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Apophyseal Avulsion Fracture

The apophysis is a secondary ossification Ossification The process of bone formation. Histogenesis of bone including ossification. Bones: Development and Ossification center found on non-weight-bearing segments of bones. The apophysis is also the site of ligament or tendon insertion and is involved in the peripheral growth of the bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types. These secondary growth centers are generally open in late childhood and may not close until early adulthood. With overuse, the apophysis may become inflamed and painful, becoming vulnerable to tearing and avulsion. An acute apophyseal avulsion fracture Avulsion fracture Tearing away of the cortical bone fragment at the location of a strong ligament or tendon attachment. The bone fragment detachment site often occurs near a soft site (e.g., growth plate) at the base where ligaments; tendons; or joint capsules attach. Overview of Bone Fractures occurs when a portion of the apophysis is pulled off by the ligament, usually secondary to explosive movements and eccentric muscular contractions. Apophyseal avulsion fractures are primarily treated conservatively, but may require surgical repair if the avulsed fragment is large or significantly displaced.

Last updated: Oct 6, 2022

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Overview

Definition

An avulsion fracture Avulsion fracture Tearing away of the cortical bone fragment at the location of a strong ligament or tendon attachment. The bone fragment detachment site often occurs near a soft site (e.g., growth plate) at the base where ligaments; tendons; or joint capsules attach. Overview of Bone Fractures occurs when part of an apophysis is ripped off by the ligament due to a sudden forceful eccentric or concentric contraction of the muscle attached to it.

Anatomy

Apophyses exist on many bones and are the insertion site of a number of ligaments. Avulsion fractures can occur at any of these sites.

  • Tibial tuberosity: attachment of patellar ligament on proximal tibia
  • Anterior superior iliac spine (ASIS): attachment of sartorius muscle; seen most commonly in adolescent sprinters
  • Anterior inferior iliac spine (AIIS): attachment of rectus femoris muscle
  • Distal pole of patella: patella sleeve fracture; rare injury characterized by separation of cartilage sleeve from ossified patella; may require surgery
  • Ischial tuberosity apophysis: hamstring insertion avulsion seen in adolescent sprinters; frequently misdiagnosed as acute hamstring tendon or muscle injury 
  • Iliac crest: insertion of oblique muscles 
  • Medial epicondyle of humerus: insertion of many muscles including the flexors of the forearm; variant of “little league elbow”
  • Olecranon Olecranon A prominent projection of the ulna that articulates with the humerus and forms the outer protuberance of the elbow joint. Arm: Anatomy: insertion of tricep tendon
Sites of pelvic apophyseal avulsion fractures

Most frequent sites of pelvic apophyseal avulsion fractures:
a: iliac crest (attachment of the obliques and rectus abdominis muscles)
b: anterior superior iliac spine (attachment of sartorius muscle; seen most commonly in adolescent sprinters)
c: anterior inferior iliac spine (attachment of rectus femoris)
d: superior aspect of the symphysis pubis (insertion of rectus abdominis muscle)
e: ischial tuberosity (hamstring insertion avulsion seen in adolescent sprinters; frequently misdiagnosed as acute hamstring tendon or muscle injury)
f: lesser trochanter of the femur (insertion of iliopsoas muscle, rarely injured in adolescents during traumatic injury)

Image by Lecturio.

Clinical Presentation and Diagnosis

Acute apophyseal injuries are generally non-contact related, but rather due to a sudden explosive eccentric muscle contraction.

History and physical exam

Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship present with:

Exam can reveal:

Imaging

  • Plain X-rays X-rays X-rays are high-energy particles of electromagnetic radiation used in the medical field for the generation of anatomical images. X-rays are projected through the body of a patient and onto a film, and this technique is called conventional or projectional radiography. X-rays:
    • Soft tissue Soft Tissue Soft Tissue Abscess swelling Swelling Inflammation and joint effusion Joint Effusion Septic Arthritis are non-specific findings often seen.
    • Avulsed bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types fragments may be visible in acute injuries.
    • Subacute injuries may reveal areas of sclerosis Sclerosis A pathological process consisting of hardening or fibrosis of an anatomical structure, often a vessel or a nerve. Wilms Tumor.
    • Calcifications due to previous trauma may be visible.
  • Computed tomography (CT) scan: 
    • May be used to assess size of fragment and amount of displacement Displacement The process by which an emotional or behavioral response that is appropriate for one situation appears in another situation for which it is inappropriate. Defense Mechanisms
    • Can assist in perioperative planning
  • Magnetic resonance imaging (MRI) scan: may be used to assess associated soft tissue Soft Tissue Soft Tissue Abscess injury

Management

Management of most acute avulsion injuries is non-surgical and based on the location and amount of displacement Displacement The process by which an emotional or behavioral response that is appropriate for one situation appears in another situation for which it is inappropriate. Defense Mechanisms of the avulsed bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types.

