Fractures of the Pelvis and Acetabulum in Pediatric

Fractures of the Pelvis and Acetabulum in Pediatric Patients Joshua Klatt, MD Revised - October, 2011 Created March 2004 by Steven Frick, MD

The Child’s Pelvis • Fundamental differences: – Bones are more malleable – Cartilage is capable of absorbing more energy – SI joint and symphysis are more elastic – Triradiate Cartilage • Injury causing growth arrest may lead to significant deformity Schlickwei W, Keck T. Pelvic and acetabular fractures in childhood. Injury. 2005; 36(suppl 1): A 57 -A 63.

Elasticity of Joints • Sacroiliac joint and pubic symphysis are more elastic • Allows significant displacement before fx • Allows for single break in the ring • Thick periosteum – Apparent dislocations may have a periosteal tube that heals like a fracture Schlickwei W, Keck T. Pelvic and acetabular fractures in childhood. Injury. 2005; 36(suppl 1): A 57 -A 63.

Pelvic Anatomy • 3 primary ossification centers: – – Ilium – appears at 9 wks Ischium – appears at 16 wks Pubis – appears at ~20 wks Endochonral ossification, just like long bones Delaere O, Dhem A. Prenatal development of the human pelvis and acetabulum. Acta Orthop Belg. 1999; 65(3): 255 -60.

Acetabular Anatomy • The 3 distinct physes of each bone making up the triradiate cartilage 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 Ponseti, I. Growth and development of the acetabulum in the normal child. Anatomical, histological, and roentgenographic studies. J Bone Joint Surg Am. 1978; 60(5): 575 -85.

Triradiate Cartilage Complex • Separates the ilium, the pubis and the ischium Ponseti, I. J Bone Joint Surg Am. 1978.

Infant Acetabulum Histologic section of infant acetabulum • • • Acetabular cartilage Triradiate cartilage Labrum Pulvinar Capsule Ilium Ponseti, I. J Bone Joint Surg Am. 1978.

Development of the Acetabulum • Interstitial growth within the horizontal flange of the triradiate cartilage contributes to the normal growth of the distal third of the ilium. • Enlargement of the acetabulum during growth is likely the result of interstitial growth within the triradiate cartilage. Ponseti, I. J Bone Joint Surg Am. 1978.

Development of the Acetabulum • Development of concavity is a response to pressure from the femoral head – In DDH with a dislocation the acetabulum will not develop appropriately • 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.

Puberty • 3 secondary ossification centers appear in the hyaline cartilage of the acetabulum – Os acetabuli • Epiphysis of the pubis • Forms most of anterior wall – Acetabular epiphysis • Epiphysis of the ilium • Forms most of superior acetabulum – Secondary ossification center of the ischium • Forms much of posterior wall

Secondary Ossification Centers SCI • OA - Os Acetabuli • AE - Acetabular Epiphysis • PB - Pubic Bone • SCI – Secondary ossification center of ischium • Ossification centers appear at age 8 to 9 yrs and fuse around 17 – 18 yrs Ponseti, I. J Bone Joint Surg Am. 1978.

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

Secondary Ossification Center • Iliac Crest : first seen at age 13 to 15 and fuses at age 15 to 17 years – Used in Risser staging • 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

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

History and Associated Injuries • Pelvic ring and acetabular fractures usually involve high energy injuries • Associated injuries – Orthopaedic – long bone or spine fractures – Urologic – bladder rupture – Vascular – less frequent than in adults, rarely life threatening

Physical Examination • A, B, C’s • Trauma evaluation • Orthopaedic exam of extremities and spine • Systematic approach to the pelvis

Examination of the Pelvis • Areas of contusion, abrasion, laceration, ecchymosis, or hematoma, especially in the perineal and pelvic areas, should be noted – Rule out open fractures in perineum/genital/rectal areas • Palpate landmarks – – Anterior superior iliac spine Crest of the ilium Sacroiliac joints Symphysis pubis

Examination of the Pelvis • Neurologic and vascular exam of the lower extremities • Provocative Tests – Compress 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

Radiographic Evaluation • There is no standard algorithm for which films to obtain in children • AP pelvis • Judet views for acetabular involvement • Inlet/Outlet views for pelvic ring injuries • Computed tomography – 2 D and possibly 3 D reconstruction • Cystography/urography if blood at meatus or on bladder catheterization

Pelvic Avulsion Fractures • Caused by forceful contraction at sites of muscle attachments through apophyses – Iliac wing – tensor fascia lata – Anterior superior iliac spine – sartorius – Anterior inferior iliac spine – rectus femoris – Ischium – hamstrings – Lesser trochanter - iliopsoas

Relative Percentages of Pelvic Avulsion Fracture Locations • • • Ischial tuberosity – 54% AIIS – 22% ASIS – 19% Pubic Symphysis – 3% Iliac Crest – 1% http: //crashingpatient. com Rossi F, Dragoni S. Acute Avulsion Fractures of the Pelvis in Adolescent Competitive Athletes. Skeletal Radiol. 2001; 30(3): 127 -31.

