A few years back in the winter we had a tremendous amount of snow. Going up on top of the roof is not fun in the middle of winter. I pushed more and more snow off the edge of the roof. When I was done doing that I came down the ladder thinking that I was on the last step of the ladder I stepped off and I twisted my knee as it hit a ceramic figurine under the snow. It tore the muscles so bad that it took months to recuperate. In the meantime I used a roll about walker to get around in the house. Once I was in the walker everything was fine. Getting on it with my problem took some time.