Correction for patient sway in radiographic biplanar imaging for three-dimensional reconstruction of the spine: in vitro study of a new method.

BACKGROUND: Three-dimensional (3D) reconstructions of the spine in the upright position are classically obtained using two-dimensional, non-simultaneous radiographic imaging. However, a subject's sway between exposures induces inaccuracy in the 3D reconstructions. PURPOSE: To evaluate the impact of patient sway between successive radiographic exposures, and to test if 3D reconstruction accuracy can be improved by a corrective method with simultaneous Moire-X-ray imaging. MATERIAL AND METHODS: Using a calibrated deformable phantom perceptible by both techniques (Moire and X-ray), the 3D positional and rotational vertebral data from 3D reconstructions with and without the corrective procedure were compared to the corresponding data of computed tomography (CT) scans, considered as a reference. All were expressed in the global axis system, as defined by the Scoliosis Research Society. RESULTS: When a sagittal sway of 10 degrees occurred between successive biplanar X-rays, the accuracy of the 3D reconstruction without correction was 8.8 mm for the anteroposterior vertebral locations and 6.4 degrees for the sagittal orientations. When the corrective method was applied, the accuracy was improved to 1.3 mm and 1.5 degrees , respectively. CONCLUSION: 3D accuracy improved significantly by using the corrective method, whatever the subject's sway. This technique is reliable for clinical appraisal of the spine, if the subject's sway does not exceed 10 degrees . For greater sway, improvement persists, but a risk of lack of accuracy exists.

Influence of the sagittal anatomy of the pelvis on the intercrestal line position.

BACKGROUND AND OBJECTIVE: The line joining the two iliac crests is classically regarded as the anatomical landmark determining the inter-vertebral space L4-L5 for the spinal punctures. Its variability has been reported but never related to predictive clinical anatomic factors identifying patients groups in which there is increased risk of miscalculation of the spinal level. METHODS: Two sagittal pelvic anatomical angles, called 'pelvic incidence' and 'pelvic lordosis' were measured on lateral X-rays of the pelvis of 132 normal individuals and 49 spondylolysis patients. The values were compared with the sagittal projection of the intercrestal line on the disco-vertebral lumbar structures. RESULTS: A strict relation was observed between this projection of the intercrestal line and the sagittal pelvic anatomical angles. The greater the pelvic incidence, the higher the intercrestal line was projected, all the more in patients with spondylolysis with a listhesis or a disc narrowing. CONCLUSIONS: The relation between the pelvic sagittal angles and the intercrestal line projection explains the variability described for this anatomical landmark. It implies precautions minimizing neurological risk in the case of a puncture carried out more cranially than expected, particularly for high values of pelvic incidence occurring in spinal pathologies such as spondylolysis, in the elderly or in the obese patients. In these cases, we recommend the use of spinal imaging during the procedure to assist selection of the desired insertion level.

[Two key describers of the sacro-acetabular relationships: the angles of sacral and acetabular incidence]. / Deux descripteurs clé des relations sacro-cotyloïdiennes : les angles d'incidence sacrée et cotyloïde Mise en évidence par le logiciel De-Visu.

