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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.

We report the first case of paraplegia observed after epidural steroid injection in the upper spine. The patient was a 42-year-old male who underwent surgery two years earlier for stenosis of the lumbar spine from L2 to the sacrum leading to early manifestations of an equina cauda syndrome. This first operation provided satisfactory function with complete resolution of the objective neurological symptoms. The patient later developed bilateral radiculalgia involving the L3 and L4 territories and was treated by radio-guided epidural steroid injection (125 mg hydrocortancyl) delivered in the L1-L2 interlaminar space. The injection was achieved with no technical difficulty and there was no injury to the dural sac. Immediately after the injection, the patient developed complete motor and sensorial paraplegia from T12. CT and MRI performed 30 min and 4h, respectively, after the accident revealed a medium-sized discal herniation behind the L2 body. No other lesion was observed. Emergency surgery was performed for radicular release but to no avail. The patient's neurological status remained unchanged and four days later the T2 MRI sequence revealed a high-intensity intramedullar signal in the cone. The diagnosis of ischemia of the medullary cone was retained, hypothetically by injury to the dominant radiculomedullary artery via an undetermined mechanism. This complication has been previously described after upper foraminal steroid injections but not after intralaminar epidural steroid injection.

Experimentally, posterolateral fusion only provides incomplete control of flexion-extension, rotation and lateral inclination forces. The stability deficit increases with increasing height of the anterior intervertebral space, which for some warrants the adjunction of an intersomatic arthrodesis in addition to the posterolateral graft. Few studies have been devoted to the impact of disc height on the outcome of posterolateral fusion. The purpose of this work was to investigate the spinal segment immobilized by the posterolateral fusion: height of the anterior intervertebral space, the clinical and radiographic impact of changes in disc height, and the short- and long-term impact of disc height measured preoperatively on clinical and radiographic outcome.In order to obtain a homogeneous group of patients, the series was limited to patients undergoing posterolateral arthrodesis for degenerative spondylolisthesis, in combination with radicular release. This was a retrospective analysis of a consecutive series of 66 patients with mean 52 months follow-up (range 3-63 months). A dedicated self-administered questionnaire was used to collect data on pre- and postoperative function, the SF-36 quality of life score, and patient satisfaction. Pre- and postoperative (early, one year, last follow-up) radiographic data were recorded: olisthesic level, disc height, intervertebral angle, intervertebral mobility (angular, anteroposterior), and global measures of sagittal balance (thoracic kyphosis, lumbar lordosis, T9 sagittal tilt, pelvic version, pelvic incidence, sacral slope). SpineView was used for all measures. Univariate analysis searched for correlations between variation in disc height and early postoperative function and quality of fusion at last follow-up. Multivariate analysis was applied to the following preoperative parameters: intervertebral angle, disc height, intervertebral mobility, sagittal balance parameters, use of osteosynthesis or not.At the olisthesic level, there was a 30% mean decrease in disc height and intervertebral angle. These variations were not correlated with functional outcome or quality of fusion observed at last follow-up. Disc height preoperatively did not affect these variations. The only factor correlated with decreased disc height was T9 sagittal tilt: disc height decreased more when T9 sagittal tilt approached 0 degrees .In this very restricted context (retrospective study, short arthrodesis for degenerative spondylolisthesis), we were unable to find any evidence supporting the notion that high disc height is an argument which should favor complementary intersomatic arthrodesis in combination with posterolateral fusion. Analysis of the spinal balance in the sagittal plane would probably allow a more pertinent assessment of the specific needs of individual patients.

