Kirurgi-induceret traume efter total versus medial unicompartmental knæarthroplasty (SITA) (SITA)

Study participants will be adults (i.e. at least 18 years old) who have diagnosis of KOA with an indication for primary Total Knee Arthroplasty (TKA).

The choice between TKA and UKA is based on the radiological presentation of the knee KOA on an x-ray. A surgery with TKA involves the replacement of both the medial and lateral compartments of the knee.

Study participants will be adults (i.e. at least 18 years old) who have diagnosis of KOA with an indication for primary medial Unicompartmental Knee Arthroplasty (UKA).

The choice between TKA and UKA is based on the radiological presentation of the knee KOA on an x-ray. A surgery with UKA involves the replacement of one compartment.

Marker of systemic inflammation and soft tissue injury

Marker of systemic inflammation and soft tissue injury

Marker of systemic inflammation and soft tissue injury

Marker of systemic inflammation and soft tissue injury

Marker of systemic inflammation and soft tissue injury

Marker of systemic inflammation and soft tissue injury

Marker of systemic inflammation and soft tissue injury

Marker of systemic inflammation and soft tissue injury

Marker of systemic inflammation and soft tissue injury

Marker of systemic inflammation and soft tissue injury

Marker of systemic inflammation and soft tissue injury

Marker of systemic inflammation and soft tissue injury

Marker of systemic inflammation and soft tissue injury

Marker of systemic inflammation and soft tissue injury

Marker of systemic inflammation and soft tissue injury

Marker of systemic inflammation and soft tissue injury

The time from when the surgeon of record starts the procedure until he/she leaves the procedure.

This information will be collected from the patient's medical record.

Postoperative x-rays of the knee are performed routinely in order to evaluate whether implants are placed in accordance with recommendations.

Pain assessed using the visual analogue score (VAS) following surgery. The Scores go from 0-10. 0 = no pain. 10 = the most pain. The patients indicate how their pain during the last 24 hours fit in to the scale.

Both preoperative and postoperative requirement of analgesia will be noted. Analgesia requirement will include Paracetamol, NSAID, Acetylic Acids and Opioids. Type of anaesthesia/sedation used during surgery will in addition be recorded. The above information will be collected from the patient's medical record.

Complications which happens during surgery.

The patients are expected to be discharged on day 1 post-surgery after a blood sample is taken at 24 hours post-surgery. It will be recorded if a patient is not able to be discharged at this time and for how many days the admission will last. The number of readmissions within 90 days of surgery and the reason for re-admission will also be recorded. This information will be collected from the patient's medical journal.

Complications (both medical and surgical) arising within 90 days of surgery will be recorded. The information will be collected from the patient's medical records.

Complications includes myocardial infarction/cardiac events, cerebrovascular events, venous thromboembolism, deep infection, reoperation, revision, and death.

Any revisions in patients within 24 months will be recorded. The reason for revision and the type of revision will be noted. The information will be collected from the patient's medical records.

The Pain Catastrophizing Scale (PCS) is a 13-item patient reported outcome measure developed to evaluate catastrophic thinking related to pain. Standardized answer options are given through a 5-point Likert scales, from 0 (not at all) to 4 (all the time). Higher scores indicate higher level of catastrophizing. A total score yielding (ranging from 0-52), along with three subscale scores assessing rumination, magnification, and helplessness.

The PDQ is a patient administered questionnaire used to assess the likelihood of a pain experience being of neuropathic origin.

The Oxford Knee Score (OKS) is a 12-item patient reported outcome questionnaire developed specifically to assess the patient's perspective on the outcomes of knee arthroplasty with respect to combined pain and physical function. Standardized answer options are given (5 Likert boxes) and each question is assigned a score from 0 to 4. Thus, a total score is calculated from 0 to 48, with 48 indication the best outcome. The OKS is short, practical, reliable, valid, and sensitive to clinically important changes over time18.

The Forgotten Joint Score was designed to assess patient outcome in patients undergoing conservative or operative treatment of the knee, and it analyses patient's ability to forget about a joint as a result of successful treatment. The questionnaire consists of 12 questions that are equally weighted and measure patient satisfaction. Standardized answer options are given (6 Likert boxes). Scores are summed to create a composite score that is converted to a 100-point scale. Higher scores indicate greater satisfaction.

EQ-5D-5L is a standardized patient-reported instrument for measurement of health outcome and quality of life. EQ-5D-5L is designed for self-completion by respondents and is ideally suited for use in surveys. The EQ-5D-5L consists of 2 pages - the EQ-5D-5L description system and the EQ Visual Analogue Scale (EQ VAS). The descriptive system comprises 5 dimensions (mobility, self-care, usual activities, pain/discomfort, and anxiety/depression). Standardized answer options are given (5 22.12.2022 Page 17 of 30 Likert boxes) and each question is assigned a score from 1 to 5. Instructions to respondents are included in the questionnaire. The EQ VAS records the respondent's self-rated health on a 20 visual analogue scale with endpoints labelled "the best health you can imagine" and "the worst health you can imagine". This information can be used as a quantitative measure of health judged by the individual respondents.

One question regarding PASS will be used to assess how many patients consider themselves well after surgery (as opposed to feeling better). PASS is assessed as a dichotomous outcome (yes/no) to the question:"Taking into account all the activities you have during your daily life, your level of pain, and also your functional impairment, do you consider that your current state is satisfactory?". The actual question asked will be in Danish (Appendix G).

We will define treatment failure in two ways:

1. Patients replying 'no' to the PASS question (above) will be asked to answer (yes/no) the following question: "Would you consider your current state as being so unsatisfactory that you think the treatment has failed?" Patients replying, 'yes' to this second question will be defined as experiencing 'treatment failure' (TF).
2. Patients who during the observation period undergo revision surgery are defined as TF. We will seek information about the reason for revision surgery (e.g. infection, malalignment, loosening/lysis, implant wear, dislocation/instability, stiffness, pain, and other reasons) in the medical records.