PURPOSE OF THE STUDY: Implantation of total hip arthroplasties raises several important questions concerning the relationship between the orientation of the lumbosacral joint and the acetabular-femoral joint; in other words, between the position of the patients trunk and the orientation of the acetabula. To elucidate better these complex relationships, we conducted a morphometry study on a sample of 51 dry pelves: pelv 26 female and 25 male specimens. MATERIAL AND METHODS: Three-dimensional coordinates of 47 homologous points were recorded for each pelvis. Data were then processed with De-Visu, a graphic visualization software. Seven parameters were compared: sacral slope, sacral incidence, and five parameters quantifying the three-dimensional orientation of the acetabula. RESULTS: The graphic modelization enabled an integral 3-D visualization of each pelvis. The sagittal view enabled simultaneous visualization of the sacrum, the sacroiliac joints, the acetabula, and their alignments, as well as the variability of their spatial relation. The position reference chosen to simulate the upright position aligned the anterior iliac spines and the superior pubic point. This position was found pertinent because the mean value of the sacral slope (41.8) and the sacral incidence (54) were not different from published series. The sacral slope was the most strongly correlated with the acetabular parameters. It exhibited a positive correlation with sagittal acetabular slope (r=0.59) and acetabular inclination (r=0.59). It exhibited a negative correlation with acetabular anteversion (R=0.45). The correlation with the sagittal acetabular slope was very strong for anteversion (r=0.92), and rose with acetabular inclination (r=-0.66). The angle formed by the two acetabular axes was highly variable (37). The correlation between this angle and inclination was very high in males (r=-0.88) and non-significant in females. There was however a very strong correlation with anteversion in females (r=-0.74) which was non-significant in males. This contrasting finding was related to the wide spread of the inclination values in males and anteversion values in females. DISCUSSION: We demonstrated a new sagittal parameter: the acetabular incidence. The summit of this angle is the center of the acetabulum. The sides are the pelvic thickness and the acetabular axes. This parameter was negatively correlated with the sacral incidence. It account simultaneously for the sagittal position of the sacrum in relation to the acetabula and for the degree of acetabular anteversion and inclination. We have demonstrated that the geometric sum of these two angles, sacral incidence and acetabular incidence, is equivalent to the sacro-acetabular angle demonstrated by Lazennec and Saillant. These authors showed that the sacro-acetabular angle is the sum of two positional parameters, the sacral slope and the sagittal acetabular tilt (or slope). The three angles -- sacral incidence, acetabular incidence, sacro-acetabular angle -- are anatomic angles which do not vary with the pelvic position.

[Unfavorable influence of the dynamic neutralization system on sagittal balance of the spine]. / Conséquences défavorables sur l'équilibre sagittal du rachis du système de neutralisation dynamique.

PURPOSE OF THE STUDY: The dynamic neutralization system (Dynesis) has been proposed for the treatment of symptomatic lumbar discopathy. This system preserves the mobility of the instrumented vertebral segment and restores discal height by posterior distraction on pedicular screws, stabilization being ensured by compression on a spacer. The potential kyphosing effect of this system and the impact on sagittal morphology of the spine were analyzed. MATERIAL AND METHODS: Twenty-six patients were studied. Lateral x-rays of the lumbar spine in the upright position were obtained before and after the surgical procedure and at mean 9.5 +/- 3.3 months follow-up. Comparisons were made between the pre- and postoperative presentation with measurement of the pelvic and spinal sagittal parameters described by Duval-Beaupère: inclination of the pelvic segment on the sacrum, lordosis, and disc wedge angles at each level (particularly the instrumented levels). Sagittal morphology was assessed pre- and postoperatively. RESULTS: Mean kyphosing effect was 6 +/- 1.4 degrees, induced by the posterior distraction system. This accentuated the initial lumbar hypolordosis related to the degenerative disease. Comparison of the pre- and postoperative films revealed four types of sagittal reaction of the lumbopelvic segment: no modification (type A), significant loss of lordosis without change at the pelvis level (type B) or with compensatory pelvic retroversion (type C), accentuation of the lordosis with pelvic anteversion (type D). CONCLUSION: The dynamic neutralization system (Dynesis) can stabilize degenerative discopathy and protect the adjacent levels. Posterior distraction perturbs the initial hypokyphosis and can lead to pelvic compensation to achieve better dynamic balance. This loss of lordosis is however a cause of excessive mechanical stress on the lumbar structures and can lead to long-term degradation. Future developments of this dynamic system should take into account the essential factor of sagittal balance.

[Rupture of the metallic lining in bicentric hemi-arthroplasties of the hip. Apropos of 3 cases]. / Ruptures du revêtement métallique dans les hémi-arthroplasties bicentriques de hanche. A propos de 3 cas.