The short- and mid-term symptom-relief of surgical treatment for lumbar stenosis is generally acknowledged, but the probability of a long-term reoperation remains to be studied. The purpose of this work was to determine the long-term risk of reoperation after surgical treatment of degenerative lumbar stenosis and to search for factors influencing this probability.All patients who underwent from 1989 to 1992 surgical treatment for degenerative lumbar spine stenosis were included in this work. At last follow-up, we noted functional outcome using a specific self-administered questionnaire, patient satisfaction, lumbalgia and radiculalgia using a visual analog scale, SF36 quality-of-life, reoperation or not with time since first operation if performed and the reasons and modalities of the reoperation. The probability of reoperation was determined with the acturarial method. A Cox model was used to search for factors linked with the probability of reoperation; variables studied were: age, comorbid factors, extent of the release, posterolateral arthrodesis or not, extent of the potential fusion, use or not of instrumentation for arthrodesis.The study included 262 patients. At last follow-up, 61 patients had died a mean 3.7+/-3 years after the operation; only one of these patients had a second operation 22 months after the first. Forty-four patients were lost to follow-up at mean 6.6+/-3 years. Among these 44 patients, four had a second operation during their initial follow-up at mean 47 months. One hundred fifty-seven patients were retained for this analysis at mean 15+/-1 years follow-up. Among these 157 patients, 29 had a second operation a mean 75 months after the first. There were four reasons for reoperating: insufficient release, destabilization within or above the zone of release, development or renewed zone of stenosis, development or renewed discal herniation. The risk of a second operation was 7.4% [95% CI 4.8-11.6], 15.4% [95% CI 10.7-21.1] and 16.5% [95% CI 11.7-219] at five, 10 and 15 years respectively after the first operation. Among the risk factors studied, only one had a significant impact on reoperation: extent of the zone of release (p=0.003). Compared with a release limited to one level, the risk of reoperation after release of three levels or more was five times greater [95% CI 1.8-12.7].

Bone comminution, serious cartilage damage, and the poor mechanical quality of osteoporotic bone create a difficult challenge for osteosynthesis of joint fractures in the elderly subject. Poor results with certain hip, elbow and shoulder fractures have lead certain authors to propose emergency arthroplasty in selected cases. We report our experience with four knee arthroplasties implanted for recent severe fracture of the proximal tibial epiphysis in elderly subjects.Four independent patients aged over 75 years presented a severe comminutive fracture of the proximal epiphysis of the tibia (Three Schatzker 5, one Schatzker 4). After obtaining the patients' informed consent, early knee arthroplasty was performed. A long-stem cemented tibial piece was used on which the epiphysis was reconstructed. Implants providing support for ligament deficits were used in all cases. Immediate weight-bearing was authorized.Follow-up ranged from two to seven years. The IKS function score (15, 60, 100, 100) depended on the patient's general status. The IKS knee score was excellent for three knees (90, 95, 95), and fair in one (45). Re-operations were not needed in any of the patients. All x-rays showed bone healing with correctly aligned limbs (less than 2 degrees deformation). There were no lucent lines at last follow-up.Early arthroplasty for complex fractures of the proximal epiphysis of the tibia is a realistic option. Using a cemented long-stem tibial piece ensures primary stability sufficient for early weight-bearing before bone healing. Use of a constrained prosthesis, or better a hinged prosthesis, can be questioned but avoids the difficulty of ligament balance on an osteoporotic knee with a destroyed joint surface. None of the patients required reoperation and the results in terms of pain were excellent. The overall outcome depends on the general status of the patient.

Several reports have examined the pathophysiology of degenerative spondylolisthesis. Very little work has however been devoted to the influence of spinal balance in the sagittal plane in its pathogenesis. The purpose of this work was to present a descriptive analysis of pelvic and spinal sagittal balance in a cohort of seventy patients treated for degenerative spondylolisthesis and to compare findings with those established in a population of 250 volunteers. The goal was to deduct pathophysiological hypotheses and identify therapeutic implications.Seventy patients were included in this study. The following variables were noted: pelvic incidence and version, sacral slope, lumbar lordosis, thoracic kyphosis, T9 sagittal tilt and S1-S2 angle. These variables were measured on digitalized lateral views of the spine using a dedicated software (SpineView). Univariate analysis of the values obtained was performed to identify the variable distributions. Multivariate analysis was applied to study the relationships between these variables and to better define perturbations of spinal balance in the anteroposterior plane. The findings were compared with those obtained in a control population.One of the essential characteristics of the cohort of patients with degenerative spondylolisthesis was the presence of an exaggerated pelvic incidence (62.6 degrees versus 54.7 degrees in the control population). The most significant determinants of T9 sagittal tilt (which reflects sagittal balance) were: pelvic version, pelvic incidence, lumbar lordosis, and L4-S1 local lordosis. One-third of our patients presented posterior tilt due to exaggerated thoracic kyphosis. The high pelvic incidence, via hyperlordosis and increased pelvic version, could be one of the factors favoring degenerative disease of the spinal unit.This work enabled us to better describe sagittal balance in patients with degenerative spondylolisthesis and to propose hypotheses concerning the underlying mechanism of progressive degeneration. We emphasize the diversity of spinal balance in these patients and the different therapeutic implications.

