[Fractures of the base of the V metatarsal bone-current concepts revised]. / Frakturen der Metatarsale Fünf Basis ­ eine Neubetrachtung.

Fractures of the base of the fifth metatarsal bone are one of the most frequent fractures to the foot and ankle. Despite the high frequency and although a number of studies are now available, treatment frequently does not follow the available evidence. Among the reasons is the inconsistent terminology used and that the studies available are neglected. The aim of this review is to present the current classifications, the available treatment studies and to derive evidence-based treatment recommendations. The term "Jones fracture" has been used inconsistently for different fracture entities and should, therefore, not be used anymore. Fractures are mostly classified according to Lawrence and Botte into three zones. However, the available studies demonstrate that type I and type II fractures according to Lawrence and Botte do not differ with respect to the prognosis. Both fractures can be successfully healed by functional treatment with weightbearing as tolerated. Consequently, a differentiation between these two zones does not seem to be meaningful. Therefore, they should be summarized as epi-metaphyseal fractures. Even dislocated, intra-articular, and multifragmentary fractures in this region can be functionally treated with good results. Fractures in the meta-diaphyseal region (Lawrence and Botte type III, distal to the IV and V intermetatarsal articulation) demonstrate a high rate of symptomatic non-unions after conservative treatment. Therefore, these fractures should be primarily treated operatively by closed reduction and intramedullary screw fixation.

[Insertional Achilles tendinopathy : Differentiated diagnostics and therapy]. / Ansatznahe Erkrankungen der Achillessehne : Differenzierte Diagnostik und Therapie.

Achilles tendinopathy at the calcaneal insertion is classified into insertional tendinopathy, retrocalcaneal and superficial bursitis. The aim of this study was to present the current evidence on conservative and surgical treatment of insertional tendinopathy of the Achilles tendon. Conservative first-line therapy includes reduction of activity levels, administration of non-steroidal anti-inflammatory drugs (NSAID), adaptation of footwear, heel wedges and orthoses or immobilization. In addition, further conservative therapy options are also available. Eccentric stretching exercises should be integral components of physiotherapy and can achieve a 40% reduction in pain. Extracorporeal shock wave therapy has been shown to reduce pain by 60% with a patient satisfaction of 80%. Due to the limited evidence, injections with platelet-rich plasma (PRP), dextrose (prolotherapy) or polidocanol (sclerotherapy) cannot currently be recommended. Operative therapy is indicated after 6 months of unsuccessful conservative therapy. Open debridement allows all pathologies to be addressed, including osseous abnormalities and intratendinous necrosis. The success rate of over 70% is contrasted by complication rates of up to 40%. The Achilles tendon should be reattached, if detached by >50%. No valid data are available for the transfer of the tendon of the flexor hallucis longus (FHL) muscle but it is frequently applied in cases of more than 50% debridement of the diameter of the Achilles tendon. Lengthening of the gastrocnemius muscle cannot be recommended because insufficient data are available. Tendoscopy is a promising treatment option for isolated retrocalcaneal bursitis and has shown similar success rates to open debridement with significantly lower complication rates.

Assessing the potential risk of rupture of abdominal aortic aneurysms.

Abdominal aortic aneurysms (AAAs) involve complex interplays between inflammatory and biomechanical factors that can be elucidated with anatomical and functional imaging. Although AAA size has been well-established in the literature to correlate with risk of rupture (and subsequent need for vascular intervention), there are other less-well-known characteristics about AAAs that also contribute to higher risk of rupture. This review focuses on biomechanical, radiological, and epidemiological characteristics of AAAs that are associated with higher rupture risk. For clinicians, knowing and considering a wide variety of risk factors in addition to AAA size is important to initiate early and proper intervention for AAA repair. Although there is no official quantitative risk score of AAA rupture risk that takes other non-size-related variables into account, if clinicians are aware of these other parameters, it is hoped that intervention can be appropriately performed for higher-risk AAAs that have not met the size-threshold for elective repair.

[Osteoid osteoma of the talus: a rare cause for pain in the ankle joint]. / Das Osteoidosteom des Talus: Eine seltene Ursache für Beschwerden des oberen Sprunggelenks.

Osteoid osteomas are typically located in the femur and tibia and are mostly easy to diagnose based on patient age, the clinical signs and plain radiographs. In contrast, the diagnosis of osteoid osteomas of the foot is often delayed because of the atypical presentation. We report the case of a 24-year-old patient with persisting pain in the ankle joint over 8 years due to an osteoid osteoma of the talus neck.

The impact of intraluminal thrombus failure on the mechanical stress in the wall of abdominal aortic aneurysms.

