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Fracture, Avulsion: ASIS, AIIS, Ischial Tuberosity, Iliac Crest

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Fracture, Avulsion: ASIS, AIIS, Ischial Tuberosity, Iliac Crest
K. Michele Kirk
Jason Mogonye
Tomoya Sakai
Basics
Description
  • Injury that typically occurs at the unfused apophysis (secondary growth center) in an adolescent athlete
  • Results from sudden, forceful, concentric or eccentric muscular contraction without external trauma
  • Also may occur from sudden excessive passive lengthening of a muscle
  • Chronic injury may occur as a result of repetitive microtrauma or overuse.
Epidemiology
Prevalence
  • Account for 13–40% of pediatric pelvic fractures
  • Ischial tuberosity most commonly avulsed and accounts for 38% of all pelvic avulsion fractures.
  • Anterosuperior iliac spine (ASIS) accounts for 32% and anteroinferior iliac spine (AIIS) for 18% (1).
  • Generally more common in males but also common in female gymnasts (2).
  • More common among adolescents than young children or adults
  • May occur in adults (“weekend warriors”)
  • Can occur bilaterally
Risk Factors
  • Athletes involved in strenuous sporting activities (soccer, football)
  • Sprinters (ASIS type I, AIIS) (1)
  • Batting in baseball (ASIS type II) (1)
  • Gymnasts, hurdlers, long jumpers, tennis players (ischial tuberosity) (3)
  • “Weekend warriors”
Etiology
  • ASIS:
    • Type I: Sudden, forceful contraction of sartorius muscle with hip in extension and knee in flexion (1)
    • Type II: Sudden, forceful contraction of tensor fasciae latae (1)
  • Ischial tuberosity: Sudden, forceful contraction of hamstring with knee extended and hip flexed (3)
  • Iliac crest: Avulsion of abdominal muscles
Diagnosis
History
  • Athlete often reports popping or snapping with immediate onset of severe pain.
  • Acute injury may be preceded by prodrome of low-level pain for up to several months owing to chronic apophysitis (1).
  • Activity at time of injury helps to define mechanism of injury.
    • Attempting to kick a ball (ASIS)
    • Clearing a hurdle (ischial tuberosity)
    • Being tackled from behind (iliac crest) (4)
  • Pattern of pain helps to localize site of avulsion fracture.
    • Ischial tuberosity avulsion fracture may radiate to posterior thigh.
    • AIIS avulsion fracture may radiate to anterior thigh.
Physical Exam
  • Signs and symptoms include:
    • Pain with localized tenderness and swelling at avulsion site
    • Limitation of motion about the site of avulsion injury
    • Difficulty (sometimes inability) bearing weight
  • Physical examination includes the following:
    • Palpate regions of suspected avulsion. Acute localized tenderness to palpation is present over involved apophysis; avulsed apophyseal fragment may be palpated.
    • Assess active and passive range of motion of involved muscle(s).
      • ASIS type I: Pain with passive extension or active flexion of hip; also pain with passive internal rotation and active external rotation of hip
      • ASIS type II: Pain with passive extension and active flexion of hip; also pain with passive external rotation and active internal rotation; pain also can be seen with active abduction and passive adduction of hip.
      • AIIS: Pain with passive extension and active flexion of hip; also pain with passive knee flexion and active knee extension
      • Ischial tuberosity: Pain with passive hip flexion and active hip extension
      • Iliac crest: Pain with contraction of abdominal muscles, lateral bending of torso, resisted hip abduction

