Author Correction: Mapping the world's free-flowing rivers.

An Amendment to this paper has been published and can be accessed via a link at the top of the paper.

Mapping the world's free-flowing rivers.

Free-flowing rivers (FFRs) support diverse, complex and dynamic ecosystems globally, providing important societal and economic services. Infrastructure development threatens the ecosystem processes, biodiversity and services that these rivers support. Here we assess the connectivity status of 12 million kilometres of rivers globally and identify those that remain free-flowing in their entire length. Only 37 per cent of rivers longer than 1,000 kilometres remain free-flowing over their entire length and 23 per cent flow uninterrupted to the ocean. Very long FFRs are largely restricted to remote regions of the Arctic and of the Amazon and Congo basins. In densely populated areas only few very long rivers remain free-flowing, such as the Irrawaddy and Salween. Dams and reservoirs and their up- and downstream propagation of fragmentation and flow regulation are the leading contributors to the loss of river connectivity. By applying a new method to quantify riverine connectivity and map FFRs, we provide a foundation for concerted global and national strategies to maintain or restore them.

Neoadjuvant irradiation of extremity soft tissue sarcoma with ions (Extrem-ion): study protocol for a randomized phase II pilot trial.

BACKGROUND: The standard of care treatment for soft tissue sarcoma of the extremities is a wide resection in combination with pre- or postoperative radiotherapy with high local control rates, sparing patients the necessity of amputation without compromising on overall survival rates. The currently preferred timing of radiotherapy is under debate. Albeit having higher rates of acute wound complications, late side effects like fibrosis, joint stiffness or edema are less frequent in preoperative compared to postoperative radiotherapy. This can be explained in smaller treatment volumes and a lower dose in the preoperative setting. Particles allow better sparing of surrounding tissues at risk, and carbon ions additionally offer biologic advantages and are preferred in less radiosensitive tumors. Hypofractionation allows for a significantly shorter treatment duration. METHODS: Extrem-ion is a prospective, randomized, monocentric phase II trial. Patients with resectable or marginally resectable, histologically confirmed soft tissue sarcoma of the extremities will be randomized between neoadjuvant proton or neoadjuvant carbon ion radiotherapy in active scanning beam application technique (39 Gy [relative biological effectiveness, RBE] in 13 fractions [5-6 fractions per week] in each arm). The primary objective is the proportion of therapies without wound healing disorder the first 120 days after surgery or discontinuation of treatment for any reason related to the treatment. The secondary endpoints of the study consist of local control, local progression-free survival, disease-free survival, overall survival, and quality of life. DISCUSSION: The aim of this study is to confirm that hypofractionated, preoperative radiotherapy is safe and feasible. The potential for reduced toxicity by the utilization of particle therapy is the rational of this trial. A subsequent randomized phase III trial will compare the hypofractionated proton and carbon ion irradiation in regards to local control. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04946357 ; Retrospectively registered June 30, 2021.

[Periprosthetic joint infections : Latest developments, strategies and treatment algorithms]. / Periprothetische Früh- und Spätinfektionen : Neuste Entwicklungen, Strategien und Behandlungsalgorithmen.

BACKGROUND: Due to their multidimensional consequences, periprosthetic joint infections are a serious complication in arthroplasty. There are disagreements in the literature regarding their classification. At the same time, a consequence for the practical procedure cannot always be derived. THERAPEUTIC PROCEDURES: In addition to debridement with antibiotics and implant retention, there are options for a one or two-stage change in the therapeutic procedure. Although the preservation of implants is only possible in the case of acute infections with a short duration of symptoms, prosthesis changes are indicated with a longer symptom duration. For both procedures, there are interinstitutional deviating indication criteria, weighing pros and cons. Both have specific problems, such as, in particular, the duration of the antibiotics course, the question of anchoring the prosthesis and, in the case of a two-stage procedure, the shape of the spacer.

[Low-grade-infections after spondylodeses-A chameleon? : Current findings and therapeutic strategies]. / Low-Grade-Infektionen in der Wirbelsäulenchirurgie ­ Ein Chamäleon? : Neuste Erkenntnisse und Behandlungsstrategien.

