IMAGING OF PEDIATRIC SKELETAL INJURY: WHAT RADIOLOGISTS SHOULD KNOW Thariqah Salamah Musculoskeletal Division, Department of Radiology Faculty of Medicine Universitas Indonesia Dr Cipto Mangunkusumo General Hospital Universitas Indonesia Hospital Introduction • Increasing participation in sports causing increased trauma in pediatric & adolescent population • Growth cartilage of physis adjacent to apophysis or epiphysis is the weakest structure of children & adolescent MSK System, while muscles, tendons, and ligaments are the strongest • Traumatic mechanisms causing muscle strains in adults can cause serious injuries to growth center in children • Distraction from chronic & repetitive musculotendinous pulls without sufficient recovery time leads to overuse injury of apophysis (apophysitis) • Untreated physeal injury causing severe morbidity and complication such as growth arrest, so early diagnosis is needed British Medical Bulletin, 2016, 120:139–159 AJR:196, March 2011 ANATOMY & PATHOPHYSIOLOGY RadioGraphics 2017; 37:1791–1812 RadioGraphics 2014; 34:449–471 • Pressure epiphysis: longitudinal growth & circumferential remodelling of long bones • Traction epiphysis (apophysis): tendon & ligament attachments Maturation & Epiphysiodesis • Distal femur: centripetal • Proximal tibia: posterior to anterior • Distal tibia: central to medial & lateral RadioGraphics 2017; 37:1791–1812 •Sports Health, 2014; 7(2): 142-153 Widening, haziness, sclerosis, irregularity, periphyseal osteopenia Extraarticular, Overuse spectrum Fracture line extending to metaphysis Extraarticular Fracture line extending to epiphysis Intraarticular SALTER HARRIS CLASSIFICATION Fracture line extending from epiphysis, crossing physis to metaphysis Intraarticular Physeal Compression fracture or crush injury Extraarticular, overuse spectrum Pathophysiology of Apophyseal Injury AJR:196, March 2011 Apophyseal Lesion • Acute apophyseal avulsion acute avulsion fracture of apophysis caused by strong muscular contraction • Traumatic apophysitis chronic inflammation of apophysis caused by strong repetitive contraction of a muscle attached to apophysis that generate submaximal loading AJR:196, March 2011 Modality Radiography CT Scan MRI Physeal Injury 1st imaging modality Detailed physeal analysis More detailed complication evaluation Direct noninvasive evaluation method for cartilage Detection of complication Apophyseal Injury Indicated in atypical cases to exclude other pathologies RADIOGRAPHY Physeal Injury • 1st imaging modality • Follow up: fracture healing, malalignment, growth disturbance • Radiolucent hyaline cartilage • Secondary signs: physeal widening, epiphyseal displacement, periphyseal osteopenia, bluring of epiphyseal & metaphyseal surface, fragmentation Apophyseal Injury • Nonspecific, inconsistent • Normal apophysis or mild irregularity & fragmentation of the apophyseal margin • Osteoporotic patches, sclerosis, mild widening of involved apophysis AJR:196, March 2011 CT SCAN Physeal Injury • Cross sectional modality for detailed physeal analysis • Extent & position of intraarticular fracture fragments • More accurate evaluation of osseous physeal bar location & extension • Remember radiation protection principles Apophyseal Injury • Epiphyseal widening • Irregularity and fragmentation of epiphyseal margin MRI MR feature of physis depends on water & collagen content T1WI Intermediate signal intensity in the epiphyseal cartilage Low signal intensity of zone of provisional calcification Intermediate weighted Intermediate signal intensity of epiphyseal cartilage High signal intensity of physis GRE High signal intensity in all form of cartilage Low signal intensity of bone RadioGraphics 2014; 34:449–471 Physeal Injury • Can demonstrate subtle physeal widening & irregularity, assess location, morphology & precise size of physeal injury • Evaluation of fibrous & osseous bar • Extension of physeal cartilage to metaphysis (cartilage intrusion) •Sports Health, 2014; 7(2): 142-153 Apophyseal Injury • Enlargement or widening of apophysis, conservation of original apophyseal shape • Increased signal intensity on water sensitive sequences in apophysis, subjacent bone marrow, adjacent muscle & fibrous periapophyseal structures (tendon, ligament, capsule, bursae) AJR:196, March 2011 COMPLICATIONS OF PHYSEAL INJURY Physeal Bar Physeal Bar Physeal Bar Harris Growth arrest line Harris Growth arrest