This study will collect information on the long term health of joints in people with haemophilia A who have started treatment with Esperoct within twelve months prior to participation to the study. This study is conducted to look at how joint health of people with haemophilia changes over time when they are receiving the medicine Esperoct. The participants will get Esperoct as prescribed to the participants by the study doctor. The participant's treatment will not be affected by their involvement in the study. Every six months, the participants will be asked to answer some questionnaires about their joints, their pain and their ability to be physically active. Their participation in the study will last for no more than 2 years. The participants are free to leave the study at any time and for any reason. This will not affect their current and future medical care.