Effect of surgical experience and spine subspecialty on the reliability of the {AO} Spine Upper Cervical Injury Classification System

OBJECTIVE The objective of this paper was to determine the interobserver reliability and intraobserver reproducibility of the AO Spine Upper Cervical Injury Classification System based on surgeon experience (< 5 years, 5–10 years, 10–20 years, and > 20 years) and surgical subspecialty (orthopedic spine surgery, neurosurgery, and "other" surgery). METHODS A total of 11,601 assessments of upper cervical spine injuries were evaluated based on the AO Spine Upper Cervical Injury Classification System. Reliability and reproducibility scores were obtained twice, with a 3-week time interval. Descriptive statistics were utilized to examine the percentage of accurately classified injuries, and Pearson’s chi-square or Fisher’s exact test was used to screen for potentially relevant differences between study participants. Kappa coefficients (κ) determined the interobserver reliability and intraobserver reproducibility. RESULTS The intraobserver reproducibility was substantial for surgeon experience level (< 5 years: 0.74 vs 5–10 years: 0.69 vs 10–20 years: 0.69 vs > 20 years: 0.70) and surgical subspecialty (orthopedic spine: 0.71 vs neurosurgery: 0.69 vs other: 0.68). Furthermore, the interobserver reliability was substantial for all surgical experience groups on assessment 1 (< 5 years: 0.67 vs 5–10 years: 0.62 vs 10–20 years: 0.61 vs > 20 years: 0.62), and only surgeons with > 20 years of experience did not have substantial reliability on assessment 2 (< 5 years: 0.62 vs 5–10 years: 0.61 vs 10–20 years: 0.61 vs > 20 years: 0.59). Orthopedic spine surgeons and neurosurgeons had substantial intraobserver reproducibility on both assessment 1 (0.64 vs 0.63) and assessment 2 (0.62 vs 0.63), while other surgeons had moderate reliability on assessment 1 (0.43) and fair reliability on assessment 2 (0.36). CONCLUSIONS The international reliability and reproducibility scores for the AO Spine Upper Cervical Injury Classification System demonstrated substantial intraobserver reproducibility and interobserver reliability regardless of surgical experience and spine subspecialty. These results support the global application of this classification system

Spectral analysis for performance evaluation in a bus network

This paper deals with the performance evaluation of a public transportation system in terms of waiting times at various connection points. The behaviour of a bus network is studied in the framework of Discrete Event Systems (DES). Two possible operating modes of buses can be observed at each connection stop: periodic and non-periodic mode. Two complementary tools, Petri nets and (max, +) algebra, are used to describe the network by a non-stationary linear state model. This one can be solved after solving the structural conflicts associated to the graphical representation. From the characteristic matrix of the mathematical model, we determine eigenvalues and eigenvectors that we use to evaluate the connection times of passengers. This work is finally illustrated with a numerical example.Transportation network Petri nets (max, +) Algebra Spectral theory Performance evaluation

Tsunami hazard assessment in the coastal area of Rabat and Salé, Morocco

In the framework of the three-year SCHEMA European project (<a href="www.schemaproject.org"target="_blank">www.schemaproject.org</a>), we present a generic methodology developed to produce tsunami building vulnerability and impact maps. We apply this methodology to the Moroccan coast. This study focuses on the Bouregreg Valley which is at the junction between Rabat (administrative capital), and Salé. Both present large populations and new infrastructure development. Using a combination of numerical modelling, field surveys, Earth Observation and GIS data, the risk has been evaluated for this vulnerable area. <br></br> Two tsunami scenarios were studied to estimate a realistic range of hazards on this coast: a worst-case scenario based on the historical Lisbon earthquake of 1755 and a moderate scenario based on the Horseshoe earthquake of 28 February 1969. For each scenario, numerical models allowed the production of tsunami hazard maps (maximum inundation extent and maximum inundation depths). Moreover, the modelling results of these two scenarios were compared with the historical data available. <br></br> A companion paper to this article (Atillah et al., 2011) presents the following steps of the methodology, namely the elaboration of building damage maps by crossing layers of building vulnerability and the so-inferred inundation depths

Tsunami vulnerability and damage assessment in the coastal area of Rabat and Salé, Morocco

This study, a companion paper to Renou et al. (2011), focuses on the application of a GIS-based method to assess building vulnerability and damage in the event of a tsunami affecting the coastal area of Rabat and Salé, Morocco. This approach, designed within the framework of the European SCHEMA project (<a href="www.schemaproject.org"target="_blank">www.schemaproject.org</a>) is based on the combination of hazard results from numerical modelling of the worst case tsunami scenario (inundation depth) based on the historical Lisbon earthquake of 1755 and the Portugal earthquake of 1969, together with vulnerability building types derived from Earth Observation data, field surveys and GIS data. The risk is then evaluated for this highly concentrated population area characterized by the implementation of a vast project of residential and touristic buildings within the flat area of the Bouregreg Valley separating the cities of Rabat and Salé. A GIS tool is used to derive building damage maps by crossing layers of inundation levels and building vulnerability. The inferred damage maps serve as a base for elaborating evacuation plans with appropriate rescue and relief processes and to prepare and consider appropriate measures to prevent the induced tsunami risk