ASIS Avulsion Fracture

Ischial Avulsion Fracture 11 yr male sprinting

CT of ischial avulsion fracture

AIIS Avulsion Fracture 13 yr female kicking a soccer ball

Pelvic Ring Injuries • Often high energy mechanism – MVA – Auto-pedestrian – Fall from height • Often other fractures present – Traumatic brain injury (TBI) – Intra-abdominal injuries – Urologic injuries • Neurologic and vascular injuries may occur with severe disruptions Torode I, Zieg D. Pelvic fractures in children. J Pediatr Orthop 1985; 5: 76 -84.

Classification of Pelvic Injuries in Children Torode 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) Torode I, Zieg D. Pelvic fractures in children. J Pediatr Orthop 1985; 5: 76 -84.

Tile Classification • Applicable in patients near skeletal maturity – More often adult type patterns • Type A – Stable • Type B – Rotationally unstable, vertically stable • Type C – Rotationally and vertically unstable Tile M. Acute Pelvic Fractures: I. Causation and Classification? J Am Acad Orthop Surg. 1996; 4(3): 143 -151.

Treatment Options • • • Bedrest Spica cast Restricted weight bearing Skeletal traction External fixation ORIF

Treatment Differences • Children tolerate bedrest/traction/immobilization better than adults • Pubic symphyseal and SI disruptions may be able to be treated closed because of potential for periosteal healing • Operative fixation should spare growth plates when possible – When not possible consider temporary (4 -6 weeks) fixation across physes with smooth pins or early hardware removal Holden C, et al. Pediatric pelvic fractures. J Am Acad Orthop Surg. 2007; 15: 172 -7.

Pelvic Ring Injuries *Often crush mechanism and can have severe soft tissue injuries as well.

Treatment • Most avulsion injuries and Tile A fractures treated with restricted or no weight bearing • Most Tile B fractures treated nonoperatively unless major deformity • Tile C fractures may need stabilization Holden C, et al. Pediatric pelvic fractures. J Am Acad Orthop Surg. 2007; 15: 172 -7.

Treatment Caveats • Treat older children and adolescents with pelvic injuries like adults • In general, pelvic injuries where posterior ring disruptions are displaced or unstable need operative treatment • Only anterior ring may need stabilization – And for shorter time period, if using external fixation Holden C, et al. Pediatric pelvic fractures. J Am Acad Orthop Surg. 2007; 15: 172 -7.

Plate Symphysis for Diastasis

13 year old, bilateral pubic rami fractures with left SI disruption subtrochanteric femur fracture

Pediatric Acetabular Fractures • Constitute only 1% to 15% of pelvic fractures in children – Much more common after the triradiate cartilage closes (12 yrs in girls, 14 yrs in boys) • Mechanism of injury similar to that in adults – Force transmitted through femoral head – Position of leg relative to pelvis and location of impact determine fracture pattern

Pediatric Acetabular Fractures • Often associated with hip dislocation • The distribution of types is different than adults – More often transverse than both column • Historically treated nonoperatively – Achieving congruent reduction with closed, conservative treatment is difficult and often impossible – Many think that the role of surgical treatment in children is expanding Heeg M, de Ridder VA. Acetabular fractures in children and adolescents. Clin Orthop Relat Res

Pediatric Acetabular Fractures Classification • Growth plate injury – Use Salter-Harris classification – Bucholz suggested that there are common injury patterns • Letournel system most frequently used – Same as used for adults • Watts classification also sometimes used Bucholz, et al. Injury to the acetabular triradiate physeal cartilage. J Bone Joint Surg Am 1982; 64(4): 600 -9.

Pediatric Acetabular Fractures Classification • Letournel system – Type A – Single wall or column – Type B – Fractures involving 2 columns – Type C – Fractures involve both columns and separate dome fragment from axial skeleton Judet, et al. Fractures of the acetabulum: classification and surgical approaches for open reduction. J Bone Joint Surg Am 1964; 46: 1615 -46.

