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

Does Surgery-Induced Trauma Influence Postoperative Safety and Outcome Comparing Total vs. Medial Unicompartmental Knee Arthroplasty (SITA): A Prospective Cohort Study

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.

Inclusion Criteria:

• Age 18 or more
• A clinical and radiological diagnosis of knee OA
• Candidate for spinal anaesthesia
• signed informed consent

Exclusion Criteria:

• Planned surgery within the observation period other than KA
• Any contraindications to the use of torniquet during surgery
• Any contraindication to the administration of pre-operative dexamethasone
• KA indication due to sequelae of e.g. fracture(s)
• Previous infection of the target knee joint
• Injection of medication or substances in the target knee within 3 months prior to participation
• Immuno-inflammatory arthritis as cause of knee OA
• Known autoimmune and/or inflammatory disease e.g. colitis ulcerosa
• Active cancer diagnosis with ongoing treatment
• Current systemic treatment with glucocorticoids equivalent to > 7.5 mg prednisolone/day
• Surgery requiring spinal/general anaesthesia within the last 3 months prior to inclusion
• Infection requiring medical/surgical treatment within the last 4 weeks prior to surgery for KA
• Neurological dysfunction compromising mobility
• Inability to understand or read Danish incl. instructions and questionnaires
• Any other condition or impairment that, in the opinion of the investigator (or his/her delegate), makes a potential participant unsuitable for participation or which obstruct participation.