Electromyography and range-of-motion measurements in German soldiers wearing different types of body armour while marching.

INTRODUCTION: In this study, we used surface electromyography (EMG) electrodes in order to measure and compare activity in the neck, back and thigh muscles of soldiers wearing two different types of body armour. A secondary objective was to analyse shoulder and hip ranges of motion using inertial motion sensors. METHODS: Fourteen male soldiers were instructed to march 6 km on a treadmill while wearing different types of body armour. All participants wore shorts and a T-shirt and the same size vest regardless of their body size. We measured back and thigh muscle activity as well as shoulder and hip ranges of motion at regular intervals during the march. RESULTS: Over the course of a 6 km march, muscle activity was already increased to 1.3 to 2.0 times after putting on the vest and increased by up to 13 times during the march with equipment. The new vest with hip belt required higher levels of muscle activity. CONCLUSIONS: Body armour with hip belt placed higher levels of stress on back and neck muscles during a 6 km march than without. There was no major difference between the two types of body armour in terms of thigh muscle activity. TRIAL REGISTRATION NUMBER: DRKS00016005.

Introduction and evaluation of a novel multi-camera surface topography system.

BACKGROUND: Surface topography can be used for the evaluation of spinal deformities without any radiation. However, so far this technique is limited to posterior trunk measurements due to the use of a single posterior camera. RESEARCH QUESTION: Purpose of this study was to introduce a new multi camera surface topography system and to test its reliability and validity. METHODS: The surface topograph uses a two-camera system for imaging and evaluating the subjects front and back simultaneously. Inter- and intra-rater reliability was tested on 40 human subjects by two observers. For validation human, subjects were scanned by MRI and surface-topography. For additional validation we used a phantom with an anthropomorphic body which was scanned by CT and surface topography. RESULTS: Inter- (0.97-0.99) and intra-rater reliability (0.81-0.98) testing revealed good and excellent results in the detection of the body surface structures and measurement of areas and volumes. CT based validation revealed good correspondence between systems in the imaging and evaluation of the phantom model (0.61-10.52 %). Results on validation of human subjects revealed good to moderate results in the detection and measurements of almost all body surface structures (1.36-13.34 %). Only measurements using jugular notch as a reference showed moderate results in validity (0.62-27.5%) testing. SIGNIFICANCE: We have introduced a novel and innovative surface topography system that allows for simultaneous anterior and posterior trunk measurements. The results of our reliability and validity tests are satisfactory. However, in particular around the jugular notch region further improvements in the surface topography reconstruction are needed.

Development of a new 360-degree surface topography application.

BACKGROUND: Surface-topography has been used for almost two decades in the radiation-free clinical evaluation of spinal posture. So far, it was limited to the analysis of back surface and spine. In order to better understand, diagnose and treat complex spinal pathologies, it is important to measure the whole torso. RESEARCH QUESTION: Purpose of this study was to introduce and test an application that allows 360° reconstruction and analysis of the patient's torso. METHODS: The application uses the information gathered from eight distinct scans and angles. For validation we used an Alderson phantom as an anthropomorphic body. Defined areas and volumes were measured by CT and surface-topography. Inter- and intra-rater reliability was tested in 35 healthy subjects by two observers. RESULTS: The results revealed good correspondence between systems in the imaging and evaluation of the Alderson model (5.3-0.5%). Inter- (0.9-0.98) and intra-rater reliability (0.8-0.95) testing revealed good and excellent results in the detection of almost all body surface structures and measurement of areas and volumes. Only area and volume measurements using jugular notch as a reference showed partly moderate results in reliability (0.62-0.93) testing. SIGNIFICANCE: We were able to introduce a novel 360° torso scan application using surface topography to reconstruct torso measurements. The results of our study showed its high validity and reliability. In the future, this application needs to be tested in patients with spinal pathologies. In summary, this new application may help to better understand, diagnose and treat patients with pathologies of torso and spine.

Comparison of two different designs of forefoot off-loader shoes and their influence on gait and spinal posture.

BACKGROUND: The purpose of forefoot off-loader shoes (FOS) is to unload the operated region of the foot in order to allow early mobilization and rehabilitation. However, little is known about the actual biomechanical effects of different designs of FOS on gait, pelvis and spine. RESEARCH QUESTION: Aim of this study was to analyse and compare the effects of two different designs of forefoot unloader shoes. METHODS: Ortho-Wedge (FOS A) and Relief-Dual® (FOS B) were evaluated in this study during standing and while walking. Changes of the pelvic position and spinal posture were measured with a surface topography system and an instrumented treadmill. Gait phases were detected automatically by a built-in pressure plate. RESULTS: Both FOS resulted in a significant increase of pelvic obliquity, pelvic torsion, lateral deviation and surface rotation (p < 0.001) while standing. Between both shoe models, pelvic obliquity and lateral deviation (p < 0.05) were significantly different. During walking, both FOS had a significant effect on spine and pelvis (p < 0.05), however only minor differences were found between the designs. All gait parameters were affected more, wearing FOS A than B. Step length were significantly longer by wearing FOS (p < 0.005). However stance phase raised and swing phase is reduced on the leg wearing FOS A (p < 0.001). SIGNIFICANCE: The study showed that FOS lead to significant changes in pelvic position and spinal posture during standing and while walking. A compensating shoe on the contralateral side is therefore recommend. Gait parameters however were affected more by the traditional FOS A half-shoe. The sole- design and shape of FOS B leads to a more physiological roll-over of the foot.

[Biomechanical modeling and the relevance for total hip arthroplasty]. / Biomechanische Modellierung und ihre Bedeutung für die Hüftendoprothetik.

BACKGROUND: Providing the hip with an endoprosthesis is one of the most common orthopedic interventions in Germany. The long-term success of such a procedure depends on the consideration of the loads due to muscle and joint forces in the planning and operative care. Patient-specific information of forces acting in vivo is not available to the surgeon in clinical routine today. This is where biomechanical modeling comes in. PROCEDURES: A field of activity of biomechanical modeling is the development of methods and procedures for the precise analysis and simulation of endoprosthetic supplies. The aim was to show the possibilities of biomechanical modeling in total hip arthroplasty by means of two examples (sensitivity analysis and pre-/postoperative comparison of intervention outcome). RESULTS: The results of the sensitivity analysis showed that by modeling the position of an optimal reconstruction of the hip rotational center can be found and the forces acting on the hip joint minimized. In the case of the pre-/postoperative comparison, it can be analyzed whether there has been a decrease or increase of load postoperatively, respectively, or whether the conditions are considered to be approximately equal to the preoperative situation. In the future, biomechanical modeling will be able to significantly improve long-term function by reducing wear and optimizing muscular function of the joint. Therefore, the routine use of validated musculoskeletal analysis in the context of standardized preoperative planning and intraoperative navigation-based implementation should be considered. Thus, validated analyses of musculoskeletal loads not only contribute to the extension of basic knowledge but also to the optimization of endoprosthetic care through their integration into the clinical workflow.