Neuroinflammation and Cognitive Dysfunction After Orthopedic Surgery

Inclusion Criteria: * ASA Physical Health Class 1-4 * Age 50-85 years * Fluent in Swedish language * Scheduled for primary hip replacement surgery due to arthrosis * MMSE (minimental state test score \>= 25. Exclusion Criteria: * Patient refusal to participate in the trial * Current autoimmune disease, including arthritis * Ongoing smoking, snuff or other nicotine compound treatment * Significant neurologic or psychiatric disorder (such as Alzheimer's disease, Parkinson's disease, Multiple sclerosis, schizophrenia, depression, diagnosis of dementia or cognitive impairment as defined by a preoperative MMSE score ≤ 24 * History of stroke with neurological sequelae. * Current severe cardiac (NYHA\>IV) or renal (plasma creatinine\> 0.250 mmol/l) Coagulopathy making spinal anesthesia and intrathecal catheter placement impossible * Terminal phase of a chronic disease. * Patient on chronic steroidal therapy * Poorly controlled diabetes mellitus. * Presumed uncooperativeness or legal incapacity.