"Do-not-touch" lesions of bone revisited.

Incidental bone lesions are encountered frequently in day-to-day practice. Many of these lesions are indeterminate requiring referral to specialist centres for further characterisation with or without biopsy; however, as biopsy has its own drawbacks, not all lesions can be subjected to biopsy. The primary role of a radiologist in these situations is to characterise these lesions based on their imaging appearances into aggressive lesions requiring biopsy and non-aggressive lesions that do not require a biopsy. The term "do-not-touch lesion" is used to describe a lesion with typical radiographic appearances that can be characterised based on radiographic appearances alone without needing a biopsy. With recent advances in imaging, many incidental lesions can be characterised into do-not-touch lesions based on their imaging appearances alone using a single imaging technique or using a combination of imaging techniques and, less frequently, with the additional help of serological investigations, without the need for biopsy. Hence, the definition of do-not-touch lesions of bone needs a revisit. In this article, we attempt to redefine do-not-touch lesions of bone and propose an imaging-based classification for characterisation of these lesions.

Management and retrospective analysis of tumors and tumor-like lesions localized in the talus.

OBJECTIVES: This study aims to investigate the characterization and follow-up results of tumors and tumor-like lesions in the talus. PATIENTS AND METHODS: Twenty-one patients (15 males, 6 females; mean age: 31.6±17 years; range, 4 to 67 years) with benign and malignant tumors or tumor-like lesions in the talus region treated and followed in our clinic between January 2007 and January 2019 were evaluated retrospectively. Radiological, pathological, surgical, and demographic features were scanned from the database. RESULTS: Patients were followed for mean 80±45.1 (range, 25 to 156) months. The most common complaint was pain and antalgic gait. Benign bone tumors were found in 15 (71%) of 21 patients, while tumor-like lesions (two intraosseous ganglia, osteomyelitis, and bone infarction) were found in four patients. The remaining two were patients with lung and bladder cancer metastasis. Lesion size was mean 2.1±0.5 (range, 1.1 to 3.3) cm. Recurrence developed in 14.3% (n=3) of the patients during follow-up. CONCLUSION: The talus is a rare location for tumors; however, benign and malignant tumors and tumor-like lesions may be localized in the talus.

No dejemos morir al hueso: interiorizándonos con los procesos óseos avasculares / Do not let the Bone Die: Interiorizing with the avascular Bone Processes

Resumen El objetivo de este artículo es realizar una revisión de las localizaciones, causas y hallazgos radiológicos específicos de los procesos avasculares óseos. Se define como isquemia ósea a las alteraciones ocasionadas por déficit de irrigación, llevando a la destrucción del hueso. Existen diferencias entre necrosis isquémica e infarto óseo, en base al sitio óseo de afectación. La etiología traumática es la más frecuente y suele ser unilateral. Los sitios de presentación más frecuentes son: cabeza femoral y humeral, rodilla y semilunar. La resonancia magnética (RM) es considerada la modalidad de imagen más sensible y específica, tanto para el diagnóstico temprano como estadificación y control. El conocimiento de las causas, características radiológicas y sus diferentes fases evitan el diagnóstico erróneo de otras etiologías, como las primarias o infecciosas, facilitando un correcto algoritmo terapéutico.

Abstract The aim of this article is to review the locations, causes and specific radiological findings of avascular bone processes. Bone ischemia is defined as the alterations caused by irrigation deficit, leading into the bone destruction. However, there are differences between ischemic necrosis and bone infarction, based on the bone site of involvement. The most frequent etiology is traumatic and is usually unilateral. The most frequent sites of presentation are: femoral and humeral head, knee, and lunate. Magnetic resonance imaging (MRI) is considered the most sensitive and specific imaging modality for early diagnosis, staging and control. The knowledge of the causes, radiological findings and their different phases avoid the erroneous diagnosis of other lesions, such as primary or infectious, facilitating a correct therapeutic algorithm.

Acetabular defects in revision hip arthroplasty: a therapy-oriented classification.

