Osteoid osteoma of the acetabular fossa: Five cases treated with percutaneous resection

SummaryBackgroundOsteoid osteoma is a painful benign osteogenic tumour for which the treatment objective is surgical resection of the nidus. The acetabular fossa is an uncommon site of involvement where surgical access can prove challenging.Materials and methodsWe report a case-series composed of five patients with osteoid osteoma of the acetabular fossa treated with percutaneous bone resection and drilling under computed tomography guidance.ResultsAll five patients had an uneventful postoperative course with immediate pain relief that was sustained over time.DiscussionThe outcomes achieved using our percutaneous technique compare favourably with those of other percutaneous methods, most notably regarding pain relief and patient tolerance of the procedure.ConclusionPercutaneous bone resection and drilling under computed tomography guidance proved effective for the treatment of osteoid osteoma involving the acetabular fossa.Level of evidenceLevel IV

Evaluation of a patient-specific finite-element model to simulate conservative treatment in adolescent idiopathic scoliosis

PublishedJournal ArticleAuthor's accepted manuscript.Study design: Retrospective validation study. Objectives: To propose a method to evaluate, from a clinical standpoint, the ability of a finite-element model (FEM) of the trunk to simulate orthotic correction of spinal deformity and to apply it to validate a previously described FEM. Summary of background data: Several FEMs of the scoliotic spine have been described in the literature. These models can prove useful in understanding the mechanisms of scoliosis progression and in optimizing its treatment, but their validation has often been lacking or incomplete. Methods: Three-dimensional (3D) geometries of 10 patients before and during conservative treatment were reconstructed from biplanar radiographs. The effect of bracing was simulated by modeling displacements induced by the brace pads. Simulated clinical indices (Cobb angle, T1-T12 and T4-T12 kyphosis, L1-L5 lordosis, apical vertebral rotation, torsion, rib hump) and vertebral orientations and positions were compared to those measured in the patients' 3D geometries. Results: Errors in clinical indices were of the same order of magnitude as the uncertainties due to 3D reconstruction; for instance, Cobb angle was simulated with a root mean square error of 5.7°, and rib hump error was 5.6°. Vertebral orientation was simulated with a root mean square error of 4.8° and vertebral position with an error of 2.5 mm. Conclusions: The methodology proposed here allowed in-depth evaluation of subject-specific simulations, confirming that FEMs of the trunk have the potential to accurately simulate brace action. These promising results provide a basis for ongoing 3D model development, toward the design of more efficient orthoses.ParisTech BiomecAM chair programProteorParisTechYves Cotrel Foundation

Direct costs associated with the management of progressive early onset scoliosis : estimations based on gold standard technique or with magnetically controlled growing rods

Background The main disadvantage of the surgical management of early onset scoliosis (EOS) using conventional growing rods is the need for iterative surgical procedures during childhood. The emergence of an innovative device using distraction-based magnetically controlled growing rods (MCGR) provides the opportunity to avoid such surgeries and therefore to improve the patient's quality of life. Hypothesis Despite the high cost of MCGR and considering its potential impact in reducing hospital stays, the use of MCGR could reduce medical resource consumption in a long-term view in comparison to traditional growing rod (TGR). Materials and methods A cost-simulation model was constructed to assess the incremental cost between the two strategies. The cost for each strategy was estimated based on probability of medical resource consumption determined from literature search as well as data from EOS patients treated in our centre. Some medical expenses were also estimated from expert interviews. The time horizon chosen was 4 years as from first surgical implantation. Costs were calculated in the perspective of the French sickness fund (using rates from year 2013) and were discounted by an annual rate of 4%. Sensitivity analyses were conducted to test model strength to various parameters. Results With a time horizon of 4 years, the estimated direct costs of TGR and MCGR strategies were 49,067 € and 42,752 €, respectively leading to an incremental costs of 6135 € in favour of MCGR strategy. In the first case, costs were mainly represented by hospital stays expenses (83.9%) whereas in the other the cost of MCGR contributed to 59.5% of the total amount. In the univariate sensitivity analysis, the tariffs of hospital stays, the tariffs of the MCG, and the frequency of distraction surgeries were the parameters with the most important impact on incremental cost. Discussion MCGR is a recent and promising innovation in the management of severe EOS. Besides improving the quality of life, its use in the treatment of severe EOS is likely to be offset by lower costs of hospital stays. Level of evidence (with study design) Level IV, economic and decision analyses, retrospective study. Keywords Early onset scoliosis; Direct costs; Spinal growing rods; Magnetically controlled growing rod

