Chronic lower back pain (CLBP) presents a significant challenge in healthcare, requiring effective tools for rehabilitation and assessment. This study explores the use of virtual reality (VR) for the assessment of CLBP and addresses two research questions. Firstly, it investigates how movements and tasks considered problematic for individuals with CLBP can be incorporated into the VR application for assessment purposes. Secondly, it examines physiotherapists' perceptions of the VR application regarding tasks, feasibility, user experience, and overall design. To answer our questions, we conducted three design workshops with physiotherapists and HCI researchers and designed three VR applications that we evaluated with six physiotherapy students. The study provides valuable insights into participants' perceptions and experiences, shedding light on both the promising aspects and potential pitfalls of using VR in physiotherapy assessment. The findings underscore the value of incorporating user feedback into the design and implementation process, emphasizing the need for a user-centered approach, and provide several implications for the design of VR applications for assessment. This study lays the groundwork for the integration of VR as a valuable tool in physiotherapy assessment for CLBP.