The spinal cord consists of nerves that connect the brain to other nerves in the body. It is like a superhighway for messages passing between the brain and the rest of the body. The spinal cord is surrounded for most of its length by the bones (vertebrae) that form the spine. If a vertebra is broken and a piece of the broken bone presses into the soft spinal cord, the cord will be injured. The cord can also be injured if the vertebrae, which are normally held in place by strong ligaments and muscles, are pushed or pulled out of alignment (called subluxation), even if the vertebrae are not fractured.
When the spinal cord is injured, the ability of the brain to communicate with the body below the level of the injury may be reduced or lost altogether. When that happens, the part of the body affected will not function normally. The “higher” (closer to the head) the spinal cord injury is, the greater the area of the body that may be affected.
Spinal cord injuries are often descried as “complete” or “incomplete.” A complete injury means that there is complete loss of sensation and muscle control below the level of the injury. Almost half of all spinal cord injuries are complete. Most spinal cord injuries, including complete injuries, result from bruising of the spinal cord or loss of blood flow to the cord, and not from cutting of the cord. A complete injury does not mean that there is no hope of any improvement.
An incomplete injury means that the person has some function below the level of the injury, even though that function is not normal. For example, a person might have weakness of the arms but still be able to move them. Another person may lose the ability to use muscles below the level of the injury only on one side of the body while losing pain and temperature sensation on the other side of the body.
Paraplegia is an impairment in motor and/or sensory function of the lower extremities. It is usually the result of spinal cord injury, which affects the neural elements of the spinal canal. The area of the spinal canal that is affected in paraplegia is either the thoracic, lumbar, or sacral regions. If both the arms and the legs are also affected by paralysis, the condition is called quadriplegia (or tetraplegia)
A fracture is a break in the continuity of the bone. While some bone fractures heal relatively quickly, others can require multiple corrective surgeries that, even when successful, can still cause adverse effects such as chronic pain or limited mobility. In general, a bone fracture results in pain, swelling, and, sometimes, bruising from internal bleeding. The patient cannot bear weight or pressure on the injured area, and may be unable to move it without severe pain. The soft tissues around the broken bone may also be injured. The area around or below the fracture may feel numb due to a loss of pulse in that area.