INTRODUCTION: The treatment of severe acetabular bone loss remains a difficult challenge. No classification system is available that combines intuitive use, structured design and offers a therapeutic recommendation according to the current literature and modern state of the art treatment options. The goal of this study is to introduce an intuitive, reproducible and reliable guideline for the evaluation and treatment of acetabular defects. METHODS: The proposed Acetabular Defect Classification (ADC) is based on the integrity of the acetabular rim and supporting structures. It consists of 4 main types of defects ascending in severity and subdivisions narrowing down-defect location. Type 1 presents an intact acetabular rim, type 2 includes a noncontained defect of the acetabular rim ≤ 10 mm, in type 3 the rim defect exceeds 10 mm and type 4 includes different kinds of pelvic discontinuity. A collective of 207 preoperative radiographs were graded according to ADC and correlated with intraoperative findings. Additionally, a randomized sample of 80 patients was graded according to ADC by 5 observers to account for inter- and intra-rater reliability. RESULTS: We evaluated the agreement of preoperative, radiographic grading and intraoperative findings presenting with a k value of 0.74. Interobserver agreement presented with a k value of 0.62 and intraobserver at a k value of 0.78. CONCLUSION: The ADC offers an intuitive, reliable and reproducible classification system. It guides the surgeon pre- and intraoperatively through a complex field of practice.

What Is the Reliability of a New Classification for Bone Defects in Revision TKA Based on Preoperative Radiographs?

BACKGROUND: Accurate quantification of bone loss facilitates preoperative planning and standardization for research purposes in patients who undergo revision TKA. The most commonly used classification to rate bone defects in this setting, the Anderson Orthopaedic Research Institute classification, does not quantify diaphyseal bone loss and reliability has not been well studied. QUESTIONS/PURPOSES: We developed a new classification scheme to rate bone defects in patients undergoing revision TKA and tested (1) the intraobserver and interobserver reliability of this classification for revision TKA based on preoperative radiographs, and (2) whether additional CT images might improve interobserver reliability. METHODS: This was a preregistered observational study. Interobserver reliability was analyzed using preoperative radiographs of 61 patients who underwent (repeat) revision TKA, and their bone defects were rated by five experienced orthopaedic surgeons. For intraobserver reliability, ratings were repeated at least 2 weeks after the first rating (Timepoints 1 and 2). Directly after the radiographic assessments of Timepoint 2, the observers were provided with CT images of each patient and asked to rate the bone defects for a third time (Timepoint 3), to assess the additional value of CT. Intraobserver and interobserver reliability were tested using Gwet's agreement coefficient 2, which is a measure of agreement between observers in categorical data. Substantial agreement was defined as coefficients between 0.61 to 0.8 and almost perfect agreement as > 0.8. RESULTS: The intraobserver reliability varied between 0.55 (95% CI 0.40 to 0.71) and 0.87 (95% CI 0.78 to 0.96) in the epiphysis, between 0.69 (95% CI 0.58 to 0.80) and 0.98 (95% CI 0.95 to 1) in the metaphysis, and between 0.95 (95% CI 0.90 to 0.99) and 0.99 (95% CI 0.98 to 1) in the diaphysis. The interobserver reliability varied between 0.48 (95% CI 0.39 to 0.57) and 0.49 (95% CI 0.42 to 0.56) in the epiphysis and between 0.81 (95% CI 0.75 to 0.87) and 0.88 (95% CI 0.83 to 0.93) in the metaphysis, and was 0.96 (95% CI 0.93 to 0.99) in the diaphysis at Timepoint 1. The interobserver reliability at Timepoint 2 was similar to that of Timepoint 1. The addition of CT images did not improve reliability (Timepoint 3). CONCLUSIONS: The bone defect classification was less reliable in the epiphyseal area compared with the metaphysis and diaphysis. This finding may be explained by prosthetic components obscuring this region or the more severe bone defects in this region. The addition of CT scans did not improve reliability. Further testing of reliability with observers from other institutions is necessary, as well as validity testing, by testing the classification in relation to intraoperative findings. LEVEL OF EVIDENCE: Level III, diagnostic study.

Finally, a step forward in nomenclature of subchondral nonneoplastic bone lesions.

This paper is a commentary on the article entitled "Nomenclature of Subchondral Nonneoplastic Bone.Lesions1" by Gorbachova, Amber, Beckmann, Bennett, Chang, Davis, Gonzalez, Hansford, Howe, Lenchik, Winalski, and Bredella. The purpose of this commentary is to provide an orthopaedic perspective on the aforementioned article and critique their analysis and proposal regarding nomenclature of subchondral bone lesions. It provides an overview and a section by section evaluation of a well-designed and executed article.

