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Der Umstand, dass bis heute nicht bekannt ist, wie viele Menschen in Deutschland zuhause versterben, wird als Ausgangspunkt der Argumentation zugunsten der Etablierung eines Sterbeortregisters gewählt. Hierfür wird die grundsätzliche Bedeutung – bei durchaus heterogenen Zielsetzungen und funktionalem Zweck – medizinischer Register erkennbar gemacht. Deutlich wird, dass von einem Sterbeortregister kurzfristig insbesondere für die Versorgungsplanung und die Gesundheitspolitik, mittelfristig aber auch für die Qualitäts-entwicklung der Versorgung sowie mittel- bis langfristig Erkenntnisse für die Versorgungsforschung und für epidemiologische Studien, ein deutlicher Nutzen zu erwarten ist. Dies betrifft alle Orte (Milieus, Settings) der Versorgung. Um solch ein Sterbeortregister inhaltlich und auch funktional wirkungsvoll auszugestalten, sollte eine interdisziplinäre Arbeitsgruppe mit transsektoraler Erfahrung über die Palliativversorgung hinausreichend zusammengeführt werden. Indes wäre allein schon die genaue – und jährlich berichtete – Ermittlung des Sterbeortes ein deutlicher und praktisch einfach zu erreichender Fortschritt.
Der Beitrag soll auf die Verlegung sterbender Menschen in Krankenhäusern und Pflegeeinrichtungen aufmerksam und dabei entstehende ethische Problemlagen bzw. Herausforderungen erkennbar machen. Grundlage hierfür sind Studien zur Versorgungspraxis; jeder vierte sterbende Heimbewohner und jeder fünfte sterbende Krankenhauspatient wird in der letzten Lebensphase verlegt. Ursachen hierfür sind vielfältig und betreffen medizinisch-pflegerische, soziale, organisatorische sowie ökonomische Faktoren. Häufig werden Verlegungen notfallähnlich aus überforderten Versorgungsbereichen hin zu Stationen mit erhöhter personeller Ausstattung sowie professioneller und sozialer Versorgungskompetenz vollzogen.
Verbesserte Menschen
(2015)
Was zunächst nur als verheißungsvolle Utopie am Zukunftshorizont der Gentechnik aufschien, ist längst dem bioethischen Diskurs entwachsen und konfrontiert uns mit grundlegenden Fragen unseres menschlichen Selbstverständnisses: die Verbesserung und zunehmende Technisierung des Menschen. In diesem Band wird das Thema Enhancement aus sozialphilosophischer und technikphilosophischer Perspektive behandelt. Thomas Zoglauer zeichnet die wesentlichen ethischen Argumentationslinien dieser Debatte nach und setzt sich kritisch mit dem Enhancement unter den Aspekten der Freiheit, sozialen Gerechtigkeit, Chancengleichheit und menschlichen Wohlergehens auseinander. Karsten Weber zeigt wie das Konzept des Cyborgs von der Science-Fiction-Literatur geprägt wurde und als utopisches Leitbild die Medizin- und Neurotechnik beeinflusst hat. Als Folge dieser Entwicklung beginnen sich die Unterschiede zwischen Mensch und Maschine und die damit verbundenen anthropologischen Dichotomien aufzulösen, was auch Konsequenzen für unser Menschenbild und die normative Bewertung des Enhancements hat.
Zur diagnostischen Unterstützung bei der Befundung laryngealer Erkrankungen soll eine Farb- und Formanalyse der Stimmlippen durchgeführt werden. In diesem Beitrag wird ein Verfahren zur Trennung der spiegelnden und diffusen Reflexionsanteile in Farbbildern des Larynx vorgestellt. Die Farbe der diffusen Komponente entspricht dabei der beleuchtungsunabhängigen Objektfarbe, während deren Wichtungsfaktoren als Eingabe für Shape-from-Shading-Verfahren zur Oberflächenrekonstruktion dienen.
Video Documentation of endoscopic findings simplifies diagnostic counseling of the patient and aids pre-operative discussion among the medical team. Judgment of such images is still subjective and can not give a quantitative evaluation of the disease process regarding diagnosis or response to treatment. Modern treatment of early laryngeal cancer with laserablation requires intensive follow up and frequent direct laryngoscopy under general anesthesia with blind biopsies to detect any tumor residual or recurrence. Inflammatory conditions of the larynx are frequently confused with other causes of dysphonia. Mapping anddigital analysis of the documented image will suggest the tumor site and avoids undue blind biopsies under anesthesia. However, varying illumination results in different colors reflected from the same object. To achieve quantitative analysis, color constancy has to be assured. Inthis paper, the environment is presented which allow the objective judgment of larngoscopies.
