Question

An elderly client develops disuse osteoporosis. The client's adult son asks why his parent has this disease. The nurse would explain that disuse osteoporosis occurs because of: A. a decrease in calcium intake. B. contractures to the lower extremities. C. lack of stress to weight-bearing activity. D. stiff and painful joints of the extremities.

Short answer

The correct explanation for the development of disuse osteoporosis is C. lack of stress to weight-bearing activity.

Step-by-step solution

Understanding Disuse Osteoporosis

Disuse osteoporosis is a condition that occurs when there is a decrease in bone mass and density due to a lack of mechanical stress. This often happens in individuals who are immobilized or unable to perform weight-bearing activities.

Eliminating Incorrect Options

Eliminate options that do not directly relate to the lack of mechanical stress on bones. A decrease in calcium intake (A) can lead to osteoporosis, but it isn't specific to disuse osteoporosis. Contractures to the lower extremities (B) and stiff and painful joints of the extremities (D) are conditions that might result from disuse, but they do not directly cause disuse osteoporosis.

Identifying the Correct Explanation

Identify that lack of stress to weight-bearing activity (C) is the direct cause of disuse osteoporosis. Bones require regular stress through weight-bearing exercises to maintain their density; without it, they begin to weaken and lose mass.

Key concepts

Bone Mass and Density

In the discussion of disuse osteoporosis, an understanding of bone mass and density is vital. Our bones are living tissue that is constantly being broken down and rebuilt in a process called remodeling. Bone mass refers to the amount of bone tissue in the skeletal structure, while bone density relates to the strength of that bone mass.

When we think about healthy bones, we envision a high bone mass and a dense bone structure, both indicative of strong bones. Over time, especially with age or immobility, bones can lose mass and become less dense, making them more susceptible to breaks and fractures. This loss is what occurs in disuse osteoporosis.

Remember that maintaining adequate intake of calcium and vitamin D, along with engaging in regular physical activity, helps support bone mass and prevent decreases in bone density. Bones have a remarkable ability to adapt their strength in proportion to the amount of mechanical stress they experience, a process known as Wolff's law.

Weight-bearing Activities

Activities that support or resist gravitational forces are classified as weight-bearing activities. These include walking, running, and lifting weights. Such activities stimulate bone formation and increase bone mineral density by imposing mechanical stress on the skeletal system.

Our bones are not static; they require regular 'exercise' as much as our muscles do. The relationship between our bones and weight-bearing activities is reciprocal – bones strengthen in response to the load placed upon them, which is also why astronauts lose bone density in the zero-gravity environment of space.

In the context of disuse osteoporosis, the lack of weight-bearing activities leads to the bone remodeling process favoring bone resorption over formation, leading to weakened bones. To prevent or counteract disuse osteoporosis, it is encouraged to engage in routine weight-bearing exercises, as this promotes the building of bone and helps maintain bone density.

Mechanical Stress on Bones

The concept of mechanical stress on bones relates to the forces bones experience during physical activities. Mechanical stress from activities such as walking, climbing stairs, or lifting objects triggers cells within the bone to lay down new bone material, strengthening the bone structure.

The body uses mechanical stresses as signals to determine where bone strength is needed; areas subjected to regular stress will increase in bone density as a protective mechanism. When there is a lack of mechanical stress due to inactivity or immobilization, the bones don't receive the necessary signals to maintain strength and start to lose mass. This is known as 'disuse osteoporosis'.

To maintain bone health, it's essential to apply a variety of stresses through different types of physical activities. Diverse and dynamic movements ensure that stress is distributed throughout different parts of the skeletal system, supporting overall bone health.