OBJECTIVES: The role of the intraluminal thrombus (ILT) in abdominal aortic aneurysm (AAA) rupture is controversial, and it is still not clear if an ILT increases or decreases AAA rupture risk. Specifically, signs of bleeding in the ILT are considered to increase AAA rupture risk. To further explore this hypothesis, intact AAAs (n = 4) with clear signs of fissures in the ILT, identified by computed tomography angiography (CTA) were investigated. METHODS: Two different cases of ILT fissuring were investigated, where (1) ILT fissures were extracted directly from the CTA data and (2) a hypothetical fissure was introduced in the otherwise-intact ILT tissue. Wall stress distributions were predicted based on detailed Finite Element (FE) models. RESULTS: ILT fissures extracted from CTA data locally increase the mechanical stress in the underlying wall by up to 30%. The largest impact on wall stress was observed if the ILT crack reaches the aneurysm wall, or if it involves large parts of the ILT. By contrast, a concentric failure in the medial ILT, which does not reach the aneurysm wall, has almost no impact on wall stress distribution. Hypothetical ILT fissures that connect the lumen with the wall cause a twofold increase of the stress in the underlying wall. CONCLUSIONS: ILT fissures increase the stress in the underlying wall, whereas regions other than that remain unaffected. If ILT fissures reach the wall or involve large parts of the ILT, the resulting increase in wall stress could possibly cause AAA rupture.

Impact of isotropic constitutive descriptions on the predicted peak wall stress in abdominal aortic aneurysms.

Biomechanics-based assessment of Abdominal Aortic Aneurysm (AAA) rupture risk has gained considerable scientific and clinical momentum. However, computation of peak wall stress (PWS) using state-of-the-art finite element models is time demanding. This study investigates which features of the constitutive description of AAA wall are decisive for achieving acceptable stress predictions in it. Influence of five different isotropic constitutive descriptions of AAA wall is tested; models reflect realistic non-linear, artificially stiff non-linear, or artificially stiff pseudo-linear constitutive descriptions of AAA wall. Influence of the AAA wall model is tested on idealized (n=4) and patient-specific (n=16) AAA geometries. Wall stress computations consider a (hypothetical) load-free configuration and include residual stresses homogenizing the stresses across the wall. Wall stress differences amongst the different descriptions were statistically analyzed. When the qualitatively similar non-linear response of the AAA wall with low initial stiffness and subsequent strain stiffening was taken into consideration, wall stress (and PWS) predictions did not change significantly. Keeping this non-linear feature when using an artificially stiff wall can save up to 30% of the computational time, without significant change in PWS. In contrast, a stiff pseudo-linear elastic model may underestimate the PWS and is not reliable for AAA wall stress computations.

Structure-based constitutive model can accurately predict planar biaxial properties of aortic wall tissue.

Structure-based constitutive models might help in exploring mechanisms by which arterial wall histology is linked to wall mechanics. This study aims to validate a recently proposed structure-based constitutive model. Specifically, the model's ability to predict mechanical biaxial response of porcine aortic tissue with predefined collagen structure was tested. Histological slices from porcine thoracic aorta wall (n=9) were automatically processed to quantify the collagen fiber organization, and mechanical testing identified the non-linear properties of the wall samples (n=18) over a wide range of biaxial stretches. Histological and mechanical experimental data were used to identify the model parameters of a recently proposed multi-scale constitutive description for arterial layers. The model predictive capability was tested with respect to interpolation and extrapolation. Collagen in the media was predominantly aligned in circumferential direction (planar von Mises distribution with concentration parameter bM=1.03 ± 0.23), and its coherence decreased gradually from the luminal to the abluminal tissue layers (inner media, b=1.54 ± 0.40; outer media, b=0.72 ± 0.20). In contrast, the collagen in the adventitia was aligned almost isotropically (bA=0.27 ± 0.11), and no features, such as families of coherent fibers, were identified. The applied constitutive model captured the aorta biaxial properties accurately (coefficient of determination R(2)=0.95 ± 0.03) over the entire range of biaxial deformations and with physically meaningful model parameters. Good predictive properties, well outside the parameter identification space, were observed (R(2)=0.92 ± 0.04). Multi-scale constitutive models equipped with realistic micro-histological data can predict macroscopic non-linear aorta wall properties. Collagen largely defines already low strain properties of media, which explains the origin of wall anisotropy seen at this strain level. The structure and mechanical properties of adventitia are well designed to protect the media from axial and circumferential overloads.

Loss of N-linked glycans in the V3-loop region of gp120 is correlated to an enhanced infectivity of HIV-1.

We describe mutants of human immunodeficiency virus type-1 (HIV-1) strain NL4-3, which are lacking the thirteenth, fifteenth, or seventeenth sites for N-linked glycosylation (g13, g15, g17) of the envelope protein gp120. All three sites are located within the hypervariable V3 loop region of gp120. Those mutants lacking carbohydrates g15 or combinations of g15/g17 showed markedly higher infectivity for GHOST cells (human osteosarcoma cells) expressing CXCR4 (GHOST-X4), compared to the fully glycosylated NL4-3 wild type virus. In addition, these mutants could also infect cells which exhibits low background expression of CXCR4, corresponding to <10% of that observed for GHOST-X4 cells. In addition to the enhanced infectivity observed, mutants lacking g15 and g17 showed increased resistance to inhibition by SDF-1, the natural ligand of CXCR4. Thus, loss of the oligosaccharides g15 and g17 in the V3 region of gp120 markedly influences CXCR4-specific infection.