EOS is a new low dose radiographic system based on micro-pattern gaseous detector technology. The purpose was to compare the value of EOS and MRI in the evaluation of degenerative intervertebral disc disease.Thirty one fresh lumbar discs were studied with EOS, MRI, and discography. Finally, the discs were dissected for macroscopy. They were graded according to their degenerative level using each imaging modality. Osteophytes, herniations, calcifications, loss of disc height, discographic tears or ligamentous ossification were recorded as anomalies. Morphometric data were measured from the cadaveric sections and low-dose radiographs.Thirty nine percent of the discs were narrowed, with a high correlation between EOS and MRI. Anterior and posterior disc margins were respectively depicted in 22% and 64% of cases with EOS vs 84% and 97% with MRI. MRI showed a disc herniation in 9 cases. The correlation between EOS and MRI was poor for the analysis of anterior and posterior disc margins, and disc herniation. Modic 2 abnormalities were present in 19% of disc levels at MRI. Osteophytes were visible in 65% of disc levels with EOS. The density of the disc space was homogeneous in 65% of cases. In the remaining cases, intradiscal calcifications were detected with EOS and confirmed at macroscopy.The EOS low dose images allow a good characterisation of disc abnormalities. Especially, intervertebral disc height, density variations and finer bony details (osteophytes) were detected with high confidence. EOS is a promising new low dose radiographic method for spine imaging.

We report a case of total spinal cord disruption confirmed surgically. The spinal cord injury resulted from a traumatic event involving the thoracic spine which did not provoke any bone lesion. The patient presented joint injury and unilateral ligament damage. No spinal fracture was observed. In patients with neurological signs, the imaging work-up should associate CT-scan and magnetic resonance imaging to obtain a complete study of the bone and joint structures as well as the ligaments and the spinal cord.

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.

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.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.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.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.

We propose a new technique for sacroiliac fixation for the treatment of pelvic fracture with vertical and horizontal instability (Tile class C). This fixation technique allows control of vertical displacement while allowing, if needed, a certain degree of movement in the horizontal plane to facilitate reduction of anterior lesions. The technique involves insertion of two sacral screws, one in S1 and one in S2, and two iliac screws. The iliac screws are inserted in the posterior iliac crest through two sacroiliac connectors placed on a rod linking the two sacral screws. Vertical displacement is controlled by blocking the screw heads on the connecting rod. If needed, a certain degree of horizontal mobility of the half pelvis can be allowed by loosening the connectors on the rods. This technique was used for 4 patients. Anatomic reduction was achieved and no secondary movement of the osteosynthesis material nor secondary displacement were observed. The quality of the fixation allowed rapid weight bearing in the standing position and early walking without crutches. This type of fixation can only be used for type C12 fractures in the Tile classification.

Some discussion remains concerning the quality of the long-term functional outcome after surgical treatment of lumbar spinal stenosis. The purpose of this retrospective observational study was to evaluate outcome ten years after surgical treatment of lumbar spinal stenosis and to determine the rate of reoperation as well as to identify factors influencing outcome at last follow-up.Between January 1990 and December 1992, 141 patients underwent surgery for lumbar stenosis all were included in present study. Mean follow-up was ten years. At last follow-up, functional signs were assessed with a designated self-administered questionnaire with items for lumbar and radicular pain, signs of radicular ischemia, and patient satisfaction and two visual analog scales for lumbar and radicular pain. Other data recorded included: epidemiological and morphological features of the study population, comorbidities, presence or not of objective neurological signs, anatomy of the stenosis, and results of two self-administered questionnaires on quality of life (SF36) and anxiety-depression (GHA28). Two data analysis methods were applied. The first was a descriptive analysis to quantify the importance of functional signs observed at last follow-up, patient satisfaction, and rate of recurrence as well as reasons for reoperation. The second was a multivariate analysis designed to identify factors influencing the score obtained on the designated stenosis self-administered questionnaire.Fifteen patients had undergone a revision procedure on the lumbar spine. At last follow-up overall satisfaction was 71%. The best results were obtained for radiculalgia and intermittent neurogenic claudication. Residual lumbalgia was the main complaint at last follow-up. The patient's psychological profile was found to be the predominant factor influencing functional outcome. Other factors having an effect in this population were: reoperation, persistence of objective neurological disorders, degree of comorbidity.For the majority of patients, surgical treatment of lumbar spinal stenosis provides good long-term results and patient satisfaction. At ten years, the risk of reoperation was 10% in this population. Compared with data in the literature, these results are better than with medical treatment. Surgery enables these patients to have a quality of life similar to an age-matched control population.

