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Introduction Time is of the essence in the management of severely injured patients. This is especially true in patients with mediastinal vascular injury (MVI). This rare, yet life threatening injury needs early detection and immediate decision making. According to the ATLS guidelines [American College of Surgeon Committee on Trauma in Advanced Trauma Life Support (ATLS®), 10th edn, 2018], chest radiography (CXR) is one of the first-line imaging examinations in the Trauma Resuscitation Unit (TRU), especially in patients with MVI. Yet thorough interpretation and the competence of identifying pathological findings are essential for accurate diagnosis and drawing appropriate conclusion for further management. The present study evaluates the role of CXR in detecting MVI in the early management of severely injured patients. Method We addressed the question in two ways. (1) We performed a retrospective, observational, single-center study and included all primary blunt trauma patients over a period of 2 years that had been admitted to the TRU of a Level-I Trauma Center. Mediastinal/chest (M/C) ratio measurements were calculated from CXRs at three different levels of the mediastinum to identify MVI. Two groups were built: with MVI (VThx) and without MVI (control). The accuracy of the CXR findings were compared with the results of whole-body computed tomography scans (WBCT). (2) We performed another retrospective study and evaluated the usage of sonography, CXR and WBCT over 15 years (2005–2019) in level-I–III Trauma Centers in Germany as documented in the TraumaRegister DGU® (TR-DGU). Results Study I showed that in 2 years 267 patients suffered from a significant blunt thoracic trauma (AIS ≥ 3) and met the inclusion criteria. 27 (10%) of them suffered MVI (VThx). Through the initial CXR in a supine position, MVI was detected in 56–92.6% at aortic arch level and in 44.4–100% at valve level, depending on different M/C-ratios (2.0–3.0). The specificity at different thresholds of M/C ratio was 63.3–2.9% at aortic arch level and 52.9–0.4% at valve level. The ROC curve showed a statistically random process. No significant differences of the cardiac silhouette were observed between VThx and Control (mean cardiac width was 136.5 mm, p = 0.44). Study II included 251,095 patients from the TR-DGU. A continuous reduction of the usage of CXR in the TRU could be observed from 75% in 2005 to 25% in 2019. WBCT usage increased from 35% in 2005 to 80% in 2019. This development was observed in all trauma centers independently from their designated level of care. Conclusion According to the TRU management guidelines (American College of Surgeon Committee on Trauma in Advanced Trauma Life Support (ATLS®), 10th edn, 2018; Reissig and Kroegel in Eur J Radiol 53:463–470, 2005) CXR in supine position is performed to detect pneumothorax, hemothorax and MVI. Our study showed that sensitivity and specificity of CXR in detecting MVI was statistically and clinically not reliable. Previous studies have already shown that CXR is inferior to sonography in detecting pneumothorax and hemothorax. Therefore, we challenge the guidelines and suggest that the use of CXR in the early management of severely injured patients should be individualized. If sonography and WBCT are available and reasonable, CXR is unnecessary and time consuming. The clinical reality reflected in the usage of CXR and WBCT over time, as documented in the TR-DGU, seems to support our statement.

Background The present study used a systematic review to analyse the risk of perioperative injections during arthroscopic reconstruction of the rotator cuff of the shoulder. The questions of interest were whether perioperative local injection increases the infection risk and whether the number of postoperative revisions is increased. Material and Methods A systematic review of the U. S. National Library of Medicine/National Institutes of Health (PubMed) database and the Cochrane Library was performed using the PRISMA checklist. The keywords used were “shoulder” and “arthroscopy” and “injection” and “risk”. In the course of the study, work that was not also primarily concerned with the reconstruction of the rotator cuff was excluded. English original articles and case series were included that contained at least some arthroscopic reconstructions of the rotator cuff. The risk of bias was determined using the Newcastle-Ottawa Scale. The content of the articles relevant to the research questions was analysed. Results 48 hits were primarily generated. 9 articles corresponded to the inclusion criteria and were analysed. In the 6 studies with details on the injected substances, cortisone was used in 98 – 100% of the cases. The reported infection and revision rates based on insurance data were higher with injection than without. The risk of bias in the studies analysed here was rather low based on the Newcastle-Ottawa Score. The risk of infection after a cortisone injection before, during or after surgery was increased. Injection was associated with infection in up to 8% of cases with injections within two weeks of surgery. The risk of infection was increased by up to 11 times with injections within 4 weeks after the operation. Likewise, the risk of revision surgery after injection was increased, with the time intervals between injection and surgery sometimes differing between studies. Discussion Local infections and to a lesser extent revision surgery are associated with perioperative injections (with cortisone) within 3 months preoperatively and 4 weeks postoperatively. However, there were only database studies of insurance data with several studies from a few centres. Thus, no causal relationships could be proven. Currently, however, the following can be recommended using a cautious approach: The interval between injection with cortisone before surgery should be at least 2 weeks, better 3 months. No cortisone injections should be applied intraoperatively. Postoperatively, cortisone should not be injected for at least 4 weeks. If, in exceptional cases, deviations from these time limits are required, patients should be informed about an increased risk of complications.