Quantitative Farbmessungen sollen die Diagnostik laryngealer Erkrankungen unterstützen. Dabei wird der Farbeindruck nicht nur durch die Reflexionseigenschaften des Gewebes sondern auch durch die Farbe der verwendeten Lichtquelle beeinflußt. Der hier vorgestellte Farbkonstanz-Algorithmus basiert auf dem dichromatischen Reflexionsmodell und liefert eine pixelweise Trennung des Farbbildes in seine beiden Faxbanteile. Die Körperfarbe entspricht dabei der gewebespezifischen Reflexion, die Oberfächenfarbe der Strahlung der Lichtquelle.
Nutzung eines Farbkonstanz-Algorithmus zur Entfernung von Glanzlichtern in laryngoskopischen Bildern
(1998)
1 Einführung
Funktionelle und organische Störungen im Larynx beeinträchtigen die Ausdrucksfähigkeit des Menschen. Zur Diagnostik und Verlaufkontrolle werden die Stimmlippen im Larynx mit Hilfe der Video-Laryngoskopie aufgenommen. Zur optimalen Farbmessung wird dazu an das Lupenendoskop eine 3-Chip-CCD-Kamera angeschlossen, die eine unabhängige Aufnahme der drei Farbkanäle erlaubt. Die bisherige subjektive Befundung ist von der Erfahrung des Untersuchers abhängig und läßt nur eine grobe Klassifikation der Krankheitsbilder zu. Zur Objektivierung werden daher quantitative Parameter für Farbe, Textur und Schwingung entwickelt. Neben dem Einfluß der wechselnden Lichtquellenfarbe auf den Farbeindruck ist die Sekretauflage auf den Stimmlippen ein Problem bei der Farb-und Texturanalyse. Sie kann zu ausgedehnten Glanzlichtern führen und so weite Bereiche der Stimmlippen für die Farb-und Texturanalyse unbrauchbar machen. Dieser Beitrag stellt einen Farbkonstanz-Algorithmus vor, der unabhängig von der Lichtquelle quantitative Farbwerte des Gewebes liefert und die Glanzlichtdetektion und -elimination ermöglicht.
2 Methodik
Ziel des Farbkonstanz-Algorithmus ist die Trennung von Lichtquellen-und Gewebefarbe. Unter Verwendung des dichromatischen Reflexionsmodells [1] kann die Oberflächenreflexion mit der Farbe der Lichtquelle und die Körperreflexion mit der Gewebefarbe identifiziert werden. Der Farbeindruck entsteht aus der Linearkombination beider Farbkomponenten. Ihre Gewichtung ist von der Aufnahmegeometrie abhängig, insbesondere vom Winkel zwischen Oberflächennormalen und dem Positionsvektor der Lichtquelle. In einem zweistufigen Verfahren wird zunächst die Lichtquellenfarbe geschätzt, dann die Gewebefarbe ermittelt. Hieraus können beide Farbanteile durch die Berechnung der Gewichtsfaktoren pixelweise getrennt werden.
Laryngoscopic images of the vocal tract are used for diagnostic purposes. Quantitative mea-surements like changes of the glottis size or the surface of the vocal cords during an image sequence can be helpful to describe the healing process or to compare the findings of diffe-rent patients. Typically the endoscopic images are circulary symmetric distorted (barrel di-stortion). Therefore measurements of geometric dimensions depend on the object´s position in the image. In this paper an algorithm is presented which allows the computation of the translational invariant "real" object size by correcting the image distortion without using additional calibration of the optical environment.
Background
Breast reconstruction is an important coping tool for patients undergoing a mastectomy. There are numerous surgical techniques in breast reconstruction surgery (BRS). Regardless of the technique used, creating a symmetric outcome is crucial for patients and plastic surgeons. Three-dimensional surface imaging enables surgeons and patients to assess the outcome’s symmetry in BRS. To discriminate between autologous and alloplastic techniques, we analyzed both techniques using objective optical computerized symmetry analysis. Software was developed that enables clinicians to assess optical breast symmetry using three-dimensional surface imaging.
Methods
Twenty-seven patients who had undergone autologous (n = 12) or alloplastic (n = 15) BRS received three-dimensional surface imaging. Anthropomorphic data were collected digitally using semiautomatic measurements and automatic measurements. Automatic measurements were taken using the newly developed software. To quantify symmetry, a Symmetry Index is proposed.
Results
Statistical analysis revealed that there is no dif- ference in the outcome symmetry between the two groups (t test for independent samples; p = 0.48, two-tailed).
Conclusion
This study’s findings provide a foundation for qualitative symmetry assessment in BRS using automatized digital anthropometry. In the present trial, no difference in the outcomes’ optical symmetry was detected between autologous and alloplastic approaches.
Objective:
Complex hue/saturation images as a new approach for color texture classification using Gabor filters are introduced and compared with common techniques.
