Clinical Research Directory

Inclusion Criteria: * Group A: persons judging themselves to be of good subjective health without any knee problems, aged 35-65 years * Groups B\&C: participant in MAC registry, completed patient reported-outcome measurements (PROM) questionnaires at 2y or 5y within the last 6 months, aged 35-65 years, unilateral knee surgery (another side as internal control), B1/C1: the normal group is defined as patients closely around the median COMI scores of their respective group (determined medians are: 2yr females: 0.9 / 2yr males: 0.7 / 5yr females: 0.5 / 5yr males: 0.5), B2/C2: the poor outcomes group consists of patients with scores ≥ 2. * Group D: patient booked for TKA due to severe OA, aged 35-75 years Exclusion Criteria: * inability to give consent or follow procedures * no understanding of German language * open wounds or tissue injuries * irritated or infected sections on the limbs * Class II obesity defined by Body Mass Index (BMI) ≥ 35 kg/m2 (comorbidities associated with obesity should be investigated in future studies) * uncooperative patients who disregard or cannot follow instructions, including those who abuse drugs and/or alcohol * Pregnant or with intention to get pregnant (x-rays) * Current address outside of Switzerland * Groups B\&C: revision surgeries at the operated knee, death, known pathologies or former injuries of the comparator knee