Kim 2007.

Methods	RCT stated Randomisation based on sequential pool derived from a table of randomised numbers Duration of study: 5.6 years
Participants	Inclusion and exclusion criteria not described Selection yielded bilateral procedures on 173 patients with osteoarthritis and on 1 patient with rheumatoid arthritis Korea: 174 patients (348 knees) 112 female, 62 male, age 67 (45‐85) years
Interventions	Fixed: PFC Sigma (DePuy) Mobile: PFC Sigma, rotating platform (DePuy) Routine patellar resurfacing All components cemented Flexion space with bone resection
Outcomes	KSS, HSS, alignment, component positions, radiolucent lines, lateral patellar tilt Only final, long‐term outcome (5.6 years) given Point estimates and ranges given
Notes	No benefits received from any commercial party No declarations of interest reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Sequential pool based on a table of randomised numbers
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Participant blinding not described; surgeon not blinded
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Outcome assessor blinded
Incomplete outcome data (attrition bias) All outcomes	High risk	Drop‐out rate given and acceptable; no intention‐to‐treat analysis
Selective reporting (reporting bias)	Unclear risk	No protocol available
Other bias	Low risk	Homogeneity in participant groups on prognostic factors; co‐interventions described in sufficient detail