Method:
The interpretation of hue and saturationas polar coordinates allows direct use of the HSV-colorspace for Fourier transform. This technique is applied for Gabor feature extraction of color textures. In contrast to other color features based on the RGB-colorspace [1] the combination of color bands is done previous to the filtering.
Results:
The performance of the new HS-featuresis compared with that of RGB based as well as grayscale Gabor features by evaluating the classifi-cation of 30 natural textures. The new HS-featuresshow same results like the best RGB features but allow a more compact representation. On the averagethe color features improve the results of grayscale features.
Conclusion:
The consideration of the color information enhances the classification of color texture. The choice of colorspace cannot be adjudged finally, but the introduced features suggest the use of the HSV-colorspace with less features than RGB.
Objectives
Tumor size is a well recognized prognostic factor in early stage cervical carcinoma (CX). However, limited knowledge exists about the value of tumor size in surgically treated CX with extrauterine extension.
Methods
245 cases of local advanced CX (FIGO stage IIA and IIB) who received upfront surgery were evaluated regarding tumor size, regarding the prediction of pelvic lymph node involvement and recurrence free and overall survival during a median follow-up time of 54 months (95% CI 45.4–62.6 months). Tumors larger than 4 cm were defined as bulky stage disease.
Results
Bulky disease was seen in 46.1% (113/245). 60.2% of these patients showed pelvic lymph node involvement, compared to 42.4% (56/132) in non-bulky tumors (p = 0.006; odds ratio: 2.2 [95% CI: 1.3–3.6]). Patients with bulky tumors showed an increase of recurrent disease (40.2% vs. 28.0%; p = 0.045). The relative risk for recurrent disease was 1.97 (95% CI: 1.3–3.0). The 5-year overall survival rate was significantly lower (67.7% [95% CI: 58.2–74.8] vs. 49.5% [95% CI: 36.8–59.1]; p = 0.0015). In multivariate analysis, tumor stage, pelvic lymph node involvement and maximal tumor size were independent prognostic factors.
Conclusions
The results suggest that tumor size, defining bulky disease as tumors larger than 4 cm, is of prognostic impact also in FIGO stage II cervical carcinomas. A revised FIGO/TNM classification system similar to the subgrouping of stage IB CX is recommended for stage II using a cut-off value of 4 cm as discriminator: stage IIA1 and stage IIB1 for tumors with ≤ 4 cm and IIA2 and IIB2 for tumors > 4 cm (i.e. bulky disease).
Objectives: Different patterns of invasion (representing different grades of tumor cell dissociation) are associated with prognostic outcome in cancer. We evaluated the prognostic value of different patterns of invasion (PI) in cervical carcinomas (CX).
Methods: Six hundred eleven surgically treated CX (FIGO IB to IIB) were re-evaluated histologically regarding the PI, using a three-level scoring system. Closed PI was defined as cohesive growth with well-delineated (pushing) borders. In finger-like PI the tumor grows in solid cords/trabecles. Highly dissociative growth in small groups or single cells was defined as spray-like PI. Types of PI were correlated to tumor stage, histo-morphologic factors and prognostic outcome.
Results: Sixty percent of the tumors showed a spray-like PI, 30% a finger-like PI and only 7.4% were of the closed type. Spray-like PI showed a significant correlation with advanced stage disease, lymphovascular space involvement, poorly differentiated tumors and pelvic lymph node metastases. Spray-like PI was accompanied by a reduced 5-year overall survival when compared to the finger-like and closed PI (68.7% vs. 80.9% vs. 88.5%; P=0.0004). The prognostic impact of the PI disappeared in node-positive patients (P=0.06) but persisted in patients without pelvic lymph node disease (P=0.03). In multivariate analysis, using COX regression model, the PI represented as independent prognostic factor.
Conclusions: Spray-like PI (i.e., highest degree of tumor cell dissociation) is associated with advanced tumor stages, increased rate of recurrency and a reduced overall survival. In separate analysis of patients with and without lymph node metastases, the impact of PI persisted only in node-negative cases as a prognostic factor.
Several kinds of cellular adhesion molecules, like different splicing variants of CD 44, have gained important as prognostic or markers for metastatic disease. Fresh frozen samples from 64 cervical carcinoma (CX) were stored in liquid nitrogen and examined using ELISA-technique, testing the prognostic impact. Normal cervical tissue served as control. CD 44-v6 concentration, was significant elevated in tumor tissue, when compared to the controls (P=0.04). There was no correlation to tumor stage (P=0.61), lymphovascular space involvement (P=0.075) or pelvic lymph node involvement (P=0.81). The CD 44-v6 concentration was not informative regarding recurrence-free and overall survival. Contrary to immunohistochemistry, the quantification of CD 44-v6 using ELISA-technique does not provide any further information.
