Table 2.

Comparison between the 2 fundamental studies of the project

Application of Lean Six Sigma Tools to Orthopaedic Surgery
	First Study	Second Study
Type of intervention	Hip replacement surgery	Knee replacement surgery
# patients before improvements	79	131
# patients after improvements	48	87
Analysis period before improvements	Jun 2011 to Dec 2012	Jun 2011 to May 2013
Analysis period after improvements	Jan 2013 to Dec 2013	Jan 2014 to Dec 2015
Define phase	•Project chart	•Project chart
	•SIPOC diagram	•Gantt chart
		•Input process output (IPO) diagram
Measure phase	•Run chart	•Shapiro‐Wilk and statistical tests
	•Run tests	•Run chart
		•Run tests
Analysis phase	•Value Stream Map	•Value Stream Map
	•Brainstorming	•Brainstorming
	•Ishikawa fishbone	•Interview with health care professional
Improve phase	•Activation pre‐hospital service	•Simplification of complex bureaucratic procedures
	•Simplification of complex bureaucratic procedures	•Standardization of the patient discharge process
	•Standardization of the patient discharge process	•Promotion of the health care information system through meetings
		•Information activities for the clinical staff
Control phase	•Student's t test for comparative analysis	•Mann‐Whitney U test for comparative analysis
	•Periodical review meetings	•Periodical review meetings
	•Internal auditing	•Internal auditing
	•Periodical updates of the run chart	•Periodical updates of the run chart
Length of stay reduction (%)	44	42