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Purpose Optimal anatomical reduction and stable fixation of acetabular fractures are important in avoiding secondary dislocation and osteoarthritis. Biomechanical studies of treatment options of acetabular fractures aim to evaluate the biomechanical properties of different fixation methods. As the setup of the biomechanical test can influence the experimental results, this review aimed to analyze the characteristics, comparability and clinical implications of studies on biomechanical test setups and finite element analyses in the fixation of acetabular fractures. Methods A systematic literature research was conducted according to the PRISMA guidelines, using the PubMed/MEDLINE and Web of Science databases. 44 studies conducting biomechanical analyses of fixation of acetabular fractures were identified, which met the predefined inclusion and exclusion criteria and which were published in English between 2000 and April 16, 2021. The studies were analyzed with respect to distinct parameters, including fracture type, material of pelvis model, investigated fixation construct, loading direction, loading protocol, maximum loading force, outcome parameter and measurement method. Results In summary, there was no standardized test setup within the studies on fixation constructs for acetabular fractures. It is therefore difficult to compare the studies directly, as they employ a variety of different test parameters. Furthermore, the clinical implications of the biomechanical studies should be scrutinized, since several test parameters were not based on observations of the human physiology. Conclusion The limited comparability and restricted clinical implications should be kept in mind when interpreting the results of biomechanical studies and when designing test setups to evaluate fixation methods for acetabular fractures.

Introduction: Clinical trials currently evaluate the use of mesenchymal stem cells (MSCs) for the treatment of non-union bone fractures. The stem cells are injected directly into the non-union area of a bone via a cannula. During this injection process, pressure and shear forces affect the MSCs which could influence the viability of the cells. One parameter that influences the level of the shear forces is the volume flow. The aim of this study is to show whether the injection process with two different volume flows influences the cell viability. Methods: MSCs were isolated from bone tissue, harvested during arthroplasty. Afterwards, they were diluted to a concentration of 1 million cells/mL and 1 mL of this suspension was injected through a cannula with 200 mm length and 2 mm diameter (14 G) with volume flows of 38 and 100 mL/min. The evaluation was performed by detecting living, apoptotic, and dead cells using flow cytometry. The statistical analysis was performed with a Kruskal-Wallis-test to identify significant differences and with a TOST procedure for significant equivalence. The significance level was set to 5 % and the equivalence margin to 20 %. Results: The cell population of healthy cells was in the control group 85.88±2.98 %. After an injection with 38 mL/min the population of healthy cells was 86.04±2.53 % and with 100 ml/min 85.48±1.64 %. The statistical analysis revealed no significant difference between these groups (p = 0.99), but a significant equivalence between the control group and the two volume flows (38 mL/min: p = 0.002, 100 mL/min: p = 0.001). In addition the results show no increase of apoptotic and dead cells in the population after injection. Conclusion: The results indicate that the injection process through the cannula with these volume flows has no effect on the viability of the MSCs.

Introduction Biomechanical studies have proved that locking plates have better primary stability besides versatility regarding fracture pattern while reducing bone contact and bridging the gap, whereas conventional nonlocking plates (plus lag screw) depend on bone-plate compression. The clinical benefit of locking plates over nonlocking plates remains unanswered, however. Therefore, this retrospective cohort study was set up to test the hypothesis that the use of locking plates for unstable ankle fractures will result in fewer re-displacements, superior bony healing, and functional and clinical outcomes better than observed in the nonlocking cohort. Methods Bimalleolar ankle fractures (AO 44-B2) without syndesmotic injury treated with either a locking or a nonlocking plate were included. Groups were compared for complications, bone healing, secondary dislocation, progressions of osteoarthritis, and clinical outcome using patient-reported outcome measures. Results Data revealed no clinical outcome differences (Olerud-Molander Ankle Score: nonlocking 88.2 ± 14.4, locking 88.8 ± 12.3, P = .69, robust two 1-sided test for equality (RTOST): P = .03; American Orthopaedic Foot and Ankle Score: nonlocking 91.2 ± 12.9, locking 91.8 ± 11.3, P = .96, RTOST: P = .04). Nevertheless, a significant postoperative progression of osteoarthritis was detected in both groups (P = .04). This was independent of implant (P = .16). Although difference was not significant, locking plates were preferred in older (P = .78) and sicker patients (P = .63) and in cases with severer osteoarthritis (P = .16), and were associated with a higher complication rate (P = .42) and secondary dislocation (nonlocking 9.4%, locking 18.2%; P = .42). Re-displacement, however, was not a compelling reason for revision. Conclusions The present study shows statistically significant equality of both types of implants. Contrary to our expectation, locking plates seemed to be associated with a higher risk for re-displacement. Overall, the use of either locking or nonlocking plates for unstable AO 44-B2 fractures is safe and successful despite significant progression of osteoarthritis. Level of Evidence: III, Retrospective observational cohort study

This study aims to assess if there is an evident correlation between fusion length and rehabilitation success after trauma to the cervical spine that could potentially be used to predict functional outcomes. This monocentric study was conducted in the Spinal-Cord-Injury center of the Berufsgenossenschaftliches Klinikum Hamburg. Data sets of 199 patients from the Spinal-Cord-Injury center admitted between the beginning of 2003 and the end of 2018 were subjected to statistical analyses. The Spinal Cord Independence Measure II (SCIM II) difference between admission and discharge was chosen as the primary outcome variable of a multiple linear regression analysis, including several other variables. The length of fusion, SCIM at admission and the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) values at admission could be identified as significant predictors. The cervical fusion length could be identified as an independent predictor of the functional outcome within our model. This correlation most likely mediates for the range of motion as well as partly for injury severity. This is much harder to evaluate in a newly admitted rehabilitation patient than a single numerical value that represents its rehabilitative implications, such as fusion length. Together with an initial assessment of the SCIM and ISNCSCI, it provides a solid basis for outcome prediction.

Background: Articular cartilage has an exceptionally poor capacity for healing, but Autologous Matrix Induced Chondrogenesis is a procedure with a substantial body of literature that demonstrates its performance in chondral and osteochondral repair. However, data concerning dynamic postural stability after cartilage repair procedures is lacking. Objective: Therefore, the present study was designed to assess postural stability following cartilage repair in the knee. Methods: 20 adults had undergone Autologous Matrix Induced Chondrogenesis for the treatment of full-thickness cartilage defects, with minimum 36 months of follow-up. Clinical outcomes were evaluated by patient reported outcome measures while dynamic postural stability was assessed using the star excursion balance test. The untreated, contralateral limbs served as controls. Results: At a mean follow-up of 43 months, patients reported a Visual Analog Score for pain of 1.6±2.2, a mean Lysholm score of 78.5±17.9 and a mean Knee Osteoarthritis Outcome Score of 143.3±16.1. The star excursion balance test showed no significant difference between limbs. Conclusion: With no difference in dynamic postural stability, our results indicate that this treatment provides a positive clinical outcome, with no deficits in postural stability when compared to the contralateral, untreated leg.

