Jacobs 2011.

Methods	RCT, multi‐centre Computer‐generated block‐stratified randomisation Duration of the study: 1 year
Participants	Inclusion: patient diagnosed with osteoarthritis; candidate for primary TKA; expected to undergo only 1 arthroplasty procedure within next 12 months; 60–75 years old; preoperative alignment (varus or valgus) < 10 °; BMI < 30; lives independently Exclusion: missing/insufficient PCL The Netherlands/Switzerland: 92 participants Fixed: n = 46, 32 female, age 67.6 (± 4.4) years Mobile: n = 46, 33 female, age 66.7 (± 4.6) years
Interventions	Fixed: balanSysTM type (Mathys Medical Ltd) Mobile: balanSysTM type (Mathys Medical Ltd) No patellar resurfacing Tibia and femur components cemented
Outcomes	Active flexion, KSS function, KSS clinical Assessments: preoperative and at 3 months, 6 months and 12 months Average and standard deviation given
Notes	Funded by Mathys Medical Ltd No declarations of interest reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated block‐stratified randomisation
Allocation concealment (selection bias)	Low risk	Closed envelopes
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Participant blinded; surgeon not blinded
Blinding of outcome assessment (detection bias) All outcomes	High risk	No blinding attempted at any of the assessments
Incomplete outcome data (attrition bias) All outcomes	High risk	1 centre with 30 participants was excluded from analysis because of randomisation error; no intention‐to‐treat analysis
Selective reporting (reporting bias)	Low risk	Protocol available and prespecified outcomes reported
Other bias	Low risk	Homogeneity in participant groups on prognostic factors; co‐interventions described in sufficient detail