Why is it important for a client to avoid using someone else's crutches?

Using someone else's crutches can pose significant risks primarily because they may not fit properly. Crutches are designed to be adjusted according to an individual's height and specific needs. If they are the wrong size, this improper fit can lead to ineffective use, which could increase the risk of falls or further injury.

Additionally, using incorrectly fitted crutches can lead to improper posture and gait, potentially causing discomfort or strain on other parts of the body, such as the wrists, shoulders, and back. It’s crucial for crutches to be appropriately adjusted to provide the necessary support and to promote a safe and effective mode of ambulation for the individual using them.

The other options, while they might hold some merit, do not highlight the most pressing concern regarding safety and efficacy with using assistive devices like crutches.