Purpose The goal of this study was to provide recent data on incidence of spinal cord injuries (SCI) in Germany. Methods The source of information was data collected via the mandatory submission of ICD-10 GM Codes by German public hospitals after patient discharge. Data from 2013 to 2020 were retrieved from the databases of the Federal Bureau of Statistics. ICD-10 Codes for acute SCI were identified. Statistical analysis was performed using Jamovi and Excel. Results A total of 10,360 patients were reported, of whom 58.7% suffered from a cervical, 30.8% a thoracic and 10.4% a lumbar lesion. Two peaks in incidence were observed at approximately 30 and 70 years old. A population-size-adjusted overall incidence of 15.73 (SD 0.77) per million per year was calculated. We calculated the incidences in several subpopulations and discovered significantly higher incidences among males and among those over the age of 60. We discovered that differences in age groups mainly concerned injuries of the upper spine, with the incidence in the lumbar spine being similar among age groups. In addition, we found that while the probability of suffering from SCI increases with age, the relative risk of suffering from a complete injury decreases. Conclusions This study closes a long-lasting gap in epidemiological data regarding SCI in Germany, specifically by updating the incidence rates. We found that incidence depends on age, gender and type of lesion. We also provide some new angles for future research, especially considering the relative reduction in complete injuries among the elderly.

PurposeAs part of a fracture treatment registry, a questionnaire was developed to record the general state of health of the patients, the result of fracture treatment and complications. This resulted in the "Fracture Evaluation Since Hospitalization" score, or FRESH- score. The development and validation of the FRESH- score is the subject of this manuscript. MethodsFor validation, the EQ-5D-5L was used as a matching questionnaire. 237 patients were contacted via mail and received both questionnaires. The reliability was determined testing the internal consistency by Cronbach's alpha, convergent validity was tested with the Pearson correlation, construct validity was determined using the Wilcoxon rank sum test, as well as the paired t-test.ResultsCronbach's alpha for reliability was moderate at 0.57. Convergent validity using Pearson's correlation resulted in a moderate correlation with a coefficient of 0.41. Construct validity was determined using the Wilcoxon rank sum test, as well as the paired t-test. Both methods showed a high significance of p=0.0287 and a tendency p=0.0677, which represents a relationship between the two samples. Content validity was tested using missing values, which were low at 8% on average.ConclusionThe FRESH- score proved to be reasonable, reliable and sufficiently valid. Application with a larger samples would strengthen the validity of the questionnaire. The score fills a gap between existing questionnaires in orthopedics. An advantage of the FRESH- score is its concise set up and broad applicability.

Mesenchymal stem cells (MSCs) gain an increasing focus in the field of regenerative medicine due to their differentiation abilities into chondrocytes, adipocytes, and osteoblastic cells. However, it is apparent that the transformation processes are extremely complex and cause cellular heterogeneity. The study aimed to characterize differences between MSCs and cells after adipogenic (AD) or osteoblastic (OB) differentiation at the proteome level. Comparative proteomic profiling was performed using tandem mass spectrometry in data-independent acquisition mode. Proteins were quantified by deep neural networks in library-free mode and correlated to the Molecular Signature Database (MSigDB) hallmark gene set collections for functional annotation. We analyzed 4108 proteins across all samples, which revealed a distinct clustering between MSCs and cell differentiation states. Protein expression profiling identified activation of the Peroxisome proliferator-activated receptors (PPARs) signaling pathway after AD. In addition, two distinct protein marker panels could be defined for osteoblastic and adipocytic cell lineages. Hereby, overexpression of AEBP1 and MCM4 for OB as well as of FABP4 for AD was detected as the most promising molecular markers. Combination of deep neural network and machine-learning algorithms with data-independent mass spectrometry distinguish MSCs and cell lineages after adipogenic or osteoblastic differentiation. We identified specific proteins as the molecular basis for bone formation, which could be used for regenerative medicine in the future.

Background Bone-graft substitutes are commonly used for the augmentation of traumatic bone defects in tibial plateau fractures. However, their clinical performance compared with that of autologous bone-grafting, the gold standard in bone defect reconstruction, still remains under debate. This study investigates the differences in quality of life, pain, and radiographic outcomes in the treatment of tibial plateau fracture-associated bone defects with either autologous bone grafts or a bioresorbable hydroxyapatite and calcium sulfate cement (CERAMENT BONE VOID FILLER [CBVF]; BONESUPPORT). Methods In this study, 135 patients with acute depression and split-depression fractures of the proximal part of the tibia (OTA/AO types 41-B2 and 41-B3) were enrolled in a prospective, controlled, randomized, multicenter trial including 20 hospitals in Germany. Patients were randomized to receive either autologous iliac bone graft or CBVF for reconstruction of the bone defect. The primary outcome measures were the Short Form (SF)-12 version 2 Physical Component Summary (PCS) score at week 26 (the study was designed to show noninferiority of the CBVF with regard to the PCS with a prespecified margin of -5 points) and the pain level at 26 weeks postoperatively measured by a visual analog scale (VAS). The secondary outcomes were the SF-12 version 2 Mental Component Summary (MCS) and SF-12 PCS scores at weeks 1, 6, and 12 and bone-healing on radiographs. Results Age, sex, fixation methods, and fracture pattern were comparable in both groups. There were no significant differences (p > 0.05) in the SF-12 PCS or VAS scores at postoperative week 26. There was a significant reduction of blood loss (p = 0.007) and pain levels (p = 0.008) at postoperative day 1 in the CBVF group. The rates of fracture-healing, defect remodeling, and articular subsidence were not significantly different (p > 0.05) in both groups. Conclusions Bioresorbable CBVF was noninferior to autologous bone graft with regard to both patient-reported and radiographic outcomes in tibial plateau fractures of OTA/AO types 41-B2 and 41-B3. Level of evidence Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Background: Plate osteosynthesis depicts the gold standard to surgically treat pubic symphysis disruptions. However, high rates of implant failure after plate osteosynthesis are reported, probably because of the iatrogenic arthrodesis of this fibrocartilaginous joint. Therefore, flexible implants for treatment of pubic symphysis disruptions appear to be a sensible solution. Methods: In this biomechanical screening study, we designed and investigated a flexible implant, which consists of two plates connected with an ultra-high molecular weight polyethylene fiber cord. We mechanically tested eye splices as a possible fixation method of the cords by performing tensile load to failure tests. Afterwards, we developed a biomechanically appropriate plate design and cord routing between the plates. Finally, we biomechanically tested the flexible implant under tensile and shear loading until failure. Findings: When fixing a 1 mm ultra-high molecular weight polyethylene fiber cord with eye splices, a load at failure of 1570.74 N was detected under tensile loading. None of the eye splices failed but the cords itself ruptured. The load at failure of the designed cord routing in criss-cross technique and fixation within the plates amounts 4742.09 N under tensile and 2699.77 N under shear load. Interpretation: We developed a novel flexible implant for repair of pubic symphysis disruptions using ultra-high molecular weight polyethylene fiber cords connected to osteosynthesis plates. We identified eye splices as a mechanically optimal fixation method and proved that the ultra-high molecular weight polyethylene fiber cord routing and fixation of the flexible implant clearly withstands physiological forces acting on the pubic symphysis.