ZusammenfassungHintergrundBei Patienten, die im Rahmen eines Traumas an Knie- und Sprunggelenk eine Verletzung mit Abscheren eines osteochondralen „flake“ erleiden, ist heute die Refixation mittels resorbierbarer Implantate eine häufig verwendete Therapieoption. Hierzu gibt es bisher wenige Studien mit klinischen Langzeitergebnissen. Ziel dieser Studie war die Erfassung der klinischen und MR-morphologischen Langzeitergebnisse nach Refixation mittels resorbierbarer PLLA-Implantate.Material und MethodenIn dieser retrospektiven Studie wurden 12 Patienten mit 13 Läsionen erfasst, die im Schnitt 13,9 (±1,2) Jahre zuvor eine Refixation eines durchschnittlich 3,33 cm2(±2,33) großen osteochondralen Flake an Knie- (10 Patienten) und oberem Sprunggelenk (2 Patienten) mit resorbierbaren Implantaten (Nägel, Stifte, Schrauben) aus Polylactid (PLLA) (Fa. Bionx, Tampere, Finnland) erhalten hatten. Zur Objektivierung des klinischen Ergebnisses wurden 8 etablierte Scores (VASS, Tegner, Lysholm, McDermott, KSS, WOMAC, AOFAS, FADI+Sports) verwendet. Des Weiteren wurden die knöcherne Integration und Knorpelmorphologie mittels protonengewichteter und knorpelsensitiver „3D-double-echo-steady-state“(DESS)-Sequenzen im MRT (3 T) erfasst. Zur Objektivierung der Ergebnisse diente ein modifizierter MRT-Score nach Henderson et al.ErgebnisseNach 13,9 (±1,2) Jahren zeigten sich sowohl für die Knie- als auch die Sprunggelenkpatienten sehr gute Ergebnisse (Knie: VASS: 1,2 (±1,7); Tegner 4,4 (±1,3); Lysholm 85,7 (±12,2); McDermott 90,7 (±8,6); KSS 189 (±14,2); WOMAC (6,16 % (±8,45))), (OSG: VASS: 2,5 (±2,5); Tegner 5,5 (±1,5); Lysholm 87 (±13), McDermott 88 (±12); WOMAC (8,54 % (±8,54); AOFAS 75,5 (±24,5); FADI+Sports 118 (±18))). In der MRT zeigte sich in allen 12 Fällen eine gute Integration des refixierten Flake. In 5 Fällen kam es zu einer moderaten subchondralen Zystenbildung (∅ ≤1 mm). Allerdings zeigten alle Patienten milde Veränderungen der Knorpelkontur. Hieraus ergab sich ein durchschnittlicher modifizierter Henderson-Score-Wert von 14,4 (±2,0) (Bestwert: 8, schlechtester Wert: 32), was einem guten MR-morphologischen Ergebnis entspricht.SchlussfolgerungAufgrund der klinischen und auch MR-morphologischen Langzeitergebnisse ist die Refixation von osteochondralen Flakes mittels resorbierbarer Implantate (PLLA) als empfehlenswertes Verfahren zu werten.

Importance: Costal cartilage calcification (CCC) of the cartilage graft, commonly used in reconstruction of nasal/auricular deformities, can cause poor surgical outcome, but structural and quantita...

Porous structure properties are known to conduct initial and long-term stability of titanium alloy implants. This study aims to assess the histomorphometric effect of a 3-D porosity in Ti-6Al-4V implants (PI) on osseointegration in comparison to solid Ti-6Al-4V implants (SI). The PI was produced in a spaceholder method and sintering and has a pore size of mean 400 µm (50 µm to 500 µm) and mimics human trabecular bone. Pairs of PI and equal sized SI as reference were bilaterally implanted at random in the lateral femoral condyle of 16 Chinchilla-Bastard rabbits. The animals were sacrificed after 4 and 12 weeks for histomorphometric analysis. The histomorphometric evaluation confirmed a successful short-term osseohealing (4 weeks) and mid-term osseoremodeling (12 weeks) for both types of implants. The total newly formed bone area was larger for PI than for SI after 4 and 12 weeks, with the intraporous bone area being accountable for the significant difference (p0.05). A more detailed observation of bone area distribution revealed a bony accumulation in a radius of +/- 500 µm around the implant surface after remodeling. The bone-to-implant contact (BIC) increased significantly (p0.05) from 4 to 12 weeks (PI 26.23 % to 42.68 %; SI 28.44 % to 47.47 %) for both types of implants. Due to different surface properties, however, PI had a significant (p0.05) larger absolute osseous contact (mm) to the implant circumference compared to the SI (4 weeks: 7.46 mm vs 5.72 mm; 12 weeks: 11.57 mm vs 9.52 mm [PI vs. SI]). The regional influences (trabecular vs. cortical) on bone formation and the intraporous distribution were also presented. Conclusively, the porous structure and surface properties of PI enable a successful and regular osseointegration and enhance the bony fixation compared to solid implants under experimental conditions.

