Ferdinand 2002.

Methods	Single‐centre RCT, bilateral CTS (each hand treated with each of the techniques)
Participants	25 participants (20 women, 5 men, mean age 54.9 years) with bilateral idiopathic CTS randomised to undergo ECTR to one hand and OCTR to the other. CTR was undertaken sequentially under the same anaesthetic
Interventions	1‐portal ECTR (Agee technique) vs OCTR
Outcomes	Follow‐up at 6 weeks, 3 and 6 months and 1 year Degree of resolution of symptoms, pain, tenderness (VAS), time of return to work, time of return to full activity, patient satisfaction
Notes	In 3 hands allocated to ECTR, a conversion to OCTR was required due to inadequate view intraoperatively
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomisation was by standard computerised methods to determine which side underwent endoscopy
Allocation concealment (selection bias)	Unclear risk	Method of concealment not described
Blinding of participants and personnel (performance bias) All outcomes	High risk	No information given. Participants and personnel could not be blinded.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	The participant concealed the wounds with adherent dressings before each assessment to ensure that the assessor continued to be blinded to the type of release which had been performed
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	In 3 hands allocated to ECTR, a conversion to OCTR was obtained due to inadequate view intraoperatively. However, there was no reference to ITT analysis
Selective reporting (reporting bias)	Unclear risk	No SDs were reported
Other bias	Unclear risk	The authors declare no benefits from commercial party It is not clear whether baseline differences occurred