Three cases of rupture of outer shell of biarticular prostheses used for femoral head fractures are reported. Insufficient thickness of this metallic surface is observed at the pole of the cups. The biomechanical forces inducing the rupture of such a defective surface are the result of mobility of the acetabular horns with weight-bearing. This 3-dimensional behavior of the acetabulum may explain the individual variations of mobility of the floating cups.

[Fracture-avulsion of the anterior tibial tuberosity in adolescents]. / Fracture-avulsion de la tubérosité tibiale antérieure chez l'adolescent.

A rare case of a 14-year-old girl with an avulsion-fracture of the tibial tuberosity is reported (type III-A). This lesion is described mainly in boys. The authors explain the classification of the different types of avulsion fracture according to the epiphyseal development of the upper end of the tibia and the stage of maturation at the time of trauma.

[Synovial cyst of the hip. Apropos of a case manifested by venous compression]. / Kyste synovial de la hanche. A propos d'un cas révélé par une compression veineuse.

Femoral vein compression by a synovial cyst of the hip is described, and the differential diagnosis is discussed. Such a lesion may be associated with rheumatoid arthritis, idiopathic necrosis of the femoral head or acute arthritis. The various clinical patterns are reviewed.

[Camptocormia or reducible lumbar kyphosis in elderly subjects. Apropos of 2 cases of lipoid degeneration of the paravertebral muscles]. / "Camptocormie" ou cyphose lombaire réductible du sujet âgé. A propos de deux cas de dégénérescence graisseuse des muscles paravertébraux.

Two cases of "camptocormia" or progressive and reducible kyphosis acquired in the elderly are reported. This sagittal imbalance of the spine is induced by fatty involution of the paravertebral muscles. One case was symmetrical, the other one unilateral. This rare pathology should be considered during the spinal examination. Bony fusion is problematic owing to the muscular insufficiency. The primary treatment is medical, by strengthening and corticotherapy.

[Y-shaped cartilage in the development of the normal pelvis and in congenital hip dislocation]. / Le cartilage en Y dans la croissance du bassin normal et dans la luxation congénitale de la hanche.

The authors use a radiographic approach to demonstrate the primary role of the triradiate cartilage in hip development in the normal child and in congenital dislocation of the hip. The orientation of this cartilage with respect to the dysplasia gives an indication as to the prognosis of the CDH. The acetabular angle is of lesser interest with respect to the orientation of the triradiate cartilage on the pelvic radiographic examination.

[Limb lengthening in children and osteogenesis using the technics of Wagner and Ilizarov and their modifications]. / L'allongement des membres chez l'enfant et l'ostéogenèse dans les techniques de Wagner et Ilizarov et leur modification.

Different methods of lower limb lengthening are reviewed, related to delays in strengthening and type of callus: Wagner's technique (5 cases), decortication 3 weeks before osteotomy (1 case), and Ilizarov's technique (10 cases on 8 tibiae and 6 femurs). In 5 cases, decortication with osteotomy-closure and waiting 2 weeks before beginning lengthening, was performed. This was carried out at 1 mm/day. The type of fixator is unimportant. This technique allows a restitution of the tubular bone structure in 3 or 4 months in a periosteo-cortico-medullary callus.

[Revision of arthrodesis of the knee using total prosthesis. Case report]. / Désarthrodèse de genou par prothèse totale. A propos d'un cas.

The authors report the case of a 62-year-old patient whose desire to recover mobility of the knee, arthrodesed 22 years ago, led them to perform a total arthroplasty. The result was satisfactory. The contraindications and implications of such procedures are discussed with reference to 13 other cases reported in the literature.

[Congenital pseudarthrosis of the clavicle. Apropos of a case report and literature review]. / La pseudarthrose congénitale de la clavicule. A propos d'une observation et revue de la littérature.

A new case of congenital nonunion of the clavicle is reported with a histological description. Medullar drilling and bone grafting "in loco" was performed during the surgical procedure. The etiologic hypotheses are discussed. The authors compare congenital nonunions between the pathologies associated with the necessity of medullar drilling for consolidation.