Introduction: The plain film chest x-ray in supine position (CXR) during the initial management of severely injured patients has almost lost its clinical relevance, since it has been challenged by extended focused assessment with sonography in trauma (eFAST) in early trauma management, due to its superiority in detecting a pneumo-/hematothorax. One of the last diagnostic fields in such setting of CXR is the mediastinal vascular injury. These injuries are rare yet life-threatening events. The most easily accessible diagnostic tool to identify these patients would be CXR as it is still one of the standard diagnostic tools in the early assessment of severely injured patients with significant thoracic trauma (Abbreviated Injury Scale, AIS ≥3). This study evaluates the role of early CXR in the Trauma Resuscitation Unit (TRU) in the last diagnostic field where eFAST cannot provide an answer: detecting mediastinal vascular injury in severely injured patients.Method: This retrospective, observational, single-centre study included all primary blunt trauma patients of a 24 months time period, that had been admitted to the TRU. Mediastinal/chest (M/C) ratio measurements were taken from CXRs at three defined levels of the mediastinum. The accuracy of the CXR findings were compared to whole-body computed tomography scans (WBCT) and therapeutic consequences were observed. Additionally a 15 years (2005–2019) time period out of the TraumaRegister DGU® was evaluated regarding usage of eFAST, CXR und WBCT in Level-1, -2, and − 3 Trauma Centres in Germany.Results: A total of 267 patients showed a significant blunt thoracic trauma (27 with mediastinal vascular injury (VThx)). The initial CXR in a supine position was unreliable for detecting mediastinal vascular injury. The sensitivity and specificity at different thresholds of maximum M/C ratio (2.0–3.0) were not clinically acceptable. The aortic contour and haemato- and pneumothorax were not reliably detected in the initial CXRs. No significant differences in the cardiac silhouette were observed between patients with or without mediastinal vascular injury (mean cardiac width, 136.5 mm, p = 0.44). No therapeutic consequences were drawn after CXR in the study period. The data from the TR-DGU (N = 251,095) showed a continuous reduction of CXR from 75% (2005) to 25% (2019), while WBCT raised from 35% to a steady level of about 80%. This development was seen in all trauma hospitals almost simultaneously.Conclusion: In present guidelines, CXR remains an integral diagnostic element during early TRU management, although several prior publications show the superior role of eFAST. Our data support that in most cases, CXR is time consuming and provides no benefit during initial management of severely injured patients and might delay the use of WBCT. The trauma centres in Germany have already significantly reduced the usage of CXR in the TRU. We therefore recommend to revise current guidelines and emphasise eFAST and rapid diagnostic through WBCT if rapidly available.

In the present study, we analyzed the histological characteristics of osseointegration of an open-porous Ti-6Al-4V material that was produced in a space holder method creating a 3-D through-pores trabecular design that mimics the inhomogeneity and size relationships of trabecular bone in macro- as well as microstructure. Pairs of cylindrical implants with a porosity of 49 % and an average pore diameter of 400 µm (PI) or equal sized solid, corundum blasted devices (SI) as reference were bilaterally implanted press fit in the lateral condyles of 16 rabbits. Histological examination was performed after 4 weeks of short-term osseohealing and 12 weeks of mid-term osseoremodeling and we summarized the criteria for sequential osseointegration. After 4 weeks, osteoid had already been largely replaced by mineralized woven bone in both types of implants but was only represented to a greater extent in the deeper pores of PI. The cortical as well as trabecular region showed regular osseohealing with excessive and spatially undirected formation of immature woven bone. A dense bone mass was found in the cortical area, while in the trabecular region the bone mass was reduced distinctly, presenting large lacuna-like recesses and a demarcating trabecular structure. The pores near the implant surface contained more mineralized woven bone than the deeper pores. After 12 weeks, the osseoremodeling was largely completed with a physiological maturation to lamellar bone. The newly formed bone mass increased for PI and SI compared to the 4-week group and osteoid was only detectable in the deeper pores. The inhomogeneous trabecular design of the pores enables an excellent ingrowth of mineralized lamellar bone after remodeling to a pore depth of 1800 µm, which proves a functional load transfer from the surrounding bone into the implant. According to the concept of osseointegration by Branemark and Albrektsson, the histological evaluation confirms a successful, superior osseointegration of the presented porous properties improving long-term implant stability. The presented study protocol allows an excellent evaluation and comparison of the sequential osseointegration from short-term osseohealing to mid-term osseoremodeling.

Porosity in titanium alloy materials improves the bony integration and mechanical properties of implants. In certain areas of application such as vertebral spacers or trabecular bone replacement (e.g. wedge augmentation in prosthetics), surface structures are desirable that promote bone integration and have biomechanical properties that are resistant to intraosseous load transfers and at the same time resemble the stiffness of bone to possible reduce the risk of stress shielding. In the present study, we investigated the biomechanical push-out behavior of an open-porous Ti–6Al–4V material that was produced in a space-holder and sintering method creating a 3-D through-pores trabecular design that corresponds with the inhomogeneity and size relationships of trabecular bone. The short-term and mid-term effects of the material properties on osseointegration in a biomechanical push-out study were compared to those of to a conventional solid Ti–6Al–4V material. In order to raise the measurement accuracy we implemented a strict study protocol. Pairs of cylindrical implants with a porosity of 49% and an average pore diameter of 400 μm and equal sized solid, corundum blasted devices as reference were bilaterally implanted press fit in the lateral femoral condyles of 14 rabbits. After sacrifice at 4 and 12 weeks, a push-out test was performed while the test set-up was designed to ensure conformity of implant axes and direction of applied force. Maximum holding force, Young's modulus, and mode of failure were recorded. Results of maximum push-out force (F-max) revealed a significant material effect (p Conclusively, the porous implant offers surface properties that significantly improve its osseous stability compared to solid material under experimental conditions. In addition, we have optimized our study protocol for biomechanical push-out tests to produce precise and comparable results.

