Exam 2 Review:  Chapter 6:  Bone Fractures

bone fracture - Any clinically-significant break in a bone; in the first several decades of life, usually due to a trauma, but in old age, usually due to osteoporosis.  [See Fig. 6.14, p. 191]

fracture hematoma - The localized inflamed painful swelling filled with clotted blood resulting from a break in a blood vessel (within the bone, the marrow space, the periosteum, or the surrounding tissue) associated with a bone fracture; it represents the first stage in repair of a bone fracture.

procallus = fibrocartilaginous callus = soft callus - the first stage (approximately one week) in the healing of a bone fracture; connective tissue stem cells and capillary blood vessels penetrate the inflamed fracture hematoma and as phagocytes clear the debris from the injury, new fibrous connective tissue matrix, then new cartilage matrix, and finally new bone matrix begin to form; the procallus material usually extends beyond the volume previously occupied by the uninjured bone; it represents the second stage in repair of a bone fracture.

bony callus = hard callus - the second, final stage (several weeks to months in duration) in the healing of a bone fracture; osteoclasts continue to dissolve away the fibrous and cartilaginous components of the injury site while osteoblasts continue to replace that material with new bone matrix; bone remodeling will continue until the normal dimensions and composition of the bone are recreated; it represents the third and final stage in repair of a bone fracture, though some additional bone remodelling will often follow over time.

Bony Callus in radius and ulna of small child

[For examples of bone fractures, see Table 6.2, p. 192.]

simple fracture -  A bone fracture that causes little or no damage to the surrounding soft tissues and does not communicate with the surface by an open wound.  [aka closed fracture]

compound fracture - A bone fracture in which there is an open wound from the surface down to the fracture.  [aka open fracture]

comminuted fracture - A bone fracture in which the bone is broken into several parts.

greenstick fracture - A partial bone fracture, usually occurring in children, in which the bone is bent but only broken on one side.

spiral fracture - A bone fracture in which an excessive  twisting force (torsion) caused the injury leaving a ragged or crumbled edge at the site of the break.

An Example Case:  Toddler's fracture: Careful examination of images revealed a subtle, oblique lucency (shadow line) traversing the distal tibial diaphysis and metaphysis consistent with a toddler's fracture (see Image 1).

A toddler's fracture is a nondisplaced spiral fracture of the distal third of the tibia resulting from a fall that causes twisting torque on the lower leg. It is the most commonly identified fracture in preschool-aged children presenting with a limp. This fracture is typically seen in patients aged 1-3 years when they begin weight bearing and when the toddler is just learning to walk. However, the fracture can occur in children as old as 6 years. This patient presented with the typical presentation of a reluctance and refusal to walk or weight bear on the affected leg and no history of trauma.

Both the physician examining the patient and the radiologist interpreting the radiographs often do not recognize the fracture. Because of the spiral nature of the fracture, internally rotated, oblique radiographs can aid in identifying the acute fracture.

Treatment for a radiographically obvious toddler's fracture usually includes application of a long-leg or below-the-knee cast for 3-6 weeks. If the initial radiographs are negative but toddler's fracture is still suspected, treatment is controversial and can involve splinting for comfort and repeat radiography in 7-10 days or application of a simple cast in all children to avoid a delay in treatment.

No reported complications have resulted from a failure to diagnose the injury when it occurs. However, in 1 study, children with radiographically or other imaging–confirmed fractures were not placed into a cast at the time of injury, and limping persisted in 10%; this limping resolved after they were treated with a cast. Follow-up radiographs obtained after 7-10 days may begin to show sclerosis evolving at the fracture site and the development of periosteal new bone along the tibial diaphysis (see Image 2). If a presumed toddler's fracture is not apparent on radiographs obtained after 10 days in an otherwise well child, further evaluation, eg, with bone scanning or MRI, is recommended to rule out malignancy or osteomyelitis.
 

transverse fracture - A bone fracture in which the fracture line is at right angles to the long axis of the bone.

impacted fracture - A bone fracture in which the fragments are driven into each other so as to be immovable.

depressed fracture - A bone fracture of the skull where a piece of bone is pushed inward.

List:

6.  eleven types of bone fractures.

          simple fracture, compound fracture, comminuted fracture, greenstick fracture, epiphyseal fracture,
          spiral fracture, transverse fracture, impacted fracture, depressed fracture, hairline fracture, stress fracture.

Describe:

4. the process of healing in a broken bone.

          (1) fracture hematoma forms: blood clots; inflammation develops; connective tissue stem cells and new blood vessels invade the hematoma
          (2) procallus = fibrocartilaginous callus = soft callus forms: hematoma is replaced by highly vascular cellular fibrous connective tissue (granulation tissue) and various calcification centers form, producing masses of hyaline cartilage which fuse to form the soft callus.
          (3) bony callus = hard callus forms:  additional connective tissue stem cells and new blood vessels invade the soft callus; osteoclasts degrade the cartilage of the soft callus; osteoblasts invade the soft callus and replace the remaining fibrous connective tissue and hyaline cartilage with new bony matrix, forming the hard callus.
          (4) remodeling occurs:  the bony callus = hard callus is a mass of compact bone; osteoclasts and osteoblasts will remodel the hard callus to reintroduce regions of spongy bone or medullary cavity as appropriate to the original form of the bone in the location of the break.

          For Fracture Repair Figures.


5. What are similarities in the healing process of bone compared to skin described on p.136-137?

          (1)  If blood vessels in the dermis are ruptured, a blood clot will form.
          (2)  Inflammation develops in the site of the injury.
          (3)  Highly vascular cellular fibrous connective tissue (granulation tissue) forms temporarily at the site of the injury.
          (4)  Parenchymal repair occurs.

          (Visit Inflammation and Repair for additional review.)

Sketch and Label

7. the stages of fracture repair.

          For Fracture Repair Figures.  See these figures for more details.

          Fracture produces hematoma - no repair at this point.

          Soft / fibrocatilaginous callus forms - repair has begun.

          Hard / bony callus forms - repair is well along.

          Healed bone has remodeled - repair is complete.