Retrospective analysis of the spino-pelvic alignment in a population of 85 patients with a lumbar degenerative disease. Several previous publications reported the analysis of spino-pelvic alignment in the normal and low back pain population. Data suggested that patients with lumbar diseases have variations of sagittal alignment such as less distal lordosis, more proximal lumbar lordosis and a more vertical sacrum. Nevertheless most of these variations have been reported without reference to the pelvis shape which is well-known to strongly influence spino-pelvic alignment. The objective of this study was to analyse spino-pelvic parameters, including pelvis shape, in a population of 85 patients with a lumbar degenerative disease and compare these patients with a control group of normal volunteers. We analysed three different lumbar degenerative diseases: disc herniation (DH), n = 25; degenerative disc disease (DDD), n = 32; degenerative spondylolisthesis (DSPL), n = 28. Spino-pelvic alignment was analysed pre-operatively on full spine radiographs. Spino-pelvic parameters were measured as following: pelvic incidence, sacral slope, pelvic tilt, lumbar lordosis, thoracic kyphosis, spino-sacral angle and positioning of C7 plumb line. For each group of patients the sagittal profile was compared with a control population of 154 asymptomatic adults that was the subject of a previous study. In order to understand variations of spino-pelvic parameters in the patients' population a stratification (matching) according to the pelvic incidence was done between the control group and each group of patients. Concerning first the pelvis shape, patients with DH and those with DDD demonstrated to have a mean pelvic incidence equal to 49.8 degrees and 51.6 degrees, respectively, versus 52 degrees for the control group (no significant difference). Only young patients, less than 45 years old, with a disc disease (DH or DDD) demonstrated to have a pelvic incidence significantly lower (48.3 degrees) than the control group, P < 0.05. On the contrary, in the DSPL group the pelvic incidence was significantly greater (60 degrees) than the control group (52 degrees), P < 0.0005. Secondly the three groups of patients were characterized by significant variations in spino-pelvic alignment: anterior translation of the C7 plumb line (P < 0.005 for DH, P < 0.05 for DDD and P < 0.05 for DSPL); loss of lumbar lordosis after matching according to pelvic incidence (P < 0.0005 for DH, DDD and DSPL); decrease of sacral slope after matching according to pelvic incidence (P = 0.001 for DH, P < 0.0005 for DDD and P < 0.0005 for DSPL). Measurement of the pelvic incidence and matching according to this parameter between each group of patients and the control group permitted to understand variations of spino-pelvic parameters in a population of patients.

Matching according to the PI between the patients in the study and the control group enabled us to understand variations of the spinopelvic parameters in a population of patients with DSPL. DSPL patients were characterized by a greater PI than the asymptomatic population; therefore, we suggest that a high PI may be a predisposing factor in developing DSPL. Finally, we observed significant variations in spinopelvic alignment, such as loss of lordosis and sagittal unbalance, which were partially compensated by pelvis back tilt and hyperextension in the upper lumbar spine.

BackgroundFrench GPs in training have an important role in making hospitals function and are the future workforce, however burnout among this group is not uncommon.

The Roy-Camille technique demonstrated a progressive decrease of its safety zone from C3-C6. At C5 and C6 there is a great probability to have a transarticular screw with a Roy-Camille screw. A similar variation was not observed for the Magerl technique. These anatomic results seem to be in relation with the morphologic variability of lateral masses from C3-C6 as demonstrated by an increase of the height/thickness ratio at the lower part of the cervical spine. According to these anatomic considerations and previously published biomechanical data, Roy-Camille technique appears to be the best option at C3 and C4. On the opposite at C5 and C6, the choice is more difficult considering that there is no biomechanical difference between the two techniques and that the Magerl technique is safer but a more demanding procedure.