BackgroundLoosening of prostheses and functional disorders represent a far-reaching problem in the clinic, and the long-term outcomes are essentially determined by wear. Despite all advances, up to 10% of prostheses still fail after 10 years. In particular, more active patients show increased revision rates.MethodsThe objective of this thesis is to examine whether the applied microstructures of the articulating surfaces can lead to a reduction in abrasion. Three different structural geometries (dimples, offset lines, grid lines) were defined. In an experimental test setup according to DIN ISO 6474 (Deutsches Institut für Normung, International Organization for Standardization), a tribological test of metal and ceramic pairings was performed using two-dimensional ring-on-disc (RoD) tests.ResultsIn both material groups, the structuring had a positive effect on the wear behaviour. In the ceramic group, an abrasion reduction of 22.6% was achieved. However, it is important to take into account the limited informative value due to the hardness of the material. Two of the three Cobalt-Chrome-Molybdenum (CoCrMo) structure geometries (grids, offset lines) also showed a significant reduction in abrasion compared to the reference group, with a maximum wear reduction of 55.5%.ConclusionBy reducing abrasion, surface structuring could be used to extend the life of prostheses and minimise the number of revisions.

The focus of medical-didactic research is the improvement of clinical-practical training. One way to support practical skills training in a time- and resource-saving way is to provide instructional videos. Often the freely available instructional videos do not meet didactic or content requirements. Creating your own videos can therefore be a useful alternative for teachers. There are a variety of instructions on the Internet for shooting instruction videos. To date, this does not include any concrete instructions/assistance for the production of medical instructional videos. However, the presentation of medical learning content in particular can contain many hurdles. The aim of this work was to design a checklist for the creation of instructional videos, which can be used as a guide.As a first step, a systematic literature search was carried out to identify works that deal with the creation and not the use of medical instructional videos. To date, corresponding publications do not exist. In a workshop, the participants, who already gained experience in creating this type of video, exchanged ideas. These were critically discussed and analyzed. As a result, a checklist was created. In a subsequent multi-step review process, the checklist was reviewed with regard to applicability, comprehensibility, completeness and quality of the items.Four phases in the creation of an instructional video could be differentiated: preliminary reflections, preparation, day of filming, post-production. The checklist is structured accordingly and should be actively processed phase by phase. The checklist is created in such a way that it can be used and edited without reading this text. Particular focus is placed on the patient and his needs.The checklist created provides useful help in the creation of medical instructional videos and can for the first time serve as a guide especially for orthopedic and accident surgical instructional videos.Im Fokus der medizindidaktischen Forschung steht die Verbesserung der klinisch-praktischen Ausbildung. Eine Möglichkeit, die Ausbildung in praktischen Fertigkeiten zeit- und ressourcensparend zu unterstützen, bieten Lehrvideos. Häufig genügen die frei verfügbaren Lehrvideos weder didaktischen noch inhaltlichen Ansprüchen. Die Erstellung eigener Videos kann daher für Lehrende eine sinnvolle Alternative sein. Im Internet existiert eine Vielzahl von Anleitungen zum Dreh von Unterrichtsvideos. Darunter sind bis dato keine konkreten Anleitungen/Hilfestellungen zur Erstellung medizinischer Lehrvideos. Jedoch insbesondere die Darstellung medizinscher Lerninhalte kann viele Hürden enthalten. Ziel der vorliegenden Arbeit war die Konzeptionierung einer Checkliste für die Erstellung von Lehrvideos, die als Leitfaden genutzt werden kann.Als 1. Schritt erfolgte eine systematische Literaturrecherche, um Arbeiten zu identifizieren, welche die Erstellung und nicht die Anwendung medizinischer Lehrvideos behandeln. Entsprechende Publikationen existieren bis dato nicht. In einem Workshop haben die Teilnehmenden, die bereits Erfahrung in der Erstellung dieser Art von Videos sammelten, sich ausgetauscht. Diese wurden kritisch diskutiert und analysiert. Resultierend entstand eine Checkliste. In einem nachfolgenden mehrstufigen Review-Prozess wurde die Checkliste in Hinblick auf Anwendbarkeit, Verständlichkeit, Vollständigkeit und Qualität der Items überprüft.Es konnten 4 Phasen bei der Erstellung eines Lehrvideos differenziert werden: Vorüberlegungen, Vorbereitung, Drehtag, Nachbearbeitung. Die Checkliste ist entsprechend gegliedert und sollte Phase für Phase aktiv abgearbeitet werden. Die Checkliste ist so erstellt, dass sie ohne Lektüre dieses Textes genutzt und bearbeitet werden kann. Besonderer Fokus wird auf den Patienten und seine Bedürfnisse gelegt.Die erstellte Checkliste biete eine sinnvolle Hilfe bei der Erstellung medizinischer Lehrvideos und kann erstmalig speziell für orthopädische und unfallchirurgische Lehrvideos als Leitfaden dienen.

ZusammenfassungZiel dieses Artikels ist, die Konzeptionierung eines primärqualifizierenden Bachelorstudiengangs Physiotherapie darzustellen, der aufgrund seiner Angliederung an die Hochschulmedizin sowie durch seinen innovativen Ansatz als Novum in der physiotherapeutischen Akademisierung in Deutschland gelten kann. Hierbei wurde die bisherige Ausbildung in der Physiotherapie durch eine Adaption der Qualifikationsziele novelliert. Heraus kam ein Modell, das wissenschaftliches und berufspraktisches Wissen von Beginn an verzahnt. Dabei fördern einige Lehrveranstaltungen gezielt Interprofessionalität. Die Praktika sind vollständig in das Curriculum integriert. Das modellhafte Konzept wird durch ein umfangreiches Qualitätsmanagement überwacht. Der Ansatz entspricht allgemeinen Expertenempfehlungen und kann als Modell für andere Hochschulen genutzt werden.

