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Biomechanical modelling of the spine is of high clinical significance, either for implant evaluation or for surgery planning. Nevertheless, assessment of patient specific material properties still remains an issue, especially the viscoelastic characteristics of lumbar intervertebral discs (IVD). MRI, a dedicated system for IVD examination, provides a signal that is correlated with the biochemical content of the disc. Since IVD composition and its mechanical properties are related, the objectives of this study were to investigate how MRI could inform about viscoelastic properties of lumbar discs, determined from creep experiments. For that purpose, an in vitro protocol was carried out regarding 14 human L1-L2 IVDs; each unfrozen specimen was imaged using MRI and biomechanically tested with 10 min creep under 400 N load. Three-parameter rheologic models were used to fit the experimental curves. Additionally, geometry was obtained and degeneration was assessed using both MRI grading and physical inspection (destructive analysis). Mean creep displacement was 0.19 mm after 10 min. MRI scaling categorized elastic modulus and viscosity of the IVDs in 2 clearly distinct groups without overlaps according to degeneration: mean values for elastic modulus were 12.9 MPa and 5.7 MPa, respectively for mildly and severely degenerated IVDs; mean values for viscosity were 5.7 GPa s and 2.2 GPa s, respectively for mildly and severely degenerated IVDs. Classification derived from physical inspection did not reveal a clear discrimination. MRI could hence provide a quantification of IVDs viscoelastic properties, leading to in vivo direct estimation of material characteristics necessary for patient specific modelling.

Resume Les auteurs rapportent un cas de luxation laterale complete de la charniere thoracolombaire, d’origine traumatique, sans atteinte osseuse, chez une jeune adulte, compliquee d’une atteinte neurologique complete. La revue des cas similaires deja publies permet de degager les principes de la prise en charges. Le traitement est toujours chirurgical, la voie posterieure est privilegiee. La visualisation du fourreau dural doit preceder toute manœuvre de reduction, independamment du statut neurologique. La stabilisation instrumentale intervenant ensuite, afin de perenniser la reduction obtenue.

STUDY DESIGN A prospective, randomized, controlled, multicenter clinical study. OBJECTIVE To evaluate the safety and feasibility of osteogenic protein (OP)-1 in 1-level lumbar spine instrumented posterolateral fusions. SUMMARY OF BACKGROUND DATA Instrumented posterolateral fusion with the use of autograft is a commonly performed procedure for a variety of spinal disorders. However, harvesting of bone from the iliac crest is associated with complications. A promising alternative for autograft are bone morphogenetic proteins. METHODS As part of a larger prospective, randomized, multicenter study, 36 patients were included, who received a 1-level instrumented posterolateral fusion of the lumbar spine. All patients had a degenerative or isthmic spondylolisthesis with symptoms of neurologic compression. There were 2 treatment arms: OP-1 combined with locally available bone from laminectomy (OP-1 group) or iliac crest autograft (autograft group). The primary outcome was the fusion rate based on a computed tomography scan after 1-year follow-up. The clinical outcome was measured using the Oswestry Disability Index. Additionally, the safety of OP-1 was evaluated by comparing the number and severity of adverse events that occurred between both groups. RESULTS Using strict criteria, fusion rates of 63% were found in the OP-1 group and 67% in the control group (P = 0.95). There was a decrease in Oswestry scores at subsequent postoperative time points compared with preoperative values (P > 0.001). There were no significant differences in the mean Oswestry scores between the study group and control group at any time point (P = 0.56). No product-related adverse events occurred. CONCLUSION The results demonstrate that OP-1 combined with locally obtained autograft is a safe and effective alternative for iliac crest autograft in instrumented single-level posterolateral fusions of the lumbar spine. The main advantage of OP-1 is that it avoids morbidity associated with the harvesting of autogenous bone grafts from the iliac crest.

