Descriptive profile of scapulothoracic position, strength and flexibility variables in adolescent elite tennis players

Study design Descriptive study, cross-sectional design. Background Tennis requires repetitive overhead movement patterns that can lead to upper extremity injury. The scapula plays a vital role in injury-free playing. Scapular dysfunction has been associated with shoulder injury in the overhead athlete. Objectives The purpose of this study was to describe variables regarding scapular position, muscle strength and flexibility in young elite tennis players. Methods Thirty-five adolescent Swedish elite tennis players (19 boys, aged 13.6 (+/-1.4) years, 16 girls, aged 12.6 (+/-1.3) years), selected on the basis of their national ranking, underwent a clinical screening protocol consisting of: scapular upward rotation at several angles of arm elevation; isometric scapular muscle strength; and anthropometric measurement of pectoralis minor (PM) length. Results The players showed significantly more scapular upward rotation on their dominant side (p<0.001). For both genders, upper trapezius (p=0.003) and serratus anterior (p=0.01) strength was significantly greater on the dominant side, whereas middle and lower trapezius strength showed no side differences. PM was shorter on the dominant side (p<0.001), and in the female players (p=0.006) compared with the boys. Conclusion These results indicate some sports-related adaptations of young tennis players on their dominant side at the scapulothoracic level to exposure to their sport. These data may assist the clinician in the prevention and rehabilitation of sport-specific injuries in adolescent tennis players

New low-stress PECVD poly-SiGe layers for MEMS

Thick poly-SiGe layers, deposited by plasma-enhanced chemical vapor deposition (PECVD), are very promising structural layers for use in microaccelerometers, microgyroscopes or for thin-film encapsulation, especially for applications where the thermal budget is limited. In this work it is shown for the first time that these layers are an attractive alternative to low-pressure CVD (LPCVD) poly-Si or poly-SiGe because of their high growth rate (100-200 nm/min) and low deposition temperature (520/spl deg/C-590/spl deg/C). The combination of both of these features is impossible to achieve with either LPCVD SiGe (2-30 nm/min growth rate) or LPCVD poly-Si (annealing temperature higher than 900/spl deg/C to achieve structural layer having low tensile stress). Additional advantages are that no nucleation layer is needed (deposition directly on SiO/sub 2/ is possible) and that the as-deposited layers are polycrystalline. No stress or dopant activation anneal of the structural layer is needed since in situ phosphorus doping gives an as-deposited tensile stress down to 20 MPa, and a resistivity of 10 m/spl Omega/-cm to 30 m/spl Omega/-cm. With in situ boron doping, resistivities down to 0.6 m/spl Omega/-cm are possible. The use of these films as an encapsulation layer above an accelerometer is shown

Patellofemoral pain syndrome (PFPS): a systematic review of anatomy and potential risk factors

Patellofemoral Pain Syndrome (PFPS), a common cause of anterior knee pain, is successfully treated in over 2/3 of patients through rehabilitation protocols designed to reduce pain and return function to the individual. Applying preventive medicine strategies, the majority of cases of PFPS may be avoided if a pre-diagnosis can be made by clinician or certified athletic trainer testing the current researched potential risk factors during a Preparticipation Screening Evaluation (PPSE). We provide a detailed and comprehensive review of the soft tissue, arterial system, and innervation to the patellofemoral joint in order to supply the clinician with the knowledge required to assess the anatomy and make recommendations to patients identified as potentially at risk. The purpose of this article is to review knee anatomy and the literature regarding potential risk factors associated with patellofemoral pain syndrome and prehabilitation strategies. A comprehensive review of knee anatomy will present the relationships of arterial collateralization, innervations, and soft tissue alignment to the possible multifactoral mechanism involved in PFPS, while attempting to advocate future use of different treatments aimed at non-soft tissue causes of PFPS

Influence of the particle size distribution on surface quality of Maraging 300 parts produced by Laser Powder Bed Fusion

This work investigates the effect of the powder particle size distribution on the surface finish of Maraging 300 specimens, produced by the Laser Powder Bed Fusion (LPBF) process. Although it is recognized that the initial powder morphological characteristics play an important role on LPBF part density, mechanical properties and surface quality, there is a lack of empirical data that could help to link the powder properties to actual metrological established surface parameters, like Ra or Sa. For this reason, an extensive initial powder characterization is presented in this paper, for three Maraging 300 batches, and first insights on the different obtained LPBF surface quality are disclosed. The results demonstrate how small differences in particle size distribution can decrease the LPBF surface roughness consistently. Moreover, it is shown how the use of fine powder can unlock novel LPBF processing strategies to further improve surface finish, down to 1.5 µm measured Ra, and thus reduce eventual post-processing efforts.status: publishe

Effect of process parameters on the surface topography formation in precision additive metal manufacturing

The typical surface topography of parts produced by additive manufacturing differs from those produced by conventional manufacturing. During the powder bed fusion process, spatter particles may eject from the melt pool due to multi-physics phenomena. These spatter particles can have an impact on the part quality as large spatter particles that land on the top of the powder layer may shield the powder from the laser beam, resulting in lack of fusion porosity and increases surface roughness. The measurement of spatter is important to understand the process and to predict the performance of parts. In this study, the effect of laser power and scan speed on the surface topography of the top surface of Maraging steel grade 300 is investigated. The parts were produced by an in-house powder bed fusion machine LM-Q with a powder size distribution of 15 μm to 45 μm. A surface topography comparison was made between several samples which were produced by different process parameters regarding laser power and laser speed, leading to different Archimedes' densities. The surface topography was measured by a confocal microscope. The topography data were pre-processed with bi-cubic interpolation and least square plane subtraction. For the parameter evaluation, S- and F-filters with appropriate nesting index settings were used. Several conventional and surface texture parameters are evaluated in order to investigate the correlation with the production parameters.status: publishe

Screening the athlete's shoulder for impingement symptoms: a clinical reasoning algorithm for early detection of shoulder pathology

Chronic shoulder pain and dysfunction are common complaints among overhead athletes seeking care from physical medicine and rehabilitation. Impingement is a frequently described pathological condition in the overhead athlete. Impingement symptoms may be the result of rotator cuff pathology, shoulder instability, scapular dyskinesis or muscle dysfunction, biceps pathology, SLAP lesions and chronic stiffness of the posterior capsule. At present, numerous different shoulder tests have been described in literature and discussed with respect to their individual diagnostic accuracy. However, in view of the number of shoulder tests, it is often a challenge for the clinician to select the appropriate tests for diagnosing the underlying pathology. The purpose of this paper is to present and discuss a clinical algorithm which may be used in the early detection of the underlying causes of impingement symptoms. In this algorithm, a specific chronology and selection of diagnostic tests may offer the clinician a guideline in his physical examination of the athlete with shoulder pain