Pediatric Acetabular Fractures Classification • Watts classification – Type A – Small fragments that most often occur with hip dislocation – Type B – Stable linear fractures without displacement in association with pelvic fractures – Type C – Linear fractures with hip joint instability – Type D – Fractures secondary to central fracturedislocation of the hip Watts HG. Fractures of the pelvis in children. Orthop Clin North Am 1976; 7: 615 -624.

Pediatric Acetabular Fractures Classification • Injuries to the triradiate cartilage constitute physeal trauma • Bucholz Classification – Two basic patterns – Shearing Type (Salter-Harris Type I or II) – Crushing or Impaction Type (Type IV) Bucholz, et al. Injury to the acetabular triradiate physeal cartilage. J Bone Joint Surg Am 1982; 64(4): 600 -9.

Bucholz, et al. Injury to the acetabular triradiate physeal cartilage. J Bone Joint Surg Am 1982; 64(4): 600 -9.

• Pubic ramus fractures and triradiate cartilage injury • OFTEN associated ring injury • Watts Type B injury • Bucholz Shearing Type • Salter-Harris II

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 Salter. Harris Type II injuries Bucholz, et al. Injury to the acetabular triradiate physeal cartilage. J Bone Joint Surg Am 1982; 64(4): 600 -9.

Shearing Type • Effectively splits the acetabulum into superior (main weight-bearing) one-third and inferior (nonweight-bearing) two-thirds • Germinal zones contained within the physes often unaffected • Favorable prognosis for continued relatively normal growth and development of the acetabulum Bucholz, et al. Injury to the acetabular triradiate physeal cartilage. J Bone Joint Surg Am 1982; 64(4): 600 -9.

Shearing Pattern with Central Protrusio of Femoral Head • Watts Type D injury • Bucholz Shearing Type

CT Scan Shearing Type

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 Bucholz, et al. Injury to the acetabular triradiate physeal cartilage. J Bone Joint Surg Am 1982; 64(4): 600 -9.

Triradiate Cartilage • Fractures through this physeal cartilage in children can ultimately cause: – Growth arrest – Leg-length discrepancy – Faulty development of the acetabulum Heeg, et al. Injuries of the acetabular triradiate cartilage and sacroiliac joint. J Bone Joint Surg Br 70: 34 -37, 1988.

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, et al. Injury to the acetabular triradiate physeal cartilage. J Bone Joint Surg Am 1982; 64(4): 600 -9.

Incidence of Triradiate Cartilage Injury • Of pediatric patients with pelvic trauma, between 1% and 15% of patients sustain an acetabular fracture • In pediatric patients with acetabular fractures, resulting premature closure of the triradiate cartilage has an overall incidence of less than 5% (range, 0– 11%) Liporace, et al. Development and injury of the triradiate cartilage with its effects on acetabular development: review of the literature. J Trauma 2003; 54(6): 1245 -9.

Triradiate Physeal Closure • Can occur following nondisplaced or minimally displaced fractures • Possible consequences are – Progressive acetabular dysplasia – Thickening of medial acetabular wall – Shallow acetabulum and subluxation – Hypoplastic hemipelvis Bucholz, et al. Injury to the acetabular triradiate physeal cartilage. J Bone Joint Surg Am 1982; 64(4): 600 -9.

Triradiate Physeal Closure • Bucholz reported 56% (5/9) rate of growth disturbance (in injuries to triradiate) – All four of those with Salter-Harris type IV – Only one with acetabular dysplasia • Patient injured at a young age (2 yrs) Bucholz, et al. Injury to the acetabular triradiate physeal cartilage. J Bone Joint Surg Am 1982; 64(4): 600 -9.

Treatment Options • Unique nature of the developing hip joint necessitates an individualization of treatment for each pediatric acetabular fracture • Agreed that functional outcome determined by – Age at the time of injury – Articular displacement – Congruency of the hip joint Bucholz, et al. Injury to the acetabular triradiate physeal cartilage. J Bone Joint Surg Am 1982; 64(4): 600 -9.

Treatment Options • Non-operative treatment – – Traction Spica Cast Bedrest Protected mobilization • Operative treatment – ORIF – Early reconstruction – Late reconstruction

Non-operative Treatment • Mixed Results – Few articles give specific guidelines for nonoperative versus operative treatment. • Results often poor, especially in cases with – Comminution – Incongruity – When traction does not improve position of fracture fragments Liporace, et al. Development and injury of the triradiate cartilage with its effects on acetabular development: review of the literature. J Trauma 2003; 54(6): 1245 -9.

