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Updated: Oct 26 2020

Pediatric Hip Trauma Radiographic Evaluation

 Normal Anatomy
 Ossification of the hip
 Osteology & Attachments
  • Anterior view
  • Posterior view
  • Lateral view
  • Superior view
 Radiographic Views
 AP view
  • Positioning
    • patient
      • supine
      • leg IR 15-20°
    • beam
      • aim between ASIS + symphysis pubis
  • Critique
    • no rotation of pelvis
      • superimposition of ischial spine with pelvic brim
      • open obturator foramen
    • no visualization of lesser trochanters
      • too much external rotation of leg leads to increased visualization of lesser trochanter
      • superimposition of ischial spine with pelvic brim
 Lateral view
  • Positioning 
Rolled lateral
supine hip abducted 45° + knee flexed 90° mid-femoral neck

Horizontal ray/cross-table
supine contralateral hip flexed 90° + ipsilateral hip IR 15-20° femoral head
45° cephalad
Modified Dunn supine hip flexed 45° + abducted 20° 2.5 cm above pubic symphysis n/a
Frog leg
supine hip abducted 45° + knee flexed 30-40° 2.5 cm above pubic symphysis n/a
Lowenstein semi-lateral 45° on ipsilateral side hip flexed 90° mid-femoral neck 20-25° cephalad
False profile
erect hip flexed 90°pelvis ER 65° toward ipsilateral side femoral head
  • Indications
    • horizontal ray/cross-table
      • useful in trauma patients where positioning is limited by pain
    • modified dunn
      • better demonstrates relationship of femoral head with acetabulum
      • useful for confirming femoroacetabular impingement (alpha angle)
    • frog leg
      • better demonstrates shape of femoral head + head/neck transition
      • useful for confirming epiphysiolysis, SCFE, Perthes disease
    • lowenstein
      • useful as alternative to frog leg view, as it is technically easier to obtain
    • false profile
      • provides true lateral projection of femoral head/neck and oblique view of acetabulum
      • demonstrates anterior acetabular coverage of femoral head
      • useful for determining anterior center-edge angle
  • Critique 
    • horizontal ray/cross-table
      • visualization of greater trochanter
        • increased cephalad angle leads to increased visualization of greater trochanter off femoral neck but will distort/elongate femoral neck
      • no obstructing soft tissue artifact via adequate elevation of contralateral leg
    • modified dunn
      • no overhang of greater trochanter over posterior margin
      • visualization of lesser trochanter
    • frog leg/lowenstein
      • symmetrical obturator foramen + iliac wing concavity
      • superimposition of greater trochanter + femoral neck
    • false profile
      • visualization of lesser trochanter
        • too much ER leads to nonvisualization of lesser trochanter
      • demonstration of bullet sign = superimposition of ischial tuberosity
 Oblique view
  • Positioning 
Hsieh semi-prone contralateral hip elevated 40-45° femoral head
lateral decubitus on ipsilateral side pelvis tilted anteriorly 15° greater trochanter
semi-prone contralateral hip elevated 38° 2 cm above greater trochanter
12° cephalad
  • Indications
    • hsieh = posterior hip dislocation
    • lillenfeld = posterolateral pelvis
    • teufel = fovea capitis
  • Critique
 Normal Radiographic Findings


Leg-length discrepancy
AP line along inferior ischial tuberosity + line along superior aspect of lesser trochanter
0 cm
Neck-shaft angle
AP angle between femoral neck + femoral shaft


coxa vara < 120°; coxa valga > 140°
Lateral center-edge angle/angle of wiberg
AP angle between vertical line through femoral head + line along lateral acetabulum
25-40° assesses superolateral coverage: dysplasia < 20°; overcoverage > 40° 
Femoral head extrusion index
AP % of femoral head not covered by acetabulum < 25%  dysplasia > 25%
Acetabular depth
AP relationship of ilioischial line with acetabular floor vs. femoral head lateral
coxa profunda = acetabular floor touches/medial to ilioischial line; protrusion acetabuli = femoral head touches/medial to ilioischial line  
Acetabular inclination/acetabular roof angle of tonnis   AP angle between line through inferior sourcil parallel to inter-teardrop line + line from inferior to lateral sourcil
0-10°  hip instability > 10°; pincer-type FAI < 0°
Acetabular version 
AP crossover/figure-of-8 sign = relationship of anterior + posterior rim before reaching lateral sourcil 5-25° anteverted
anteverted = no crossover; retroverted = crossover, also deficient posterior wall (femoral head lateral to posterior acetabulum) + prominent ischial spine, increased by increased pelvic tilt/rotation
Hip center position
distance from medial femoral head to ilioischial line  < 10 mm  lateralized > 10 mm
Joint space width
AP weightbearing minimum distance between femoral head + acetabulum 4 mm  OA < 4 mm
Head-neck offset
AP vs. lateral relationship of anterior + posterior femoral head-neck junction symmetric radius of curvature decreased = anterior concavity > posterior; increased = anterior convexity
Head-neck offset ratio
lateral distance between line parallel to femoral neck through anterior femoral neck + anterior femoral head divided by diameter of femoral head > 0.15 cam lesion < 0.15
Alpha angle lateral angle between line from femoral head to anterolateral head-neck junction (where radius of femoral head becomes larger than neck) + line through femoral head/neck < 42° Cam lesion > 50-55°
Head sphericity
AP + lateral displacement of femoral head from reference circle < 2 mm aspherical > 2 mm
Anterior center-edge angle/angle of lequesne
false profile angle between vertical line through femoral head + line along femoral head/anterior acetabulum > 20° assesses anterior coverage; can have crossover sign but no posterior wall deficiency


 Radiographic Clinical Pearls
 Pediatric Hip Dislocation  
  • Classification
    • anterior 
      • pubic/superior = extended + ER
      • obturator/inferior = flexed + abducted + ER
    • posterior = flexed + adducted + IR
    • direct inferior/infracotyloid = luxatio erecta femoris
  • Recommended views
    • AP
      • most can be diagnosed on AP pelvis films
    • lateral
      • used to differentiate between anterior vs. posterior dislocation
      • scrutinize femoral neck to rule out fracture prior to attempting closed reduction
    • post reduction films
      • necessary to inspect for joint incongruity or nonconcentric reduction   
  • Findings
    • loss of congruence of femoral head with acetabulum   
  • Treatment criteria
    • nonoperative treatment acceptable in most cases
    • open reduction if
      • nonconcentric reduction 
      • intra-articular fragment
      • unstable acetabular rim fracture
      • irreducible by closed means
 Pediatric Proximal Femur Fractures 
  • Classification = Delbet
    Delbet Classification  
     Type Description Incidence AVN Nonunion  Images
    Type I Transphyseal (subclassify as without [IA] or with [IB] dislocation of epiphysis from acetabulum) <10%
    Type II Transcervical 40-50%
    28% 15%   
    Type III Cervicotrochanteric (or basicervical) 30-35% 18% 15-20%   
    Type IV Intertrochanteric 10-20% 5% 5%   
  • Recommended views
    • AP
    • cross-table lateral
  • Findings
    • break/offset of bony trabeculae near Ward triangle
      • indicates nondisplaced or impacted fracture
  • Treatment criteria
    • nonoperative treatment acceptable if nondisplaced type IA, II, III, IV AND < 4 years old
    • CRPP if displaced type IA, II, III or > 4 years old
    • ORIF if type IB
    • hip screw if displaced type IV or > 4 years old
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