Foot and ankle injuries John MacKenzie, MD Associate Professor in Residence Chief of Radiology at Mission Bay Medical Center Section Chief, Pediatric Radiology Disclosure Research grant from General Electric Healthcare Pediatric PET MRI T1 fat sat post gad FDG PET Take-home message Centers of growth are the key to unlocking the pediatric ankle. Take-home message Centers of growth are the key to unlocking the pediatric ankle. Take-home message If you want to be a BAD -SS pediatric radiologist… Focus on the growth centers. Outline 1. Growth centers 2. Pediatric foot/ankle lesions Challenge: We have to know a lot! Because of the overlap with adult pathology we have to be comfortable identifying a broad spectrum of disorders. Skeletal Anatomy Kids Adults vs. Muscles Physis Bone marrow Epiphysis Bone cortex Cartilage Apophysis Ligaments Tendons 1. Growth centers Ankle Growth Centers Hard to see on x-ray Epiphysis Secondary ossification center Apophysis Ankle Growth Centers Epiphyseal cartilage 5 year-old Ankle Growth Centers Secondary ossification center 5 year-old Ankle Growth Centers Apophyseal cartilage 5 year-old Ankle Growth Centers Apophyseal cartilage Tendon/ligament attachment Ankle Growth Centers Physis: weak link bone cartilage bone weak link : Ankle Growth Centers Ankle Physis Ankle Growth Centers bone Weak links cartilage Transitions are weak link. bone Chondro-osseous junctions Ankle Growth Centers bone Weak links San Andreas fault cartilage bone Ankle Growth Centers Weak links San Andreas fault 2. Pediatric foot/ankle lesions Pediatric ankle lesions – Two flavors 1. Pediatric type 2. Adult Pediatric ankle lesions – Two flavors 1. Pediatric type 2. Adult Spectrum and overlap of injuries Growth center at risk Intensity of play Growth plate closes plate Growth 10 15 20 Age (years) Spectrum and overlap of injuries Injuries to growth centers Adult-type injuries Growth center at risk Intensity of play Growth plate closes plate Growth 10 15 20 Age (years) Spectrum and overlap of injuries Injuries to growth centers Adult-type injuries Growth center at risk Growth plate closes plate Growth Apophyseal Achilles avulsion tear 10 15 20 Age (years) Spectrum and overlap of injuries Injuries to growth centers Adult-type injuries Growth center at risk ATFL tear Growth plate closes plate Growth 10 15 20 Age (years) Physeal injury Tri-plane fracture Tri-plane fracture C S Older adolescents H 18 month window prior to growth plate closure Sagittal, Horizontal, and Coronal planes Asymmetric closure of growth plate axial coronal Closure at 12-15 years Triplane fracture occurs during an 18 month window. Tillaux fracture – Also a transitional fx Tri-plane fracture – MIND the GAP No gap Intact cartilage 3D SPGRE Tri-plane fracture – MIND the GAP > 2 mm gap ORIF Triplane fracture – Classificaiton 2 part 3 part m e Anteromedial at Kump bump m = metaphysis e = epiphysis Triplane fracture – Treatment Closed reduction if gap ≤ 2 mm Usually ORIF m e m = metaphysis e = epiphysis Salter-Harris fracture classification Throw some SALT on it. I II III IV V Same Above Low Through Why do we care about Salter-Harris? Bone bar formation Limb-length discrepancy Angular deformity Normal maturation vs. bone bar after fracture of the distal tibia Bone bar vs. expected fusion Age of fusion of tibial physis Girls: 12-14 years Boys: 14-18 years Fusion begins at the anteromedial undulation (Kump’s bump) 3D Cartilage MRI for Bone Bar Mapping 3D GRE 3D Cartilage MRI for Bone Bar Mapping Intact physis Bone bars (yellow) Achilles Maximum intensity 3D GRE projection MIP image helps direct treatment Resection Intact physis <50% bone bridge >2 yrs growth potential Physeal fusion Osteotomy Bone bars (yellow) Cartilage mapping – size matters Large Small Intact physis Bone bars Achilles (yellow) Bone bar (black) Bones and articular surface Osteochondritis dissecans Osteochondritis dissecans Osteochondritis dissecans Unstable Instability = Fluid under fragment Cartilage disruption Intraarticular bodies Osteochondritis dissecans Stable Unstable T1 fs (MR arthrogram) Medial mid foot pain Buckle fracture Buckle fracture 5 types of fractures in children 1. Epiphyseal-metaphyseal (Salter-Harris) 2. Buckle (torus) fractures 3. Hairline fractures 4. Plastic bending fractures 5. Avulsion fractures Buckle fracture - Subtle and often overlooked - Axial loading on a plantar flexed foot - Heal completely - Explain child’s pain Buckle fracture 1-10 years-old Associated with ligamentous injury at the tarsometarsal joint Thus, considered a pediatric variant of the Lisfranc injury. Johnson, GF. Bunk bed fracture. AJR 1981 Entrapment Impingement syndromes Anterior Posterior (os trigonium) Medial Lateral Limited ROM or deinnervation Related to bone or soft tissue abnormalities. Foot pain & paresthesias Edematous posterior tibial nerve Tarsal tunnel - Medial impingement from ganglion Entrapment of posterior tibial nerve (or branch) Contents of tarsal tunnel Contents of tarsal tunnel Contents of tarsal tunnel Retinaculum Flexor tendons Posterior tibial nerve & branches Tarsal sinus Normal Sinus tarsi syndrome Fibrosis Normal Fat is replaced Sinus tarsi syndrome Sinus tarsi syndrome Talus Calcaneus Contents of the tarsal sinus and canal Talus Roots of extensor retinaculum Cervical & interosseous ligaments Calcaneus Vessels & nerves Sinus tarsi syndrome Usually follows inversion injury Pain lateral aspect ankle Sensation of hindfoot instability Pain relieved injection sinus Sinus tarsi syndrome Causes Traumatic 70% Misc 30% ganglion cysts Inflammation (JIA) PVNS Pes cavus / planus Posterior pain (left ankle) Kager’s fat Accessory soleus muscle Kager’s fat Pain and swelling after exercise (normal) Soft tissue mass replacing Kager’s fat Low flexor hallucis longus Any tendon + muscle can accessorize Ballet dancer with ankle pain os trigonum syndrome Fracture passes through subtalar joint Traction / chronic repetitive injuries Impingement – Os trigonum edema 10 year-old Os trigonum – Edema suggests irritation Asymptomatic Os trigonum mechanism – Compression vs. traction Os trigonum mechanism – Compression vs. traction Traction: Os trigonum apophysitis Ligaments apply traction Post. talofibular, post. tibiofibular, or interosseous ligaments may tug on ossicle. Traction: Os trigonum apophysitis Concurrent flexor hallucis longus tendonitis 2ndary ossification center fuses w/ talar body ~ age 12 Medal pain Tibialis posterior Painful os navicular Accessory navicular Bone marrow edema Imaging findings of another symptomatic skeletal variant Runner with pain Case courtesy of Peter J. Strouse, U Michigan Traction apophysitis Pain and swelling Chronic / repetitive trauma Relief in 1-6 months with rest Case courtesy of Peter J. Strouse, U Michigan Apophysis – normal fusion 8 years-old 10 years-old Same child over 2 years of skeletal development. 14 year old ballet dancer STIR T1 Severs disease Chronic repetitive injury Focal edema post. calcaneus Resolves with rest Severs disease DEBATE apophysitis stress reaction Ogden JA J Ped Ortho 2004 Severs disease DEBATE apophysitis stress reaction stress fracture Ogden JA J Ped Ortho 2004 Foot Base of fifth fracture types Normal apophysis Pseudo Jones fx Jones fx Bone marrow The bane of a pediatric radiologist! High-signal T2 weighted changes in bone marrow (normal) Similar appearance at contralateral side 1-15 years Differential diagnosis red marrow mechanics infarcts Shabshin N, et al. Ped Rad 2008 Laor and Jaramillo. Radiology. 2009 ??? Normal maturation vs. bone bar after fracture of the distal tibia Focal periphyseal edema (FOPE) May be painful Tends to occur around same time of skeletal maturation Sign of pending physeal closure? Normal maturation vs. bone bar after fracture of the distal tibia Zbojniewicz and Laor. AJR 2011 Chronic regional pain syndrome Chronic pain after trauma INTENSE marrow increase in T2 & STIR MRI may exclude other complications Sequela of trauma Insufficiency fractures Disuse bone demineralization and muscle Tendon tears and tendon atrophy Take-home message Centers of growth are the key to unlocking the pediatric ankle. Summary - Spectrum and overlap of injuries Injuries to growth centers Adult-type injuries Growth center at risk Intensity of play Growth plate closes plate Growth 10 15 20 Age (years) Summary – Unique Pediatric Anatomy Transitions are weak links. San Andreas fault Summary – Bone marrow alternations Normal Pre-physeal closure Trauma Summary – Bone marrow alternations Normal Pre-physeal closure Trauma Summary – Bone marrow alternations Normal Pre-physeal closure Trauma Thank you Normal Pre-physeal closure Trauma .