Based on what you write, it does not appear the health insurer or medical supply company would be liable for your injuries. First, your question indicates that you fell before seeking the crutches, and clearly they are not liable for that. Second, even if you fell after seeking them, they did not cause the falls and you cannot prove that you would not have fallen if you had crutches, so you cannot establishe their fault. You also cannot estabish their liability because someone is only liable for the reasonably foreseeable consequences of their acts or omissionsm, and the injuries you describe are not reasonably foreseeable. Finally, you could have taken reasonable steps yourself to get crutches faster if you needed them, such as buying or renting a pair from a surgical supply store; you chose to wait for them by mail when you did not have to, and cannot hold others liable for your choice.