Objective: To determine the utility of DNA content and DNA-related variables of proliferative activity regarding prognosis in cervical cancer.
Study design: DNA image (ICM) andflow cytometry (FCM) were performed to determine the DNA index (DI), 5c-exceeding rate (5c-ER), S-phase fraction (SPF) and proliferation index (PI) in 163 patients with surgically staged pT1b1-pT2b squamous cell cancer of the uterine cervix and treated with primary radical hysterectomy. ICM was performed on imprint cytology, obtained from fresh tumor tissue, which was also used for FCM. Results were analyzed using the chi2 test and Cox regression analysis for risk of pelvic lymph node involvement, tumor recurrence and recurrence-free survival (RFS).
Results: ICM was performed on all 163 and FCM on 133 samples. One-third of the tumors showed DNA aneuploidy. Analysis demonstrated prognostic significance of a DI > or = 1.70, with a (70:30) 2.3-fold risk of recurrence (P=.024) and reduced RFS of 10 months (P=.003) in cases of DI > or = 1.70. A high 5c-ER > 11% was associated with pelvic lymph node involvement and decreased RFS (P < or = .04). Significantly more relapses were found in tumors with SPF > 12% (70.8% vs. 29.2%, P=.007). RFS was markedly reduced in tumors with high SPF (52.3 vs. 61.1 months, P=.011). Low proliferative tumors (PI<25%) were associated with lower stage (P=.036) and increased RFS (61.2 vs. 47.1 months, P=.028). In multivariate analysis of clinicopathologic variables (pT category, nodal status, lymphovascular space involvement) and DNA related variables, pelvic lymph node involvement was the only significant predictor of RFS. In patients with nodal involvement, tumors with DI >1.70 were associated with lessfavorable outcomes.
Conclusion: DNA-related variables of cell cycle analysis were valuablefor predicting prognosis in cervical cancer patients. Tumors with DI>1.70, 5c-ER >11% and high proliferative activity (SPF>12%, PI>25%) represent a subgroup with a poor prognosis.
Recent developments in lasers have provided us the possibility of laser ocular surgery. The xenon, argon, neodymium:YAG and dye lasers have been successfully used in out-patient clinics. The excimer laser has been attracting researchers' interest in the new application of laser to cornea and lens. The erbium:YAG laser emits a 2.94-microns beam that can ablate the transparent ocular tissues such as lenses and corneas. The author has applied this laser to the cornea, lens, vitreous and other ocular tissues. The erbium:YAG laser beam was directed through a 1.5-meter-long, 200-microns-diameter fiberoptic guide. The radiant energy measured about 50 mJ at the end of the probe. The laser was emitted as a 400-microsecond pulse. Freshly enucleated rabbit eyes were used in this study. Laser burns were applied to the tissue surface at various energy settings. At minimal power, the tissues were coagulated by the erbium:YAG laser application. At a power of more than 636-954 mJ/mm2, tissue began to evaporate; the tissue loss was observed under a surgical light microscope. Corneal photoablation, lens ablation, iridotomy, trabeculotomy, cutting of the vitreous and retinal ablation were easily performed. Like the excimer laser, the erbium:YAG laser is a potential tool for ocular surgery.
Objective
The expression of uPA and PAI‐1 as parameters of tumour‐associated proteolysis has been implicated in the process of tumour cell invasion and the metastatic process. However, there is limited information on the impact of these parameters in cervical carcinoma.
Methods
Quantitative levels for uPA (n = 114) and PAI‐1 (n = 103) were researched in operatively treated, surgically staged squamous cell cancer of the uterine cervix, using an ELISA‐technique. Results were assessed regarding their impact in predicting pelvic lymph nodes metastases, tumour recurrence rate and recurrence free survival (RFS) using uni‐ and multivariate analysis.
Results
Median levels of both parameters were significantly higher in tumour tissue than in normal cervical tissue (p < 0.001). Detection of uPA gave no useful prognostic information. PAI‐1 concentration showed a positive correlation with advanced tumour stage (p = 0.008), but no significant correlation with nodal status (pN0: 2.6 vs. pN1: 4.0 ng/mg protein; p = 0.092). Using a cut‐off level of 2.4 ng/mg protein, patients with elevated PAI‐1 levels demonstrated reduced RFS (45.9 versus 52.9 months; p = 0.1). Multivariate analysis, including nodal status, tumour stage, lymphovascular space involvement and grading failed to demonstrate any prognostic impact of uPA and PAI‐1.
Conclusions
The results indicate, that PAI‐1 expression is of some prognostic impact in cervical cancer, indicating an association of elevated PAI levels with local tumour progression and reduced recurrence‐free survival.
