Final answer:
The strategy recommended to be employed only when all other strategies have proven ineffective is a therapeutic drug that inhibits osteoclast activity.
Step-by-step explanation:
In the context of reducing restraining forces, the strategy recommended to be employed only when all other strategies have proven ineffective is a therapeutic drug that inhibits osteoclast activity.
Inhibiting osteoclasts can help reduce bone resorption, which is an essential step in the breakdown of bone tissue. By inhibiting this process, the drug can help prevent further bone loss in conditions such as osteoporosis.