Psychosocial factors have been advanced as an explanation for the development of chronic disability in 20 to 30% of patients treated by lumbar disc surgery.

Aims: The overall aim of this thesis was to study the role of psychosocial factors in patients undergoing first-time lumbar disc surgery in relation to the outcome of both surgery and subsequent physiotherapy.

Methods: Sixty-nine patients with lumbar disc herniation undergoing first-time disc surgery participated in the studies; in addition, Study I included 162 knee patients for comparison. Psychosocial factors were assessed preoperatively, as was the activation of the physiological stress response system. Pain, disabil-ity and quality of life were assessed before, and 3 and 12 months after surgery. Coping and kinesiophobia were analysed before and one year after surgery. The results of two different postoperative training programmes were compared.

Results: There were no differences between disc and knee patients regarding the presence of psychosocial stress factors preoperatively (Study I). Disc patients with low diurnal cortisol variability had lower physical function, perceived fewer possibilities to influence their pain and were more prone to catastrophise than patients with high diurnal cortisol variability (Study II). The results of clinic-based physiotherapy and home training did not differ regarding postoperative disability and pain 3 months after surgery. The home-based group had less pain and higher quality of life in comparison to the clinic-based group 12 months after surgery (Study III). Patients’ expectations of returning to work could best predict pain, disability, quality of life and sick leave one year after surgery (Study IV). Psychosocial factors were only weakly asso-ciated to pain, disability, quality of life and sick leave preoperatively. However, these associations were stronger in patients with residual pain one year after surgery.

Conclusion: Psychosocial factors and, in particular, patients’ expectations regarding outcome are associated with the results of lumbar disc surgery. Assessing psychosocial factors preoperatively and developing an active home training programme after surgery could create options leading to better results for these patients.