Contact force path in total hip arthroplasty: effect of cup medialisation in a whole-body simulation
(2020)
Background:
Cup medialisation down to the true acetabular floor in total hip arthroplasty with a compensatory femoral offset increase seems to be mechanically advantageous for the abductor muscles due to the relocation of the lever arms (body weight lever arm decreased, abductor lever arm increased). However, limited information is currently available about the effects of this reconstruction type at the head cup interface, compared to an anatomical reconstruction that maintains the natural lever arms. Through a whole-body simulation analysis, we compared medialised versus anatomical reconstruction in THA to analyse the effects on: (1) contact force magnitude at the head cup interface; (2) contact force path in the cup; and (3) abductor activity.
Methods:
Musculoskeletal simulations were performed to calculate the above-mentioned parameters using inverse dynamics analysis. The differences between the virtually implanted THAs were calculated to compare the medialised versus anatomical reconstruction.
Results:
Cup medialisation with compensatory femoral offset increase led to: (1) a reduction in contact force magnitude at the head cup interface up to 6.6%; (2) a similar contact force path in the cup in terms of sliding distance and aspect ratio; and (3) a reduction in abductor activity up to 17.2% (gluteus medius).
Conclusions:
In our opinion, these potential biomechanical gains do not generally justify a fully medialised reconstruction, especially in younger patients that are more likely to undergo revision surgery in their lifetime. Cup medialisation should be performed until sufficient press fit and bony coverage of a properly sized and oriented cup can be achieved.
Based on electromyographic data and force measurements within the shoulder joint, there is an indication that muscle and resulting joint reaction forces keep increasing over an abduction angle of 90°. In inverse dynamics models, no single parameter could be attributed to simulate this force behaviour accordingly. The aim of this work is to implement kinematic, kinetic and muscle model modifications to an existing model of the shoulder (AnyBody™) and assess their single and combined effects during abduction up to 140° humeral elevation. The kinematics and the EMG activity of 10 test subjects were measured during humeral abduction. Six modifications were implemented in the model: alternative wrapping of the virtual deltoid muscle elements, utilization of a three element Hill model, strength scaling, motion capture driven clavicle elevation/protraction, translation of the GH joint in dependency of the acting forces and an alteration of the scapula/clavicle rhythm. From the six modifications, 16 different combinations were considered. Parameter combinations with the Hill model changed the resultant GH joint reaction force and led to an increase in force during abduction of the humerus above 90°. Under the premise of muscle activities and forces within the GH joint rising after 90° of humeral abduction, we propose that the Hill type muscle model is a crucial parameter for accurately modelling the shoulder. Furthermore, the outcome of this study indicates that the Hill model induces the co-contraction of the muscles of the shoulder without the need of an additional stability criterion for an inverse dynamics approach.
Fragestellung: Molekulare Analysen haben deutlich gemacht, dass maligne Tumoren durch Veränderungen des Genoms hervorgerufen werden. Im Gegensatz zu den erblich bedingten Tumorerkrankungen sind die Kenntnisse zur Bedeutung familiärer Faktoren bei den sog. sporadischen Tumoren, insbesondere beim Zervixkarzinom (CX) begrenzt. Material und Methode: Patientinnen des CX-Registers der Universitäts-Frauenklinik wurden retrospektiv bezüglich der Familienanamnese (FA) analysiert. Als positive FA wurde eine maligne Tumorerkrankung bei einem oder mehreren Verwandten ersten Grades definiert. Es wurde unterschieden, ob es sich um Zervixkarzinome, andere gynäkologische Malignome (außer Mammakarzinom) oder eine extragenitale Lokalisation handelte. Diese Daten wurden zum Erkrankungsalter und zum Nachweis pelviner Lymphknotenmetastasen in Beziehung gesetzt. Ergebnisse: 159/737 Frauen (21,6 %) wiesen eine positive FA auf. In 10,7 % der Fälle war mehr als ein Verwandter ersten Grades erkrankt; bei 6,9 % Angehörige ersten und zweiten Grades. Weibliche Verwandte ersten Grades von 42 Frauen wiesen Malignome des weiblichen Genitaltraktes (außer CX) auf. In 6,9 % waren die Mutter und/oder die Schwester an einem Zervixkarzinom erkrankt. Das Durchschnittsalter der Patientinnen mit positiver Familienanamnese (FA) unterschied sich nicht von dem derjenigen mit leerer FA, wohl aber bei getrennter Betrachtung nach der Tumorlokalisation. Bezüglich des Tumorstadiums (pTNM) und der Zahl der Patientinnen mit histologisch nachgewiesenen pelvinen Lymphknotenmetastasen bestand kein Unterschied. Schlussfolgerungen: Die bisherigen Ergebnisse deuten auch beim Zervixkarzinom auf eine familiäre Belastung hin. Dabei existieren offenbar Familien, in denen mit HPV-assoziierte Präkanzerosen bzw. Tumoren vermehrt auftreten. Besonders gefährdet sind Patientinnen, deren weibliche Anverwandte ersten Grades bereits an einer zervikalen Präkanzerose (besonders CIN III) oder einem invasiven CX erkrankt sind. Diese Frauen sollten einem engmaschigen Screening unterzogen werden.