Fehlbildungen im Bereich des Ellenbogengelenks sind seltene Erkrankungen. In nahezu allen Fallen treten dabei kongenitale Luxationen des Radiuskopfchens oder kongenitale radioulnare Synostosen auf. Wissenschaftliche Aufarbeitungen sind sehr rar und in der Regel eher historisch. Primare Fragestellung dieser Arbeit ist es, herauszuarbeiten, ob sich bei Patienten mit kongenitalen Fehlbildungen des Ellbogengelenks Einschrankungen im alltaglichen Leben und im Bewegungsausmas des Ellenbogengelenks finden, die einer Behandlung bedurfen und ob sich diese Einschrankungen je nach Art der Fehlbildung unterscheiden.

Aim Subsequent to a three-month pilot phase, recruiting patients for the newly established BFCC (Baltic Fracture Competence Centre) transnational fracture registry, a validation of the data quality needed to be carried out, applying a standardized method. Method During the literature research, the method of “adaptive monitoring” fulfilled the requirements of the registry and was applied. It consisted of a three-step audit process; firstly, scoring of the overall data quality, followed by source data verification of a sample size, relative to the scoring result, and finally, feedback to the registry on measures to improve data quality. Statistical methods for scoring of data quality and visualisation of discrepancies between registry data and source data were developed and applied. Results Initially, the data quality of the registry scored as medium. During source data verification, missing items in the registry, causing medium data quality, turned out to be absent in the source as well. A subsequent adaptation of the score evaluated the registry’s data quality as good. It was suggested to add variables to some items in order to improve the accuracy of the registry. Discussion The application of the method of adaptive monitoring has only been published by Jacke et al., with a similar improvement of the scoring result following the audit process. Displaying data from the registry in graphs helped to find missing items and discover issues with data formats. Graphically comparing the degree of agreement between the registry and source data allowed to discover systematic faults. Conclusions The method of adaptive monitoring gives a substantiated guideline for systematically evaluating and monitoring a registry’s data quality and is currently second to none. The resulting transparency of the registry’s data quality could be helpful in annual reports, as published by most major registries. As the method has been rarely applied, further successive applications in established registries would be desirable.

Einleitung: Auch im Fach Orthopadie und Unfallchirurgie (O & U) macht sich der Arztemangel bemerkbar. Curriculare Praktika, wie die Famulatur, sind sensible Schnittstellen zwischen theoretischem Studium und praktischer Anwendung. In dieser Studie soll untersucht werden, wie dieses Praktikum vonseiten der Medizinstudierenden wahrgenommen wird, und inwiefern es hier gelingen kann, sie fur O & U zu begeistern. Methode: Aus einer im Sommersemester 2012 durchgefuhrten Umfrage mit 9079 Studierenden analysierten wir die Angaben der Subgruppe, die eine mindestens 4-wochige Famulatur in O & U absolvierte. Insgesamt 37 Fragen zur Evaluation des Praktikums wurden in die Analyse einbezogen. Die Teilnehmer, die sich nach ihrer Famulatur vorstellen konnten, auch das Wahltertial in O & U zu absolvieren (PJ-Ja) wurden getrennt von denen analysiert, die dies verneinten (PJ-Nein) und Gruppenvergleiche durchgefuhrt. Ergebnisse: Insgesamt wurden Daten von 397 Famulanten eingeschlossen, die in O & U eine Famulatur absolviert haben. 55,0 % waren weiblich. 267 (67,3 %) Famulanten gaben an, auch ihr PJ-Wahltertial in O & U machen zu wollen (PJ-Ja), 130 (32,7 %) verneinten dies (PJ-Nein). In Geschlecht und Alter unterschieden sich die Gruppen (Geschlecht: χ2 = 2,50, p = 0,114; Alter: F[1, 93]

Bone plates for osteosynthesis are subject to biomechanical testing for safety and regulatory purposes. International standards applicable for those devices are designed for bone plates used in the surgical fixation of the skeletal system but not necessarily for all device variants available. We intend to summarize the test methods and parameters presented in the literature to evaluate bone plates in a clinical environment, especially for modern anatomically shaped implants. We conducted a systematic review on published biomechanical studies for lower and upper extremities (clavicle, humerus, ulna, radius, metacarpal, femur, tibia, fibula, metatarsal). The search process led to the identification of 159 relevant articles containing 330 individual tests, which were analyzed concerning various test criteria including test methods and parameters per bone segment for static and dynamic loading tests, as well as number of cycles, chosen bone model and outcome variables. The biomechanical literature for bone plates is diverse, inconsistent and heterogeneous. Test methods are not commonly applied per bone plate location and test parameters are not uniformly specified and displayed. They vary in particular for bending and torsion tests as well as for the number of loading cycles for dynamic testing. Outcome variables are not commonly applied nor defined. Consequently this paper is the first in a planned chronological series of three to identify the need (this publication), to develop a systematic procedural approach (2. publication) and to apply the process exemplary on a bone plate sample (3. publication).

The annual incidence of proximal femoral fractures is 100-150/100,000 and continues to increase with an aging population. Cut-out of hip screws after fracture fixation has been quoted as 8% in the literature. The tip-apex distance (TAD) is the strongest predictor for cut-out after operative fracture stabilisation. The aim of this study was to evaluate the novel ADAPT system (Adaptive Positioning Technology, Stryker, USA), a navigation device for intramedullary nailing of trochanteric fractures and its effect on optimising the TAD. This is the first clinical study to evaluate this new technology.The study group of 36 consecutive patients with a pertrochanteric fracture underwent intramedullary nailing for fracture fixation using ADAPT technology, while the matched control group underwent conventional Gamma-3-nailing. Matching criteria included fracture classification, gender and age. We measured the operative time and the postoperative TAD in anteroposterior (AP) and lateral radiographs of the 72 patients.The mean TAD using ADAPT was 16.9 mm (range 8.4-33.7 mm) compared with 24.9 mm (range 14.6-40.2 mm) in the reference group treated without ADAPT. Using the ADAPT system significantly improved (p 0.0005) the accuracy of lag screw placement but had no effect on operating time in fixation of femoral pertrochanteric fractures.Working with the novel ADAPT system for positioning the lag screw using the Gamma-3-nail led to a statistically highly significant reduction of the TAD compared to the reference group (p 0.001). The ADAPT system proved to be a very useful device in achieving higher surgical standards for the treatment of trochanteric fractures with intramedullary nailing. It enables higher accuracy in screw positioning and therefore better placement of the implant.

