European Vertebral  Deviations Center - Clinique du Parc - Lyon (France)  - The Lyon Method  Scientific Evidence

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Scientific Evidence

Scientific evidence is evidence that serves to either support or counter a scientific theory or hypothesis. Such evidence is expected to be empirical evidence and interpretation in accordance with scientific method. Standards for scientific evidence vary according to the field of inquiry, but the strength of scientific evidence is generally based on the results of statistical analysis and the strength of scientific controls. (Wikipedia)

Statistical analysis is used throughout biomedical research and elsewhere to assess strength of evidence. Observations of real outcomes obtained by observational study, are used to help discriminate between different mechanisms.

A prospective cohort study is a longitudinal cohort study that follows over time a group of similar individuals (cohorts) who differ with respect to certain factors under study, to determine how these factors affect rates of a certain outcome. (Wikipedia) they are a longitudinal observation over time, and the collection of results is at regular time intervals, so recall error is minimized.

Some definitions of the evidence of the Lyon Method

Prospective. A prospective study poses its questions before any patients are treated. Stated another way, a prospective study begins before the clinical outcomes of interest have occurred, and before any data are recorded. Our prospective database started in 1998, when the KINESIS digital database was used simultaneously in France and Italy. Secondary databases were created each time technological advances were integrated, for example the use of ARTbrace in 2013.

Consecutive. The correct usage of this word describes the enrolment into a study of all patients for a particular diagnosis during a defined period of time. Used correctly, the term conveys that selection bias did not affect the decision of which patients to include. Since May 2013, when ARTbrace was created, the old Lyon brace preceded by plaster cast has been systematically abandoned in favour of the new ARTbrace. There is no patient selection bias.

Significant. In its purest statistical sense, a finding is significant when a statistical test rejects a claim of no difference between groups, the null hypothesis, at a certain level of probability, the p value. The p value estimates the probability that an effect as extreme as that observed might have occurred by chance only. Most orthopaedic studies are small, with borderline significance. The specialization of the "European Center of the Spine" in the field of the treatment of vertebral deformations in France and Italy with more than 25,000 patients in our database allows to have the most important samples ever published.

A master protocol is a comprehensive protocol created for evaluating multiple hypotheses of sub-studies that are concurrently conducted. The master protocol for the Lyon treatment of vertebral deformities has not been modified for 50 years: inclusion criteria, total time, part time, weaning, physiotherapy, follow up... The only modifications concern the integration of technological advances such as treatments in day hospital, CAD / CAM systems which have replaced the traditional plaster cast, the use of new high-rigidity materials such as polyamide 6  It is therefore much easier to follow the impact of these new technologies on the final result of the treatment. The ARTbrace management protocol has not been modified since its creation.

A quasi-experiment is an empirical interventional study used to estimate the causal impact of an intervention on target population without random assignment. The integration of new technologies: EOS x-rays from 2010, 4 columns CAD / CAM sensors from 1990, Polyamide 6 high rigidity from 2013, were done without the need for randomization. Statistical real-time monitoring allowed us to immediately see the positive effects of this new technologies on the treatment results.


Leopold SS. Editorial: Words and meaning in scientific reporting: consecutive, prospective, and significant. Clin Orthop Relat Res. 2013;471(9):2731–2732. doi:10.1007/s11999-013-3162-9

J. Woodcock, L.M. LaVange. Master protocols to study multiple therapies, multiple diseases, or both. N. Engl. J. Med., 377 (1) (2017), pp. 62-70

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  The website has been updated for the last time on  February 17 2020