Local gray level dependencies of natural images can be modelled by means of co-occurrence matrices containing joint probabilities of gray-level pairs. Texture, however, is a resolution-dependent phenomenon and hence, classification depends on the chosen scale. Since there is no optimal scale for all textures we employ a multiscale approach that acquires textural features at several scales. Thus linear and nonlinear scale-spaces are analyzed by multiscale co-occurrence matrices that describe the statistical behavior of a texture in scale-space. Classification is then performed on the basis of texture features taken from the individual scale with the highest discriminatory power. By considering cross-scale occurrences of gray level pairs, the impact of filters on the feature is described and used for classification of natural textures. This novel method was found to improve classification rates of the common co-occurrence matrix approach on standard textures significantly.
Zur Lösung komplexer Segmentierungsprobleme wird eine hierarchische und farbbasierte Wasserscheidentransformation vorgestellt. Geringe Modifikationen bezüglich Startpunktwahl und Flutungsprozess resultieren in signifikanten Verbesserungen der Segmentierung. Das Verfahren wurde zur Lippendetektion in Farbbildsequenzen eingesetzt, die zur quantitativen Beschreibung von Sprechbewegungsabläufen automatisch ausgewertet werden. Die Experimente mit 245 Bildern aus 6 Sequenzen zeigten eine Fehlerrate von 13%.
The gold standard for the analysis of human kinematics and kinetics is a camera-based motion capture system in combination with force measurement platforms. Alternatively, inertial measurement units can be utilized to obtain human kinematics, while ground reaction forces are computed from full body dynamics. This setup represents a system independent from the spatial confinement of a gait laboratory. The aim of this study is the comparison of the two methods by the investigation of lower limb kinematics and the resulting joint reaction forces within the ankle-, knee- and hip joints. For this purpose, human motion during gait was captured simultaneously by both measurement techniques. 13 trials from 8 different test subjects were evaluated in total. IMU data was processed with a quaternion based Kalman Filter. The data sets were implemented into a musculoskeletal simulation program in order to drive a virtual human body model. Each sensor was aligned to the gravitational and magnetic field vectors of the earth. The angles of flexions, extensions and rotations were analyzed to determine kinematic differences. Joint reaction forces defined kinetic dissimilarities. The overall kinematic differences of both models yielded root mean square errors of 7.62°, 6.02°, 4.95°, 2.79°, 2.38° and 3.56° for ankle flexion, subtalar eversion, knee flexion, hip external rotation, hip abduction and hip flexion, respectively. The proximo-distal differences in force peaks between the models yielded overall for the ankle, 57.33 %Bodyweight(BW) ± 46.86 %BW (16.66 %(Maximum peak to peak) ± 13.62 %) for the knee 37.09 %BW ± 29.33 %BW (17.65 % ± 15.44 %) and 32.03 %BW ± 24.33 %BW (15.6 % ± 12.54 %) for the hip. The overall outcome of this work investigated an approach independent of the common setup of the gait laboratory, thus enabling a cheaper and more flexible technology as an alternative. However, kinematic and thus kinetic differences remain rather large. Future work aims to improve the contact criterion for the calculation of the ground reaction forces and the implementation of a full-body calibration algorithm for the IMU system in order to counteract magnetic field disturbances.
Common Schanz screw systems can be used to stabilize pelvic ring fractures. In order to accommodate for different patient’s requirements, implants can be placed in cranio-caudal direction into the os ilium (T1), or into the supraacetabular bone canal, and thus, in dorso-ventral direction (T2). Whereas both techniques are currently used, no data of the biomechanical behavior is available up to this date. The aim of this study is to analyze, whether T2 shows biomechanical advantages with respect to tissue and implant stresses due to the enlarged bone-implant interface. Forces acting on the pelvis were analyzed using motion capture data of a gait cycle obtained by the utilization of a musculoskeletal simulation program. A three dimensional finite element (FE) model of the pelvis with grayscale-based material properties was generated. The muscle and joint reaction forces at toe-off were applied to the FE model and instable pelvis fractures were implemented. The osteosynthesis systems were positioned within the model in order to enable the comparison between the two different surgical techniques. Stresses and displacements were analyzed for bone tissue, fracture zone and implant.
T2 lead to approx. 30% larger displacements in the fracture zone. Von-Mises stresses were larger for T2 in the implant (80 MPa vs. 227 MPa), whereas T1 leads to larger stresses in the bone tissue (200 MPa vs. 140 MPa).