BACKGROUND: Low-grade infections are caused by low-virulence pathogens. The course of these infections is often mild, which is why they are often delayed or not recognized at all. Chronic infections can lead to osteolysis and implant loosening. The rate of complications requiring revision, such as implant loosening or material failure, is known from the literature. However, the rate of low-grade infections in patients requiring spinal revision surgery remains unclear. PURPOSE: The aim of this review is to present the latest treatment strategies for low-grade infections. The diagnostic and therapeutic options are summarized in the form of algorithms. The aim of this work is to raise an awareness of the possibility of a low-grade infection in patients undergoing spinal revision surgery. MATERIALS AND METHODS: Review of the literature RESULTS: The detection of low-grade infections is difficult from both a clinical and a radiological point of view. In the event of unexplained implant loosening or failure despite the lack of local inflammatory signs and often normal laboratory parameters, a low-grade infection must be considered. Multiple microbiological sampling must be requested as part of the revision surgery. A histological examination is recommended for all revision surgery, especially if a low-grade infection is suspected. The diagnosis should ideally be completed by sonicating the implants with subsequent microbiological incubation of the preserved samples. If a low-grade infection is suspected, the biofilm-covered implant should be removed or replaced if instability/no fusion is present. The use of topical antibiotics could be useful, but its effectiveness in treating low-grade infections has not yet been sufficiently demonstrated. DISCUSSION: An algorithm for clinical decision-making in terms of diagnostic and therapeutic options is suggested.

[Specific intraoperative and secondary complications of biological reconstructions following extralesional tumour resections of malignant bone tumours]. / Operationstypische und sekundäre Komplikationen biologischer Rekonstruktionsverfahren nach extraläsionaler Tumorresektion bei malignen Knochentumoren.

BACKGROUND: The treatment of primary malignant bone tumours is interdisciplinary and individually adapted to the patient. Nowadays, limb salvage surgery is usually possible, and the subsequent reconstruction is carried out either by implantation of modular tumour megaprostheses or by biological reconstruction procedures. Special surgical and secondary complications have to be considered. OBJECTIVES: Indication and explanation of various biological reconstruction procedures and presentation of specific peri- and postoperative complications. MATERIALS AND METHODS: An adapted literature review and the contribution of our own therapy experiences and case studies for the presentation of biological reconstructions and their complication management was performed. RESULTS: In biological reconstructions, autografts, allografts or a combination of autografts and allografts are used. Stabilization is achieved with screw and plate osteosyntheses. The most common secondary complications are pseudarthrosis, interponate fracture, graft necrosis and secondary malpositions. CONCLUSION: In selected cases, particularly at the upper extremities and in dia- or metaphyseal tumour sites, biological reconstruction after extralesional tumor resection is the surgical therapy of choice. The rate of long-term revision interventions is significantly lower compared to modular tumour megaprostheses. Biological reconstructions and the treatment of specific complications have to be performed in specialized centres for musculoskeletal surgical oncology/tumor orthopedics.

[Metastatic breast cancer in the spine : Molecular predictors for choosing adequate treatment strategies]. / Spinale Mammakarzinommetastasen aus Sicht der Wirbelsäulenchirurgie : Prädiktoren auf Molekularebene zur Wahl der adäquaten Therapiestrategie.

Breast cancer is the most common malignancy affecting women and the spinal column is most likely affected by metastases. Modern oncologic treatment options have significantly prolonged survival times in the last decade. Therefore, treatment of vertebral metastases has been of special interest in spine surgery. Different scores are described to evaluate prognosis and to choose correct treatment strategies, which however only differentiate tumor entities and not specific tumor phenotypes. Breast cancer has been classified into five intrinsic subtypes with different survival rates since the turn of the millennium. The aim of this review was to describe molecular predictors of breast cancer malignancy and to better estimate expected survival times and invasiveness of therapies with regard to spinal metastases.

[Diagnostics and treatment of benign spinal tumors]. / Diagnostik und Therapie benigner Tumoren der Wirbelsäule.

Benign tumors of the spine are rare and may lead to unspecific back pain. The classification of the lesion is typically achieved with a combination of imaging techniques (MRI and CT scans) and, in some cases, a histological sampling to allow differentiation from malignant processes. Both open and interventional (CT guided) biopsies are possible, depending on the localization of the tumor. Treatment strategies are diverse, require an interdisciplinary approach, and include operative and interventional procedures. The following article gives an overview of the most important benign tumors of the spine, the typical features in imaging, and treatment strategies.

[Mazabraud and McCune-Albright syndromes in association : A case of two very rare orthopaedic tumour entities]. / Mazabraud- und McCune-Albright-Syndrom in Assoziation : Ein Fall zweier sehr seltener tumororthopädischer Entitäten.

We report on a 47-year-old woman with unilateral fibrous dysplasia and three intramuscular masses. Medical imaging revealed possible intramuscular myxomas, so that the suspected diagnosis was Mazabraud syndrome. After biopsy, the suspected diagnosis was verified by histology and molecular pathology. Due to endocrine abnormalities in the patient's medical history, McCune-Albright syndrome has was also verified.

Structural changes in the thigh muscles following trans-femoral amputation.

