A branch of the wearable sensor research focuses on monitoring the human body joints movements to prevent injuries due to musculoskeletal disorders. Different types of sensors and technologies are used as a core of a smart joint monitoring system, one of these are optical fiber sensors. Optical fiber sensors are used to monitor joint angles with the main advantages to have a high resolution, a light-weight and to be flexible. For these reasons, they can be integrated into stretchable skin-tight fabrics to create a wearable joint monitoring system. In this thesis, a prototype developed by Mitsui Chemicals has been tested. The prototype is composed of a sleeve with 5 integrated optical fiber sensors placed medially, laterally, inside-medially and inside-laterally than the knee and above the patella.