Even non-traumatic ruptures of the triceps tendon are rare, surgical therapy should be recommended in all cases, because of poor results after non-operative treatment. A golden standard for the surgical procedure is not established. A small series of traumatic distal tendon ruptures was treated surgical in our hospital and was followed up after 12 months concerning their function. Very good and good results could be found with a strong reintegration of the tendon by using transosseus sutures with non resorbable suture material. The refixation with suture anchors showed disappointing results with early pull-outs of the anchor. Revision with screw augmentation with a washer had to be performed. Concerning the biomechanical forces, which show up on the olecranon (up to 40 NM), the refixation of the triceps tendon has proved to be extremely resistant against pull out forces. The good results by using non absorbable transosseus sutures led to a standardized procedure in our trauma center, even the rupture is not traumatic.

Zusammenfassung Hintergrund Nach Osteotomie zur Korrektur des Hallux valgus sind haufig osteosynthetische Verfahren zur Stabilisierung erforderlich. Auch die hier betrachtete Chevron-Osteotomie muss mittels einer Osteosynthese stabilisiert werden. Bioresorbierbare Implantate zur Stabilisierung nach Chevron-Osteotomie sind bis dato wenig untersucht. Ziel dieser Studie war festzustellen, ob ein bioresorbierbares Implantat aus Polylaktid, das durch Ultraschall-Energie verflussigt wird und sich bei Erstarren im spongiosen Knochen verankert, sicher anwendbar ist und vergleichbar gute Ergebnisse verglichen mit der konventionellen Schraubenosteosynthese zeigt. Material und Methoden Hierzu wurde in 30 Fallen eine Chevron-Osteotomie durchgefuhrt und mit dem SonicPin-System stabilisiert. Die Patienten wurden mittels konventionellem Rontgen, MRT und anhand eines Fragebogens zur Lebensqualitat (EQ-5D) uber 4 Jahre nachuntersucht. Ergebnisse Die klinische Evaluation wies schon fruh postoperativ eine signifikante Verbesserung der Lebensqualitat nach. Die bildgebende Diagnostik zeigte sicheren knochernen Durchbau in allen Fallen ohne Anzeichen fur Fremdkorperreaktionen. Die Resorption des Implantates konnte nachgewiesen werden. Komplikationen traten nicht auf. Schlussfolgerung Zusammenfassend ist die Fixierung der Chevron-Osteotomie mittels SonicPin sicher und reproduzierbar anwendbar. Die Komplikationsrate ist vergleichbar gering zu der konventionellen Osteosynthese und eine Materialentfernung kann entfallen.

This paper follows up on a recent systematic review of test methods and parameters for biomechanical testing of bone plates and it is the first study that contains recommendations for standardized mechanical testing of bone plate-screw constructs for osteosynthesis. Following the testing philosophy of ASTM F382 and ISO 9585, we have developed standardized quasi-static and dynamic testing methods for straight linear and anatomically shaped plates, including locked type and conventional systems. The test specification comprises torsion and bending tests along the implant axis and therefore modifies and extends the methods proposed by ASTM F382. We present specific test setups in order to determine product-specific characteristics of the mechanical construct, consisting of the bone plate with corresponding screws (such as construct stiffness, yield strength, ultimate strength and fatigue properties) under the condition that it is rigidly fixed to “healthy bone”. We also address specific testing requirements that are important for the purpose of standardization, such as the positioning of the construct for testing or the number of screws in the diaphysis and metaphysis. Finally, we define the outcome parameters and associated failure criteria related to quasi-static and dynamic testing for comparative purposes. This paper does not intend to replace biomechanical testing of those devices under physiological loading conditions.

Purpose : The Direct Anterior Approach (DAA) is well established as a minimal access approach in elective orthopaedic hip surgery. For the growing number of elderly patients with femoral neck fractures treated with Bipolar Hip Hemiarthroplasty (BHH), only a few results do exist. The study shows the clinical and radiological outcome for 180 patients treated by a modified DAA with BHH. Materials and Methods : The data of 180 geriatric patients with medial femoral neck fractures were evaluated retrospectively. The general and surgical complications, mobilisation using the Timed Up and Go test (TUG), the social environment pre- and postoperative and the radiological results have been compared with established approaches for geriatric hip surgery. Results : After joint replacement, 18 (10%) patients were developed pneumonia, of which 3 (1.7%) died during hospitalisation. In 7 cases (4%), surgical revision had to be carried out: three times (1.7%) because of a seroma, three times (1.7%) because of subcutaneous infection, and one time (0.6%) because the BHH was removed, owing to deep wound infection. One dislocation (0.6%) occurred, as well as one femoral nerve lesion (0.6%) occured. 88.3% of patients were mobilised on walkers or crutches; the Timed Up and Go Test showed a significant improvement during inpatient rehabilitation. 83% were discharged to their usual social environment, 10% were transferred to a short-term care facility and 7% were relocated permanently to a nursing home. 3/4 of patients had a cemented stem alignment in the range between -5° and 5°, while 2/3 of patients had a maximum difference of 1 cm in leg length. Conclusion : Using the modified DAA, a high patient satisfaction is achieved after implantation of a BHH. The rate of major complications is just as low as in conventional approaches, and rapid mobilisation is possible.

Background The present study aimed to biomechanically evaluate a novel locking plate intended for osteosynthesis of coronoid fracture compared to mini L-plates and cannulated screws. Methods Biomechanical tests were performed on a fracture model in synthetic bones. Three groups, each with eight implant-bone-constructs, were analyzed in quasi-static and dynamic tests. Finally, samples were tested destructively for maximum strength. Results The mean (SD) highest stiffness was measured for the novel plate [693 (18) N/mm], followed by the mini L-plate [646 (37) N/mm] and the cannulated screws [249 (113) N/mm]. During the cycling testing of the novel plate and the mini L-plate, no failures occurred, although three of the eight samples of cannulated screws failed during the test. The mean (SD) maximum strength during the destructive testing was 1333 (234) N for the novel plate, 1338 (227) N for the mini-L-plate and 459 (56) N for the cannulated screws. No statistical differences were found during the destructive testing between the two plates ( p = 0.999), although statistical differences were found between both plates and the cannulated screws ( p = 0.000 each). Conclusions Osteosynthesis of the coronoid process using the novel plate is mechanically similar to the mini L-plate. Both plates were superior to osteosynthesis with cannulated screws.