  • Non-displaced or minimally displaced apophyseal avulsion fractures: 
  • For displaced fractures: Amount of displacement Displacement The process by which an emotional or behavioral response that is appropriate for one situation appears in another situation for which it is inappropriate. Defense Mechanisms, size of fragment, and demands of athlete are important factors in surgical decision.
Stress avulsion of the tibial tuberosity

Surgical refixation of avulsion fracture of the tibial tuberosity: postoperative anteroposterior and lateral radiographs of left knee after refixation of avulsion fracture of the tibial tuberosity

Image: “Radiographs of left knee” by Department of Orthopaedic Surgery and Traumatology, Kantonsspital Bruderholz, CH-4101 Bruderholz, Switzerland. License: CC BY 2.0

Clinical Relevance

Additional important pediatric skeletal injuries:

  • Greenstick fracture Greenstick fracture The bones of growing children exhibit unique characteristics, which, combined with the unique mechanisms of injury seen in children, result in fracture patterns differing significantly from those common in adults. The greenstick fracture is an incomplete fracture usually seen in long bones. Greenstick Fracture: partial-thickness fracture Fracture A fracture is a disruption of the cortex of any bone and periosteum and is commonly due to mechanical stress after an injury or accident. Open fractures due to trauma can be a medical emergency. Fractures are frequently associated with automobile accidents, workplace injuries, and trauma. Overview of Bone Fractures involving a complete break of cortex and periosteum Periosteum Thin outer membrane that surrounds a bone. It contains connective tissue, capillaries, nerves, and a number of cell types. Bones: Structure and Types on only 1 side of the bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types. Termed “greenstick” as it resembles a break in a live, “green” twig, where 1 side of the stick remains intact. High risk for refracture and should be completely immobilized. Rarely requires reduction, but should be managed cautiously to prevent malunion Malunion Hip Fractures or angulation Angulation Buckle or Torus Fracture deformities, and often should be referred for orthopedic follow-up.
  • Supracondylar fracture Supracondylar fracture Supracondylar fractures are the most common elbow fractures in the pediatric population. The most common mechanism of injury involves a fall on an outstretched hand, resulting in a fracture of the distal humerus. Patients frequently present with pain, visible deformity, and limited range of motion of the injured elbow. Supracondylar Fracture: complete fracture Fracture A fracture is a disruption of the cortex of any bone and periosteum and is commonly due to mechanical stress after an injury or accident. Open fractures due to trauma can be a medical emergency. Fractures are frequently associated with automobile accidents, workplace injuries, and trauma. Overview of Bone Fractures affecting distal humerus Humerus Bone in humans and primates extending from the shoulder joint to the elbow joint. Arm: Anatomy after falling on outstretched hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand: Anatomy (FOOSH). Commonly fractures of the elbow in children. Requires immediate orthopedic consultation as many cases are associated with neurovascular injury and require surgical intervention. 
  • Buckle or Torus fracture Buckle or Torus Fracture The bones of growing children exhibit unique characteristics. These characteristics, combined with the unique mechanisms of injury seen in children, result in fracture patterns that differ significantly from those that are common in adults. Buckle or Torus Fracture: fracture Fracture A fracture is a disruption of the cortex of any bone and periosteum and is commonly due to mechanical stress after an injury or accident. Open fractures due to trauma can be a medical emergency. Fractures are frequently associated with automobile accidents, workplace injuries, and trauma. Overview of Bone Fractures affecting growing metaphyseal bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types secondary to compression Compression Blunt Chest Trauma load, where bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types buckles or compresses. Generally considered a stable fracture Fracture A fracture is a disruption of the cortex of any bone and periosteum and is commonly due to mechanical stress after an injury or accident. Open fractures due to trauma can be a medical emergency. Fractures are frequently associated with automobile accidents, workplace injuries, and trauma. Overview of Bone Fractures. Treated by immobilization Immobilization Delirium, and has a good prognosis Prognosis A prediction of the probable outcome of a disease based on a individual’s condition and the usual course of the disease as seen in similar situations. Non-Hodgkin Lymphomas.

References

  1. Calderazzi F, Nosenzo A, Galavotti C, Menozzi M, Pogliacomi F, Ceccarelli F. (2018). Apophyseal avulsion fractures of the pelvis. A review. Acta Biomed. 2018;89(4):470-476. doi:10.23750/abm.v89i4.7632
  2. Porr J, Lucaciu C, Birkett S. (2011). Avulsion fractures of the pelvis – a qualitative systematic review of the literature. J Can Chiropr Assoc. PMID: 22131561; PMCID: PMC3222700.
  3. George MS. (2007). Fractures of the greater tuberosity of the humerus. J Am Acad Orthop Surg. doi: 10.5435/00124635-200710000-00005. PMID: 17916784.
  4. Schiller J, DeFroda S, Blood T. (2017). Lower Extremity Avulsion Fractures in the Pediatric and Adolescent Athlete. J Am Acad Orthop Surg. doi: 10.5435/JAAOS-D-15-00328. PMID: 28291142.

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