2-2-6. Fractures: Bone Repair
When a broken bone is manipulated and set into its natural position without surgery, the procedure is called a
Types of Fractures
Fractures are classified by their complexity, location, and other features (Figure 1). Table 1 outlines common types of fractures. Some fractures may be described using more than one term because it may have the features of more than one type (e.g., an open transverse fracture).
Types of Fractures
Table 1. Types of Fractures
When a bone breaks, blood flows from any vessel torn by the fracture. These vessels could be in the periosteum, osteons, and/or medullary cavity. The blood begins to clot, and about six to eight hours after the fracture, the clotting blood has formed a
Stages in Fracture Repair
Within about 48 hours after the fracture, chondrocytes from the endosteum have created an
Over the next several weeks, osteoclasts resorb the dead bone; osteogenic cells become active, divide, and differentiate into osteoblasts. The cartilage in the calli is replaced by trabecular bone via endochondral ossification (Figure 2c).
Eventually, the internal and external calli unite, compact bone replaces spongy bone at the outer margins of the fracture, and healing is complete. A slight swelling may remain on the outer surface of the bone, but quite often, that region undergoes remodeling (Figure 2d), and no external evidence of the fracture remains.
Visit this website to review different types of fractures and then take a short self-assessment quiz.
Fractured bones may be repaired by closed reduction or open reduction. Fractures are classified by their complexity, location, and other features. Common types of fractures are transverse, oblique, spiral, comminuted, impacted, greenstick, open (or compound), and closed (or simple). Healing of fractures begins with the formation of a hematoma, followed by internal and external calli. Osteoclasts resorb dead bone, while osteoblasts create new bone that replaces the cartilage in the calli. The calli eventually unite, remodeling occurs, and healing is complete.
A fracture can be both ________.
How can a fractured diaphysis release fat globules into the bloodstream?
In a compound fracture, ________.
The internal and external calli are replaced by ________.
The first type of bone to form during fracture repair is ________ bone.
Critical Thinking Questions
What is the difference between closed reduction and open reduction? In what type of fracture would closed reduction most likely occur? In what type of fracture would open reduction most likely occur?
In closed reduction, the broken ends of a fractured bone can be reset without surgery. Open reduction requires surgery to return the broken ends of the bone to their correct anatomical position. A partial fracture would likely require closed reduction. A compound fracture would require open reduction.
In terms of origin and composition, what are the differences between an internal callus and an external callus?
The internal callus is produced by cells in the endosteum and is composed of a fibrocartilaginous matrix. The external callus is produced by cells in the periosteum and consists of hyaline cartilage and bone.