Untreated knee joint empyema leads to rapid destruction of the joint and, thus far, has proven challenging to treat. This study presents data obtained after one- versus two-stage surgical approaches. Specifically, clinical outcome, complication rate, re-infection rate, duration of operation, and hospital stay are reported. Between 2006 and 2010, 67 patients with extensive knee joint empyema underwent surgical therapy. Patients underwent either a two-stage surgical approach with open joint treatment for 7–10 days or a one-stage procedure with primary closure of the knee joint after radical debridement. The two-stage procedure was performed on 36 patients, whereas the one-stage procedure was performed on 31 patients. Infection duration prior to the index procedure ranged from 3 days to 55 months (two-stage: ~5 months, one-stage: ~2.4 months). The groups did not differ significantly in demographic group characteristics. Hospital stay and duration of operation were significantly (p

Surface wear of corresponding tribological pairings is still a major problem in the application of artificial joint surgery. This study aims at developing wear reduced surfaces to utilize them in total joint arthroplasty. Using a pico-second laser, samples of medical CoCrMo metal alloy and Al2O3 ceramic were patterned by laser material removal. The subsequent tribological investigations employed a ring-on-disc method. The results showed that those samples with modified surfaces show less mass or volume loss than those with a regular, smooth surface. Using calf serum as lubricating medium, the volume loss of the structured CoCrMo samples was eight times lower than that of regular samples. By structuring Al2O3 surfaces, the wear volume could be reduced by 4.5 times. The results demonstrate that defined surface channels or pits enable the local sedimentation of wear debris. Thus, the amount of free debris could be reduced. Fewer abrasives in the lubricated so-called three-body-wear between the contact surfaces should result in less surface damage. Apart from direct influences on the wear behavior, less amounts of free debris of artificial joints should also be beneficial for avoiding undesired reactions with the surrounding soft tissues. The results from this study are very promising. Future investigations should involve the use of simulators meeting the natural conditions in the joint and in vivo studies with living organisms. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 101A: 3447–3456, 2013.

Background:The aim of our study was to develop a test setup combining realistic force transmission with physiological movement patterns at a frequency that mimicked daily use of the elbow, to assess implants in orthopedic joint reconstruction and trauma surgery.Methods:In a multidisciplinary approach, anin vitrobiomechanical testing machine was developed and manufactured that could simulate the repetitive forceful movement of the human elbow joint. The construction involved pneumatic actuators. An aluminum forearm module enabled movements in 3 degrees of freedom, while motions and forces were replicatedviaforce and angular sensors that were similar toin vivomeasurements.Results:In the initial testing, 16 human elbow joint specimens were tested at 35 Nm in up to 5000 cycles at a range of 10° extension to 110° flexion. The transmitted forces led to failure in 9 out of the 16 tested specimens, significantly more often in females and small specimens.Conclusions:It is possible to construct a testing machine to simulate nearly physiological repetitive elbow motions. The prototype has a number of technical deficiencies that could be modified. When testing implants for the human elbow with cadaver specimens, the specimen has to be chosen according to the intended use of the implant under investigation.

Processus-coronoideus-Frakturen sind selten und therapeutisch anspruchsvoll. Mit der retrospektiven Nachuntersuchung der Patienten an einem uberregionalen Traumazentrum sollten mittelfristige Behandlungsergebnisse gewonnen und prognostisch relevante Faktoren isoliert werden. Die vollstandigen Behandlungsdaten von 26 Patienten aus 5 Jahren (2004–2009) konnten ausgewertet werden. Durchschnittlich 34 Monate (SD 20) nach Unfall konnten 18 Patienten (69 %) klinisch und z. T. nativradiologisch nachuntersucht werden. Die Ergebnisse wurden statistisch ausgewertet. Das Durchschnittsalter betrug 56 Jahre (SD 14), 14 weiblich, 12 mannlich, jeweils 13 links bzw. rechts. Frakturtypen am Processus coronoideus ergaben sich nach Regan und Morrey Typ I (10), II (5) und III (11). Als zusatzliche Verletzungen wurden 19 stattgehabte Ellenbogengelenkluxationen, 18 Radiuskopfchenfrakturen, 5 proximale Ulnaschaftfrakturen und 2 Olekranonfrakturen nachgewiesen. Eine durchschnittliche Beweglichkeit von 109° (SD 17°) wurde in Extension/Flexion und eine von 154° (SD 37°) in Pronation/Supination erreicht. Elf von 19 (58 %) Patienten gaben ein stabiles Gelenk an. Der MEPS betragt durchschnittlich 78 (SD 16; 50–100) Punkte. Eine operative Therapie der ligamentaren Verletzungen nach Luxationsfraktur des Ellenbogengelenks ist statistisch bisher nicht zu begrunden. Eine stabile knocherne Rekonstruktion des Processus coronoideus ist prognostisch relevant. Eine komplette Radiuskopfchenresektion erhoht die Gelenkinstabilitat und ist mit einer signifikant hoheren Rate an Fixateurbehandlungen assoziiert.

Fractures of the humeral head account for 5% of all fractures and incidence increases with age. Depending on fracture form and patients age a wide variety of therapeutical options exist. Stable fractures can be treated conservatively, while the majority of unstable and displaced fractures require surgical treatment. Many different surgical options are available; open reduction and internal fixation are widely preferred. The S3 Proximal Humerus Plate is a contoured plate to match the complex shape of the proximal humerus. It is designed to be positioned distal to the greater tuberosity preventing subacromial impingement.Between august 1 and 30, 2007, 5 patients meeting the inclusion criteria (that is primary operative stabilization within 7 days after trauma in a standardized way and minimal follow up period of 3 month) with acute fractures of the proximal humerus were treated with S3 Proximal Humerus Plate. Follow up was performed using the Constant Score. The mean age was 59.0 years. According to the Neer classification fractures were rated as Neer 2,3 and 4. A mean Constant score of 72.3 (57-86) points was obtained.We did not observe any complications like humeral head necroses, loss of reduction, deep infection or breakage of the plate.

Summary Background Operating theatres and surgical clothing are designed to protect the patient from surgical site infections. However, there is still a risk of infection of the surgical team with blood-borne pathogens via ocular or mucocutaneous exposure. Whereas conventional surgical clothing provides some protection against contamination, surgical helmet systems (SHS) are intended to provide a high level of protection by forming a barrier for particles, aerosols and fluids between surgeon and surgical field of work. Aim The aim of this study was to quantify the contamination of the surgeon by droplets during orthopaedic procedures by an in-vitro simulation of hip and knee arthroplasty while wearing SHS versus conventional surgical clothing. Methods Hip and knee arthroplasty procedures were performed on artificial foam bone, which was continuously kept wet with a marker fluid. Each of the procedures was carried out by ten subjects wearing conventional surgical clothing or wearing SHS with integrated toga. After the simulated operation, pictures of the subjects were taken under ultraviolet illumination. Images wearing the full gown, and after removal of the gown, were evaluated for stained areas. Findings The contamination risk was 30% while wearing conventional clothing. In none of the 20 subjects using the SHS stains could staining be detected after removal of the protective clothing. Conclusion This study has demonstrated that the protective properties of the SHS are superior to conventional surgical clothing. Using SHS in high-risk procedures could reduce occupational exposure to blood-borne infections in surgeons.