Operative Treatment • ORIF – If hardware must cross triradiate cartilage, consider smooth K-wires • Early reconstruction (physeal bar excision) • Late reconstruction (pelvic osteotomy)

Acetabular Fractures in Children Indications for ORIF • Joint displacement > 2 mm • Joint incongruity • Joint instability (fracture dislocations) • Fractures with posterior instability • Persisting medial subluxation • Central fracture-dislocations • Intra-articular fragments • Open fractures Liporace, et al. Development and injury of the triradiate cartilage with its effects on acetabular development: review of the literature. J Trauma 2003; 54(6): 1245 -9.

Displaced Acetabular Fracture 3 D CT – Shows “Free Fragment”

Post-op - smooth K-wire across triradiate cartilage 6 weeks post-op

3 month follow-up

Operative Treatment • Three Case Examples – Bucholz. JBJS-Am, 1982 – Brooks and Rosman, J Trauma, 1988 – Heeg, JBJS-Br, 1988

Pre-op Post-op Bucholz, et al. Injury to the acetabular triradiate physeal cartilage. J Bone Joint Surg Am 1982; 64(4): 600 -9.

Osseous acetabular overgrowth 18 months post-op Bucholz, et al. Injury to the acetabular triradiate physeal cartilage. J Bone Joint Surg Am 1982; 64(4): 600 -9.

Pre-op Post-op Brooks E, Rosman M: Central fracture-dislocation of the hip in a child. J Trauma 28: 1590 -1592, 1988.

Osseous bridge? 48 months Post-Op Brooks E, Rosman M: Central fracture-dislocation of the hip in a child. J Trauma 28: 1590 -1592, 1988.

Heeg M, de Ridder VA. Acetabular fractures in children and adolescents. Clin Orthop Relat Res 376: 80– 6, 2000.

Largest series of pediatric acetabular fractures • • • Heeg & Ridder, Netherlands, 2000 Retrospective, 29 patients, age 2 -16 years 14 year avg follow-up 14 ORIF, 2 arthrotomy, 13 nonoperative 6 (21%) fair or poor results Central fracture dislocation relatively poor because of failure to achieve radiographic congruence, even with surgery • Need longer follow-up Heeg M, de Ridder VA. Acetabular fractures in children and adolescents. Clin Orthop Relat Res 376: 80– 6, 2000.

Operative Treatment Conclusion: – Early results appear – Good/excellent – Intermediate results questionable – One case with long-term follow-up shows poor results – Current evidence is poor quality • Need longer follow-up • Increased number of reports

Older child – displaced posterior column through triradiate “scar” ORIF with plate / lag screw on posterior column

Operative Treatment Early Reconstruction • • • Peterson and Robertson, Mayo Clinic, 1997 Single case report 14 year follow-up Initial treatment was non-operative Physeal bar excision/bone wax interposition Peterson, et al. Premature partial closure of the triradiate cartilage treated with excision of a physical osseous bar. J Bone Joint Surg Am. 1997; 79(5): 767 -70.

Operative Treatment Early Reconstruction • 5 yr s/p MVA sustains a minimally displaced R acetabular fracture Peterson. J Bone Joint Surg Am. 1997.

Operative Treatment Early Reconstruction • At age 7, tomograms shows evidence of physeal bar formation Peterson. J Bone Joint Surg Am. 1997.

Operative Treatment Early Reconstruction • Age 7 • Excision of physeal bar (1982) • Bone wax interposition • WBAT post-op day 5 Peterson. J Bone Joint Surg Am. 1997.

Operative Treatment Early Reconstruction • At age 19, there is slight increase in width of acetabular wall and lateral displacement of femoral head. • Suggests premature closure of triradiate cartilage Peterson. J Bone Joint Surg Am. 1997.

Operative Treatment Early Reconstruction • Conclusion: – Small physeal bars are amenable to excision – Premature closure of triradiate can still occur despite bar excision – Recommendation: Early recognition and treatment prior to premature closure of entire physis and permanent osseous deformity – Based on extremely limited data/experience Peterson. J Bone Joint Surg Am. 1997.

