Fractures of the Pelvis and Acetabulum in Pediatric Patients

1. Fractures of the Pelvis and Acetabulum in Pediatric Patients Steven Frick, MD Created March 2004; Revised August 2006

2. Anatomy - Pelvis • Iliac bone with iliac apophysis • Ischium with apophysis • Pubic bones – physeal connection at ischiopubic junction • Sacrum – SI joint 2/3 synchondrosis, 1/3 synovial joint • Pubic symphysis - synchondrosis

3. The Child’s Pelvis • Fundamental Differences: • Bones more malleable • Cartilage capable of absorbing more energy • Joints more elastic • Triradiate Cartilage

4. Elasticity of Joints • Sacroiliac Joint and Pubic Symphysis more elastic • Allows significant displacement • Allows for single break in the ring • Thick periosteum – apparent dislocations may have a periosteal tube that heals like a fracture

5. AcetabularAnatomy • 3 Primary Ossification Centers: • Pubis • Ischium • Ilium

6. Acetabular Anatomy • These 3 distinct physes along all cartilage borders allow hemispheric growth of both the acetabulum and pelvis. • The 3 ossification centers meet and fuse at the triradiate cartilage at age 13-16 years

7. Infant Acetabulum Triradiate Cartilage Complex • Separates the Iliac bone, the Pubic bone and the Ischial Bone

8. Infant Acetabulum Histologic Section of Infant Acetabulum • Acetabular Cartilage • Triradiate Cartilage • Labrum • Pulvinar • Capsule • Ilium From Ponseti et al, JBJS

9. Development of the Acetabulum • Interstitial growth within the Triradiate cartilage complex allows enlargement • Concavity = response to the femoral head

10. Development of the Acetabulum • Depth of the acetabulum results from: • interstitial growth in the acetabular cartilage • appositional growth of the periphery of this cartilage • periosteal new bone formation at the acetabular margin.

11. Puberty • 3 Secondary Ossification center appear in the Hyaline Cartilage: • os acetabuli (epiphysis of the pubis) • acetabular epiphysis (epiphysis of the ilium) • secondary ossification center of the ischium

12. Adolescent Acetabulum Adolescent’s Innominate Bone Secondary Ossification Centers • OA - Os Acetabuli • AE - Acetabular Epiphysis • PB - Pubic Bone • SCI - Secondary Ossification Center of the Ischium SCI

13. Adolescent Acetabulum • The Os Acetabuli forms the anterior wall of the acetabulum • The Acetabular Epiphysis forms a good part of the superior wall of the acetabulum • The secondary ossification center of the ischium develops into the ischial acetabular cartilage

14. Anatomy • Other Secondary Ossification Centers of the Pelvis • iliac crest • ischial apophysis • anterior inferior iliac spine • pubic tubercle • angle of the pubis • ischial spine • lateral wing of the sacrum

15. Secondary Ossification Center • Iliac Crest : first seen at age 13 to 15 and fuses at age 15 to 17 years • Ischium : first seen at age 15 to 17 and fuses at age 19 to 25 years • ASIS : first seen about age 14 and fusing at age 16 *(Important to know these secondary ossification centers so they will not be confused with avulsion fractures)

16. Weakness of Cartilage • Avulsion fractures occur more often in children and adolescents through apophysis • Fractures of the acetabulum into the triradiate cartilage may occur with less energy than adult acetabular fractures

17. History and Associated Injuries • Usually high energy injuries for pelvic ring and acetabular fractures • Other associated injuries • Orthopaedic – long bone or spine fractures • Urologic – bladder rupture • Vascular – less frequent than in adults

18. Physical Examination • A, B, C’s • Trauma evaluation • Orthopaedic exam all extremities and spine • Systematic approach to the Pelvis

19. Examination of the Pelvis • Areas of contusion, abrasion, laceration, ecchymosis, or hematoma, especially in the perineal and pelvic areas, should be recorded. • Landmarks such as the anterior superior iliac spine, crest of the ilium, sacroiliac joints, and symphysis pubis should be palpated. • Carefully evaluate perineum/genital/rectal areas in fractures with significant displacement to rule out open fractures

20. Examination of the Pelvis • Provocative Tests (ie. Compressing the pelvic ring with anterior-posterior and lateral compression stress) • The range of motion of the extremities, especially of the hip joint, should be determined • Neurologic and vascular exam of the lower extremities

21. Radiographic Evaluation • Standard AP Pelvis • Judet views for acetabular involvement • Inlet/Outlet views for pelvic ring injuries • Computed tomography • 2-d and 3-d reconstruction • Cystography and/or urography if blood at meatus or on bladder catheterization

22. Pelvic Avulsion Fracture Injuries • At sites of muscle attachments through apophyses, caused by forceful contraction • Iliac wing – tensor fascia lata • Anterior superior iliac spine – sartorius • Anterior inferior iliac spine – rectus femoris • Ischium – hamstrings • Lesser trochanter - iliopsoas

