<p>Povratak na posao nakon operacije lumbalne diskus hernije determinisan je funkcionalnim stanjem, prisustvom i stepenom tegoba od strane lumbosakralne kičme, zahtevima na radnom mestu bolesnika ali i psihosocijalnim faktorima, koji pri oceni radne sposobnosti zaposlnih zahtevaju individualni pristup. Grupa pacijenata koja se neće vratiti na posao može biti identifikovana putem prognostičkog modela. Cilj ove studije je definisanje prognostičkog modela za povratak na posao bolesnika operisanih zbog lumbalne diskus hernije kao i identifikacija najznačajnijih faktora rizika odgovornih za lo&scaron; ishod operativnog lečenja, posmatrano kroz prizmu povratka na posao. Istraživanje je prospektivna studija koja je obuhvatila ukupno 200 ispitanika, koji su operisani zbog lumbalne diskus hernije na jednom nivou i praćeni su u vremenskom period do 12 meseci nakon operativnog lečenja. U statističku ananlizu je u&scaron;lo 153 bolesnika, koji su ispunili kriterijume selekcije ispitanika studije. Nakon određivanja značaja posmatranih biolo&scaron;kih, profesionalnih i psihosocijalnih faktora rizika za povratak na posao, kreirani su i evaluirani prognostički modeli bazirani na svim i na odabranim atributima desetostrukom kros-validacijom: stablo odlučivanja (DT), model vi&scaron;eslojnih perceptrona (MLP) i model potpornih vektora (SVM). Za predviđanje povratka na posao najveću tačnost, specifičnost i senzitivnost za odabrane atribute postiže model potpornih - podržavajućih vektora (SVM). Najbolju intuitivnu i praktičnu vrednost za predviđanje povratka na posao pruža model stabla odluka (DT). Identifikacijom najznačajnijih faktora rizika za nepovoljan ishod povratka na posao omogućeno je preventivno delovanje na iste, u cilju smanjenja broja pacijenata sa umanjenjem radne sposobnosti i invaliditeta.</p> / <p>Return to work after lumbar discectomy is determinated by functional status, presence and degree of discomfort in the lumbosacral spine, the requirements in the workplace of patients and psychosocial factors that in the assessment of working capabilities require an individual approach. Groups of patients which don&rsquo;t return to work after surgery could be identified by predictive model. The aim of this study is to define prognostic model to return to work patients after lumbar discectomy, as well as the identification major risk factors responsible for the poor outcome of operative treatment viewed through the prism of returning to work. This prospective study included a total of 200 patients, who underwent surgery for lumbar disc herniation on one level and were followed up in period of 12 months following surgery. The statistical analysis included 153 patients who fulfilled all selection criteria of the study subjects. After determining significance of the observed biological, professional and psychosocial risk factors for return to work, prognostic models were designed and evaluated based on all and selected attributes by tenfold cross-validation: decision tree (DT) model of multilayer perception (MLP) model and support vector (SVM). For the prediction of return to work best accuracy, specificity and sensitivity for selected attributes, is achieved by supporting vector model (SVM). The decision tree model (DT) provides the best intuitive and practical value for predicting return to work. By identifying the most important risk factors for adverse outcome for return to work it is made possible for preventive actions, to reduce the number of patients with reduced work ability and disability.</p>

Ce travail de thèse a pour but l’étude des douleurs de dos qui surviennent chez l’astronaute présentant davantage de hernies discales par rapport à une population contrôle. Nos recherches visent à comprendre la physiopathologie de ce phénomène et à étudier les conséquences cliniques de ce déconditionnement vertébral qui participe également aux troubles posturaux. Cet axe de recherche est recommandé par les différentes agences spatiales internationales. Pour cela nous avons eu l’opportunité d’analyser les données dans deux modèles d’études des effets de la microgravité : l’immersion sèche (n=11) et l’alitement tête déclive (n=9) et un état analogue, le confinement (n=4). Seuls les principaux résultats de l’immersion sèche, méthode d’étude nouvelle de notre paradigme, sont rapportés dans ce résumé. Celle-ci a permis grâce à l’imagerie et la spectroscopie par résonnance magnétique nucléaire de la colonne vertébrale, d’analyser en 3 dimensions le disque intervertébral et d’objectiver l’augmentation du contenu en eau (+17%) du volume de ce disque (+9,5%). Les variations du tonus des muscles paravertébraux et des membres inférieurs ont été mesurées avec la très récente et non-invasive technologie MyotonPRO. Une diminution du tonus musculaire (-7,3%) a été retrouvée, associée à une atrophie musculaire (-10,6%) ainsi qu’une perte de force démontrée sur les membres inférieurs. Ces résultats, attestant un déconditionnement musculaire, sont cohérents avec le déconditionnement postural immédiatement après immersion sèche. Nous avons également étudié les paramètres d’occlusion dentaire, qui font partie des entrées posturales et peuvent affecter la bonne stabilité du corps. Finalement deux éléments interviennent dans l’explication des dysfonctions vertébrales : l’augmentation de la taille de la colonne liée à celle du volume des disques intervertébraux. On note également une atrophie des muscles paravertébraux, qui joue un rôle majeur dans la posture. Nous avons par ailleurs montré le rôle de l’occlusion dentaire dans le déconditionnement vertébral et postural. En conclusion : le tonus musculaire, la bonne mobilité vertébrale et l’équilibre de l’occlusion dentaire sont des éléments à préserver pendant et après un séjour en impesanteur, afin d’éviter les effets délétères du déconditionnement. / This work focuses on the study of back pain experienced by astronauts, who present with a greater incidence of herniated discs compared to a control population. Our research aims at understanding the physiopathology of this phenomenon and to study the clinical consequences of vertebral deconditioning which also contributes to postural disorders. This line of research has been recommended by the various international space agencies. For this reason, we had the opportunity to analyze data in two models simulating the effects of microgravity: dry immersion (n = 11) and head-down bed rest (n = 9), and a similar state, confinement (n = 4). Only the main results of dry immersion, a new method of studying our paradigm, are reported in this summary. Using magnetic resonance imaging and spectroscopy of the vertebral column, it was possible to analyze the intervertebral disc in 3 dimensions and to objectify the increase in water content (+ 17%) and the increase in intervertebral disc volume (+ 9.5%). Variations in paravertebral and lower limb muscle tone were measured with the very recent, and non-invasive, MyotonPRO technology. A decrease in muscle tone (-7.3%) was found to be associated with muscular atrophy (-10.6%) as well as a loss of strength in the lower limbs. These results, attesting to muscle deconditioning, are consistent with postural impairment immediately after dry immersion. We also studied variations in dental occlusion, which is involved with the maintenance of posture and could affect balance. In summary, two elements are involved in the explanation of vertebral dysfunction: the increase in spine height, related to increased intervertebral discs volume and paravertebral muscles atrophy, which plays a major role in posture. However, we also showed a role of dental occlusion in vertebral and postural deconditioning. In conclusion: muscle tone, good vertebral mobility, and dental occlusion are elements to be preserve during and after an exposure to weightlessness to avoid the deleterious effects of deconditioning.