Surgery Induced Trauma After Total Versus Medial Unicompartmental Knee Arthroplasty (SITA)

Osteoarthritis (OA) is the most common type of arthritis, characterized by pain and physical disability. More than 10% of persons \> 55 years have symptomatic OA, primarily involving the knees. Knee arthroplasty is considered a successful orthopaedic procedure in progressed knee OA (KOA) with severe pain and disability where non-surgical treatments have been tried. It has long been recognized that injury to the body, either from trauma or surgery causes an inflammatory response. As TKA is considered a more invasive procedure compared with UKA, TKA and UKA may not trigger inflammatory reactions of the same magnitude. Differences in inflammatory response between TKA and UKA could help explain why differences in outcome are present, despite both procedures being technically successful. Even though knee arthroplasty is a very common and successful procedure, there are no existing studies comparing the invasiveness of TKA and UKA. As morbidity and mortality rates differ between the groups, the aim of this prospective cohort study is to investigate whether the post-operative inflammatory responses differ between TKA and UKA, and secondarily whether this difference can explain the difference in outcome between the two procedures. The investigators hypothesize that TKA generates a larger postoperative systemic inflammatory response compared with UKA due to more extensive periarticular soft tissue and bone trauma. The study's primary outcome is C-reactive Protein (CRP) measured in blood 24 hours after surgery (22-26 hours after surgery \~ day 1). Participants which are candidates for either a TKA or a UKA will through serial blood test measurement have their postoperative systemic inflammatory response measured. This further will be correlated to the clinical and functional outcomes over a 2-years postoperative follow-up period.