[Supple intervertebral stabilization according to Graf. Evaluation of its use and technical approach]. / La stabilisation intervertébrale souple selon Graf. Bilan d'utilisation et apports de la technique.

The authors report their clinical experience with Graf's supple intervertebral stabilization system. The results are discussed with respect to the biomechanical and clinical definitions of vertebral instability and the natural evolution of degenerative disease of the lumbar spine. The result are favorable for the cases with clinical instability, but are not as good for the degenerative cases or after discectomy. In spite of the short-term clinical benefits for the cases with pathological articular hypermobility, the authors are cautious regarding the use of this technique. They emphasize the unknown long-term clinical and biomechanical evolution and the difficulties encountered for secondary arthrodesis caused by the volume of the pedicular screws.

[Femoro-patellar prosthesis. A retrospective study of 45 consecutive cases with a follow-up of 3-12 years]. / Les prothèses fémoro-patellaires. Etude rétrospective de 45 cas successifs avec un recul de 3 à 12 ans.

Forty-five consecutive patients operated between 1986 and 1995 were evaluated to assess the long term results of patellofemoral arthroplasty. Revision had to be performed in 8 cases for the following reasons: loosening (3), lateral impingement (3), malposition (1) and persistent patella instability (1). Two groups of patients were identified based upon the preoperative assessment: 21 had primary osteoarthritis without anatomic malalignment (group C) and 24 had a history of patellofemoral instability and trochlear dysplasia demonstrated by clinical and radiological evaluation (group D). Only 43% of good results were found in group C whereas in group D, the percentage of good results was close to 83%. The most common cause of poor results in group C was the degenerative involvement of the femorotibial compartments (5 patients had to undergo total knee arthroplasty subsequently). For group D patients, femorotibial osteoarthritis was not a determinant factor as regards the outcome of patellofemoral arthroplasty. To the authors, it appears that the best indication for patellofemoral arthroplasty is femoropatellar osteoarthritis with malalignment in patients having a normal femorotibial axis even in the presence of femorotibial osteoarthritis as long as the latter does not exceed grade II.

Proposal for a plan of treatment of congenital dislocation of the hip (Belgian Association of Pediatric Orthopaedics).

After several round table discussions between the members of the Belgian Association of Pediatric Orthopedics (BAPO) a plan of treatment of congenital dislocation of the hip was adopted. The purpose of this publication, is to propose this plan as a basis for a general approach to the problem of congenital dislocation of the hip (CDH).

[Benign osteonecrosis of vertebral body versus neoplastic lesions. Limitations of CT and magnetic resonance imaging]. / Osteonécrose bénigne du corps vertébral versus lésion néoplasique. Limites de l'imagerie en CT-scan et résonance magnétique.

A case of vertebral necrosis of L4 is reported in a young woman without previous steroid therapy. Only the intraoperative histological examination was able to confirm the diagnosis as a benign vertebral collapse, because the CT scan and MR imaging were suggestive of a malignant involvement. The authors report the various criteria proposed to distinguish benign and malignant vertebral collapse with magnetic resonance imaging. These equivocal criteria should be viewed within the context of tissue replacement within the necrotic area during the evolution. Transpedicular biopsy is emphasized. Only the histological examination is specific and allows right planning of the surgical procedure.

[Arthrosynovial cyst of the hip after total hip arthroplasty with a ceramic-on-ceramic interface]. / Kyste arthro-synovial de hanche sur prothèse totale à couple de friction céramique-céramique.

An inguinal arthrosynovial cyst of the hip joint developed after total hip arthroplasty leading to compression of the femoral vein. This complication occurred after implantation of a non-cemented prosthesis with a ceramic-on-ceramic interface inserted in a polyethylene sandwich. Multiple foreign bodies composed of both ceramic and polyethylene particles were visualized microscopically. Later, rupture of the joint interface required implant replacement. This cyst was a precursor sign of a deteriorating prosthesis surface.