The purpose of this study was first to assess the feasibility of C7 transpedicular screwing with a morphological study and secondly to evaluate the safety of such a surgical technique when guided only by posterior landmarks. Eighteen C7 vertebrae, harvested from fresh human cadavers, were included in this study. First the morphometry of C7 pedicle was performed on computed tomography with multiplanar reconstructions. Results of this quantitative anatomy were compared with the literature data. Secondly 30 pedicle screws, whose placement was guided only by anatomical features on the posterior face of the dorsal arch, were inserted in 15 C7 vertebrae. A second computed tomographic examination was done after the surgical procedure to check the screw placement in both planes. The average pedicular width was 6+/-1.2 mm and the average height was 5.8+/-1.1 mm. The pedicle angulation in the transverse plane was 33.3 degrees +/-6.6 degrees, the pedicle angulation in the sagittal plane was 4.3 degrees +/-4.5 degrees downward with reference to the lower endplate of C7. The average distance from the entry point of transpedicular screwing to the anterior cortex of the vertebral body was 29+/-3 mm. Concerning the safety of transpedicular screwing, 63% of screws were found entirely inside the pedicle without any violation of the pedicle cortex. Most of pedicle violations were observed in the transverse plane. No grade II violation of the pedicle was observed. Dimensions of the C7 pedicle are amply compatible with transpedicular fixation using 3.5 mm screws. Such a surgical technique seems to be an interesting option when posterior fixation of C7 is required. Nevertheless morphological guidelines appeared not to be sufficient to ensure safe transpedicular screwing. Laminoforaminotomy is strongly recommended, although it has not been evaluated in this study.

Putting a screening or a diagnostic test into everyday use requires the determination of its threshold. The authors present methods that yield a point and an interval estimation of the threshold that maximize the population utility whenever the test results are normally or log-normally distributed among healthy and among diseased subjects, with equal variances. These methods were assessed for bias, coverage probability, coverage symmetry, and confidence-interval width using simulation. They proved to be asymptotically nonbiased and to have a satisfactory coverage probability whenever the sample sizes of the healthy and the diseased subjects are equal to or greater than 50. The methods were next applied to determine an optimal threshold for the antibody load used to diagnose congenital toxoplasmosis at birth. The methods are easy to implement and impose few constraints; however, the sample sizes should be carefully determined according to the required accuracy.

Object. The purpose of this study was to assess human cervical spine pullout force after lateral mass fixation involving two different techniques: the Roy-Camille and the Magerl techniques. Although such comparisons have been conducted previously, because of the heterogeneity of results and the importance of this procedure in clinical practice, it is essential to have data derived from a prospective and randomized biomechanical study involving a sufficient sample of human cervical spines. The authors also evaluated the influence of the sex, the vertebral level, the bone mineral density (BMD), the length of bone purchase, and the thickness of the anterior cortical purchase. Methods. Twenty-one adult cervical spines were harvested from fresh human cadavers. Computerized tomography was performed before and after placing 3.5-mm titanium lateral mass screws from C-3 to C-6. Pullout forces were evaluated using a material testing machine. The load was applied until the pullout of the screw was observed. A total of 152 pullout tests were available, 76 for each type of screw fixation. The statistical analysis was mainly performed using the Kaplan—Meier survival method. The mean pullout force was 266 ± 124 N for the Roy-Camille technique and 231 ± 94 N for the Magerl technique (p < 0.025). For the C3–4 specimen group, Roy-Camille screws were demonstrated to exert a significantly higher resistance to pullout forces (299 ± 114 N) compared with Magerl screws (242 ± 97 N), whereas no difference was found between the two techniques for the C5–6 specimen group (Roy-Camille 236 ± 122 N and Magerl 220 ± 86 N). Independent of the procedure, pullout strengths were greater at the C3–4 level (271 ± 114 N) than the C5–6 level (228 ± 105 N) (p < 0.05). No significant correlation between the cancellous BMD, the thickness of the anterior cortical purchase, the length of bone purchase, and maximal pullout forces was found for either technique. Conclusions. The difference between pullout forces associated with the Roy-Camille and the Magerl techniques was not as significant as has been previously suggested in the literature. It was interesting to note the influence of the vertebral level: Roy-Camille screws demonstrated greater pullout strength (23%) at the C3–4 vertebral level than Magerl screws but no significant difference between the techniques was observed at C5–6.

No abstract