Objectives To investigate if cartilage calcification (CC) is a systemic process, the purpose of this study was to determine the prevalence and the amount of meniscal/hyaline CC of the knee joint in the general population by high-resolution imaging (DCR) and to evaluate the association between CC with cartilage degeneration and age. Methods Cross-sectional DCR-study of 180 knee joints of 90 donors (42 female/48 male, mean age 62.3y). Histological hyaline (OARSI) and meniscal (Krenn) cartilage degeneration was determined of all knees. Results CC was observed in 100% of the donors (bilaterally in 98%), hyaline cartilage calcification (HCC) in 92% and meniscal calcification (MC) in 100%. CC was detected in more than three out of six distinct cartilage areas in 84.4% of all knees. The mean amount of CC correlated between both sides of donors, the different analyzed areas of the knee joint and between the various types of cartilage structures. There was more calcification in meniscal than in hyaline cartilage (factor 5.3) and in the medial than the lateral compartment (factor 1.2). HCC/MC were already detectable with only mild cartilage lesions and the amount correlated with histological cartilage degeneration, but not with age. Conclusions The present study provides evidence that meniscal and hyaline CC occurs in a pattern that is compatible with CC being a systemically driven process and that meniscal fibrocartilage is more prone to calcification than hyaline cartilage. Furthermore, the age-independent association between the amount of CC and the grade of degeneration in both hyaline and meniscal cartilage, suggests that CC is an obligatory early event in initiating cartilage degeneration.

Intratendinous lesions of the rotator cuff of the shoulder are frequent and may be a distinct clinical entity. Nevertheless, there are only a few publications which deal specifically with this subject. This study analyses the existing literature for the arthroscopic reconstruction of the intratendinous lesion of the supraspinatus tendon, by means of a systematic review, and identifies relevant research questions for future studies.In January 2017, a systematic review of the U. S. National Library of Medicine/National Institutes of Health (PubMed) Database and the Cochrane Library was conducted using the PRISMA checklist. The search words were "supraspinatus" and "interstitial"; "supraspinatus", "tear" and "intratendinous"; "supraspinatus" and "concealed". In the course of the review, articles written in English with at least a partial arthroscopic case series dealing with the reconstruction of the supraspinatus tendon were identified and further analysed.Primarily 70 hits could be generated. Five articles met the inclusion criteria and were analysed in detail. The number of arthroscopic cases ranged between 6 and 33. Level of evidence was IV in all studies. The diagnosis of an intratendinous lesion was made by MR imaging when T2/fat-saturated sequences showed an intratendinous high intensity signal without disruption of the bursal or articular layer. Three different concepts were followed in surgical treatment: opening of the intratendinous lesion from the bursal or articular side or by complete resection of the lesion. The reconstruction was performed with suture anchors in all cases. In the majority of cases, an acromioplasty was also performed. The reported clinical results were mostly good. Healing of the tendon was shown by MR imaging in 81.5 to 100% of cases.After failure of conservative treatment, symptomatic intratendinous lesions of the supraspinatus tendon can be localised intraoperatively and reconstructed after failure of conservative treatment. The expected results are good in the medium term. The evidence level of the studies analysed was low. Future studies should examine the role of alternative conservative and surgical therapies.Intratendinöse Läsionen der Rotatorenmanschette der Schulter treten in relevanter Fallzahl auf und stellen möglichweise eine eigene klinische Entität dar. Dennoch gibt es bislang wenig Fachliteratur, die sich spezifisch hiermit beschäftigt. Die hier vorliegende Arbeit analysiert anhand eines systematischen Reviews die vorhandene Fachliteratur zur arthroskopischen Rekonstruktion der intratendinösen Läsion der Supraspinatussehne und ermittelt relevante Forschungsfragen für zukünftige Studien.Im Januar 2017 wurde eine systematische Durchsicht der Datenbank U. S. National Library of Medicine/National Institutes of Health (PubMed) und der Cochrane Library unter Anwendung der PRISMA-Checkliste durchgeführt. Als Suchwörter dienten „supraspinatus“ und „interstitial“; „supraspinatus“, „tear“ und „intratendinous“; „supraspinatus“ und „concealed“. Anhand der Durchsicht der gefundenen Literatur wurden Artikel mit zumindest anteiligen arthroskopischen Fallserien mit einer Rekonstruktion der Supraspinatussehne in englischer Sprache identifiziert.Es konnten primär 70 Treffer generiert werden. Fünf Artikel entsprachen den Einschlusskriterien und wurden weitergehend inhaltlich analysiert. Die arthroskopische Fallzahl lag zwischen 6 und 33. Die Evidenz betrug ohne Ausnahme Level IV. Die Diagnose wurde kernspintomografisch gestellt, wenn eine intratendinöse Signalanhebung in der Supraspinatussehne in T2-/fettgesättigten Sequenzen ohne Durchbrechung nach bursal oder artikulär zu erkennen war. Drei verschiedene Konzepte wurden in der operativen Behandlung verfolgt: Eröffnung der intratendinösen Läsion von bursal, von artikulär oder Eröffnung durch komplette Resektion des betroffenen Sehnenanteils. Die Rekonstruktion erfolgte jeweils mit Fadenankern. In der Mehrzahl der Fälle wurde zusätzlich eine Akromioplastik durchgeführt. Die berichteten klinischen Ergebnisse waren mehrheitlich gut. Kernspintomografisch gesicherte Einheilungsquoten lagen zwischen 81,5 und 100%.Symptomatische und therapierefraktäre intratendinöse Läsionen der Supraspinatussehne können intraoperativ lokalisiert und rekonstruiert werden. Die zu erwartenden Ergebnisse sind mittelfristig gut. Der Evidenzlevel der analysierten Studien war für das Fachgebiet niedrig. Zukünftige Studien sollten die Rolle alternativer konservativer und operativer Therapieansätze untersuchen.

