Why do you think wheelchair-bound people with paralyzed lower limbs have thin, weak bones of the leg and thigh?

Verified step by step guidance

1. Understand the concept of Wolff's Law, which states that bone grows and remodels in response to the forces that are placed upon it.
2. Recognize that in individuals with paralyzed lower limbs, there is a lack of mechanical stress and weight-bearing activity on the bones of the legs and thighs.
3. Explain that the absence of these forces leads to decreased bone density and strength, a condition known as disuse osteoporosis.
4. Discuss how the lack of movement and muscle contraction in the lower limbs contributes to reduced stimulation of bone-forming cells, known as osteoblasts.
5. Conclude that the combination of these factors results in thinner, weaker bones in the legs and thighs of wheelchair-bound individuals with paralyzed lower limbs.

Key Concepts

Bone Density and Weight-Bearing Activity

Bone density is the measure of the amount of mineral matter per square centimeter of bones. Weight-bearing activities stimulate bone formation and maintain bone density. Individuals who are wheelchair-bound often lack the mechanical stress that comes from walking or standing, leading to decreased bone density and resulting in thin, weak bones.

Disuse Osteoporosis

Disuse osteoporosis is a condition where bones lose density and strength due to lack of physical activity. In wheelchair-bound individuals, the absence of regular weight-bearing movements can lead to accelerated bone loss, particularly in the lower limbs, making bones more susceptible to fractures and deformities.

Muscle Atrophy and Its Impact on Bone Health

Muscle atrophy refers to the wasting or loss of muscle tissue, which can occur when muscles are not used regularly. Since muscles exert forces on bones, the reduction in muscle mass and strength in wheelchair users can contribute to bone weakening, as the lack of muscle activity diminishes the signals that promote bone maintenance and growth.