INTRODUCTION: Evidence based medicine (EBM) is frequently used as the basis for clinical guidelines and reimbursement recommendations. The hierarchy of evidence is: Level I - randomized controlled trials (RCTs); Level II - nonrandomized cohort studies; Level III - case control studies, Level IV - case series, and Level V - expert opinion. RCTs are generally required when developing clinical guidelines or reimbursement recommendations for drugs. OBJECTIVES: The purpose of this case review is to illustrate an application of EBM to an innovative surgical procedure and highlight how the recommendations for use changed with new evidence. METHODS: NICE guidelines for arthroscopic surgery for femoro-acetabular impingement were reviewed. This case study was selected because the treatment modality represents a new surgical technology in which guidelines for coverage recommendations, first promulgated in 2007, were later changed in 2011, illustrating the impact of additional evidence generation. RESULTS: In 2007, efficacy evidence considered by NICE were two case series, with 158 and 10 patients respectively. In 2011, efficacy evidence considered by NICE covered 1126 patients from 3 non-randomized controlled studies (none compared with natural history or non-arthroscopic surgical techniques), 5 case series (with 100 to 200 hips), and 1 case report. Twenty-two smaller case series were also identified. In 2011, four out of five specialist advisors viewed the procedure as established while one advisor considered the efficacy and safety still to be uncertain. In 2007, NICE concluded “current evidence … does not appear adequate for this procedure to be used without special arrangements for consent and for audit or research” while in 2011 NICE concluded “current evidence…..is adequate in terms of symptom relief in the short and medium term.” CONCLUSIONS: For innovative surgical procedures in the UK, non-randomized controlled studies and case series, supported by specialist recommendation, may be sufficient for a positive recommendation by NICE.