Durch die Zulassungsbeschrankungen zum Medizinstudium, sich andernde Anspruche an die „Work-Life-Balance“ und eingeschrankte langfristige berufliche Perspektiven kampfen insbesondere chirurgische Facher mit einem Nachwuchsmangel. Ziele der chirurgischen Abteilungen in der studentischen Ausbildung an den Universitatskliniken sind einerseits die konkrete Wissensvermittlung von fachlichen Zusammenhangen und andererseits das Wecken des Interesses fur die Chirurgie. Ziel der vorliegenden Studie war es, die Etablierung eines studentischen unfallchirurgischen Rufdienstes (RD-Stud) zu evaluieren und den Nutzen wissenschaftlich auszuwerten. In der vorliegenden Studie wurde der RD-Stud durch eine Pra-/Postevaluation anhand von Fragebogen mit der unterstutzenden Projektion von Rontgenbildern im Rahmen eines Lehrmoduls vergleichend mit Studierenden des 4. Fachsemesters und PJ-Studierenden untersucht. Die Rufdienststudierenden wiesen dabei sowohl vor der Lehreinheit als auch danach bessere Testergebnisse auf als die beiden anderen Gruppen. Durch die Etablierung eines RD-Stud zur Assistenz im Schockraum und bei operativen Notfalleingriffen konnen die Studierenden das Verstandnis fur chirurgische Diagnosestellung und Therapiekonzepte verbessern. Gleichzeitig erlernen sie eine zunehmende Sicherheit bei fachlichen Entscheidungen. Bei einem nur geringen Zusatzlehraufwand wird hierdurch eine erfolgreiche Nachwuchsforderung realisiert. Durch den RD-Stud konnte die Arbeitsbelastung der arztlichen Kollegen reduziert werden. Aufgrund einer geminderten Inanspruchnahme des arztlichen Rufdienstes konnten Personalkosten in Hohe von 23.659,86 Euro jahrlich eingespart werden. Es zeigt sich in der vorliegenden Analyse eine hervorragende Aufwand-Nutzen-Bilanz dieses Modells, das sich an der Universitatsmedizin Gottingen in mehreren chirurgischen Kliniken inzwischen erfolgreich etabliert hat. Es kommt neben der praxisorientierten Vermittlung von chirurgischen Lehrinhalten zu einer erfolgreichen Nachwuchsforderung sowie Ressourceneinsparung der arztlichen Rufdienste.