OUTCOME OF PERIPROSTHETIC FEMORAL FRACTURES IN HIP ARTHROPLASTY

Periprosthetic fractures are one of the main reasons for revision surgery according to the data of large joint replacement registers. Treatment of patients with periprosthetic fractures is associated with a big number of complications and still keeps its relevance. Purpose of the study is to evaluate treatment outcome of patients with periprosthetic femoral fractures in hip replacement. Material and Methods. The authors performed a retrospective analysis of medical histories of 76 patients who underwent treatment of periprosthetic femoral fractures. The patients were divided into groups by the Unified Classification System (UCS). Follow up period was from 6 to 124 months (mean of 34.90±28.81). Results. 3 cases (3.9%) of periprosthetic femoral fractures were the complications after primary hip arthroplasty and occurred intraoperatively, 75 cases (96.1%) were complications after revision surgery; 56 cases (71.8%) were reported with uncemented and 22 cases (28.2%) with cemented femoral components. In 30 cases (38.5%) fractures had a iatrogenic nature and occurred intraoperatively, in 48 cases (61.5%) — occurred due to high- and low energy trauma. Type B fractures were observed most often — in 53 cases (68%). Conservative treatment, fixation by cerclage or by plate and screws has proven to be the least effective operative options. In the group of patients with extended osteotomy of the greater trochanter the healing was achieved in 90.5% of cases, while in the group without osteotomy — in 75% of cases. Low healing rate of periprosthetic fractures was observed for A and B1 type fractures (65% and 66.7% respectively). Follow up of patients with B2, B3 and C type fractures demonstrated consolidation in more than 80% of cases. Various complications were reported in 17 cases (21.8%). Conclusion. Effective treatment of patients with periprosthetic femoral fractures was associated with extended osteotomy of the greater trochanter (γ = 0.51; p = 0.032), absence of complications in postoperative period (R = 0.55; p = 0.00001), B2, B3 and C fracture types (γ = 0.40; p = 0.02) and use of revision uncemented femoral components with distal fixation (γ = 0.35; p = 0.018). In the authors opinion use of sutures or cerclage wires are not effective in cases of trochanteric fractures and stable femoral components; it would be preferable to perform internal fixation by a plate with hooks such as Dall-Miles. In case of doubts in regard of stem stability the revision should rather stipulate use of uncemented femoral components, in particular long stems with distal fixation

Custom Triflange Acetabular Components for Revision Hip Arthroplasty in the Patients with Severe Acetabular Defects: Planning, Surgical Technique, Outcomes

Employment of custom triflange acetabular components (CTAC) is one of the few options for pelvic reconstruction in the patients requiring complex acetabulum revisions with Paprosky 2 C, 3 A and 3 B defects and pelvic ring disruption.The purpose of the study was to describe the features of planning, surgical technique, and short-term treatment outcomes of the patients with significant acetabular defects, in which the revision hip arthroplasty was performed using the CTAC.Materials and Methods. A single-center analysis of a series of consecutive patients was performed: 50 complex acetabulum revisions in 47 patients (16 men and 31 women). The average age of the patients was 60±12 years (from 31 to 82; Me 62 years), the average body mass index was 29.7±6.3 kg/m2 (18.4 to 46.3; Me 29.0 kg/m).Results. The mean follow-up was 22±13 months (from 3 to 3.6 years; Me 20 months). The average Harris score increased from 27±7 (from 15 to 39; Me 27) before surgery to 64±16 (from 22 to 90; Me 67) a year after (p<0.001). The level of pain according to VAS before surgery was 7±1 points (from 5 to 9; Me 7), after treatment it decreased to 2±1 points (from 0 to 7; Me 1, p<0.001). In 17 cases out of 50 (34%), there was at least one complication: dislocations — 7 (14%) cases; infection — 3 (6%); loosening — 2 (4%); complications associated with the femoral component — 4 (8%), including 3 intraoperative fractures and 1 postoperative, associated with loosening of the implant; pronounced disturbances of static and locomotor functions — 2 (4%). 12 cases out of 50 (24%) required another surgery, all of which were performed in a year. The Kaplan-Meyer survival rate for the hip implants was 0.71, for the CTAC — 0.87.Conclusion. Employment of the CTAC for revision hip arthroplasty in the patients with significant acetabulum defects and pelvic ring disruption allows reliable fixation of the endoprosthesis components. The STAC placement technique is more anatomical than use of structural allografts, several augments or sup-cage systems. It allows reconstruction of extensive bone defects, theoretically avoiding the long-term problems with allografts, modular trabecular components, antiprotrusion systems and cup-cage. Although, to prove this, the longer follow-up is needed