23. Relative Percentages of Pelvic Avulsion Fracture Locations

24. ASIS Avulsion Fracture

25. Ischial Avulsion Fracture- 11 year old Sprinting

26. Ischial Avulsion Fracture CT

27. AIIS Avulsion – 13 yo Female Kicking a Soccer Ball

28. Pelvic Ring Injuries • Often high energy mechanism • MVC, pedestrian vs. car, fall from height • Often other fractures present • TBI, intraabdominal and urologic injuries often associated • Neurologic and vascular injuries may occur with severe disruptions

29. Classification of Pelvic Injuries in ChildrenTorode and Zieg modification of Watts classification • Type I – avulsion fractures • Type II - Iliac wing fractures • Type III – stable pelvic ring injuries • Type IV – any fracture pattern creating a free bony fragment (unstable pelvic ring injuries)

30. Tile Classification(applicable to adolescents / patients near skeletal maturity) • Type A – stable • Type B – rotationally unstable, vertically stable • Type C – rotationally and vertically unstable

31. Treatment Options • Bedrest • Spica cast • Mobilization with restricted weightbearing • Skeletal traction • External fixation • ORIF

32. Treatment Differences • Pubic symphyseal and SI disruptions may be able to be treated closed because of potential for periosteal healing • Children tolerate bedrest/traction/immobilization better than adults • Operative fixation should spare growth plates when possible • When not possible consider temporary (4-6 weeks) fixation across physes with smooth pins

33. Pelvic Ring Injuries- Often Crush Mechanism and Can Have Severe Soft Tissue Injuries as well

34. Plate Symphysis for Diastasis

35. Treatment • Most avulsion injuries, Tile A fractures treated with restricted or no weightbearing • Most Tile B fractures treated nonoperatively unless major deformity • Tile C fractures may need stabilization

36. Treatment Caveats • Older children and adolescents with pelvic injuries treated like adults • Operative treatment in general for pelvic injuries where posterior ring disruptions are displaced or unstable • May be able to stabilize anterior ring only, and for shorter time period if using external fixation

37. 13 year old, bilateral pubic rami fractures with left SI disruptionsubtrochanteric femur fracture

38. Pediatric Acetabular Fractures • Not common • Historically treated nonoperatively • Classification by injury pattern (shear or compression), growth plate injury, or as in adults with Letournel

39. Incidence of TriradiateCartilage Injury Review of the Literature: (0.8% - 15%) • 2/237 (0.8%) Jurkovskj 1945 • 3/52 (6%) Bryan and Tullos (1 significant) 1979 • 4/84 (5%) Reed 1976 • 13/221 (11.9%) Ljubosic 1967 • ~12% Bucholz et al 1982 • 4/27 (15%) Heeg et al 1988

40. Pubic ramus fractures and triradiate cartilage injury OFTEN associated ring injury

41. Triradiate Cartilage Fractures through this physeal cartilage in children can ultimately cause: • growth arrest • leg-length discrepancy • faulty development of the acetabulum

42. Age is a significant risk factor in the development of post-traumatic acetabular dysplasia. Children younger than ten years of age at the time of injury are at greatest risk Bucholz 1982

43. Triradiate Physeal Closure • Can occur following nondisplaced or minimally displaced fractures • Possible consequences are progressive acetabular dysplasia with shallow acetabulum and subluxation, thickening of medial acetabular wall, hypoplastic hemipelvis

44. Classification of Injury • Injuries to the triradiate cartilage constitute physeal trauma • Two basic patterns: • Shearing Type (Salter-Harris Type 1 or 2) • Crushing or Impaction Type (Type 5)

45. Bucholz et al: JBJS(A) 1982

46. Shearing Pattern with Central Protrusio of Femoral Head

47. CT Scan Shearing Type

48. Shearing Type • Blow to the pubic or ischial ramus or the proximal end of the femur • Injury at the interface of the 2 superior arms of the triradiate cartilage and the metaphysis of the ilium • A triangular medial metaphyseal fragment (Thurston-Holland sign) may be seen in the S-H Type II injuries • Blow to the pubic or ischial ramus or the proximal end of the femur • Injury at the interface of the 2 superior arms of the triradiate cartilage and the metaphysis of the ilium • A triangular medial metaphyseal fragment (Thurston-Holland sign) may be seen

49. Shearing Type • Effectively splits the acetabulum into superior (main weight-bearing) one-third and inferior (non-weight-bearing) two-thirds • Germinal zones contained within the physes unaffected • Favorable prognosis for continued relatively normal growth and development of the acetabulum

50. Crushing or Impaction Type • Difficult to detect on initial radiographs • Narrowing of the triradiate space suggests this injury pattern (rarely seen) • Premature closure of the triradiate cartilage appears to be the usual outcome • The earlier in life the premature closure occurs, the greater the eventual acetabular deformity