateral subluxation of talonavicular joint • lateral column collapse = due to comminuted calcaneocuboid joint Plantar (7%) force to plantar foot • avulsion fracture = navicular, talus, anterior process of calcaneus Lisfranc injury Recommended views AP lateral oblique stress may be helpful to show instability when non-weight bearing radiographs are normal and there is high suspicion weight-bearing with comparison view may be necessary to confirm diagnosis Findings five critical radiographic signs that indicate presence of midfoot instability discontinuity of a line drawn from the medial base of the 2nd metatarsal to the medial side of the middle cuneiform seen on AP view diagnostic of Lisfranc injury widening of the interval between the 1st and 2nd ray seen on AP view may see bony fragment (fleck sign) in 1st intermetatarsal space represents avulsion of Lisfranc ligament from base of 2nd metatarsal diagnostic of Lisfranc injury dorsal displacement of the proximal base of the 1st or 2nd metatarsal seen on lateral view medial side of the base of the 4th metatarsal does not line up with medial side of cuboid seen on oblique view disruption of the medial column line (line tangential to the medial aspect of the navicular and the medial cuneiform) seen on oblique view Treatment criteria nonoperative treatment acceptable if no displacement on weight-bearing and stress radiographs and no evidence of bony injury on CT (usually dorsal sprains) certain nonoperative candidates nonambulatory patients presence of serious vascular disease severe peripheral neuropathy instability in only the transverse plane ORIF if any evidence of instability (> 2mm shift) primary arthrodesis of 1st, 2nd, and 3rd TMT joints if purely ligamentous arch injuries delayed treatment chronic deformity midfoot arthrodesis if destabilization of the midfoot's architecture with progressive arch collapse and forefoot abduction chronic Lisfranc injuries that have led to advanced midfoot arthrosis and have failed conservative therapy 5th metatarsal base fracture Classification Classification Class Description Images Zone 1(pseudo Jones fx) Proximal tubercle (rarely enters 5th tarsometatarsal joint) Due to long plantar ligament, lateral band of the plantar fascia, or contraction of the peroneus brevis Nonunions uncommon Zone 2(Jones fx) Metaphyseal-diaphyseal junction Involves the 4th-5th metatarsal articulation Vascular watershed area Acute injury Increased risk of nonunion (15-30%) Zone 3 Proximal diaphyseal fracture Distal to the 4th-5th metatarsal articulation Stress fracture in athletes Associated with cavovarus foot deformities or sensory neuropathies Increased risk of nonunion Recommended views AP lateral oblique Treatment criteria nonoperative treatment acceptable if zone 1 zone 2 (Jones fx) in recreational athlete zone 3 intramedullary screw fixation if zone 2 (Jones fx) in elite or competitive athletes zone 3 fx with sclerosis/nonunion or in athletic individual Metatarsal fracture Recommended views AP lateral oblique Treatment criteria nonoperative treatment acceptable if 1st metatarsal non-displaced fractures 2nd-4th (central) metatarsals isolated fractures non-displaced or minimally displaced fractures ORIF if open fractures first metatarsal any displacement central metatarsals sagittal plane deformity more than 10 degrees >4mm translation multiple fractures Tarsal navicular fracture Classification avulsion results from plantarflexion vs. eversion/inversion can involve talonavicular or naviculocuneiform ligaments tuberosity results from eversion with simultaneous contraction of PTT body = Sangeorzan results from axial loading Sangeorzan Classification of Navicular Body Fractures(based on plane of fracture and degree of comminution) Type I Transverse fracture of dorsal fragment that involves < 50% of bone.No associated deformity Type II Oblique fracture, usually from dorsal-lateral to plantar-medial.May have forefoot aDDuction deformity. Type IIII Central or lateral comminution.ABDuction deformity. Recommended views AP lateral oblique best view to see tuberosity fractures Treatment criteria nonoperative treatment acceptable if acute avulsion fractures most tuberosity fractures minimally displaced ype I and II navicular body fractures ORIF if avulsion fractures involving > 25% of articular surface tuberosity fractures with > 5mm diastasis or large intra-articular fragment displaced or intra-articular type I and II navicular body fractures ORIF followed by ex-fix vs. primary fusion if type III navicular body fractures Sesamoid injury Classification medial/tibial sesamoid more common attaches to adductor hallucis lateral/fibular sesamoid attaches to abductor hallucis Recommended views AP lateral tangential lewis causton Findings proximal migration of sesamoids be suspicious of intrinsic minus hallux Treatment criteria nonoperative treatment acceptable in most cases partial or total sesamoidectomy if nonoperative management fails after 3-12 months autologous bone grafting if nonunion or fracture dorsiflexion osteotomy if plantarflexed first ray with sesamoid injury