p07 pediatric pelvis, aceta

Fractures of the Pelvis and Acetabulum in Pediatric Patients

Steven Frick, MD

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

The Child’s Pelvis

• Fundamental Differences:– Bones more malleable– Cartilage capable of absorbing more energy– Joints more elastic– Triradiate Cartilage

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

AcetabularAnatomy

• 3 Primary Ossification Centers:– Pubis– Ischium– Ilium

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

Infant Acetabulum

Triradiate Cartilage Complex

• Separates the Iliac bone, the Pubic bone and the Ischial Bone

Infant Acetabulum

Histologic Section of Infant Acetabulum

• Acetabular Cartilage• Triradiate Cartilage• Labrum• Pulvinar• Capsule• Ilium

From Ponseti et al, JBJS

Development of the Acetabulum

• Interstitial growth within the Triradiate cartilage complex allows enlargement

• Concavity = response to the femoral head

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.

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

Adolescent AcetabulumAdolescent’s Innominate

BoneSecondary Ossification Centers

• OA - Os Acetabuli

• AE - Acetabular Epiphysis

• PB - Pubic Bone

• SCI - Secondary Ossification Center of the Ischium

SCI

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

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

• 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 apophysis

• Fractures of the acetabulum into the triradiate cartilage may occur with less energy than adult acetabular fractures

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

Physical Examination

• A, B, C’s• Trauma evaluation• Orthopaedic exam all 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 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

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

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

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

Relative Percentages of Pelvic Avulsion Fracture Locations

ASIS Avulsion Fracture

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

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)

Tile Classification(applicable to adolescents /

patients near skeletal maturity)

• Type A – stable• Type B – rotationally unstable, vertically

stable• Type C – rotationally and vertically

unstable

Treatment Options

• Bedrest• Spica cast• Mobilization with restricted weightbearing• Skeletal traction• External fixation• ORIF

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

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

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

13 Year Old, Bilateral Pubic Rami Fractures with Left SI DisruptionSubtrochanteric Femur Fracture

Pediatric Acetabular Fractures

• Not common • Historically treated nonoperatively• Classification by injury pattern (shear or

compression), growth plate injury, or as in adults with Letournel

Incidence of Triradiate Cartilage 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

Pubic ramus fractures and triradiate cartilage injury

OFTEN associated ring injury

Triradiate Cartilage

Fractures through this physeal cartilage in children can ultimately cause:– growth arrest– leg-length discrepancy– faulty development of the acetabulum

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

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

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)

Bucholz et al: JBJS(A) 1982

Shearing Pattern with Central Protrusio of Femoral Head

CT Scan Shearing Type

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

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

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

Treatment Options

• Non-operative Treatment• Operative Treatment

– ORIF– Early Reconstruction– Late Reconstruction

Non-operative Treatment

Majority in the LiteratureTreatment:

– Traction– Spica Cast– Bedrest– Protected mobilization

• Bucholz et al reported 50% (4/8) rate of growth disturbance

• Only one with acetabular dysplasia– this patient injured at a young age

Bucholz et al 1982

Non-operative Treatment

Conclusion:• Mixed Results• Results often poor, especially in cases with

comminution, incongruity and when traction does not improve position of fracture fragments

Operative Treatment

• ORIF• Early Reconstruction (Physeal Bar excision)• Late Reconstruction (Pelvic Osteotomy)

Acetabular Fractures in Children- Indications for ORIF

• Joint displacement > 2mm• Joint incongruity• Joint instability (fracture dislocations)• Able to undergo anesthetic

Displaced Acetabular Fracute3D CT – Shows “Free Fragment”

Post-Op- smooth Kwire across Triradiate cartliage

6 Weeks Post-Op

3 Month Follow-up

Literature Review: ORIF Pediatric Acetabular FractureAuthor Age at Injury Time of F/U Comment_____________________

Bucholz et al 6 18mo Asymptomatic; lost 15 degrees of IR1982 X-ray: Osseous Acetabular overgrowth

Brooks and 10 48mo Asymptomatic; full range of motionRosman X-ray: Normal1988

Heeg et al 9 72mo Skeletally Mature; pain-free, but walks1988 w/ severe limp; 25 degree fixed flx, 25 degrees fixed IR, 20 degrees fixed

adduct, 3 cm short X-ray: subluxation of femoral head

Operative Treatment-ORIF• Three Case Reports

– Bucholz et al: JBJS (A), 1982– Brooks and Rosman: J of T, 1988– Heeg et al: JBJS (B), 1988

Pre-Op Post-Op

Bucholz et al 1982

Bucholz et al 1982

At 18 months Post-Op

Osseous Acetabular Overgrowth

Pre-Op Post-Op

Brooks and Rosman 1988

Brooks and Rosman 1988

At 48 months Post-Op

?Osseous Bridge?

Operative Treatment ORIF

Conclusion:– Early Results appear Good/Excellent– Intermediate results questionable– One case with Long-term follow-up shows

Poor results – Need longer followup

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

Heeg et al. CORR July 2000

• Retrospective, 29 patients, age 2-16 years• 14 year avg followup• ORIF 14, arthrotomy 2 , 13 nonoperative• All but one satisfactory function• Central fracture dislocation relatively poor

because of failure to achieve radiographic congruence, even with surgery

• Need longer followup

Operative TreatmentEarly Reconstruction

• Hamlet and Robertson: JBJS(A)1997• Single Case Report• 14 year follow-up• Initial treatment = Non-operative• Physeal Bar Excision/Bone Wax

Interposition

Operative TreatmentEarly Reconstruction

• 5 YO s/p MVA sustains a minimally displaced R acetabular fracture

Operative TreatmentEarly Reconstruction

• At age 7, tomograms shows evidence of physeal bar formation

Operative TreatmentEarly Reconstruction

• Age 7• S/p excision of

physeal bar (1982)• Bone wax

interposition• WBAT post-op day 5

Operative TreatmentEarly 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

Operative TreatmentEarly Reconstruction

• Conclusion:– Small physeal bars are amenable to excision– Premature closure of Triradiate still occurs

despite bar excision– Recommend: Early recognition and treatment

prior to premature closure of entire physis and permanent osseous deformity

• “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 TreatmentLate 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 at maturity

Operative TreatmentLate Reconstruction (SALVAGE)

Conclusion:– Results Not KNOWN– Salvage procedure

Chiari Osteotomy

Conclusion• Pediatric Acetabular fractures are rare• Potential complication = 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 include:– Age (<10 years)– S-H 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

• Reconstruction– Early – Late

• Results:– No Long-term follow-up

Conclusion

Recommendation:• Non/Min displaced fractures = Non-operative

– Patient treated non-operatively should be followed for at least one – two years

– Those that progress to premature triradiate cartilage fusion = consider Early Reconstruction

– Those presenting late with subluxation= Salvage Procedure

• Displaced fractures = ORIF

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