Knowing your musculoskeletal anatomy is the absolute fundamental when it comes to diagnosing injury, building rehabilitation programs and assessing what / who needs to be involved in creating a comprehensive healing plan for the client. If you struggle with this, study it relentlessly. If you are not sure how to apply this knowledge, go mentor under someone who does. If you are not getting the results you intend for your client, go find someone who can help.
Once you learn how the body operates, you will then understand what it is that is injured / damaged when the body isn’t operating as it should.