Aim The diagnosis and treatment of patellar dislocation is very complex. The aim of this study is to give an overview of the biomechanics of the patellofemoral joint and to point out the latest developments in diagnosis and treatment of patellar dislocation. Method The authors electronically searched Medline, Cochrane and Embase for studies on the biomechanics of the patellofemoral joint and for conservative and surgical treatments after patellar dislocation. We extracted baseline demographics, biomechanical, conservation and surgical details. Results Understanding the biomechanics of the patellofemoral joint is necessary to understand the pathology of patellar dislocation. The patellofemoral joint consists of a complex system of static, active and passive stabilising factors. Patellar instability can result from osseous and soft-tissue abnormalities, such as trochlear dysplasia, patella alta, a high tibial tuberosity trochlear groove (TTTG) distance, weaknesses of the vastus medialis obliquus or a lesion of the medial retinaculum. Recent studies have focused on the medial patellofemoral ligament (MPFL) and have shown that the MPFL is the most significant passive stabiliser of the patella. Following patellar dislocation, an MRI should be standard practice to detect an MPFL rupture, osteochondral lesions or other risk factors for redislocation. An acute first-time patellar dislocation without osteochondral lesions and without severe risk factors for a redislocation should follow a conservative treatment plan. If surgical treatment is required, the best postoperative results occur when the MPFL is reconstructed, leading to a redislocation rate of 5%, this includes cases that have a dysplastic trochlea. Duplication of the medial retinaculum show very inconsistent results in the literature, possibly due to the fact that the essential pathomorphology of patellar dislocation is not addressed. Addressing the exact location of the rupture of the MPFL with a suture is possibly more convenient, especially after first-time dislocation with associated risk factors for a redislocation. Recent literature does not encourage the use of lateral release, since this can increase patellar instability. Indications for lateral release include persistent patellar instability or pain reduction in an older arthritic subject. For correcting a patellofemoral malalignment, the TTTG distance should be measured and a medial transposition of the anterior tibial tubercle hinged on a distal periosteal attachment should be considered. Cartilage lesions on the medial facet of the patella are a contra-indication for medial tubercle transposition. For cartilage lesions of the lateral facet, antero-medialization of the tibial tubercle can be successful. A tubercle osteotomy can be efficiently combined with MPFL reconstruction. We believe that patients with open epiphyseal plates should be treated with duplication of the medial retinaculum. In the presence of patellar maltracking, an additional subperiostal soft tissue release with medialisation of the distal part of the patellar tendon can be performed. Conclusion It seems that the predominating factors for patellar dislocation are heterogenic morphology in combination with individual predisposition. Non-surgical treatment is typically recommended for primary patellar dislocation without any osteochondral lesions and in the absence of significant risk factors for redislocation. If surgical treatment is deemed necessary, addressing the essential pathomorphology has become the primary focus.

AIM Refixation of osteochondral fractures with resorbable implants is a common surgical treatment. There are almost no studies that prove good clinical outcomes. Hence, the aim of the study was to evaluate the mid-term results after refixation of osteochondral fractures. METHODS The results of 12 patients were recorded 6.5 (±1) years after refixation of osteochondral fractures measuring 3.4 cm (2) (±2.5) of the knee (8 ×) or the ankle joint (4 ×) with resorbable inplants. Clinical scores and a modified MRI score based on that of Henderson et al. were used. RESULTS The clinical scores showed good to excellent results after 6.5 (±1) years (VAS pain: 1.9 [±2.4], Tegner: 5.0 [±1.7], Lysholm: 84.8 [±14.3], McDermott: 91.3 [±7.9], Knee Society: 189.4 [±12.1]). MRI showed with one exception good integration of the fractures. In 3 cases subchondral cysts could be found. In 7 cases changes in the chondral outline occurred. The effect of this was a modified Henderson score of 12.6 (±3.7). The MRI results did not correlate with the clinical outcome. CONCLUSION Because of its good clinical results the refixation with resorbable implants can be recommended to treat osteochondral fractures.

Background A trend toward young women being at greatest risk for primary and recurrent dislocation of the patella is evident in the current literature. However, a causative factor is missing, and differences in the anatomical risk factors between men and women are less defined. Purpose To identify differences between the sexes in the anatomy of lateral patellar instability. Study Design Case control study; Level of evidence, 3. Methods Knee magnetic resonance images were collected from 100 patients treated for lateral patellar instability. Images were obtained from 157 patients without patellar instability who served as controls. Using 2-way analyses of variance, the influence of patellar dislocation, gender, and their interaction were analyzed with regard to sulcus angle, trochlear depth, trochlear asymmetry, patellar height, and the tibial tubercle—trochlear groove (TT-TG) distance. Mechanisms of injury of first-time dislocations were divided into high-risk, low-risk, and no-risk pivoting activities and direct hits. Results For all response variables, a significant effect was observed for the incidence of patellar dislocation (all P < .01). In addition, sulcus angle, trochlear asymmetry, and trochlear depth depended significantly on gender (all P < .01) but patellar height did not (P = .13). A significant interaction between patellar dislocation and gender was observed for the TT-TG distance (P = .02). The mean difference in TT-TG distance between study and control groups was 4.1 mm for women (P < .01) and 1.6 mm for men (P = .05). Low-risk and no-risk pivoting injuries were most common in women, whereas first-time dislocations in men occurred mostly during high-risk pivoting activities (P < .01). Conclusion The data from this study indicate that trochlear dysplasia and the TT-TG distance is more prominent in women who dislocate the patella. Both factors might contribute to an increased risk of lateral patellar instability in the female patient as illustrated by the fact that dislocations occurred most often during low-risk or no-risk pivoting activities in women.