Objectives: There is only sparse data on clinical results and complications of the third-generation Gamma nailing system (Gamma3, Stryker). Therefore, we started a large multi-centre case series in 2008. The aim of this paper is to present the study design and early results of a single arm of a prospective, consecutive, monitored, post-market follow-up evaluation of Gamma3 nails. Methods: From September 2009 to January 2012, 154 consecutive patients with an average age of 80 ± 1.43 years (50-99 years) and a trochanteric femoral fracture were included in the local arm of the trial. All patients that fulfilled the inclusion criteria were treated with a Gamma3 nail. Preoperative variables included age, gender, fracture classification, walking ability (Merle d’Aubigné score), daily activity level (retrospective Zuckerman score), ASA rating of operative risk, waiting time for operation, use of walker or crutches and body mass index (BMI). Skin-to-skin time, fluoroscopy time, blood loss, intraoperative complications and device information were recorded for each patient. Follow-up postoperative assessment was undertaken at 4, 12 and 24 months. Hip range of motion, pain around the hip and the tight, walking ability (Merle d’Aubigné score, Sahlgrenska mobility score) and management of daily life (Zuckerman score) were used to evaluate the outcome. Results: The descriptive data of age, gender, BMI, ASA classification, fracture type and skin-to-skin time is similar to other studies. Median fluoroscopy time was 62 seconds (range: 4-225 seconds) and significantly shorter in closed reductions. No intraoperative implant-related complication was recorded. A cut-out of the leg-screw during assessment period occurred in 2.6% patients (n = 4). At the 12-month assessment two (1.8%) non-unions were identified and two patients (1.8%) had broken the femoral shaft below the 180 mm nail after a fall. Analysis of the scores showed significantly declined mobility and activity in daily life four months after operation which increased significantly from four to 12 months and increased slightly between 12 and 24 months after fracture. Conclusion: A low implant-associated complication rate was achieved in geriatric patients with trochanteric femoral fractures using the Gamma3 nail. A better outcome concerning mobility, activity in daily life and complications compared to the Gamma2 nail could not be found in comparison to historic data.

Surface wear of corresponding tribological pairings is still a major problem in the application of artificial joint surgery. This study aims at developing wear reduced surfaces to utilize them in total joint arthroplasty. Using a pico-second laser, samples of medical CoCrMo metal alloy and Al2 O3 ceramic were patterned by laser material removal. The subsequent tribological investigations employed a ring-on-disc method. The results showed that those samples with modified surfaces show less mass or volume loss than those with a regular, smooth surface. Using calf serum as lubricating medium, the volume loss of the structured CoCrMo samples was eight times lower than that of regular samples. By structuring Al2 O3 surfaces, the wear volume could be reduced by 4.5 times. The results demonstrate that defined surface channels or pits enable the local sedimentation of wear debris. Thus, the amount of free debris could be reduced. Fewer abrasives in the lubricated so-called three-body-wear between the contact surfaces should result in less surface damage. Apart from direct influences on the wear behavior, less amounts of free debris of artificial joints should also be beneficial for avoiding undesired reactions with the surrounding soft tissues. The results from this study are very promising. Future investigations should involve the use of simulators meeting the natural conditions in the joint and in vivo studies with living organisms.

Background Non-union continues to be one of the orthopedist’s greatest challenges. Despite effective culture methods, the detection of low-grade infection in patients with non-union following tibial fracture still presents a challenge. We investigated whether “aseptic” tibial non-union can be the result of an unrecognized infection. Methods A total of 23 patients with non-union following tibial shaft fractures without clinical signs of infection were investigated. Intraoperative biopsy samples obtained from the non-union site were examined by means of routine culture methods and by polymerase chain reaction (PCR) for the detection of 16 S ribosomal RNA (rRNA). Control subjects included 12 patients with tibial shaft fractures. Results 23 patients (8 women and 15 men; mean age: 47.4 years) were included into this study. Preoperative C-reactive protein levels (mean: 20.8 mg/l) and WBC counts (mean: 8,359/μl) in the study group were not significantly higher than in the control group. None of the samples of non-union routine cultures yielded microorganism growth. Bacterial isolates were found by conventional culturing methods in only 1 case of an open fracture from the control group. In this case, PCR yielded negative results. 16 S rRNA was detected in tissue specimens from 2 patients (8.7%) with non-union. The analysis of these variable species-specific sequences enabled the identification of specific microorganisms (1x Methylobacterium species, 1x Staphylococcus species). Both PCR-positive patients were culture-negative. Conclusions The combination of microbiological culture and broad-range PCR seems to substantially add to the number of microbiological diagnoses obtained and may improve the clinican’s ability to tailor therapy to the individual patient’s needs.

Background:Cubitus varus deformity is the most common late complication after distal humeral fractures in children. Typical symptoms are increasing instability especially the posterolateral rotatory instability (POLRI), lateral elbow pain and cosmetic problems. Different ways of correction have been described but a gold standard has not yet been established.Methods:In this study the clinical outcome 6,5 months after supracondylar closed wedge osteotomy stabilized with locking plates in four young adults was investigated: three with a posttraumatic varus deformity and one with a posttraumatic valgus deformity of the distal humerus.Results:All patients showed good or excellent results in the Mayo Elbow Performance Score (MEPS) and the Disabilities of the Arm, Shoulder and Hand score (DASH). In one case, a revision because of a delayed union was necessary, in another case a preexisting pseudarthrosis of the radial epicondyle remained. Neither a residual instability of the elbow joint, nor any significant prominence of the lateral epicondyle was observed.Conclusion:The supracondylar closed wedge osteotomy stabilized by a locking plate is an effective procedure for the correction of posttraumatic distal humerus deformities in young adults with good final functional results.