Resume La fracture des pedicules de C2, ou « Hangman's fracture » d’un cote, la fracture « Tear-Drop » de l’autre ont ete jusqu’a present decrites comme deux entites distinctes. La premiere causee par un mecanisme d’extension-distraction et la seconde par un mecanisme de compression-flexion. Le cas clinique rapporte dans ce travail montre, au niveau de la deuxieme vertebre cervicale, l’association de ces deux types de fractures, sans complications neurologiques. Un traitement chirurgical a permis la reduction et la stabilisation des lesions osseuses et de celles du segment mobile entre C2 et C3. La voie d’abord presternocleidomastoidienne sus-hyoidienne droite a ete choisie dans ce but, la deformation principale siegeant entre le corps de la deuxieme et de la troisieme vertebre cervicale.

Los autores describen diferentes tecnicas de fijacion lumboiliaca o sacroiliaca en el tratamiento quirurgico de las lesiones inestables posteriores del anillo pelvico. Se distinguen las fijaciones sacropelvicas, que implican a la articulacion sacroiliaca, de las fijaciones lumbopelvicas, que implican s la articulacion sacroiliaca y la charnela lumbosacra. Las fijaciones sacropelvicas estan indicadas en las lesiones de la interlinea sacroiliaca y del aleron sacro con un pediculo de S1 intacto. Las fracturas en U del sacro y las fracturas sacras en las zonas II o III de Denis son subsidiarias de los montajes lumbopelvicos.

Resume Si l’efficacite sur la symptomatologie fonctionnelle a court et moyen terme du traitement chirurgical d’une stenose lombaire est generalement admise, la probabilite de reintervention a long terme de ces patients n’a jamais ete etudiee. Les objectifs de ce travail ont ete d’evaluer le risque a long terme de reintervention apres traitement chirurgical d’une stenose canalaire lombaire et de determiner quels etaient les facteurs pouvant influencer celui-ci. Tous les patients operes de stenose lombaire de 1989 a 1992 ont ete inclus dans ce travail. Au dernier recul ont ete etudies le resultat fonctionnel par l’intermediaire d’un autoquestionnaire specifique, d’un indice de satisfaction, d’une evaluation visuelle analogique de la lombalgie et des radiculalgies et d’un indice de qualite de vie, le SF36 ; la survenue ou non d’une reintervention en precisant la date de celle-ci par rapport a la date operatoire, son motif et les modalites de la reintervention. La probabilite de reintervention a ete etudiee selon la methode actuarielle. L’influence des facteurs suivants sur la probabilite de survenue d’un tel evenement a ete etudiee par l’intermediaire d’un modele de Cox : âge, facteurs de comorbidite, etendue de la zone de liberation, realisation ou non d’une arthrodese posterolaterale, utilisation ou non d’une osteosynthese. Deux cent soixante-deux patients ont ete inclus dans cette etude. Au dernier examen, 61 patients etaient decedes, 44 ont ete perdus de vue et 157 ont ete revus avec un recul moyen de 15 ans. Trente-quatre patients ont necessite une reintervention. Quatre motifs de reintervention ont ete identifies, la destabilisation au sein ou au-dessus de la zone de liberation, une liberation insuffisante, l’apparition ou la reapparition d’une zone de stenose, l’apparition ou la reapparition d’une hernie discale. Le risque de reintervention chirurgicale a ete evalue a 7,4, 15,4 et 16,5 % respectivement a cinq, dix et 15 ans de l’intervention initiale. De l’ensemble des facteurs de risques etudies, seul un a modifie de facon significative la survenue d’une reintervention chirurgicale : l’etendue de la zone de liberation ( p = 0,003).

