Multidimensional evaluation of the pain profile as prognostic factor in individuals with hip or knee osteoarthritis receiving total joint replacement: protocol of a 2-year longitudinal prognostic cohort study.

Introduction: Knee and hip osteoarthritis are two highly prevalent musculoskeletal pain conditions. Unsuccessful rates after hip/knee replacement range from 10% to 20%. Subjects with sensitisation manifestations are vulnerable to worse clinical outcomes. Most studies have analysed outcomes up to 1 year after surgery. The aim of this 2-year longitudinal study will be to evaluate sensory-related, psychological and psychophysical pain sensitisation manifestations and a potential epigenetic biomarker as prognostic clinical outcomes for the development of chronic postoperative pain after knee or hip replacement.

Methods And Analysis: A prospective longitudinal study with a 2-year follow-up period will be conducted. The prognostic variables will include pain, function, related-disability, anxiety, depression, quality of life, sensitisation-associated symptoms, kinesiophobia, neuropathic pain and catastrophising, and expectative of the intervention will be assessed before surgery. We will also evaluate the presence of the Val158Met polymorphism as a possible epigenetic marker. Clinical outcomes including pain, related-disability and self-perceived satisfaction, sensitisation-associated symptoms and neuropathic pain will be assessed 3, 6, 12, 18 and 24 months after surgery. These variables will be used to construct three prediction models: (1) pain and function, (2) sensitisation-associated symptomatology and (3) neuropathic pain features classifying those patients in responders and non-responders. Data from knee or hip osteoarthritis will be analysed separately. Statistical analyses will be conducted with logistic regressions.

Ethics And Dissemination: The study has been approved by the Ethics Committee of both institutions involved (Hospital Universitario Fundación Alcorcón (HUFA) 19-141 and Universidad Rey Juan Carlos (URJC) 0312201917319). Participants will sign the written informed consent before their inclusion. Study results will be disseminated through peer-reviewed publications and presentations at scientific meetings.