Why does osteoporosis happen after SCI?

Author: SCIRE Community Team | Reviewer: B. Catharine Craven | Published: 11 October 2017 | Updated: 14 March 2019

Spinal cord injury can affect the body in a number of different ways that contribute to osteoporosis. These changes may include:

Spinal cord injury affects many different systems in the body. Changes in the immune, hormone, circulatory, and nervous systems after SCI contribute to weaker bones after SCI. The role of these factors is not fully understood.

Weight-bearing activities, like standing and walking, place forces through the bones of the legs and hips that stimulate the bones to become stronger. When a person spends less time standing and more time sitting, the bones experience fewer forces and adapt by becoming less dense and weaker.

Foods containing calcium and vitamin D help maintain bone strength.^3-6

Because muscles are connected to bones by tendons, the repeated pulling of muscles on bones during movement stimulates the bones to become stronger. When muscles become weak or paralyzed, the muscles atrophy and the muscles and bones nearby have fat deposited in them and there are not as many forces applied to the bones.

Physical activity and nutritional habits can also influence the bones. After SCI, rates of physical activity, which can help to strengthen bone, are often lower than in people without SCI. In addition, changes in nutritional habits, such as reduced calcium and vitamin D intake can also contribute to low bone density after SCI.