Resume Peu de travaux ont ete consacres a l’etude de l’influence de la hauteur discale sur le devenir d’une arthrodese posterolaterale (APL). L’objectif de ce travail a ete d’evaluer, au sein d’un segment rachidien immobilise par une APL : l’evolution de la hauteur de l’espace intersomatique, le retentissement clinique et radiologique d’eventuelles variations de la hauteur discale et l’influence a court et long termes de la hauteur discale constatee en preoperatoire sur les resultats cliniques et radiologiques. Afin d’obtenir un groupe de patients homogenes, nous avons limite notre etude aux APL realisees pour spondylolisthesis degeneratif. Cette etude retrospective continue porte sur 66 patients evalues avec un recul moyen de 52 mois. La symptomatologie fonctionnelle a ete etudiee en pre- et postoperatoire selon un autoquestionnaire specifique, un indice de qualite de vie le (SF-36) et un indice de satisfaction. Radiologiquement ont ete evalues en preoperatoire, en postoperatoire immediat, a un an de l’intervention et au dernier recul : au niveau de l’etage olisthesique, la hauteur discale, l’angulation intervertebrale, les mobilites intervertebrales angulaires et anteroposterieures et plus globalement les parametres caracterisant l’equilibre sagittal du rachis. Les variations de hauteur discale ont ete correlees a l’evolution du resultat fonctionnel constate en postoperatoire immediat et a la qualite de la fusion evaluee au dernier recul. L’influence sur les variations de hauteur discale des parametres preoperatoires suivants a ete etudiee a l’aide d’une analyse multivariee : angulation intervertebrale, hauteur discale, mobilites intervertebrales, parametres de l’equilibre sagittal, utilisation ou non d’une osteosynthese. A l’etage olisthesique les diminutions moyennes de hauteur discale et d’angulation intervertebrale constatees ont ete de 30 %. Ces variations n’etaient correlees ni a l’evolution du resultat fonctionnel ni a la qualite de la fusion constatee au dernier recul. La hauteur discale initiale n’avait aucune influence sur ces variations. Le seul facteur influencant la diminution de hauteur discale etait la gite sagittale T9, plus celle-ci etait proche de 0 plus la diminution constatee etait importante. Dans le cadre tres strict que nous nous etions impose, l’argument d’une hauteur discale elevee pour justifier d’une arthrodese intersomatique en complement d’une arthrodese posterolaterale ne nous est pas apparu comme determinant. L’analyse de la situation d’equilibre dans le plan sagittal du rachis permettra une orientation plus pertinente dans le choix de la strategie therapeutique la mieux adaptee au patient.

To evaluate the long-term clinical and radiographic results in patients treated for 61C3-2 (OTA class) pelvic ring disruption with a posterior bridging sacroiliac fixation. Retrospective clinical and radiological study. University Hospital. Between May 2002 and March 2003, seven patients with sacroiliac dislocation were treated with a technique developed for the treatment of pelvic injuries with vertical and horizontal instability. We applied spino-pelvic fixation techniques, using spine instrumentation, to stabilize an SI dislocation. This technique consists of two 5 mm diameter screws inserted into the S1 pedicle and S2 ala. A 5.5 mm rod joins the 2 sacral screws to two 7 mm screws placed into the posterior iliac crest and secured into the cancellous mass of the posterior ilium . The described technique stabilizes the SI-joint by performing a bridging osteosynthesis instead of the commonly performed iliosacral screw osteosynthesis passing the SI-joint. Symphyseal platting is performed to reduce and stabilize the anterior ring if necessary. Data were analyzed as follows: pelvic fracture classification; functional outcome; radiographic outcome; Leg length discrapency; and CT scan aspect of the sacroiliac joint. Associated pelvic injuries were present in all the patients and include symphysis rupture and acetabular fractures. Four of the seven patients had fractures of the lower extremities. Follow-up was available for all patients at an average of 27 months (range, 32–24 months). Neither septic nor cutaneous complications were reported. No loss of post-op reduction and no fixation failure were observed. The functional results noted at the last examination were satisfactory with a mean Majeed score of 93. In our opinion, this surgical technique may be indicated in Tile type C1.2 (61C3-2 OTA class) pelvic ring disruption. It obviously reaches its limits in sacral fractures. The technique described provides effective control of vertical displacement while providing a certain degree of horizontal mobility to facilitate reduction and osteosynthesis of anterior lesions. The quality of the fixation allowed early weight bearing.

