This is a multi-centre prospective cohort study with 140 participants. Eligible patients with moderate/severe symptomatic knee osteoarthritis will be identified at hospital outpatient clinics. A baseline assessment will provide a comprehensive description of the somatosensory characteristics of each participant by means of clinical examination, quantitative sensory testing and validated questionnaires measuring pain and functional capacity. Participants will then undergo physiotherapy treatment, in line with current clinical guidelines. Follow-up post physiotherapy treatment (estimated to be at 3 months) will assess pain, disability (sub-scales of Western Ontario and McMasters University Score Osteoarthritis Index) and participants' global rating of change. These primary outcome measures will dichotomise participants into treatment 'responders' and 'non-responders' according to the Osteoarthritis Research Society International (OARSI) treatment responder criteria.