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Diagnostic Tests & Interpretation
Imaging
  • Anteroposterior view of pelvis: May demonstrate avulsion of a portion of involved apophysis; fragments may be mildly to severely displaced. Chronic avulsions may result in prominent bone formation and nonunion. Radiographic appearance of exostosis may be confused with osseous malignancy or osteomyelitis.
  • Oblique view of pelvis: May better demonstrate avulsions of iliac crest
  • CT scan: May be helpful in chronic cases or those without a clear history; may aid in management of ischial tuberosity avulsions complicated by impingement of sciatic nerve (4)
  • US: May visualize ASIS or AIIS avulsion fractures
Differential Diagnosis
  • Apophysitis
  • Muscle strain
  • Tendon avulsion without fracture
  • Malignancy, especially in an adult with nontraumatic pelvic avulsion fracture (4)
Treatment
  • Ice application
  • Analgesics
  • Immobilization
  • Rest
  • Positioning of the limb to relieve tension on the involved muscle group
  • Crutch therapy may be required initially, with progressive weight-bearing as pain decreases and range of motion improves.
  • Start with non-weight-bearing for ischial tuberosity avulsion fractures. Proceed with progressive weight-bearing when pain-free with abduction and extension of hip (5).
Additional Treatment
Additional Therapies
  • Gradual increase in active and passive excursion of involved muscle group to achieve full active range of motion
  • Progressive resistance exercise program, followed by integration of injured musculotendinous unit with the other muscles of the hip and pelvis
  • Sport-specific training followed by return to sport when pain-free and with normal motion and strength of involved muscle
Surgery/Other Procedures
  • Surgery generally is not needed.
  • Open reduction and internal fixation (ORIF) is considered when fragment is displaced >2 cm (some even say up to 3 cm), especially for ischial tuberosity avulsion (4).
  • ORIF may be considered for nonunion or exostosis causing pain or functional impairment.
Ongoing Care
Follow-Up Recommendations
Most fractures heal with conservative treatment.
Prognosis
Athletes typically are able to return to full activity without restrictions or long-term sequelae; however, this may take up to 6 mos.
Complications
  • Exostosis is the most commonly reported complication following nonoperative management.
  • Nonunion of fracture fragment
  • ASIS fractures may cause meralgia paresthetica owing to associated injury to the lateral femoral cutaneous nerve. This typically resolves spontaneously (1), but surgical intervention may be considered for severe, persistent symptoms.
References
1. White KK, Williams SK, Mubarak SJ. Definition of two types of anterior superior iliac spine avulsion fractures. J Pediatr Orthop. 2002;22:578–582.
2. Rossi F, Dragoni S. Acute avulsion fractures of the pelvis in adolescent competitive athletes: prevalence, location and sports distribution of 203 cases collected. Skeletal Radiol. 2001;30:127–131.
3. Vandervliet JM, Vanhoenacker FM, Snoeckx A, et al. Sports-related acute and chronic avulsion injuries in children and adolescents with special emphasis on tennis. Br J Sports Med. 2007;41:827–831.
4. Sanders TG, Zlatkin MB. Avulsion injuries of the pelvis. Semin Musculoskeletal Radiol. 2008;12:42–53.
5. Steerman JG, Reeder MT, Udermann BE, et al. Avulsion fracture of the iliac crest apophysis in a collegiate wrestler. Clin J Sports Med. 2008;18:102–103.
Additional Reading
Paletta GA, Andrish JT. Injuries about the hip and pelvis in the young athlete. Clin Sports Med. 1995;14:591–628.
Rossi F, Dragoni S. Acute avulsion fractures of the pelvis in adolescent competitive athletes: prevalence, location and sports distrivution of 203 cases collected. Skeletal Radiol. 2001;30:127–131.
Stevens MA, El-Khoury GY, Kathol MH, et al. Imaging features of avulsion injuries. Radiographics. 1999;19:655–672.
Winfield C, Salis RE, Massimino F, eds. ACSM's essentials of sports medicine. St. Louis: Mosby, 1997.
Codes
ICD9
  • 808.41 Closed fracture of ilium
  • 808.42 Closed fracture of ischium
Clinical Pearls
  • Depending on fracture location, most can return to some sort of activity by 4–8 wks.
  • Full return to activity can take up to 6 mos.


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