• “Theoretically, if the osseous bridge were removed surgically, growth would resume and the normal shape of the acetabulum might be preserved. However, the rapid development of the osseous bridge and progression to closure of the triradiate cartilage certainly suggest that resection of the bridge and implantation of fat…may not have much success. ” Bucholz et al, 1982

Operative Treatment Late Reconstruction (Salvage) • Two case reports – Blair and Hanson: JBJS(A) 1979 – Scuderi and Bronson: CORR 1987 • • Conservative management initially Premature closure of triradiate cartilage Symptomatic treatment Chiari osteotomy 2 to 3 years prior to maturity

Operative Treatment Late Reconstruction (Salvage) Conclusion: – Long-term results unknown – Salvage procedure Chiari Osteotomy

Conclusion • Pediatric acetabular fractures are rare • Potential complication of triradiate cartilage injury • Traumatic acetabular dysplasia – Growth arrest – Faulty development of the acetabulum • Shallow acetabulum • Femoral head subluxation/dislocation – Leg-length discrepancy

Conclusion • Risk factors for bar/growth disturbance include: – Age (<10 years) – Salter-Harris type 5 injury pattern • Diagnosis: – High level of suspicion – CT scan helpful

Conclusion • Treatment – Non-operative (Majority) – Operative • Acute ORIF – Gaining favor – Similar treatment principles as adults (>2 mm displacement) • Reconstruction – Early – Late • Results – No long-term follow-up in literature

Conclusion • Non/min displaced fractures = Non-operative – Patient treated non-operatively should be followed for at least one to two years – Those that progress to premature triradiate cartilage fusion = consider early reconstruction – Those presenting late with subluxation = salvage procedure • Displaced fractures – ORIF using adult principles – If hardware across triradiate required, use smooth wires

Bibliography • Blair W, Hanson C. Traumatic closure of the triradiate cartilage: report of a case. J Bone Joint Surg Am 1979; 61(1): 144 -5. • Brooks E, Rosman M. Central fracture-dislocation of the hip in a child. J Trauma 28: 1590 -1592, 1988. • Bucholz R, Ezaki M, Ogden J. Injury to the acetabular triradiate physeal cartilage. J Bone Joint Surg Am 64(4): 600 -9, 1982. • Delaere O, Dhem A. Prenatal development of the human pelvis and acetabulum. Acta Orthop Belg. 1999; 65(3): 255 -60. • Habacker TA, Heinrich SD, Dehne R. Fracture of the superior pelvic quadrant in a child. J Pediatr Orthop 15: 69 -72, 1995. • Hall BB, Klassen RA. Acetabular fractures in children: A long-term follow-up study. Orthop Trans 6: 353. 1982. • Heeg M, Visser JD, Oostvogel HJM. Injuries of the acetabular triradiate cartilage and sacroiliac joint. J Bone Joint Surg Br 70: 34 -37, 1988. • Heeg M, Klasen HJ, Visser JD. Acetabular fractures in children and adolescents. J Bone Joint Surg-Br 71: 418 -421, 1989.

Bibliography • Heeg M, de Ridder VA. Acetabular fractures in children and adolescents. Clin Orthop Relat Res 376: 80– 6, 2000. • Holden CP, Holman J, Herman MJ. Pediatric pelvic fractures. J Am Acad Orthop Surg. 2007; 15: 172 -7. • Judet, R, Judet J, Letournel E. Fractures of the acetabulum: classification and surgical approaches for open reduction. J Bone Joint Surg Am 1964; 46: 1615 -46. • Liporace F, Ong B, Mohaideen A, Ong A, Koval K. Development and injury of the triradiate cartilage with its effects on acetabular development: review of the literature. J Trauma 2003; 54(6): 1245 -9. • Peterson HA, Robertson RC. Premature partial closure of the triradiate cartilage treated with excision of a physical osseous bar. Case report with a fourteen-year follow-up. J Bone Joint Surg Am. 1997; 79(5): 767 -70. • Ponseti, I. Growth and development of the acetabulum in the normal child. Anatomical, histological, and roentgenographic studies. J Bone Joint Surg Am. 1978; 60(5): 575 -85.

Bibliography • Rossi F, Dragoni S. Acute Avulsion Fractures of the Pelvis in Adolescent Competitive Athletes. Skeletal Radiol. 2001; 30(3): 127 -31. • Schlickwei W, Keck T. Pelvic and acetabular fractures in childhood. Injury. 2005; 36(suppl 1): A 57 -A 63. • Scuderi G, Bronson MJ. Triradiate cartilage injury. Report of two cases and review of the literature. Clin Orthop Relat Res 1987; 217: 179 -89. • Tile M. Acute Pelvic Fractures: I. Causation and Classification? J Am Acad Orthop Surg. 1996; 4(3): 143 -151. • Torode I, Zieg D. Pelvic fractures in children. J Pediatr Orthop 1985; 5: 76 -84. • Watts HG. Fractures of the pelvis in children. Orthop Clin North Am 1976; 7: 615624. If you would like to volunteer as an author for the Resident Slide Project or recommend updates to any of the following slides, please send an email to ota@ota. org Return to Pediatrics Index