line Soft tissue interposition Harris Growth arrest line Soft tissue interposition Harris Growth arrest line Physeal Bar RadioGraphics 2017; 37:1791–1812 Physeal Bar • Osseous or fibrous • Continuing overuse after acute physeal trauma, poor reduction of fracture, extension of fracture line into bony component of epiphysis • Epiphyseal undulation location such as central of distal femur, periphery of proximal tibia • Central premature closure of physeal plate: length discrepancy without angular deformity • Eccentric premature closure of physeal plate: angular deformity Harris Growth Arrest Line • Inconsistency of bone growth • Parallel to physeal plate • Absence of a Harris growth arrest line in the injured extremity may indicate complete cessation of growth • Decreasing distance between the growth arrest line and the physis suggests growth deceleration • A partial growth disturbance may manifest itself with progressive malalignment or with obliquely oriented/ tethered Harris growth arrest lines Soft Tissue Physeal Interposition • Uncommon • Indication for open reduction • Periosteum is most common trapped material with higher risk for bone bridge formation • Persistent > 3 mm physeal widening on post reduction radiographs RadioGraphics 2016; 36:1807–1827 Growth Disturbance • Longitudinal or angular growth disturbance • Depends on grading & area of trauma, chronological & skeletal age, projection of growth • Distal end of long bone is more prone to growth disturbance compared to proximal end RadioGraphics 2017; 37:1791–1812 PATTERN OF PEDIATRIC PHYSEAL AND APOPHYSEAL TRAUMA Gymnast Wrist RadioGraphics 2016; 36:1672–1687 Widening of distal radius physis, irregular metaphyseal border, metaphyseal sclerosis RadioGraphics 2014; 34:472–490 Widening & irregularity of distal radial physis, Metaphyseal intrusion associated with focal failure of physeal cartilage ossification Little Leaguer’s Shoulder • Proximal humeral physeal trauma • Repetitive stress from traction / rotation • 11-16 yo • Physeal widening and thickening • Physeal hyperintensity on fluid sensitive MR sequences RadioGraphics 2016; 36:1672–1687 Tillaux & Triplane Transitional Fracture • Transitional: within 18 mo of physeal closure (14-16 yo) • Lateral aspect of distal tibia closes last, more susceptible to injury • Juvenile tillaux fracture: epiphysis only. Triplane fracture: epiphysis-metaphysis • AP, mortise, lateral projection in conjuction with CT • Report type of fracture, plane of fracture, distance of displacement/distraction RadioGraphics 2016; 36:1807–1827 INFERIOR PATELLAR POLE APOPHYSITIS (SINDING-LARSEN-JOHANSSON SYNDROME) Fragmentation of inferior patellar pole with surrounding soft tissue edema Rev Chil Radiol 2016; 22(3): 121-132 Fragmentation and edema of inferior patellar pole with edema of proximal patellar tendon AJR:196, March 2011 Proximal Tibial Tubercle Apophysitis (Osgood-Schlatter Disease) Fragmentation of tibial tuberosity with soft tissue swelling at the projection of patellar tendon Tibial tuberosity prominence and edema. Edema of distal patellar tendon and Hoffa’s fat pad . AJR:196, March 2011 Calcaneal Apophysitis (Sever’s Disease) Normal calcaneal apophysis on radiograph Edema and widening of calcaneal apophysis on MRI AJR:196, March 2011 Traction Apophysitis of 5th Metatarsal Base (Iselin’s disease) Child with lateral foot pain. Slightly irregular 5th metatarsal base apophysis obliquely oriented to 5th metatarsal base with surrounding soft tissue swelling PITFALLS Developmental Normal Variants Focal Periphyseal Edema & Focal Physeal Widening • Focal periphyseal edema is asymptomatic &inconsequential. Might be physiologic response to physeal closure • Focal physeal widening also called physeal stress injury. T2 hyperintense tongue shaped physeal widening. Warranted cessation of causal sport activities Physeal Bar • Detected on MRI as early as 2 mo after trauma, usually 1 year • Describe size, location, partial/complete bar • Radiography, CT: Osseous bridge across physis • MRI: Linear structure isointense to bone extending across the physis TAKE HOME MESSAGES • Early recognition of physeal injury is crucial to prevent severe morbidity & growth sequele • Radiography, CT, & MRI are the most commonly used imaging modalities • MRI is the best modality for physeal evaluation • Interpretation needs knowledge of epiphysiodesis pattern, pitfalls, & complications