Effects of disc degeneration (DD) on mobility under loads have been demonstrated, but they are not taken into account when providing experimental corridors for ranges of motion (ROM); this could explain that these corridors are usually very large. Other influencing factors such as lumbar level or geometry have seldom been studied, and never conjointly. The objectives of the study were to understand relationships between intervertebral discs (IVDs) mobility disparity and disc characteristics using medical imaging. For that purpose, an in vitro biomechanical and imaging protocol was conducted on human lumbar IVDs: 22 specimens (14 L1-L2 and eight L4-L5) were considered. Radiography, MRI, discography and macroscopic slices were obtained. Flexion/extension, lateral bending and torsion 10 Nm moments were applied on each specimen, with and without posterior elements. 3D motion of the upper vertebra was recorded. After testing, morphometric data was measured, DD was assessed and pathological singularities were identified. Mobility corridors for each spinal level in all loading modes were very large. For example, lateral bending ROMs within L1-L2 group ranged from 0.5° to 10.5°. Abnormal behaviours such as excessive ROMs or extension greater than flexion were listed. In most cases, imaging could identify the reasons of these erratic behaviours (scoliosis, calcification, retrolisthesis, etc.). After discarding six discs carrying major anomalies identified by imagery, mobility corridors were drastically reduced (min 3°, max 6.5° for the same L1-L2 lateral bending example). In specimens without abnormalities, relationship between geometry and ROMs could be revealed. As a conclusion, this study provided more relevant data for ROM of lumbar spine functional units. For the first time relationships could be considered between image attributes and mechanical properties.

Retrospective review of three cases. Severe trauma can be responsible for a complete spinal anterior dislocation with a 100% anterior slip of the vertebral body. Three cases of this uncommon lesion are reported. France. The data of three cases of complete spinal anterior dislocation with a 100% anterior slip of the vertebral body were retrospectively reviewed. In all the cases, the vertebral dislocation was responsible for a severe neurological deficit and all patients had severe associated lesions. The diagnosis was made on plain radiographs. In one case of a multilevel injury, an extensive instrumented spinal fusion was necessary. In spite of the severe injury, two neurological deficits improved thanks to pedicular fractures, which widen the canal. The therapeutic goal is to achieve emergent vertebral alignment, neurological decompression and solid spinal fusion. A posterior facilitates this. Reduction of vertebral dislocation can be difficult to achieve and it is therefore mandatory to perform complete arthrectomy of the injured levels before reduction. Especially in young patients, severe disc lesions secondary to the wide vertebral displacement make it necessary to perform circumferential fusion.

Recent studies suggested a predominant role of spinopelvic parameters to explain lumbosacral spondylolisthesis pathogeny. We compare the pelvic incidence and other parameters of sagittal spinopelvic balance in adolescents and young adults with developmental spondylolisthesis to those parameters in a control group of healthy volunteers. We compared the angular parameters of the sagittal balance of the spine in a cohort of 244 patients with a developmental L5-S1 spondylolisthesis with those of a control cohort of 300 healthy volunteers. A descriptive and correlation study was performed. The L5 anterior slipping and lumbosacral kyphosis in spondylolisthesis patients was described using multiple regression analysis study. Our study demonstrates that the related measures of sagittal spinopelvic alignment are disturbed in adolescents and young adults with developmental spondylolisthesis. These subjects stand with an increased sacral slope, pelvic tilt and lumbar lordosis but with a decreased thoracic kyphosis. Pelvic incidence was significantly higher in spondylolisthesis patients as compared with controls but was not clearly correlated with the grade of slipping. We showed the same "sagittal balance strategy" in spondylolisthesis patients as in the control group regarding correlations between pelvic incidence, sacral slope, pelvic tilt and lumbar lordosis. We believe that the lumbosacral kyphosis is a stronger factor than pelvic incidence which need to be taken into account as a predominant factor in theories of pathogenesis of lumbosacral spondylolithesis. We thus believe that increased lumbar lordosis associated with L5-S1 spondylolisthesis is secondary to the high pelvic incidence and is an important factor causing high shear stresses at the L5-S1 pars interarticularis. However, the "local" sagittal imbalance of the lumbosacral junction is compensated by adjacent mobile segments in the upper lumbar spine, the pelvis orientation and the thoracic spine. The result is not optimal but a satisfactory global sagittal balance of the trunk, even in the most severe grade of slipping.