Both implantation techniques showed a good biomechanical behavior. Differences could be found with respect to tissue strains and deformations in the fracture zone. If bone quality or fracture healing are of concern, T2 or T1 should be used, respectively. However, both techniques seem to be applicable for cases with no special requirements. Further analyses aim to investigate the behavior under cyclic loading.
Thoracolumbar spine model with articulated ribcage for the prediction of dynamic spinal loading
(2016)
Musculoskeletal modeling offers an invaluable insight into the spine biomechanics. A better understanding of thoracic spine kinetics is essential for understanding disease processes and developing new prevention and treatment methods. Current models of the thoracic region are not designed for segmental load estimation, or do not include the complex construct of the ribcage, despite its potentially important role in load transmission. In this paper, we describe a numerical musculoskeletal model of the thoracolumbar spine with articulated ribcage, modeled as a system of individual vertebral segments, elastic elements and thoracic muscles, based on a previously established lumbar spine model and data from the literature. The inverse dynamics simulations of the model allow the prediction of spinal loading as well as costal joints kinetics and kinematics. The intradiscal pressure predicted by the model correlated well (R2=0.89) with reported intradiscal pressure measurements, providing a first validation of the model. The inclusion of the ribcage did not affect segmental force predictions when the thoracic spine did not perform motion. During thoracic motion tasks, the ribcage had an important influence on the predicted compressive forces and muscle activation patterns. The compressive forces were reduced by up to 32%, or distributed more evenly between thoracic vertebrae, when compared to the predictions of the model without ribcage, for mild thoracic flexion and hyperextension tasks, respectively. The presented musculoskeletal model provides a tool for investigating thoracic spine loading and load sharing between vertebral column and ribcage during dynamic activities. Further validation for specific applications is still necessary.
Effect of the fractured calcaneus's peripheral fragment displacement on the triceps surae function
(2015)
We have developed a novel, computer-assisted operation method for minimal-invasive total hip replacement (THR) following the concept of “femur first/combined anteversion,” which incorporates various aspects of performing a functional optimization of the prosthetic stem and cup position (CAS FF). The purpose of this study is to assess whether the hip joint reaction forces and patient’s gait parameters are being improved by CAS FF in relation to conventional THR (CON). We enrolled 60 patients (28 CAS FF/32 CON) and invited them for gait analysis at three time points (preoperatively, postop six months, and postop 12 months). Data retrieved from gait analysis was processed using patient-specific musculoskeletal models. The target parameters were hip reaction force magnitude (hrf), symmetries, and orientation with respect to the cup. Hrf in the CAS FF group were closer to a young healthy normal. Phase-shift symmetry showed an increase in the CAS FF group. Hrf orientation in the CAS FF group was closer to optimum, though no edge or rim-loading occurred in the CON group as well. The CAS FF group showed an improved hrf orientation in an early stage and a trend to an improved long-term outcome.
Different target areas within the concept of combined cup and stem anteversion have been published for total hip arthroplasty (THA). We asked whether component positioning according to eight standard combined anteversion rules is associated with (1) more physiological gait patterns, (2) higher improvement of gait variables and (3) better clinical outcome after THA.In a prospective clinical study, 60 patients received cementless THA through an anterolateral MIS approach in a lateral decubitus position. Six weeks postoperatively, implant position was analysed using 3D-CT by an independent external institute. Preoperatively, six and 12 months postoperatively range of motion, normalized walking speed and hip flexion symmetry index were measured using 3D motion-capture gait analysis. Patient-related outcome measures (HHS, HOOS, EQ-5D) were obtained by an observer blinded to 3D-CT results. Eight combined anteversion definitions and Lewinnek's "safe zone" were evaluated regarding their impact on gait patterns and clinical outcome.Combined cup and stem anteversion according to standard combined anteversion definitions as well as cup placement within Lewinnek's "safe zone" did not influence range of motion, normalized walking speed and/or hip flexion symmetry index six and 12 months after THA. Similarly, increase of gait parameters within the first year after THA was comparable between all eight combined anteversion rules. Clinical outcome measures like HHS, HOOS and EQ-5D did not show any benefit for either of the combined anteversion definitions.Standard combined cup and stem anteversion rules do not improve postoperative outcome as measured by gait analysis and clinical scores within one year after THA.