Purpose The objective of this study was to analyze the injury patterns of the medial patellofemoral ligament (MPFL) in acute lateral patellar dislocations (LPDs) considering the anatomically relevant factors of patellar instability. Methods Knee magnetic resonance images were collected from 73 patients within 7 weeks after LPD, and the injury patterns of the MPFL were evaluated for trochlear dysplasia, for patellar height, and for the tibial tuberosity–trochlear groove (TT-TG) distance. Results Injury to the MPFL was found in 98.6% of the patients (72 of 73) after the acute LPD, with a complete tear in 51.4% (37 of 72), most frequently localized at the femoral attachment site, and a partial tear in 48.6% (35 of 72). Injury to the femoral origin (Fem), to the midsubstance (Mid), and to the patellar insertion (Pat) of the MPFL was found in 50.0% (36 of 72), 13.9% (10 of 72), and 13.9% (10 of 72), respectively. More than 1 site of injury was found in 22.2% (16 of 72), most frequently as a combined injury at the femoral origin and at the patellar insertion sites (Pat+Fem) (13 of 16). The study population, as well as the Pat, Fem, and Pat+Fem subgroups, showed significantly different values of trochlear dysplasia and patellar height when compared with the control group, whereas the data of the Mid group were not significantly different. In addition, injury at the patellar insertion (Pat) was accompanied by a significantly increased TT-TG distance when compared not only with the control group but also with the Fem, Mid, and Pat+Fem groups. Conclusions The data from our study indicate that patterns of MPFL injury depend on trochlear dysplasia, patellar height, and TT-TG distance. They show a new aspect in the complex interplay between active, passive, and static stabilizers of the patellofemoral joint. Level of Evidence Level IV, diagnostic case-control study.

The medial and lateral tibia plateau geometry has been linked with the severity of trochlear dysplasia. The aim of the present study was to evaluate the tibial slope and the femoral posterior condylar offset in a cohort of consecutive subjects with a trochlear dysplastic femur to investigate whether the condylar offset correlates with, and thus potentially compensates for, tibial slope asymmetry. Magnetic resonance imaging was used to assess the severity of trochlear dysplasia as well as the tibial slope and posterior offset of the femoral condyles separately for the medial and lateral compartment of the knee joint in 98 subjects with a trochlear dysplastic femur and 88 control subjects. A significant positive correlation was found for the medial tibial slope and the medial posterior condylar offset in the study group (r(2) = 0.1566; P < 0.001). This relationship was significant for all subtypes of trochlear dysplasia and was most pronounced in the severe trochlear dysplastic femur (Dejour type D) (r(2) = 0.3734; P = 0.04). No correlation was found for the lateral condylar offset and the lateral tibial slope in the study group or for the condylar offset and the tibial slope on both sides in the control group. The positive correlation between the medial femoral condylar offset and the medial tibial slope, that is, a greater degree of the medial tibial slope indicated a larger offset of the medial femoral condyle, appears to represent a general anthropomorphic characteristic of distal femur geometry in patients with a trochlear dysplastic femur.

In rotator cuff repair, strong and long-lasting suturing techniques that do not require additional implants are needed. This study examines the ultimate load to failure and the Young’s modulus at the suture–tendon interface for a novel single-loop knot stitch and double-loop knot stitch. These values are compared to those of the modified Mason–Allen stitch. Twenty-four infraspinatus muscles with tendons were dissected from porcine shoulders (twelve Goettingen minipigs). The preparations were randomly allocated to three groups of eight samples. Load-to-failure testing of the single-loop knot stitch, the double-loop knot stitch and the mMAS were performed using a Zwick 1446 universal testing machine (Zwick-Roell AG, Ulm, Germany). The highest ultimate load to failure for the three techniques occurred with the double-loop knot stitch with a median value of 382.2 N (range 291.8–454.2 N). These values were significantly higher than those of the single-loop knot stitch, which had a median value of 259.5 N (range 139.6–366.3 N) and the modified Mason–Allen stitch, which had a median value of 309.3 N (range 84.55–382.9 N). The values of the single-loop knot stitch and the modified Mason–Allen stitch did not differ significantly. Regarding the Young’s modulus, no significant differences were found between the double-loop knot stitch with a median value of 496.02 N/mm² (range 400.4–572.6 N/mm²) and the modified Mason–Allen stitch with 498.5 N/mm² (range 375.5–749.2 N/mm²) with respect to the stiffness of the suture–tendon complex. The median value for the Young’s modulus of the single-loop knot stitch of 392.1 N/mm² (range 285.7–510.6 N/mm²) was significantly lower than those of the double-loop knot stitch and modified Mason–Allen stitch. This in vitro animal study demonstrated that both the single-loop knot stitch and the double-loop knot stitch have excellent ultimate load-to-failure properties when used for rotator cuff repair. The introduced single-loop knot stitch and double-loop knot stitch offer an alternative to other common used stitch techniques in rotator cuff repair.

