A fracture is a broken bone. It will heal whether or not a physician resets it in its anatomical position. If the bone is not reset correctly, the healing process will keep the bone in its deformed position.

When a broken bone is manipulated and set into its natural position without surgery, the procedure is called a closed reduction. Open reduction requires surgery to expose the fracture and reset the bone. While some fractures can be minor, others are quite severe and result in grave complications. For example, a fractured diaphysis of the femur has the potential to release fat globules into the bloodstream. These can become lodged in the capillary beds of the lungs, leading to respiratory distress and if not treated quickly, death.

1. TYPES OF FRACTURES

Fractures are classified by their complexity, location, and other features (Figure 6.20). Table 6.4 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).

2. BONE REPAIR

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 fracture hematoma (Figure 6.21a). The disruption of blood flow to the bone results in the death of bone cells around the fracture.

Within about 48 hours after the fracture, chondrocytes from the endosteum have created an internal callus (plural = calli) by secreting a fibrocartilaginous matrix between the two ends of the broken bone, while the periosteal chondrocytes and osteoblasts create an external callus of hyaline cartilage and bone, respectively, around the outside of the break (Figure 6.21b). This stabilizes the fracture.

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 6.21c).

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 6.21d), and no external evidence of the fracture remains.

3. COMMON FRACTURES

3.1 Fracture of Clavicle

The clavicle (collarbone) is the most common bone fractured in people. Symptoms typically include pain at the site of the break and a decreased ability to move the affected arm.

It is often caused by a fall onto a shoulder, outstretched arm, or direct trauma. The fracture can also occur in a baby during childbirth. The middle section of the clavicle is most often involved. Diagnosis is typically based on symptoms and confirmed with X-rays. Complications can include a collection of air in the pleural space surrounding the lung (pneumothorax), injury to the nerves or blood vessels in the area, and an unpleasant appearance.

Clavicle fractures heal readily without deformity and are typically treated by putting the arm in a sling, and pain medication. It can take up to five months for the strength of the bone to return to normal. Surgical repair is not often used, but may be needed in the case of an open fracture, involvement of the nerves or blood vessels, or shortening of the clavicle in a young person.

3.2 Fracture of Distal Radius (Wrist)

This fracture of the distal forearm in which the broken end of the radius is bent backwards, is also called Colles' fracture. Symptoms may include pain, swelling, deformity, and bruising.[2] Complications may include damage to the median nerve.

The fracture is most commonly caused by people falling onto a hard surface and breaking their fall with outstretched hand. Risk factors include osteoporosis, which occurs in elderly and/or post-menopausal women. The diagnosis may be confirmed with X-rays. Treatment may include casting or surgery.

3.3 Fracture of Neck of Femur (Hip)

A hip fracture is a break that occurs in the upper part of the femur. This often occurs at its weakest point, the neck between head and the trochanter. Symptoms may include pain around the hip, particularly with movement, and shortening of the leg. Usually the person cannot walk.

They most often occur as a result of a fall. Risk factors include osteoporosis, taking many medications, alcohol use, and metastatic cancer. Hip fractures become more common with age and women are more often affected than men. Diagnosis is generally by X-rays. Magnetic resonance imaging, a CT scan, or a bone scan may occasionally be required to make the diagnosis.

Treatment options include conservative treatment with pain medication (analgesia) or surgery, involving either a total hip replacement or stabilizing the fracture with screws.

3.4 Stress (Hairline) Fractures

A stress fracture is a fatigue-induced fracture of the bone caused by repeated stress over time. Instead of resulting from a single severe impact, stress fractures are the result of accumulated trauma from repeated submaximal loading, such as running or jumping. Stress fractures commonly occur in sedentary people who suddenly undertake a burst of exercise (whose bones are not used to the task). They may also occur in sportsmen completing high volume, high impact training and in soldiers who march long distances.

Stress fractures can be described as very small slivers or cracks in the bone; and are sometimes referred to as "hairline fractures." Stress fractures most frequently occur in weight-bearing bones, such as the tibia (bone of the lower leg), metatarsals, and bones of the ankle. Less common are fractures to the femur, pelvis, and sacrum.

Bones are constantly attempting to remodel and repair themselves, especially during a sport where extraordinary stress is applied to the bone. Over time, if enough stress is placed on the bone that it exhausts the capacity of the bone to remodel, a weakened site—a stress fracture—may appear on the bone. The fracture does not appear suddenly. It occurs from repeated traumas, none of which is sufficient to cause a sudden break, but which, when added together, overwhelm the osteoblasts that remodel the bone.