Summary Purpose of the study: Traumatic lumbosacral dislocation is a rare lesion often characterised by a fracture dislocation of L5-S1 articular facets associated with anterior L5 slipping. Because of its rarity, the surgical strategy of lumbosacral traumatic dislocation remains controversial. We report the most important series of traumatic lumbosacral dislocation. The cases of six men and five women are presented. We discuss the diagnosis and surgical treatment options regarding the different type of lesions. A moderate anterior slipping of L5 over S1 was present in eight cases. The lesion was a bilateral lumbosacral fracture dislocation in eight cases, a pure lateral dislocation in two cases and a unilateral rotatory dislocation in one case. Patients were multiple-trauma patients in eight cases. A radicular deficit was present in two cases. All patients were treated surgically with a posterior osteosynthesis and fusion. A circumferential fusion was made in six cases. In four cases, the anterior fusion was made during the posterior approach. The postoperative course was favorable in all the cases. One patient necessitated secondarily an iterative posterior lumbosacral fixation and anterior fibular bone graft because of a lumbosacral pseudarthrosis. Traumatic dislocation of the lumbosacral junction is a rare and severe spinal fracture which occurs in patients after high energy trauma and could be initially misdiagnosed. We devised a new classification based on anatomical lesions. Treatment is always surgical, requiring reduction, osteosynthesis, and fusion. In case of L5 anterior slipping, it is crucial to assess the L5S1 disc by MRI or surgical exploration for disc disruption. In such case, we recommend to perform circumferential fusion to prevent lumbosacral pseudarthrodesis.

Resume La comminution osseuse, la gravite des lesions cartilagineuses ainsi que la faible qualite biomecanique de l’os porotique rendent difficile la tenue de la synthese des fractures articulaires du patient âge. Les resultats aleatoires des syntheses ont motive la realisation d’arthroplasties en urgence pour certaines fractures de la hanche, de l’epaule et du coude. Nous rapportons 4 cas de protheses de genou implantees pour fracture recente grave de l’epiphyse tibiale. Quatre patientes autonomes et informees âgees de plus de 75 ans ont presente une fracture comminutive grave de l’epiphyse proximale du tibia (3 fractures Schatzker 5, 1 Schatzker 4). Il a ete propose et realise une arthroplastie du genou precoce. La piece tibiale presentait une longue tige cimentee sur laquelle etait reconstruite l’epiphyse. Les operateurs ont systematiquement implante une prothese contrainte. L’appui immediat etait autorise. Le recul varie de 2 a 7 ans. Le score IKS fonction (15, 60, 100, 100) dependait de l’etat general de la patiente. Le score IKS genou etait excellent dans 3 cas (90, 95, 95) moyen dans un cas (45). Aucune patiente n’a ete reprise. Toutes les radiographies objectivaient une consolidation, les membres etaient correctement axes (deformation inferieure a 2). Il n’existait pas de lisere evolutif visible au plus grand recul. La realisation d’une arthroplastie de genou en urgence pour les fractures complexes de l’epiphyse tibiale proximale est possible. L’utilisation d’une tige tibiale cimentee permet d’obtenir une stabilite primaire suffisante pour permettre l’appui en attendant la consolidation. L’utilisation d’une prothese contrainte et surtout d’un prothese a charniere est discutable mais permet d’esquiver la difficulte de l’equilibrage ligamentaire sur l’interligne detruite d’un genou traumatique. Aucune patiente n’a ete reoperee et les resultats sont excellents sur la douleur. Le score global est fonction de l’etat general de la patiente.