The blood supply to the proximal patella is provided primarily via intraosseous vessels from the inferior patella. Two vascular systems within the patella are distinguished: Tiny arteries penetrate the middle third of the anterior patellar surface via vascular foramina and continue in a proximal direction. Additional vessels enter the patella at its distal pole, between the patellar ligament and the articular surface, and also run proximally. As a result of the double vascular supply to the distal portion and the vulnerable blood supply to the proximal part, localized osteonecroses subsequent to fracture may occur within the patella and nearly exclusively affect the upper portion of the patella. Such focal regions of osteonecrosis may appear radiographically as localized regions of hyperdensity within the patella. The aim of this study was to investigate the extent to which radiologically hyperdense areas, possibly representing localized osteonecrosis, may occur subsequent to surgical treatment of a patella fracture and the influence that they have on the outcome of the fracture. Retrospective analysis of 100 patients who had been treated operatively for a patella fracture from January 1998 to December 2008 was conducted. The subjective pain rating, clinical scores, and patient satisfaction scores were recorded. Existing X-rays were assessed with regard to possible increased radiological dense areas. After an average of 60.61 ( ± 33.88) months, it was possible to perform a clinical follow-up on 60 patients aged 45.48 ( ± 18.51) years. Radiographic follow-up of all patients revealed that nine patients (9%) exhibited a hyperdense area in the proximal patella portion. X-rays showed radiopaque areas between 1 and 2 months after surgery. In seven cases, the radiological finding disappeared after six months. In two patients with persisting radiologically dense areas, bone necrosis was verified by means of magnetic resonance imaging (MRI) examination and a histological assessment, respectively. The clinical outcome of these patients with a hyperdense area on the patella, in this small series, was not shown to be worse than those who demonstrated normal healing. Radiologically hyperdense areas subsequent to patella fracture may represent partial osteonecrosis caused by localized vascular compromise. This was confirmed by MRI and histological examinations in two patients with persistent hyperdense lesions. The clinical outcome of patients with hyperdense zones seems to be poorer than that of patients without such findings, but no statistical difference was shown in this small series. It is possible that earlier surgical treatment and thus a shorter ischemic period as well as tissue-conserving operative techniques could prevent the occurrence of partial necroses. This hypothesis would require further study.

The purpose of this study was to identify the risk factors for recurrent lateral patellar dislocations and to incorporate those factors into a patellar instability severity score.Sixty-one patients [male/female 35/26; median age 19 years (range 9-51 years)] formed the study group for this investigation. Within the study group, 40 patients experienced a patellar redislocation within 24 months after the primary dislocation, whereas 21 patients, who were assessed after a median follow-up of 37 months (range 24-60 months), had not experienced a subsequent episode of lateral patellar instability. In all patients, age at the time of the primary dislocation, gender, the affected body side, body mass index, bilateral instability, physical activity according to Baecke's questionnaire, the grade of trochlear dysplasia, patellar height, tibial tuberosity-trochlear groove (TT-TG) distance, and patellar tilt were assessed. The odds ratio (OR) of each factor with regard to the patellar redislocation was calculated using contingency tables. Based on these data, a "patellar instability severity score" was calculated.The patellar instability severity score has six factors: age, bilateral instability, the severity of trochlear dysplasia, patella alta, TT-TG distance, and patellar tilt; the total possible score is seven. Reapplying this score to the study population revealed a median score of 4 points (range 2-7) for those patients with an early episode of patellar redislocation and a median score of 3 points (range 1-6) for those without a redislocation (p=0.0004). The OR for recurrent dislocations was 4.88 (95% CI 1.57-15.17) for the patients who scored 4 or more points when compared with the patients who scored 3 or fewer points (p=0.0064).Based on the individual patient data, the patellar instability severity score allows an initial risk assessment for experiencing a recurrent patellar dislocation and might help differentiate between responders and non-responders to conservative treatment after primary lateral patellar instability.Case-control study, Level III.

Firstly, the way of implementing approximatively the initial rollback of the natural tibiofemoral joint (TFJ) in a total knee replacement (AEQUOS G1 TKR) is discussed. By configuration of the curvatures of the medial and lateral articulating surfaces a cam gear mechanism with positive drive can be installed, which works under force closure of the femoral and tibial surfaces. Briefly the geometric design features in flexion/extension are described and construction-conditioned kinematical and functional properties that arise are discussed. Due to a positive drive of the cam gear under the force closure during the stance phase of gait the articulating surfaces predominantly roll. As a result of rolling, a sliding friction is avoided, thus the resistance to motion is reduced during the stance phase. Secondly, in vivo fluoroscopic measurements of the patella tendon angle during flexion/extension are presented. The patella tendon angle/ knee flexion angle characteristic and the kinematic profile in trend were similar to those observed in the native knee during gait (0°-60°).

A novel class of total knee replacement (AEQUOS G1) is introduced which features a unique design of the articular surfaces. Based on the anatomy of the human knee and differing from all other prostheses, the lateral tibial "plateau" is convexly curved and the lateral femoral condyle is posteriorly shifted in relation to the medial femoral condyle. Under compressive forces the configuration of the articular surfaces of human knees constrains the relative motion of femur and tibia in flexion/extension. This constrained motion is equivalent to that of a four-bar linkage, the virtual 4 pivots of which are given by the centres of curvature of the articulating surfaces. The dimensions of the four-bar linkage were optimized to the effect that constrained motion of the total knee replacement (TKR) follows the flexional motion of the human knee in close approximation, particularly during gait. In pilot studies lateral X-ray pictures have demonstrated that AEQUOS G1 can feature the natural rollback in vivo. Rollback relieves the load of the patello-femoral joint and minimizes retropatellar pressure. This mechanism should reduce the prevalence of anterior knee pain. The articulating surfaces roll predominantly in the stance phase. Consequently sliding friction is replaced by the lesser rolling friction under load. Producing rollback should minimize material wear due to friction and maximize the lifetime of the prosthesis. To definitely confirm these theses one has to wait for the long term results.