INTRODUCTION: Early ambulation is the principal objective in trans-femoral amputees. Postamputation modifications complicate the rehabilitation process due to a reduced control at the interface between stump and prosthesis. The aim of this study is to determine whether magnetic resonance imaging depicts the amount of fatty degeneration of the thigh muscles after trans-femoral amputation (TFA). METHODS: A total of 12 patients following a TFA on the basis of a bone neoplasm or metastasis with an evaluable postoperative MRI were identified. Using the Goutallier classification, the fatty degeneration of the thigh muscles was analyzed in the middle (M) and at the distal end (E) of the residual limb at T1 (10.6 months) and T2 (25.6 months). RESULTS: Analysis at two different levels showed different grades of fatty degeneration of thigh muscles after TFA at T1 and T2. Comparing fatty degeneration at both levels of the stump, the quadriceps femoris revealed a significant change (p = 0.01) at T1 and M. sartorius and adductor (p = 0.02) at T2. CONCLUSIONS: MRI is an excellent diagnostic tool to evaluate fatty degeneration after TFA. The highest amount of fatty degeneration of the quadriceps muscle was monitored within the first 10 months. Early physiotherapy is important to strengthen the remaining stump muscles during rehabilitation.

[Osteoidosteoma. From diagnosis to treatment]. / Osteoidosteom. Von der Diagnose zur Behandlung.

An osteoid osteoma is a benign bone-forming tumor which usually presents in childhood and adolescence and is characterized by extensive nocturnal pain. Computed tomography (CT) is used to reveal the typical radiolucent nidus surrounded by a sclerotic reaction and in magnetic resonance imaging (MRI) a nidal enhancement and perifocal edema can confirm the diagnosis. Having shown excellent success rates radiofrequency ablation has become the treatment of choice which allows minimally invasive and precise destruction of nidal tumor tissue. By using thermal protection techniques and multiple ablation positions successful therapy of perineural tumors and niduses with diameters of more than 2 cm are possible.

[Standards of microbiological diagnostics of spondylodiscitis]. / Standards der mikrobiologische Diagnostik der Spondylodiszitis.

In most cases spondylodiscitis is due to a monomicrobial infection caused by hematogenous dissemination of Staphylococcus aureus. There are, however, many other possible pathogens causing spondylodiscitis and the pathogen responsible can only be identified in approximately 50% of cases. This leads to delayed diagnosis and therapy and an increased morbidity and mortality rate. Failures in planning and performing material recovery are often the reason. As pathogen-specific antimicrobial treatment according to the results of susceptibility testing is the main component of interdisciplinary therapy, all available methods for identification of the pathogen, such as blood cultures, intraoperative and computed tomography (CT) guided biopsies of inflammatory fluids and tissues as well as molecular biological methods should be performed to optimize antimicrobial therapy.

[Radiological diagnostics of spinal tumors. Part 1: general tumor diagnostics and special diagnostics of extradural tumors]. / Radiologische Diagnostik spinaler Tumoren. Teil 1: Allgemeine Tumordiagnostik und spezielle Diagnostik extraduraler Tumoren.

Radiological investigation of spinal tumors includes identification of the suspect lesions as well as their relation to surrounding critical structures, such as nerve roots and the myelon. With the use of computed tomography (CT) the delineation of bone and with magnetic resonance tomography the assessment of bone marrow and soft tissue are possible with high-spatial resolution and multi-planar reconstructions. The consolidation of clinical information, distribution pattern and morphology of the lesion itself results in the final radiological evaluation. Because of low invasiveness and complications, CT-guided biopsy is a common tool in cases of suspected lesions. With the help of multi-planar reconstructions even difficult approaches are possible without impairment of critical structures. This review article discusses typical imaging characteristics of common tumors originating from the vertebral column after a section on basic and general aspects of tumor diagnostics.

[Role and limitations of vertebroplasty and kyphoplasty in the management of spinal metastases]. / Rolle und Grenzen der Vertebro-/Kyphoplastie im Metastasenmanagement der Wirbelsäule.

The spine is the most common site for skeletal metastases. Tumor-induced osteolysis may lead to pain, dysfunction and ultimately vertebral fracture. In some patients conventional surgery is not suitable because of the palliative therapy approach. Just for this patient population it was shown that cement augmentation of the vertebra is an effective therapy option and plays an important role. Nevertheless, cement augmentation of the vertebra has its limitations and should only be applied by appropriate indications.

[Management of spinal metastases, strategies and surgical indications]. / Management der Wirbelsäulenmetastasen, Strategien und operative Indikationen.

The number of bone metastases increases with prolonged survival of primary tumors of kidney, breast, prostate and other tumors. The spine is the most frequent site of bone metastases. This leads to high number of patients where the decision has to be made what kind of treatment should be the best. Several scores have been developed to solve this problem. The decision has to include the biology of the metastatic disease according to primary tumor and dissemination of the disease, the general condition of the patient, the residual stability of the spine, the neurologic status and most important the quality of life of the patient. Treatment options range from conservative treatment up to en bloc resection of the metastatic lesion. Therefore, the strategy of treatment always has to be decided on an individual base.

