Bone fracture


A bone fracture is a medical condition in which there is a partial or complete break in the continuity of any bone in the body. In more severe cases, the bone may be broken into several fragments, known as a comminuted fracture. An open fracture is a bone fracture where the broken bone breaks through the skin.
A bone fracture may be the result of high force impact or stress, or a minimal trauma injury as a result of certain medical conditions that weaken the bones, such as osteoporosis, osteopenia, bone cancer, or osteogenesis imperfecta, where the fracture is then properly termed a pathologic fracture. Most bone fractures require urgent medical attention to prevent further injury.

Signs and symptoms

Although bone tissue contains no pain receptors, a bone fracture is painful for several reasons:
Damage to adjacent structures such as nerves, muscles or blood vessels, spinal cord, and nerve roots, or cranial contents may cause other specific signs and symptoms.

Complications

Some fractures may lead to serious complications, including a condition known as compartment syndrome. If not treated, eventually, compartment syndrome may require amputation of the affected limb. Other complications may include non-union, where the fractured bone fails to heal, or malunion, where the fractured bone heals in a deformed manner. One form of malunion is the malrotation of a bone, which is especially common after femoral and tibial fractures.
Complications of fractures may be classified into three broad groups, depending upon their time of occurrence. These are as follows –
  1. Immediate complications – occurs at the time of the fracture.
  2. Early complications – occurring in the initial few days after the fracture.
  3. Late complications – occurring a long time after the fracture.


ImmediateEarlyLate
Systemic
Systemic
  • Hypovolemic shock
  • ARDS – Acute respiratory distress syndrome
  • Fat embolism syndrome
  • Deep vein thrombosis
  • Pulmonary Embolism syndrome
  • Aseptic traumatic fever
  • Sepsis
  • Crush syndrome
    		• Imperfect union of the fracture
  • Delayed union
  • Non-union
  • Malunion
  • Cross union
    • Local
  • Injury to major vessels
  • Injury to muscles and tendons
  • Injury to joints
  • Injury to viscera
    		• Local
  • Infection
  • Compartment syndrome
    		• Others
  • Avascular necrosis
  • Shortening
  • Joint stiffness
  • Sudeck's dystrophy
  • Osteomyelitis
  • Ischaemic contracture
  • Myositis ossificans
  • Osteoarthritis

    • Pathophysiology

    The natural process of healing a fracture starts when the injured bone and surrounding tissues bleed, forming a fracture hematoma. The blood coagulates to form a blood clot situated between the broken fragments. Within a few days, blood vessels grow into the jelly-like matrix of the blood clot. The new blood vessels bring phagocytes to the area, which gradually removes the non-viable material. The blood vessels also bring fibroblasts in the walls of the vessels and these multiply and produce collagen fibres. In this way, the blood clot is replaced by a matrix of collagen. Collagen's rubbery consistency allows bone fragments to move only a small amount unless severe or persistent force is applied.
    At this stage, some of the fibroblasts begin to lay down bone matrix in the form of collagen monomers. These monomers spontaneously assemble to form the bone matrix, for which bone crystals are deposited in amongst, in the form of insoluble crystals. This mineralization of the collagen matrix stiffens it and transforms it into bone. In fact, bone is a mineralized collagen matrix; if the mineral is dissolved out of bone, it becomes rubbery. Healing bone callus on average is sufficiently mineralized to show up on X-ray within 6 weeks in adults and less in children. This initial "woven" bone does not have the strong mechanical properties of mature bone. By a process of remodelling, the woven bone is replaced by mature "lamellar" bone. The whole process may take up to 18 months, but in adults, the strength of the healing bone is usually 80% of normal by 3 months after the injury.
    Several factors may help or hinder the bone healing process. For example, tobacco smoking hinders the process of bone healing, and adequate nutrition will help the bone healing process. Weight-bearing stress on bone, after the bone has healed sufficiently to bear the weight, also builds bone strength.
    Although there are theoretical concerns about NSAIDs slowing the rate of healing, there is not enough evidence to warrant withholding the use of this type analgesic in simple fractures.

    Effects of smoking

    Smokers generally have lower bone density than non-smokers, so they have a much higher risk of fractures. There is also evidence that smoking delays bone healing.

    Diagnosis

    A bone fracture may be diagnosed based on the history given and the physical examination performed. Radiographic imaging is often performed to confirm the diagnosis. Under certain circumstances, radiographic examination of the nearby joints is indicated to exclude dislocations and fracture-dislocations. In situations where projectional radiography alone is insufficient, Computed Tomography or Magnetic Resonance Imaging may be indicated.

    Classification

    In orthopedic medicine, fractures are classified in various ways. Historically, they are named after the physician who first described the fracture conditions; however, there are more systematic classifications as well.
    They may be divided into stable versus unstable depending on the likelihood that they may shift further.

    Mechanism

    • Traumatic fracture – a fracture due to sustained trauma. e.g., fractures caused by a fall, road traffic accident, fight, etc.
    • Pathologic fracture – A fracture through a bone that has been made weak by some underlying disease is called a pathological fracture. e.g., a fracture through a bone weakened by metastasis. Osteoporosis is the most common cause of pathological fracture.
    • Periprosthetic fracture – a fracture at the point of mechanical weakness at the end of an implant.

      Soft-tissue involvement

    • Closed/simple fractures are those in which the overlying skin is intact
    • Open/compound fractures involve wounds that communicate with the fracture, or where fracture hematoma is exposed, and may thus expose bone to contamination. Open injuries carry a higher risk of infection. Reports indicate an incidence of infection after internal fixation of closed fractures of 1-2%, rising to 30% in open fractures.
    • * Clean fracture
    • * Contaminated fracture

      Displacement

    • Non-displaced
    • Displaced
    • * Translated, or ad latus, with sideways displacement.
    • * Angulated
    • * Rotated
    • * Shortened, a reduction in overall bone length when displaced fracture fragments overlap

      Fracture pattern

    • Linear fracture – a fracture that is parallel to the bone's long axis
    • Transverse fracture – a fracture that is at a right angle to the bone's long axis
    • Oblique fracture – a fracture that is diagonal to a bone's long axis
    • Spiral fracture – a fracture where at least one part of the bone has been twisted
    • Compression fracture/wedge fracture – usually occurs in the vertebrae, for example when the front portion of a vertebra in the spine collapses due to osteoporosis
    • Impacted fracture – a fracture caused when bone fragments are driven into each other
    • Avulsion fracture – a fracture where a fragment of bone is separated from the main mass

      Fragments

    • Incomplete fracture – a fracture in which the bone fragments are still partially joined; in such cases, there is a crack in the osseous tissue that does not completely traverse the width of the bone.
    • Complete fracture – a fracture in which bone fragments separate completely.
    • Comminuted fracture – a fracture in which the bone has broken into several pieces.

      Anatomical location

    An anatomical classification may begin with specifying the involved body part, such as the head or arm, followed by more specific localization. Fractures that have additional definition criteria than merely localization often may be classified as subtypes of fractures, such as a Holstein-Lewis fracture being a subtype of a humerus fracture. Most typical examples in an orthopaedic classification given in the previous section cannot be classified appropriately into any specific part of an anatomical classification, however, as they may apply to multiple anatomical fracture sites.