Multiple factors are important for the functional and health-related quality of life (HRQoL) assessment of patients with lumbar degenerative disc disease (DDD), both before and after surgical treatment. The surgeon's experience and background as well as a detailed analysis of both intrinsic and environmental factors constitute the cornerstones of the pre-operative evaluation and help to determine the optimal surgical treatment, tailored to the individual patient requiring lumbar spine surgery (LSS). In the era of evidence-based medicine and increasing demand for quality control, the worldwide trend is to use standardized methods such as questionnaires and scores to assess the functional impairment of patients scheduled for LSS, as well as for the outcome assessment after treatment. Nowadays, the tools most widely used in daily clinical practice include the Oswestry Disability Index and the Roland-Morris Disability Index to assess functional outcome, as well as the Short-Form 36 or 12 and EuroQol-5D to assess HRQoL, besides additional measures including the Visual Analogue Scale to measure back and leg pain intensity. All these assessment tools are, however, highly subjective in their nature. Currently, the perioperative assessment lacks objective standardized measures. We therefore introduced the Timed Up and Go (TUG) test to measure objective functional impairment (OFI) in patients with lumbar DDD. The TUG test evaluates basic but nonetheless important functions such as standing up, ambulating, changing direction, ambulating again and seating oneself. These are fundamental functions for patients to recuperate their activities of daily living and regain HRQoL after LSS. Moreover, the TUG test is fast and simple to perform, as it only necessitates an armchair and 3 meters of walking space. The goal of this project is to compare the TUG test with established patient reported outcome measures, to demonstrate that the TUG test is a useful tool to evaluate OFI in patients with lumbar DDD, as well as to establish its relationship to different patient-specific and radiological parameters, e.g. sex, age, body mass index, mental and smoking status, as well as Pfirrmann disc and Modic endplate degenerative changes scores.