The increase of end-stage osteoarthritis (OA) in an increasingly younger population is directly correlated with the rising incidence of obesity. As a result, knee arthroplasty (KA), which is a definitive end-stage treatment option, is increasingly performed on working age people. Knowledge and understanding of the underlying factors that drive the ability for people to return to work is crucial.

First and foremost, the investigators would have like to have a clear idea of the percentage of patients who return to work and at what time postoperatively. The investigators would also determine the different factors influencing employment in the patient population after undergoing a knee arthroplasty and register the evolution in the necessity of pain medication pre-and postoperatively. Ideally, the investigators can include a short questionnaire regarding return to sports to gather valuable information.

The increase of end-stage osteoarthritis (OA) in an increasingly younger population is directly correlated with the rising incidence of obesity. As a result, knee arthroplasty (KA), which is a definitive end-stage treatment option, is increasingly performed on working age people. Knowledge and understanding of the underlying factors that drive the ability for people to return to work is crucial.

First and foremost, the investigators would have like to have a clear idea of the percentage of patients who return to work and at what time postoperatively. The investigators would also determine the different factors influencing employment in the patient population after undergoing a knee arthroplasty and register the evolution in the necessity of pain medication pre-and postoperatively. Ideally, the investigators can include a short questionnaire regarding return to sports to gather valuable information.

Adult patients with an indication for primary knee arthroplasty (total + unicondylar) can take part in the study. This will be decided by clinical examination and radiographic evaluation, having the result of the previous therapies and the patient-specific needs in mind (standard of care). The patients have to be younger than or equal to 63 years old at the time of surgery and actively been working 2 years prior to surgery.

In line with the standard of care, the patients will be seen after 4-8 weeks, 3-4 months and 1 year postoperatively. Radiological examinations are foreseen at 4-8 weeks and 1 year postoperatively (standard of care). Pre-operatively, a general questionnaire is filled in by the patients. The patient questionnaires Knee Society Score (KSS), Knee Injury and Osteoarthritis Outcome Score (KOOS), Forgotten Knee Joint Score, Quickscan, Work, Osteoarthritis and joint-Replacement Questionnaire (WORQ) will be filled in by the patients during the screening visit and on each consultation at 4-8 weeks, 3-4 months, 6 months, 1 year and 1,5 year. The Tegner score will be filled in by the patients pre-operatively and at 1 year postoperatively.

Inclusion Criteria:

• Informed consent
• Primary knee arthroplasty (total + unicondylar)
• Patients younger than or equal to 63 years old at the time of surgery
• Actively been working 2 year prior to surgery.

Exclusion Criteria:

• No informed consent
• Revision surgery
• Patients older than 63 years of age at the time of surgery
• Patients who haven't were unable to work due to other, non-knee related, health issues