Objectives: A biomechanical study was performed to test the hypothesis that a varus deformity of the humeral head decreases supraspinatus (SSP) efficiency and increases deltoid elevation forces in human specimens. Methods: Twenty-four fresh-frozen human shoulder specimens were prepared by preserving the rotator cuff and deltoid. A defined, medial closed-wedge osteotomy was performed and lateral locked plate applied to simulate a varus deformity of 45° in Group I (n = 8) and 20° in Group II (n = 8). The control group (n = 8) was not osteotomized. The effect of the deformities on arm elevation forces was measured in a robot-assisted shoulder simulator under a physiologically loaded rotator cuff during three elevation phases. Phase 1 encompassed 0° to 30°, Phase 2 was from 30° to 60°, and Phase 3 included 60° to 90° of shoulder elevation. Results: SSP efficiency, defined as the degree of elevation attained per unit muscle force, was significantly less in Group I compared with Group II (P = 0.036) and the control group (P = 0.039) (Group I = 0.12 ± 0.03°/N, Group II 0.18 ± 0.05°/N, and control group 0.24 ± 0.10°/N). Under physiological loading of the rotator cuff, the deltoid (DELT) elevation forces were significantly greater in Group I (P phase 1 = 0.015, P phasc 3 = 0.001) and Group II (P phase 1 = 0.015, P phase 3 = 0.006) compared with the control group in elevation Phase 1 (Group I: 3.20 ± 1.04 N/°, Group II: 3.03 ± 0.96 N/°, control group: 2.01 ± 0.53 N/°) and Phase 3 (Group I: 2.50 ± 0.85 N/°, Group II: 1.55 ± 0.28 N/°, control group: 1.21 ± 0.18 N/°). When the SSP was unloaded, the DELT elevation forces were significantly greater in Group 1 than in Group II (P = 0.040) and the control group (P = 0.004) during elevation Phase 3 (Group I: 2.12 ± 0.60 N/°, Group II: 1.47 ± 0.34 N/°, control group: 1.24 ± 0.32 N/°). Conclusions: A varus deformity of the humeral head changes the pretension of the rotator cuff and results in a significantly decreased SSP efficiency (45° varus) and significantly higher arm elevation forces (20° varus). Clinically, the study's findings are relevant because they indicate that varus deformities of more than 20° should not be accepted intraoperatively and might indicate the need for surgical correction in case of subsequent symptoms.

Although there is a clear trend toward internal fixation for ankle arthrodesis, there is general consensus that external fixation is required for cases of posttraumatic infection. We retrospectively evaluated the technique and clinical long term results of external fixation in a triangular frame for cases of posttraumatic infection of the ankle. From 1993 to 2006 a consecutive series of 155 patients with an infection of the ankle was included in our study. 133 cases of the advanced "Gächter" stage III and IV were treated with arthrodesis. We treated the patients with a two step treatment plan. After radical debridement and sequestrectomy the malleoli and the joint surfaces were resected. An AO fixator was applied with two Steinmann-nails inserted in the tibia and in the calcaneus and the gap was temporary filled with gentamicin beads as the first step. In the second step we performed an autologous bone graft after a period of four weeks. The case notes were evaluated regarding trauma history, medical complaints, further injuries and illnesses, walking and pain status and occupational issues. Mean age at the index procedure was 49.7 years (18-82), 104 patients were male (67,1%). Follow up examination after mean 4.5 years included a standardised questionnaire and a clinical examination including the criteria of the AO-FAS-Score and radiographs. 92,7% of the cases lead to a stable arthrodesis. In 5 patients the arthrodesis was found partly-stable. In six patients (4,5%) the infection was not controllable during the treatment process. These patients had to be treated with a below knee amputation. The mean AOFAS score at follow up was 63,7 (53-92). Overall there is a high degree of remaining disability. The complication rate and the reduced patient comfort reserve this method mainly for infection. Joint salvage is possible in the majority of cases with an earlier stage I and II infection.

The purpose of this study was to evaluate the outcome of deltoid muscle flap transfer for the treatment of irreparable rotator cuff tears. In a retrospective study 20 consecutive patients were evaluated. The index procedure took place between 2000 and 2003. Fifteen patients were male, mean age was 62 years. Inclusion criterion was a rotator cuff defect Bateman grade IV. Exclusion criteria were smaller defects, shoulder instability and fractures of the injured shoulder. An open reconstruction with acromioplasty and a pedicled delta flap was performed. Follow up period was mean 42 months. Follow-up included clinical examination, Magnetic Resonance Imaging (MRI) and the Constant and Simple (CS) shoulder tests. According to the Constant shoulder test the results were good in 13 patients, fair in 5 and unsatisfactory in 2. The pre-operative Constant Score improved from mean 25.7 points (±5.3) to 72.3 (±7.8) at follow-up. The mean values for the subcategories of CS increased significantly from 3.9 to 14.4 points for pain and from 4.2 to 15.9 points for activities daily routine (p0.05). Results of the Simple Shoulder Test showed a significant increase of the mean values from pre-operative 4.3 to 14.7 points post-operatively. MRI showed a subacromial covering of the defect in all cases, all flaps where intact on MRI but always the flap showed marked fatty degeneration. In conclusion, the delta flap is a simple method for the repair of large defects of the rotator cuff leading to satisfying medium results.

The cut-out of the sliding screw is one of the most common complications in the treatment of intertrochanteric fractures. The reasons for the cut-out are: a suboptimal position of the hip-screw in the femoral head, the type of fracture and poor bone quality. The aim of this study was to reproduce the cut-out event biomechanically and to evaluate the possible prevention of this event by the use of a biopolymer augmentation of the hip screw. Concerning the density and compression force of osteoporotic femoral bone polyurethane foam according to the terms of the Association for Standard Testing Material (ASTMF 1839-97) was used as test material. The polyurethane foam Lumoltan 200 with a compression force of 3.3 Mpa and a density of 0.192 g/cm3 was used to reproduce the osteoporotic bone of the femoral fragment (density 12 lbm/ft3). A cylinder of 50 mm of length and 50 mm of width was produced by a rotary splint raising procedure with planar contact. The axial load of the system was performed by a hydraulic force cylinder of a universal test machine type Zwick 1455, Ulm, Germany. The CCD-angle of the used TGN-System was preset at 130 degrees. The migration pattern of the hip screw in the polyurethane foam was measured and expressed as a curve of the distance in millimeter [mm] against the applied load in Newton [N] up to the cut-out point. During the tests the implants reached a critical changing point from stable to unstable with an increased load progression of steps of 50 Newton. This unstable point was characterized by an increased migration speed in millimeters and higher descending gradient in the migration curve. This peak of the migration curve served as an indicator for the change of the hip screw position in the simulated bone material. The applied load in the non-augmented implant showed that in this group for a density degree of 12 (0,192 g/cm3) the mean force at the failure point was 1431 Newton (± 52 Newton). In the augmented implant we found that the mean force at the failure point was 1987 Newton (± 84 Newton). This difference was statistically significant. In conclusion, the bone density is a significant factor for the stability of the hip screw implant. The osteosynthesis with screws in material with low density increases the chance for cut-out. A biopolymer augmented hip screw could significantly improve the stability of the fixation. The use of augmentation with a fast hardening bone replacement material containing polymer-ceramic changes the point of failure under axial load in the osteoporotic bone model and could significantly improve the failure point. Our study results indicate, that a decrease of failure in terms of cut-out can be achieved with polymer augmentation of hip screws in osteoporotic bones.