Tibiofibular syndesmosis in acute ankle fractures: additional value of an oblique MR image plane

Item does not contain fulltextOBJECTIVE: To evaluate the additional value of a 45� oblique MRI scan plane for assessing the anterior and posterior distal tibiofibular syndesmotic ligaments in patients with an acute ankle fracture. MATERIALS AND METHODS: Prospectively, data were collected for 44 consecutive patients with an acute ankle fracture who underwent a radiograph (AP, lateral, and mortise view) as well as an MRI in both the standard three orthogonal planes and in an additional 45� oblique plane. The fractures on the radiographs were classified according to Lauge-Hansen (LH). The anterior (ATIFL) and posterior (PTIFL) distal tibiofibular ligaments, as well as the presence of a bony avulsion in both the axial and oblique planes was evaluated on MRI. MRI findings regarding syndesmotic injury in the axial and oblique planes were compared to syndesmotic injury predicted by LH. Kappa and the agreement score were calculated to determine the interobserver agreement. The Wilcoxon signed rank test and McNemar's test were used to compare the two scan planes. RESULTS: The interobserver agreement (?) and agreement score [AS (\%)] regarding injury of the ATIFL and PTIFL and the presence of a fibular or tibial avulsion fracture were good to excellent in both the axial and oblique image planes (? 0.61-0.92, AS 84-95\%). For both ligaments the oblique image plane indicated significantly less injury than the axial plane (p?<?0.001). There was no significant difference in detection of an avulsion fracture in the axial or oblique plane, neither anteriorly (p?=?0.50) nor posteriorly (p?=?1.00). With syndesmotic injury as predicted by LH as comparison, the specificity in the oblique MR plane increased for both anterior (to 86\% from 7\%) and posterior (to 86\% from 48\%) syndesmotic injury when compared to the axial plane. CONCLUSION: Our results show the additional value of an 45� oblique MR image plane for detection of injury of the anterior and posterior distal tibiofibular syndesmoses in acute ankle fractures. Findings of syndesmotic injury in the oblique MRI plane were closer to the diagnosis as assumed by the Lauge-Hansen classification than in the axial plane. With more accurate information, the surgeon can better decide when to stabilize syndesmotic injury in acute ankle fractures

To retain or remove the syndesmotic screw: a review of literature

Introduction: Syndesmotic positioning screws are frequently placed in unstable ankle fractures. Many facets of adequate placement techniques have been the subject of various studies. Whether or not the syndesmosis screw should be removed prior to weight-bearing is still debated. In this study, the recent literature is reviewed concerning the need for removal of the syndesmotic screw. Materials and methods: A comprehensive literature search was conducted in the electronic databases of the Cochrane Library, Pubmed Medline and EMbase from January 2000 to October 2010. Results: A total of seven studies were identified in the literature. Most studies found no difference in outcome between retained or removed screws. Patients with screws that were broken, or showed loosening, had similar or improved outcome compared to patients with removed screws. Removal of the syndesmotic screws, when deemed necessary, is usually not performed before 8-12 weeks. Conclusion: There is paucity in randomized controlled trials on the absolute need for removal of the syndesmotic screw. However, current literature suggests that it might be reserved for intact screws that cause hardware irritation or reduced range of motion after 4-6 months

Biomechanical Factors Influencing the Performance of Elite Alpine Ski Racers

BackgroundAlpine ski racing is a popular international winter sport that is complex and challenging from physical, technical, and tactical perspectives. Despite the vast amount of scientific literature focusing on this sport, including topical reviews on physiology, ski-snow friction, and injuries, no review has yet addressed the biomechanics of elite alpine ski racers and which factors influence performance. In World Cup events, winning margins are often mere fractions of a second and biomechanics may well be a determining factor in podium place finishes. Objective The aim of this paper was to systematically review the scientific literature to identify the biomechanical factors that influence the performance of elite alpine ski racers, with an emphasis on slalom, giant slalom, super-G, and downhill events. Methods Four electronic databases were searched using relevant medical subject headings and key words, with an additional manual search of reference lists, relevant journals, and key authors in the field. Articles were included if they addressed human biomechanics, elite alpine skiing, and performance. Only original research articles published in peer-reviewed journals and in the English language were reviewed. Articles that focused on skiing disciplines other than the four of primary interest were excluded (e.g., mogul, ski-cross and freestyle skiing). The articles subsequently included for review were quality assessed using a modified version of a validated quality assessment checklist. Data on the study population, design, location, and findings relating biomechanics to performance in alpine ski racers were extracted from each article using a standard data extraction form. Results A total of 12 articles met the inclusion criteria, were reviewed, and scored an average of 69 ± 13 % (range 40–89 %) upon quality assessment. Five of the studies focused on giant slalom, four on slalom, and three on downhill disciplines, although these latter three articles were also relevant to super-G events. Investigations on speed skiing (i.e., downhill and super-G) primarily examined the effect of aerodynamic drag on performance, whereas the others examined turn characteristics, energetic principles, technical and tactical skills, and individual traits of high-performing skiers. The range of biomechanical factors reported to influence performance included energy dissipation and conservation, aerodynamic drag and frictional forces, ground reaction force, turn radius, and trajectory of the skis and/or centre of mass. The biomechanical differences between turn techniques, inter-dependency of turns, and abilities of individuals were also identified as influential factors in skiing performance. In the case of slalom and giant slalom events, performance could be enhanced by steering the skis in such a manner to reduce the ski-snow friction and thereby energy dissipated. This was accomplished by earlier initiation of turns, longer path length and trajectory, earlier and smoother application of ground reaction forces, and carving (rather than skidding). During speed skiing, minimizing the exposed frontal area and positioning the arms close to the body were shown to reduce the energy loss due to aerodynamic drag and thereby decrease run times. In actual races, a consistently good performance (i.e., fast time) on different sections of the course, terrains, and snow conditions was a characteristic feature of winners during technical events because these skiers could maximize gains from their individual strengths and minimize losses from their respective weaknesses. Limitations Most of the articles reviewed were limited to investigating a relatively small sample size, which is a usual limitation in research on elite athletes. Of further concern was the low number of females studied, representing less than 4 % of all the subjects examined in the articles reviewed. In addition, although overall run time is the ultimate measure of performance in alpine ski racing, several other measures of instantaneous performance were also employed to compare skiers, including the aerodynamic drag coefficient, velocity, section time, time lost per change in elevation, and mechanical energy behaviours, which makes cross-study inferences problematic. Moreover, most studies examined performance through a limited number of gates (i.e., 2–4 gates), presumably because the most commonly used measurement systems can only capture small volumes on a ski field with a reasonable accuracy for positional data. Whether the biomechanical measures defining high instantaneous performance can be maintained throughout an entire race course remains to be determined for both male and female skiers. Conclusions Effective alpine skiing performance involves the efficient use of potential energy, the ability to minimize ski-snow friction and aerodynamic drag, maintain high velocities, and choose the optimal trajectory. Individual tactics and techniques should also be considered in both training and competition. To achieve better run times, consistency in performance across numerous sections and varied terrains should be emphasized over excellence in individual sections and specific conditions.Publ online 28 Dec 2013Swedish Winter Sports Research Centr