Resume Les objectifs de ce travail ont ete de determiner les parametres caracterisant la statique rachidienne dans le plan sagittal d’un groupe de 70 patients operes pour spondylolisthesis degeneratif et de les comparer avec ceux d’une population de 250 temoins. Les parametres suivants ont ete pris en compte : incidence et version pelvienne, pente sacree, lordose lombaire, cyphose thoracique, gite sagittale T9 et angulation S1-S2. A partir de ces valeurs ont ete effectuees : une analyse univariee afin de preciser les principales caracteristiques de distribution des parametres pris en compte ; une etude multivariee afin d’etudier les variations de ces parametres les uns par rapport aux autres et ainsi de mieux definir les perturbations de l’equilibre sagittal de ces patients ; une comparaison des parametres etudies a ceux d’une population temoin. L’une des caracteristiques essentielles de la cohorte analysee etait la presence d’une forte incidence pelvienne (62,6 versus 54,7). La valeur elevee de ce parametre pourrait etre, par l’intermediaire de l’hyperlordose et de l’augmentation de la version pelvienne qu’elle induit, l’un des facteurs de degenerescence d’une unite fonctionnelle rachidienne et a terme d’un glissement degeneratif. Les determinants les plus significatifs de la gite sagittale T9 etaient : la version pelvienne, l’incidence pelvienne, la lordose lombaire et la lordose locale L4-S1. Un tiers de nos patients etait en situation de gite anterieure essentiellement en raison d’une importante cyphose lombosacree, un tiers avait une gite sagittale T9 normale et un tiers etait en situation de gite posterieure en raison d’une forte cyphose thoracique associee. Ce travail nous a permis de mieux caracteriser les parametres de l’equilibre sagittal du spondylolisthesis degeneratif, d’emettre quelques hypotheses vis-a-vis du mecanisme constitutif de tels glissements degeneratifs et de souligner la diversite des situations d’equilibre de ces patients avec les implications therapeutiques que cela comporte.

Resume Objectifs L’utilisation d’un detecteur Charpak permet d’obtenir des radiographies avec des doses reduites de 10 a 30 fois. L’objectif de cette etude cadaverique etait de caracteriser l’aspect du disque intervertebral avec ce nouveau systeme de radiographie basse dose : l’EOS. Materiels et Methodes Trente et un espaces disco-somatiques dorsolombaires ont ete preleves chez des sujets âges de 55 a 93 ans, et images avec 1) le prototype EOS, 2) une IRM avec des images sagittales T1 et T2, 3) une discographie, puis coupes pour examen anatomique. Les parametres evalues et classifies etaient : la degenerescence et la morphologie discale (hauteur, limites anterieure et posterieure), l’aspect des plateaux et des corps vertebraux. Une analyse statistique a permis d’etudier la reproductibilite inter et intra observateur et les correlations entre les differentes methodes d’imagerie. Resultats Tous les disques etaient degeneratifs. Il existait une bonne correlation entre radiographie basse dose et IRM, pour les parametres : hauteur intervertebrale, contours, et osteophytes des plateaux et des corps vertebraux. L’IRM etait plus performante pour l’analyse des limites anterieure et posterieure du disque, et la caracterisation de l’os sous-chondral. Conclusion L’imagerie basse dose permet une evaluation precise des contours osseux de l’espace intervertebral.

Tear-drop fracture of the axis is an exceptional spinal fracture which generally occurs after high-energy trauma with hyper-extension of the cervical spine. Purely anterior fracture can occur with no real impact on stability. Orthopedic treatment provides good results in this situation. If the fracture is posterior, it continues into the C2-C3 intervertebral disc and the common posterior vertebral ligament, leading to C2C3 instability and possible retrolisthesis of C2 over C3 and neurological involvement. We report a case of tear-drop fracture of C2 with C3 instability without neurological involvement. This patient underwent posterior fixation with C2C3 arthrodesis which provided good quality bone fusion without secondary displacement or clinical aggravation.