[Infected total knee prosthesis. Guidance for therapeutic choice]. / Les prothèses totales de genou infectées. Orientation du choix thérapeutique.

PURPOSE OF THE STUDY: The aim of the study is to assess the functional results and septic evolution in the treatment of infected total knee arthroplasties. MATERIAL AND METHODS: 22 patients were reviewed; 8 were initially treated in our institution and 14 transferred from other hospitals. Articular debridement alone leaving the prosthesis in situ was initiated in 3 of our 8 patients as well as in 6 of the transferred cases. In both groups, this procedure appeared to be a failure. Prosthetic-reimplantation procedure was elected in 10 patients either as a one-stage (5 cases) or a two-stage surgery (5 cases). This has been successfully rated in 7 cases. Femoro-tibial arthrodesis was performed in 15 patients, three of them being a failure of the prosthetic reimplantation. Follow-up ranges from 16 months to 9 years with well documented records. RESULTS: As stated earlier, articular debridement alone has not proven to be a helpful procedure since it did not eradicate the septic complication in any case. Prosthetic reimplantation has been a successful treatment in 7 of the 10 attempted cases. The one-stage procedure is providing the best functional result. Recurrent infection occurred in 3 cases: there were patients with poor host defense (diabetes, arteritis, old age, ...) with resistant bacteria complicating a hinge-knee prosthesis. Femoro-tibial arthrodesis was achieved in 10 of the 15 patients and necessitated all together 23 surgical operations. The highest union rate was observed in cases where sterile conditions were achieved, fixation being performed with an intramedullary nail. Failure of arthrodesis confines the patients in such an uncomfortable situation that 2 of them has asked for an amputation. DISCUSSION AND CONCLUSION: Early surgical debridement may occasionally salve a prosthesis when it is performed shortly after the onset of infection, in an unloosened unconstrained prosthesis infected by a low-virulence organism. In our study, no patient but one met those criteria. For those cases nevertheless, our procedure of choice is now the one-stage reimplantation who seems to be more effective for eradicating the infection and gives rise to a better clinical result. The two-stage reimplantation is the current procedure for handling an infected knee prosthesis. Some patients are still excluded from this procedure because of their poor health condition, bone loss, inadequate viability of skin and extensor mechanism or an uncontrolled sepsis. For such a case, arthrodesis remains the most reliable method of management, especially when it can be stabilized with an intramedullary fixation, which implies to perform a two-stage arthrodesis.

[Extraction of a foreign body from the elbow using arthroscopy]. / L'extraction de corps étrangers du coude par arthroscopie.

Arthroscopy of the elbow is now a good diagnostic and therapeutic method, particularly for the removal of loose bodies which are frequently found in the elbow, whatever their etiology. The authors have investigated the advantages and disadvantages of different sites of entry and the technique of removal of loose bodies in five cases. The technical ease of the procedure and the simplicity of the after-care makes it the method of choice in this condition.

Follow-up of the sagittal spine by optical technique.

OBJECTIVES: Report the use of an optical technique for individual monitoring of the sagittal morphology of the spine in an upright position while avoid irradiation. SUBJECTS AND METHODS: The series consists of 15 asymptomatic subjects and 326 cases with spinal disorders. Sagittal analysis is expressed by the global trunk tilt (GTT), the intensity of the curves and their level of inflection. RESULTS: The confidence interval is 2 to 3° and 3 to 6mm according to the parameters. A significant correlation was observed for the global axis measured by optical or radiological techniques. Variations in intensity and proportion of thoracic and lumbar sagittal curves were observed according to the disease, as well as their evolution over a period of 5 to 30 months. Various "strategies" of adaptation have been observed during repeated examinations. DISCUSSION: This non-radiating technique allows to be repeated after initial X-rays, for regular monitoring of a disturbance or a therapeutic effect. Its understandable imaging allows the patient to be aware of his situation. CONCLUSION: This optical technique is reliable and safe for monitoring the sagittal balance while helping further therapeutic target.