On a Friday evening last April, I stood up from my sofa to walk into another room. As I did, I caught my foot on a piece of furniture, and was catapulted into the air, falling and landing hard on my left shoulder. I knew as soon as it happened that it was a bad injury. At first, I could not sit up and I could not move my arm. I had to hold it close to my body with my other hand. The pain was intense.