Overview of Bone Fractures

Overview

Definition

A fracture is a disruption in the cortex of a bone. 

Epidemiology

• Around 50 million/year in the United States
• Closely associated with the prevalence and incidence of:
  • Automobile accidents
  • Occupational injuries
  • Trauma
• Increased in patients with comorbid conditions that predispose them to falls:
  • Epilepsy
  • Syncope
  • Osteoporosis
• Men affected more often than women

Classification

Risk factors

• Smoking
• Osteoporosis
• Diabetes
• Immunosuppression with steroids
• Age

Pathophysiology

The general principle behind all fractures is that the bone is subjected to a load that overcomes the bone’s bearing capacity, leading to loss of structural integrity. 

• Traumatic mechanisms of fracture:
  • Blunt: direct transference of energy by a blunt object
  • Penetrating: direct discontinuity of tissues by sharp objects or gunshot
  • Blast: transference of kinetic energy by the blast wave that results from explosive devices
• Primary fracture healing: achieved with the proper anatomic reduction of the fractured segments 
  • Hematoma formation: 1st 5 days 
  • Fibrocartilaginous callus formation: days 5–11
  • Bony callus formation: days 11–18
  • Bone remodeling: from day 18 and continuing for many months
• Secondary healing occurs when anatomic reduction or compression is not feasible: 
  • Fracture phase
  • Soft callus formation
  • Hard callus formation
  • Remodeling phase

Clinical Presentation

A thorough history with recent injury or fall details, risk factors for fracture, medications, and past history of a previous fracture are all important.

History

• Fall: How did it occur?
• Recent trauma: 
  • Automobile accident
  • Injury
  • Struck with an object
• Sudden onset of pain 
• Inability to move the affected body part
• Patients with osteoporosis may experience no- or low-impact trauma.
• Less acute causes of fractures:
  • Stress fractures can occur with repeated impact, such as with running:
    • Can be missed on an X-ray
    • More easily diagnosed on an MRI or a bone scan
  • Avascular necrosis can cause fracture of the scaphoid bone in the hand or the femoral head in the hip.

Physical examination

• Deformity of the affected location (e.g., hip fracture)
• Pain exacerbated on palpation and percussion
• Edema and inflammation
• Crepitus on palpation 
• Immobility due to pain
• Joint instability
• Inability to bear weight due to pain 
• Signs of compartment syndrome if such is being developed:
  • Coldness of the distal extremity
  • Paresthesias or paresis
  • Reduced sensitivity
  • Absent pulses
  • Volkmann contracture (prolonged ischemia)
• Other signs in the context of a patient with trauma:
  • Hematomas/ecchymosis
  • Excoriations/lacerations

Diagnosis

The diagnosis of a possible fracture is made clinically initially and confirmed on diagnostic imaging.

Imaging

• X-ray findings: fracture lines/discontinuity of anatomy
  • Linear lucency
  • Sharp angles
  • No surrounding cortex at the fracture site
  • Irregular margins
  • False positive readings:
    • Can be due to nutrient vessels that appear as linear lucencies
    • Nutrient canals are smooth and have a sclerotic margin.
    • Accessory ossicles: bone fragments that form a secondary ossification center and are not due to a fracture
    • Sesamoid bones: extra “bone islands” that form in a tendon
• Ultrasonography:
  • High sensitivity and specificity
  • Used in emergency departments and sports facilities 
  • No ionizing radiation
• CT scan and MRI:
  • Beneficial for stress fractures or spinal fractures
  • Provide good visualization of the fracture site and possible displacement

Descriptions of fractures on imaging

• Location
• Displaced or nondisplaced
• Extent:
  • Complete: extends through the entire cortex
    • More common in adults
    • Transverse: perpendicular to the long axis of the bone
    • Oblique: diagonal to the long access of the bone.
    • Spiral: caused by a twisting force
  • Incomplete: extends through only part of the cortex 
    • Most commonly seen in children
    • Greenstick fracture
    • Buckle fracture
• Comminuted: produces > 2 fragments
  • Segmental: Central portion of the bone shaft becomes an isolated segment.
  • Butterfly: Central portion has a triangular shape.
• Simple: produces only 2 fragments
• Intraarticular (crosses a joint surface) or extraarticular (does not cross)
• Integrity of limb compartments:
  • Closed: Fractured ends remain within their original compartment.
  • Open fractures:
    • 1 or both fractured ends pierce through the skin and end up exposed.
    • May be difficult to see
    • May have active bleeding
• Displacement: describes the amount by which the distal segment is offset from the proximal segment
  • Angulation: the degree to which the distal segment is angulated from its original position
  • Override: the amount by which the proximal and distal fragments overlap each other
• Impaction: the amount by which the distal fragment has impacted into the proximal fragment
• Distraction: how far apart the proximal and distal fragments are (the opposite of overlap)
• Avulsion fracture: a bone fragment that is “pulled off” by a ligament or a tendon