Coûts directs de prise en charge des scolioses infantiles et juvéniles sévères : estimations en fonction de l’utilisation des tiges de croissance conventionnelles ou des tiges de croissance magnétiques

Contexte L’inconvénient majeur de la prise en charge des scolioses graves de survenue précoce (SGP) par la technique sans fusion avec distraction chirurgicale (tige de croissance conventionnelle) est la nécessité de recourir à des chirurgies itératives pendant l’enfance. La diffusion récente des tiges de croissance magnétiques (TCM) offre la possibilité d’éviter de telles chirurgies et par conséquent, d’améliorer la qualité de vie des patients. Hypothèse Malgré le coût élevé des TCM et considérant leur impact potentiel sur la diminution du nombre de séjours hospitaliers, l’utilisation de ces tiges est susceptible de réduire la consommation de ressources médicales à long terme en comparaison des tiges de croissance conventionnelles (TCC). Matériel et méthode Un modèle d’évaluation médicoéconomique a été construit afin d’évaluer et comparer le coût des deux stratégies. Ce coût a été estimé à partir des probabilités de consommation de ressources médicales tirées d’une analyse de la littérature ainsi que des données d’une cohorte de patients avec SGP traités dans notre centre. Certaines ressources médicales ont également été estimées à dire d’experts. Un horizon temporel de quatre ans à partir de la première implantation chirurgicale a été retenu. Les coûts ont été évalués selon la perspective de l’assurance maladie française (en utilisant les tarifs de l’année 2013) et ont été actualisés avec un taux annuel de 4 %. Des analyses de sensibilité ont été conduites sur les différents paramètres du modèle afin d’évaluer sa robustesse. Résultats Sur un horizon temporel de quatre ans, les coûts directs estimés pour les stratégies TCC et TCM ont été de 49 067 euros et 42 752 euros respectivement, soit un différentiel de coût de −6135 euros en faveur de la stratégie TCM. Dans le premier cas, les coûts étaient principalement représentés par les séjours hospitaliers (83,9 %), alors que dans la stratégie TCM, le coût de la tige a contribué pour 59,5 % du montant total. L’analyse de sensibilité univariée a permis d’identifier les paramètres ayant la plus grande influence sur le différentiel de coût en particulier : le coût des séjours hospitaliers, le coût des TCM, et la fréquence des distractions chirurgicales. Discussion La stratégie TCM est une technique récente et prometteuse dans la prise en charge des SGP. En plus d’améliorer la qualité de vie des patients, son utilisation dans le traitement des SGP est susceptible d’être associée à une moindre consommation de ressources médicales. Background: The main disadvantage of the surgical management of early onset scoliosis (EOS) using conventional growing rods is the need for iterative surgical procedures during childhood. The emergence of an innovative device using distraction-based magnetically controlled growing rods (MCGR) provides the opportunity to avoid such surgeries and therefore to improve the patient’s quality of life. Hypothesis: Despite the high cost of MCGR and considering its potential impact in reducing hospital stays, the use of MCGR could reduce medical resource consumption in a long-term view in comparison to traditional growing rod (TGR). Materials and methods: A cost-simulation model was constructed to assess the incremental cost between the two strategies. The cost for each strategy was estimated based on probability of medical resource consumption determined from literature search as well as data from EOS patients treated in our centre. Some medical expenses were also estimated from expertinterviews. The time horizon chosen was 4 years as from first surgical implantation. Costs were calculated in the perspective of the French sickness fund (using rates from year 2013) and were discounted by an annual rate of 4%. Sensitivity analyses were conducted to test model strength to various parameters. Results: With a time horizon of 4 years, the estimated direct costs of TGR and MCGR strategies were 49,067 D and 42,752 D, respectively leading to an incremental costs of 6135 D in favour of MCGR strategy. In the first case, costs were mainly represented by hospital stays expenses (83.9%) whereas in the other the cost of MCGR contributed to 59.5% ofthe total amount. In the univariate sensitivity analysis,the tariffs of hospital stays, the tariffs of the MCG, and the frequency of distraction surgeries were the parameters with the most important impact on incremental cost. Discussion: MCGR is a recent and promising innovation in the management of severe EOS. Besides improving the quality of life, its use in the treatment of severe EOS is likely to be offset by lower costs of hospital stays