[Radiofrequency ablation in spinal osteoid osteoma. Options and limits]. / Radiofrequenzablation bei Osteoidosteomen der Wirbelsäule. Möglichkeiten und Grenzen.

Osteoid osteoma was first described by Jaffe in 1935 as a benign bone neoplasm mainly located in the diaphyseal areas of long bones: 10% are located in the spine, mainly in the lumbar and thoracic posterior elements. Therapy is required due to nocturnal pain independent of the physical load and responds especially well to anti-inflammatory drugs due to the excessive production of prostaglandins in the nidus. Diagnosis is confirmed by multi-slice computed tomography (CT), magnetic resonance imaging (MRI) and skeletal scintigraphy scans. In cases with typical symptoms and imaging, open biopsies are rarely needed. Although CT-guided radiofrequency ablation is accepted as the gold standard treatment option for osteoid osteoma in the extremities, this technique is limited in spinal applications due to the risk of thermal damage to adjacent neurovascular structures. Technical advances in the administration of radiofrequency ablation have, however, resulted in new and expanded indications in the spine so that the necessity for open surgical excision of spinal osteoid osteoma is becoming less.

[Gold standard for implant selection in operative therapy of spondylitis/spondylodiscitis]. / Goldstandard bei der Implantatwahl zur operativen Therapie der Spondylitis/Spondylodiszitis.

The operative therapy management of vertebral osteomyelitis including debridement and stabilization is well established. Autologous bone is the preferred graft material but is limited due to availability, failure of consolidation in large defects and donor morbidity. Titanium mesh cages are alternatively equally well evaluated and other materials are also mentioned. Immobilization of affected segments is the fundamental requirement for healing of osteomyelitis. The operative therapy of choice is meticulous debridement and internal stabilization of the defect. Autologous bone seems to provide the best conditions to bridge and consolidate defects. Bone marrow aspirate, reaming irrigator aspiration (RIA) and bone marrow protein (BMP) in combination with cages have the same qualities considering bone healing but they are not yet sufficiently evaluated for management of vertebral osteomyelitis. Autologous bone graft remains the gold standard, nevertheless, its disadvantages point out the need for alternative grafts. Titanium is well proven to provide stability but bone substitutes are not sufficiently evaluated but seem to be promising.

[Pyogenic spondylodiscitis: therapy algorithm and a new classification for therapeutic decision-making]. / Pyogene Spondylodiszitis : Therapiealgorithmus und neue Klassifikation zur therapeutischen Entscheidungsfindung.

The incidence of pyogenic spondylodiscitis is low but has been steadily increasing in recent years. To date there has been no consensus concerning selection of the appropriate treatment, management and strategies and the recommendations for an operative strategy are still a highly controversial issue. In the literature a few statements have been published concerning therapeutic decision-making in pyogenic spondylodiscitis. The classification given in this article is based on clinical experience and retrospective data analysis considering the degree of segmental bony destruction, grade of kyphosis and instability, epidural involvement of the disease and neurological deficits, which are pivotal for therapeutic decision-making. The therapeutic procedure can be defined based on this classification.

[Vertebral stability in management of spinal metastases. Criteria and strategies for operative interventions]. / "Wirbelkörperstabilität" im spinalen Metastasenmanagement. Kriterien und Strategien zur operativen Intervention.

BACKGROUND: Metastases are responsible for most tumor manifestations of the spine. About 25% are symptomatic; however, due to interdisciplinary management the tumor-associated mortality is regressing. Associated acute spinal cord injury (SCI) syndromes raise patient morbidity with a loss of independence and quality of life associated with a fair potential for recovery. Therefore, the management is focused on the avoidance of SCI. The assessment of mechanical stability of vertebral bodies is a central part of decision-making when considering operative therapy. This review gives an update on the current evidence-based data for metastasis management. DECISION MAKING: The NOMS concept is well established. Especially the parameters origin, neurologic symptoms, stability and vascularization are described and illustrated by clinical cases. OPERATIVE THERAPY CONCEPTS: Evidence-based operative therapy concepts are shown reflecting palliative and curative approaches. ASSESSMENT OF PARAMETERS FOR THERAPY ALGORITHM: Clinical and radiological parameters help to find the individual therapy. Generally a number of scores with significant time expenditure are needed. The spine instability neoplastic score (SINS) simplifies the management. Operative therapy shows the best results for the parameters pain and quality of life. However, potential perioperative and postoperative complications have to be estimated and should be avoided. Using these facts our therapy algorithm is helpful for therapy management. CONCLUSIONS: With rising life expectancy operative therapy is of increasing relevance. Decision-making uses information about tumor origin, neurologic symptoms, stability, prognostic factors and vascularisation to determine the individual therapy.