PURPOSE OF THE STUDY Incidence of complications following lumbar or lumbosacral fusion is still an imprecise notion. The aim of this prospective observational study was to determine the frequency of intraoperative and early postoperative complications after this procedure and to analyze favoring factors. MATERIAL AND METHODS Twenty-one orthopedic units participated in this study which included 872 patients who underwent lumbar or lumbosacral fusion procedures involving the sector limited by L1 and S1. A minimum of 6 months follow-up was required for inclusion. Four types of complications were studied: general complications, infection, neurological and meningeal complications, mechanical problems. The following preoperative and intraoperative parameters were recorded: epidemiological and morphological data, history of lumbar spine surgery, comorbid conditions, indication for surgery, and technical aspects of the fusion. Two types of analysis were performed. The first was a descriptive analysis designed to determined the overall incidence of complications and the incidence of each type of complication. A multivariate analysis was then performed in order to determine factors influencing occurrence of complications. RESULTS Mean follow-up was 13 months, mean age of the cohort was 51 +/- 15.5 years. Prior lumbar surgery was noted in 12% of the patients. A decompression procedure was associated in 40% of the patients due to lumbar stenosis. Posterolateral arthrodesis was used in 71% of the patients and 91% were instrumented. Most of the fusions were short, involving one or two levels. One or more intraoperative or early postoperative complications were observed in 200 patients (23%). The incidences of the four types of complications expressed in percent of the total cohort were 9.7%, 5.6%, 8.6%, and 3.6% for general, infectious, neurological and meningeal, and mechanical complications respectively. Three factors exhibited a significant correlation with occurrence of complications, irrespective of the type: excess weight, presence of several comorbid conditions, and extent of the zone of fusion. CONCLUSION This study enabled a precise assessment of the incidence of complications subsequent to lumbar or lumbosacral fusion: 23%. The incidence of serious complications requiring a reoperation was 14.7%. This finding, together with the factors found to influence occurrence of these complications should be kept in mind when determining indications for lumbar or lumbosacral fusion.

Resume La migration intracardiaque d’un plomb d’arme a feu a partir d’un tronc veineux peripherique est tres rare. Elle est facilitee par la taille et le nombre lors de l’impact, comme c’est le cas pour la grenaille ; ce passage est asymptomatique et peut se faire jusqu’a 15 ans apres la blessure. Plusieurs problemes doivent etre evoques : le mecanisme de son passage dans le cœur (vitesse propre et retour veineux), le diagnostic topographique (radiographie pulmonaire, echographie transthoracique, transœsophagienne et tomodensitometrie), les consequences locales de ce projectile (erosion locale, caillotage, endocardite), la destination possible d’une nouvelle migration (embolie pulmonaire, cœur gauche), les indications d’extraction, la surveillance. L’extraction ne doit pas etre systematique, mais uniquement en cas de foramen ovale rendant possible une embolisation systemique aux consequences cliniques gravissimes ou en cas de complications. Les auteurs rapportent l’observation d’un patient de 22 ans pour lequel ils ont choisi abstention et surveillance.

SummaryThe authors describe a case of traumatic lateral spine dislocation at the thoracolumbar junction level, without fracture, in a healthy young adult, complicated by a complete neurological deficit. The main aspects of surgical management are discussed based on a review of the literature. Control of the spinal cord is a mandatory first step, before reduction, independently of neurological deficits considerations. Instrumented stabilization and fusion are achieved thereafter; levels selection for instrumentation and fusion depends on the injury location.

