Recommended core outcomes regarding body structure, activity and participation are used. Primary outcomes: Participation in work life defined as days of sick-leave and participation in everyday life. Secondary outcomes will be patients' ratings of global treatment effects and pain intensity. Process measures: prognostic psychosocial factors possible to address in physical therapy such as functional self-efficacy, fear of movement and patient expectations on treatment effects. Depression, seen as a confounder, will be controlled for. Calculation of costs will include avoidable cost of the implementation, sunk costs will be ignored. Direct health care costs, i.e. use of health care services will be identified, measured and priced to assess costs from a societal perspective. Indirect costs, i.e. production loss due to sick leave and health care visits will be estimated. Cost-benefit will be calculated from the perspective of the society. Economic benefits will be measured as the net value of production gained for society, with an appropriate discount rate. Costs for society will be calculated on direct health care costs.