Sagital balance of the spine is a fundamental element necessary for understanding spinal disease and instituting proper treatment. The aim of this prospective work was to establish the physiological values of pelvic and spinal parameters of sagital balance of the spine and to investigate their interactions.Pelvic and spinal parameters were measured on the standing radiographs of 250 healthy volunteers. The following parameters were measured on lateral views including the head, the spine and the pelvis: lumbar lordosis, thoracic kyphosis, sagital tilt at T9, sacral inclination, pelvic incidence, pelvic version, intervertebral angulation, and the vertebral cuneiformization from T9 to S1. These measurements were taken after digitalization of the radiographs. Two types of analysis were performed: a descriptive univariate analysis to characterize the angular parameters and multivariate analysis (correlation, principal component analysis) to detail the relative variations of these parameters.Mean values were: maximal lumbar lordosis 61 +/- 12.7 degrees, maximal thoracic kyphosis 41.4 +/- 9.2 degrees, sacral inclination 44.2 +/- 8.5 degrees, pelvic version 13 +/- 6 degrees, pelvic incidence 55 +/- 11.2 degrees, sagital tilt at T9 10.5 +/- 3.1 degrees. There was a strong correlation between sacral inclination and pelvic incidence (r=0.86), pelvic version and pelvic incidence (r=0.66), lumbar lordosis pelvic incidence pelvic version and thoracic kyphosis (r=0.9) and finally between pelvic incidence and the following parameters: sagital tilt at T9, sacral inclination, pelvic version, lumbar lordosis, and thoracic kyphosis (r=0.98). The relations between the different parameters studied demonstrated that saggital tilt at T9, which reflects spinal balance, is determined by three independent factors. The first is a linear combination of pelvic incidence, lumbar lordosis, and sacral inclination. The second is pelvic version. The third is thoracic kyposis.This work provided a useful tool for analyzing and understanding anteroposterior imbalance in patients with spinal disease and also a means of calculating corrections to be made with treatment, established from the linear regression equations which were elaborated.

Parameters determining sagittal balance are essential for optimal analysis and treatment of many spinal disorders. The purpose of this work was to validate a software designed to measure the principal parameters involved in sagittal balance of the spine.Six parameters (lumbar lordosis, thoracic kyphosis, sagittal tilt at T9, pelvic index, pelvic tilt, slope of the sacrum) were measured on lateral views of the spine from 100 healthy volunteers free of any spinal disease. Two measurement techniques were used: manual measurement and automatic computerized measurement with this software. We hypothesized that manual measures could be accepted as reference values because they are currently the most widely used and because the computerized measurements were obtained using digitalized images that may have modified interpretation. The software was therefore validated by comparing the angles measured manually with the computer output. Inter- and intraobserver coefficients of variation were calculated for the two measurement techniques. One operator performed both series of measurements (manual and computerized). Two other operators preformed two series of independent measures using one of the measurement techniques. Finally, two new operators performed a complete series of measurements using both measurement techniques. Comparisons were performed with the t test for paired variables with calculation of the coefficients of correlation. Intraclass coefficients of correlation were determined for inter- and intra-observer variability.There was an excellent correlation between the manual measurements and the computerized measurements with intra-class coefficients of correlation varying from 0.82 to 0.96. Inter- and intra-observer variabilities were comparable for the two measurement techniques used to determine thoracic kyphosis, lumbar lordosis, pelvic index, pelvic tilt, and slope of the sacrum. Inter- and intra-observer variability was lower when the sagittal tilt was measured with the software specially designed.This comparison between two techniques for measuring pelvic and spinal parameters of sagittal balance of the spine demonstrated a good correlation between manual and the computerized measurements obtained with the software to be evaluated. Computer-assisted measurements not only provided a saving in time but also minimized inter- and intra-observer variability for the estimation of certain parameters.