Influence of minimally invasive total hip replacement on hip reaction forces and their orientations
(2014)
Minimally invasive surgery (MIS) is becoming increasingly popular. Supporters claim that the main advantages of MIS total hip replacement (THR) are less pain and a faster rehabilitation and recovery. Critics claim that safety and efficacy of MIS are yet to be determined. We focused on a biomechanical comparison between surgical standard and MIS approaches for THR during the early recovery of patients. A validated, parameterized musculoskeletal model was set to perform a squat of a 50th percentile healthy European male. A bilateral motion was chosen to investigate effects on the contralateral side. Surgical approaches were simulated by excluding the incised muscles from the computations. Resulting hip reaction forces and their symmetry and orientation were analyzed. MIS THR seemed less influential on the symmetry index of hip reaction forces between the operated and nonoperated leg when compared to the standard lateral approach. Hip reaction forces at peak loads of the standard transgluteal approach were 24% higher on the contralateral side when compared to MIS approaches. Our results suggest that MIS THR contributes to a greater symmetry of hip reaction forces in absolute value as well as force-orientation following THR.
In the last few years, increasingly kicks to the head were observed as a criminal offense. This study examined the
influence of age, shoe type and kicking direction on the severity of head trauma.
Male test persons were divided into two groups “Old” and “Young”. Both groups were equipped with light
sneakers and combat boots. A standard laboratory crash dummy was used to simulate the victim’s body. First, the
dummy’s head, free floating above the ground, was kicked vertically. Second, the dummy’s head was kicked
horizontally. Established injury criteria were used to quantify the injury risk.
No influence concerning the type of foot wear and no difference between the groups “Old” and “Young” could be
found. For all analyses, kicking vertically generally lead to a higher risk for the subject compared to kicking
horizontally.
In this study, only the integral effect of the kicks could be analyzed. A detailed injury pattern cannot directly be
derived from the data. Nevertheless, the presented data show the massive potential of injuries associated with head
kicks.
Meniscal tears in the avascular zone have a poor self-healing potential, however partial meniscectomy predisposes the knee for early osteoarthritis. Tissue engineering with mesenchymal stem cells and a hyaluronan collagen based scaffold is a promising approach to repair meniscal tears in the avascular zone. 4 mm longitudinal meniscal tears in the avascular zone of lateral menisci of New Zealand White Rabbits were performed. The defect was left empty, sutured with a 5-0 suture or filled with a hyaluronan/collagen composite matrix without cells, with platelet rich plasma or with autologous mesenchymal stem cells. Matrices with stem cells were in part precultured in chondrogenic medium for 14 days prior to the implantation. Menisci were harvested at 6 and 12 weeks. The developed repair tissue was analyzed macroscopically, histologically and biomechanically. Untreated defects, defects treated with suture alone, with cell-free or with platelet rich plasma seeded implants showed a muted fibrous healing response. The implantation of stem cell-matrix constructs initiated fibrocartilage-like repair tissue, with better integration and biomechanical properties in the precultured stem cell-matrix group. A hyaluronan-collagen based composite scaffold seeded with mesenchymal stem cells is more effective in the repair avascular meniscal tear with stable meniscus-like tissue and to restore the native meniscus.
Measuring functional outcome after total hip replacement with subject-specific hip joint loading
(2012)
Total hip replacement is an often-performed orthopedic surgical procedure; the amount of procedures undertaken will increase since our life expectancy is growing. In order to optimize function, hip biomechanics should be restored to as near normal as possible. The goal of this pilot study was to determine whether or not it is feasible to compute the vectorial hip reaction force pathways on the head of the prosthesis and the force angles relative to the cup of the prosthesis that occur during gait in total hip replacement patients, serving as an objective measurement of the functional outcome following hip replacement. A three-dimensional gait analysis, measuring ground reaction forces and kinematics, was performed. The data retrieved from the gait analysis was used as the input for the musculoskeletal model to compute vectorial joint reaction forces for data processing. To evaluate the position and orientation of the joint reaction forces, the force path, as well as the force angles for the operated and non-operated joint, has been calculated during the stance phase of the specific leg. The force path for subject 2 on the non-operated side is only located in the posterior-lateral quarter, as is the force path for subject 1. In contrast to this subject, the force path for subject 2 at the operated hip joint can be found only within the anterior quarter of the head of the implant, where it is nearly equally distributed in the medio-lateral half of the prosthesis head. The force-inclination angles on the cup of subject 1, with respect to the plane of the socket face, indicates that the force vector is mainly positioned in the same quadrant when compared with subject 2 (in a cup-fixed coordinate system). The force-anteversion angle behaves similarly to the force-inclination angle, even when the effects are not as pronounced. The proposed methods in this article are aiming to define two functional outcomes of total hip replacement that are related to wear and rim loading. It is accepted that wear is not only a function of time, but a function of use. Owing to the methods listed in this article, we are able to determine a) the applied force and b) the sliding distance (force pathway) in a subject-specific manner. The computed hip-reaction force angles and the distance to the rim cup are a measurement for cup or rim loading, and occurs in the so-called safe-zones. This method may well give us insight into the biomechanical situation during gait, after receiving total hip replacement, that we need to fully understand the mechanisms acting on a hip joint and to prove a possible increase of functional outcome after receiving total hip replacement.