###### Abstract  
The authors offer their perspective on the application of Lean Six Sigma methodology to surgical pathways, from referral to post-operative rehabilitation, and how it has resulted in sustainable improvements in patient outcomes, and patient and staff satisfaction. The origin of Lean Six Sigma is described before considering its application to improving scheduled surgical care. The concept of 'flow', and its relevance to pre-, intra-, and post-operative care, is discussed as well as the role of Lean Six Sigma in supporting innovation and in promoting an organizational culture that promotes openness to new ideas. The elements of the methodology that render it especially suitable for the redesign of surgical pathways include eliciting the customer voice, co-design, enabling system awareness and inculcating a continuous improvement mindset. The necessary conditions for the successful implementation of Lean Six Sigma initiatives include managerial support, high-quality education and training, and alignment with organizational strategy. Future directions for practice and research are discussed before presenting a key finding from the literature and from the authors' collective experience: Lean Six Sigma initiatives will not lead to sustainable improvements where the key elements of the methodology are not recognized and enacted, and where the necessary conditions are absent. lean; six sigma; surgery; pre-operative; peri-operative; recovery; rehabilitation +
Footnote †: journal: _Sciences_  
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opportunities and challenges for health services staff [6]. These challenges can vary widely across different countries and regions, and require context-specific solutions and strategies to address them effectively. One key area of healthcare that presents an enduring challenge is scheduled (or planned) surgery; problems include timely patient access to surgery and the availability of surgery-designated beds [7]. The issue of long waiting times for scheduled surgeries is not a recent phenomenon but it has been exacerbated by the COVID-19 pandemic [8]. A recent study estimated that worldwide, 28.4 million surgeries were either postponed or cancelled during the peak of COVID-19 disruption [9]. Lengthy surgical waiting times have been shown to adversely affect patients, both psychologically, through increased pre-operative anxiety, stress, frustration, and anger [10], and physically, through poorer pre-operative quality of life and reduced physical functioning [11]. [PERSON] described healthcare organisations as the most complex form of human organisation to manage [12], suggesting that the complexity derives in part from the confluence of clinicians (e.g., doctors, nurses, and other health and social care professionals) and other stakeholders (e.g., patients, relatives, and other health system professions and occupations), often with seemingly incompatible perspectives and competing timelines. A surgical patient's journey from initial consultation and diagnosis to actual surgical intervention and rehabilitation reflects the complexity [PERSON] highlighted, relying on an intricate interplay of clinical and administrative processes that support the work of surgeons and the wider multidisciplinary team [13]. [PERSON]'s seminal work explored conceptual frameworks that can be usefully brought to bear on process improvement [14]. [PERSON] and [PERSON], in a review of the empirical literature on Lean Six Sigma, found that it is one of the most frequent continuous improvement methodologies used for process and quality improvement in hospitals today [15]. The authors of this paper include qualified Lean Six Sigma practitioners and healthcare professionals with over 30 years' experience with backgrounds in nursing, physiotherapy, biotechnology, architectural healthcare design, and healthcare research and education. Additionally, authors 1 and 4 have extensive clinical and managerial experience in the areas of peri-operative and post-operative care and rehabilitation.