- Bone: A unit of the skeleton composed of the hardest variety of connective tissue. Bones give shape and support to the body. In addition to surrounding and protecting vital organs, they serve as points of attachment for the muscles of the limbs, making movement possible.
- Joint: The area where two or more bones articulate with one another. Joints are usually classified in terms of the amount of motion permitted at the articulation. Most joints of the extremities are synovial joints, which allow the greatest amount of motion.
- Ligament: A bundle of connective tissue forming part of the fibrous capsule surrounding a joint and attached to it. Every joint of the extremities is reinforced by two or more ligaments, whose purpose is to stabilize the joint by confining its movements to specific planes and preventing movement beyond physiologic limits.
- Tendon: The fibrous structure connecting a voluntary muscle to bone, cartilage, or ligaments. Tendons enable muscles to effect motion in the joint or body area to which they are attached.
- Fracture: A disruption of bone tissue. Fractures may be caused by: (1) an application of force exceeding the strength of the bone, (2) repetitive stress, or (3) an invasive process that undermines the bone’s integrity.
- Dislocation: Complete disruption of a joint, such that the articular surfaces of the bones that comprise the joint are no longer in contact with one another.
- Subluxation: Partial disruption of a joint, in which some degree of contact between the articular surfaces remains.
- Fracture-dislocation or fracture-subluxation: Disruption of a joint combined with fracture of at least one of the bones involved in the articulation.
- Strain: A tearing injury to muscle fibers resulting from excessive tension or overuse.
- Sprain: A tearing injury to one or more ligaments of a joint, which occurs when the joint is forced beyond the limits of its normal planes of motion.
Properly assessing and treating bony injuries in the ED requires an understanding of the physiologic processes by which fractures are created and by which they heal. Practical knowledge of fracture pathophysiology may provide the index of suspicion needed to diagnose an injury that might otherwise be missed. It also may help prevent or minimize complications and sometimes may form the basis for advising the patient regarding the outlook for recovery of function.
Although fractures are sometimes classified in terms of the mechanism that created them, they also may be described in terms of the physiology involved.
Most fractures are the result of significant trauma to healthy bone. The bony cortex may be disrupted by a variety of forces, including a direct blow, axial loading, angular (bending) forces, torque (twisting stress), or a combination of these.
Fractures that result from relatively minor trauma to diseased or otherwise abnormal bone are ...