Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	“Consecutive cases from each clinical population were randomly assigned to treatment by FLEK or by PK. The randomization code was generated using a permuted block size of 2.”
Allocation concealment (selection bias)	High risk	Allocation cannot be concealed with a block size of 2
Blinding of participants (performance bias)	Unclear risk	Not specified
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not specified
Incomplete outcome data (attrition bias) All outcomes	High risk	“In the FLEK group, four patients did not receive the allocated treatment due to significant preoperative events and were eventually excluded from the study analysis. All patients in the PK group received the allocated treatment.” The proportions lost to follow-up were not low: 29/40 in FLEK group and 39/40 in PKP group and the study investigators did not perform intention-to-treat analysis
Selective reporting (reporting bias)	Unclear risk	Protocol not available
Other bias	Low risk	No other source of bias identified