Objectifs Les complications post-operatoires de la chirurgie du rachis lombaire degeneratif ne sont pas exceptionnelles. Le taux de reintervention apres cure de hernie discale est de 12 % mais il est de 23 % dans les stenoses lombaires. L’objectif est de presenter les principales complications, leur physiopathologie et l’apport de l’imagerie moderne dans leur depistage. Materiels et methodes Nous avons revu les scanners de rachis lombaire opere, realises au cours des six derniers mois, pratiques en routine, suite a l’acquisition d’un scanner 64 barrettes dans un centre de chirurgie du rachis. Nous presentons une revue des complications rares ou frequentes que l’on doit rechercher a court, moyen ou long terme. Resultats Les plaies durales et les infections ne sont pas rares a court terme. A long terme les restenoses, les insuffisances de liberation et les destabilisations doivent imperativement etre reconnues. Les nouveaux scanners 64 barrettes permettent en outre d’apprecier de maniere saisissante les complications liees au materiel d’osteosynthese (chambre de mobilisation, fracture de vis etc). Conclusion L’imagerie du rachis lombaire opere est une demande de plus en plus frequente. Le radiologue doit absolument connaitre les complications en particulier celles qui feront discuter une re-intervention.

Finite Element spine modeling can be useful for computer assisted surgery planning providing help in assessing the risk of mechanical failure. The aim of this study is to provide a patient specific finite element model of the lumbar spine where surgical gesture was considered and to evaluate its relevance as a predictive tool for lumbar spine surgery. A three-dimensional FEM of the L1-Sacrum lumbar spine with geometrical personalization was used. Mechanical properties were based on published data. Then, main characteristics of degenerative pathologies and surgical gestures were considered, and posterior implants were modeled. The sacrum was fixed and Flexion compression loads were applied on the L1 vertebra. Then, results of simulations were post-processed to obtain stresses in the discs and along implants. Clinical cases were collected to evaluate the models relevance. 66 cases instrumented with rigid screw rod systems were considered. 13 of the collected cases were “failed cases” in which patients had screw breakage or screw loosening. Blind simulations were performed for all these patients and the results were qualitatively compared with the clinical outcome. Numerical results highlighted the specific behavior of 12 models for which loads on screws and rods were markedly higher than those of all others. The analysis of the clinical outcome emphasized that 9 of these 13 models corresponded to patients with a mechanical failure. For the first time a patient specific model was proposed for lumbar spine surgery planning. By increasing the number of modeled clinical cases, it could be possible to improve this model and to provide an help for surgery planning.

Objectifs Savoir realiser et interpreter l’imagerie d’une tumeur du rachis. Connaitre l’interet respectif des differentes modalites d’imagerie (radiographies, TDM, IRM, angiographie). Connaitre la demarche diagnostique devant une tumeur rachidienne. Pouvoir donner une liste de diagnostics differentiels pour guider la prise en charge therapeutique. Savoir discuter l’indication d’une biopsie percutanee. Materiels et methodes Cette etude retrospective multicentrique illustre l’imagerie des tumeurs rachidiennes les plus frequentes. Plusieurs cas typiques sont presentes. Resultats La demarche diagnostique repose sur l’âge, l’analyse topographique de la lesion et sur l’analyse de la semiologie elementaire des lesions. Quelques aspects pseudo-tumoraux sont a connaitre. Certaines tumeurs telles l’osteome osteoide ou l’angiome ont souvent un aspect typique et ne posent pas de probleme diagnostique. Nous exposons egalement la semiologie des autres tumeurs benignes du rachis les plus frequentes comme l’osteoblastome, le kyste anevrysmal, la tumeur a cellule geante, l’exostose, et l’osteochondrome. La semiologie des tumeurs malignes rachidiennes les plus frequentes telles que le plasmocytome, le lymphome, le chordome, le chondrosarcome, le sarcome d’Ewing, et l’osteosarcome est egalement presentee. Conclusion Une approche diagnostique systematique permet de reconnaitre certaines tumeurs rachidiennes dont les aspects sont caracteristiques. Dans les autres cas, une gamme diagnostique restreinte peut etre proposee.