Secondary findings

• Increased opacity of soft tissues (acute inflammation and edema)
• Joint effusion
• Periosteal reaction/callus formation

Gustilo and Anderson classification of open fractures

• Grade 1: clean wound < 1 cm in length, simple fracture
• Grade 2: open wound 1–10 cm, no flaps or extensive tissue damage
• Grade 3: open segmental fracture with extensive soft tissue injuries, also includes wounds more > 8 hours old
• Grade 3a: adequate soft tissue covering of the fracture despite extensive soft tissue damage
• Grade 3b: inadequate soft tissue covering; periosteal stripping
• Grade 3c: open fracture with a vascular injury that requires surgery for viability of the limb

Management

The goal of fracture management by reducing it and allowing the normal healing process to take place is to restore the anatomy, reduce pain, and allow the patient to return to the previous level of functioning.

Manipulative reduction and immobilization (splints)

• Fractured ends are manipulated back into position and immobilized using a splint or a cast. 
• Successful reduction should be achieved within a few hours after the injury.
• Reduction is either the definitive management or temporary until surgery can be performed.
• An X-ray must be obtained after immobilization to ensure adequate reduction.

Open fractures

Open fractures require prompt management in the emergency department and transfer to the operating room (OR) for definitive management and hospitalization.

• “Rule of 3” irrigation with normal saline (according to Gustilo and Anderson):
  • Grade 1: 3 L
  • Grade 2: 6 L
  • Grade 3: 9 L
  • Continues in the OR
• Debridement and removal of contaminating debris
• Tetanus prophylaxis if: 
  • Patient has not completed the tetanus toxoid immunization series
  • No booster in the past 5 years
  • If there is a high likelihood of Clostridium tetani contamination → tetanus toxoid + human tetanus immunoglobulin (HTIG)
• Antibiotics
• Sterile dressing
• Immobilization
• Analgesia as needed

Complications

• Neurovascular injury: Chronic numbness or paresthesia may result in the area of a fracture depending on the extent of injury to the nerves in that area.
• Deep vein thrombosis (DVT): 
  • Blood clots can form in the arm or leg veins after a period of immobility and decreased activity.  
  • Anticoagulants are indicated if the patient is at high risk for DVT.
• Fat embolism: 
  • Can occur from fat in the bone marrow traveling through a blood vessel after a fracture
  • Similar consequences as with a thrombotic embolism
• Compartment syndrome:
  • A surgical emergency
  • Usually secondary to trauma
  • Marked by increased pressure within a compartment that compromises the circulation
  • Long-bone fractures are the most common cause, with the leg and forearm compartments frequently affected.
• Osteomyelitis: bone infection
  • Results from the spread of microorganisms from wounds associated with an open fracture
  • Most commonly caused by Staphylococcus aureus
• Nonunion of the proximal and distal ends: failure to heal properly
• Premature osteoarthritis:
  • Due to cartilage destruction and changes of the subchondral bone
  • Increased risk with:
    • Older age
    • Obesity
    • Repetitive joint use
    • Trauma
• Complex regional pain syndrome:
  • A condition characterized by chronic pain, often of the distal limbs
  • Can occur after a fracture or surgery and is difficult to manage

Differential Diagnosis

• Sprains: traumatic elongation of the ligaments of a joint, causing inflammation, ecchymosis, edema, intense pain, and inability to bear weight. Sprains account for 20% of sports-related injuries.
• Malignancy: fractures after a minor injury should raise suspicion of an underlying malignant process, such as metastatic prostate, lung, breast cancer, or multiple myeloma. Diagnosis is made by imaging and possible biopsy, and management of the underlying pathology is indicated.
• Osteoporosis: severe demineralization with low bone density can cause fractures with little stress on the bone, such as with coughing, bending, or minor injuries. Osteoporosis most often presents clinically with frequent fractures and loss of vertebral height. Diagnosis is established by measuring bone mineral density. Management includes lifestyle modifications, maintaining adequate levels of calcium and vitamin D, and the use of bisphosphonates.
• Rickets and osteomalacia: disorders of decreased bone mineralization. Rickets can be due to severe vitamin D deficiency or genetic disorders. Rickets commonly presents with skeletal deformities and growth abnormalities, while osteomalacia can present with bone pain, difficulty with ambulation, and pathologic fractures. Diagnosis is made on the basis of a combination of clinical findings, laboratory tests, and imaging. Treatment includes vitamin D, calcium, and phosphorus supplementation.