The main aim of this prospective, multicentric, observational study was to validate a self-administered quality-of-life questionnaire for patients with lumbar spine stenosis treated surgically.The self-administered questionnaire was composed of eight questions exploring three dimensions: lumbalgia, radiculalgia, radicular ischemia. This questionnaire was associated with an index of neurological involvement (to take into account objective neurological data), and with an index of patient satisfaction (to assess the patient's perception of the impact of surgery on lumbalgia, radiculalgia, and gait disorders). The scoring scale was validated by studying the structure of the questionnaire (to ascertain the pertinence of the proposed three dimensions), by determining the questionnaire's reproducibility (intraobserver variability) and sensitivity to change, and by examining the contents of the questions (to assess the capacity of the scale to effectively measure the parameters it was designed to measure). Cronbach's alpha coefficient and principal component analysis were used to assess the questionnaire's structure. Reproducibility was tested on 49 patients who completed the self-administered questionnaire twice at a 15-day interval; intraclass correlation coefficients were determined. Sensibility was tested by correlating variation in the scores obtained pre- and postoperatively with the index of satisfaction; mean standard responses were determined. The validity of the questionnaire's content was assessed by correlating the scores obtained with the questionnaire to those obtained with three other self-administered questionnaires: SF36, EIFEL2 and GHA38.This work included 104 patients, 96 of whom were reviewed at consultations 6 and 12 months after surgery. The principal components analysis confirmed the presence of the three dimensions. The global Cronbach alpha coefficient was 0.86. The global intraclass coefficient of correlation was 0.95, varying from 0.86 to 0.97 depending on the dimension studied. There was a good correlation (0.82) between changes in the score studied and the index of satisfaction. All the mean standardized responses were higher than 1, indicating good sensitivity to change. There was also a good correlation between the questionnaire tested and the EIFEL2 self-administered questionnaire and the following dimensions of the SF36: physical activity, physical pain, vitality, and limitation due to physical pain.Associating a simple 8-question self-administered questionnaire with an index of satisfaction (4 questions) and an objective index of neurological involvement provided a reliable, sensitive, and reproducible assessment of the changes in functional disorders resulting from lumber stenosis before and after surgical treatment.

A 38-year old man developed compressive myelopathy due to radiation-induced osteochondroma at T7. The patient had been given radiotherapy at the age of 7 years for a lymphosarcoma situated at the lower part of the neck. Radiation is an exceptional cause of spinal compression which can be avoided by regular surveillance of patients given radiotherapy in the spinal area as children.

Venous pellet embolism to the cardia after shotgun wound is a very rare occurrence. Number and size of pellets, at the impact make this migration easier; embolism is asymptomatic and may occur 15 years after the injury. Many problems must be mentioned: mechanics of entry into the heart (own velocity, venous flow), topographic diagnosis (chest X-ray, transthoracic, transoesophageal ultrasound and CT-scan), local outcomes of this projectile (local erosion, clot, endocarditis), destination of a new migration (pulmonary embolism, left heart), indications of extraction, supervision. Extraction musn't be systematic, but only in the event of a patent foramen ovale with a risk of systemic embolism, which clinical outcomes are most serious or in the event of complications. The authors report on a 22 years old patient observation whose treatment was abstention and supervision.

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.

SummaryC2 pedicles, or “Hangman's” fracture and “Tear-Drop” fracture, have until now been described as two distinct entities, the former caused by extension-distraction and the latter by compression-flexion mechanisms. The present clinical case combined these two fracture types of the second cervical vertebra (C2), without neurologic complication. Surgical management reduced and stabilized the lesions of the bone and of the mobile segment between C2 and C3. A right-side subhyoid presternocleidomastoid approach was selected, the main deformity lying between the body of the second and third cervical vertebrae.