Nomenclature of Subchondral Nonneoplastic Bone Lesions.

OBJECTIVE. The purpose of this article is to summarize the nomenclature of nonneoplastic conditions affecting subchondral bone through a review of the medical literature and expert opinion of the Society of Skeletal Radiology Subchondral Bone Nomenclature Committee. CONCLUSION. This consensus statement summarizes current understanding of the pathophysiologic characteristics and imaging findings of subchondral nonneoplastic bone lesions and proposes nomenclature to improve effective communication across clinical specialties and help avoid diagnostic errors that could affect patient care.

Mendelian bone fragility disorders.

Mendelian bone fragility disorders are caused by genetic variants that can be inherited in an autosomal dominant, autosomal recessive or X-linked manner and have a large detrimental effect on bone strength. As a rule, the more damaging the genetic defect is, the earlier the first fracture will occur, typically during bone development. This review focusses on conditions where bone fragility is the most conspicuous characteristic, of which osteogenesis imperfecta (OI) is the best-known disorder. The large majority of individuals with an OI phenotype have disease-causing dominant variants in COL1A1 or COL1A2, the genes coding for collagen type I. Interestingly, large sequencing databases indicate that there are about 10 times more carriers of COL1A1/COL1A2 variants that should lead to OI than there are individuals with a diagnosis of OI. It is possible that at least some of these variants lead to incomplete OI phenotypes and are diagnosed as osteoporosis during adulthood. Apart from mutations affecting collagen type I production, biallelic mutations in LRP5 and WNT1 can cause very rare and severe bone fragility disorders. Heterozygous pathogenic variants in these genes are much more common and can cause the clinical picture of primary osteoporosis. As sequencing studies are more widely performed in adults with bone fragility disorders, evidence is emerging that what appears as primary osteoporosis in fact can be due to mutations in bona fide OI genes. The distinction between OI and primary osteoporosis is therefore likely to blur in future.

A new classification for proximal femur bone defects in conservative hip arthroplasty revisions.

INTRODUCTION: In last three decades, total hip replacement in young patients became an habitual procedure. Principles of bone preservation are pushing many surgeons to implant conservative femoral components in patient younger than 65 years. Despite an overall good survivorship and clinical outcomes of conservative implants, failed cases are reported and the need to revise a conservative femoral component became an occasional procedure (with high prevalence of failed resurfacing implants). METHODS: During conservative femoral component revisions, we analyzed proximal bone stock preservation, considering the type of original component removed, aetiology of failure, timing of revision, and femoral explantation technique. RESULTS: We identified four patterns of proximal femoral changes (types I-IV). We suggest, for each of them, a revision strategy directed toward a "conservative revision procedure" using conservative or primary component. Out of our 21 cases, none underwent further revision due to mechanical failure (follow-up ranging from 6 to 152 months, mean 54 months). We had two cases of re-operation: one for early septic loosening and one for prosthetic modular neck fracture. CONCLUSIONS: If literature offers well-established guidelines to femoral revision of conventional stems, there is, on the other hand, a lack of data about revision strategies in presence of failed conservative implants. Although the mean follow-up of our procedures is still too short (4.5 years) to give final conclusions, we would leave a message: a conservative hip arthroplasty is not a "one time" opportunity for young and active people. A "conservative revision" is a valid option for at least a part of them, when an early failure of primary procedure occurred.

A new classification for proximal femur bone defects in conservative hip arthroplasty revisions.

INTRODUCTION: In the last three decades, total hip replacement in young patient became a habitual procedure. Principles of bone preservation are pushing many surgeons to implant conservative femoral components in patient younger than 65 years. Despite an overall good survivorship and clinical outcomes of conservative implants, failed cases are reported and the need to revise a conservative femoral component became an occasional procedure (with high prevalence of failed resurfacing implants). METHODS: During conservative femoral component revisions, we analyzed proximal bone stock preservation, considering the type of original component removed, etiology of failure, timing of revision, and femoral explantation technique. RESULTS: We identified four patterns of proximal femoral changes (types I-IV). We suggest, for each of them, a revision strategy directed toward a "conservative revision procedure" using conservative or primary component. Out of our 21 cases, none underwent further revision due to mechanical failure (follow-up ranging from 6 to 152 months, mean 54 months). We had two case of re-operation: one for early septic loosening and one for prosthetic modular neck fracture. CONCLUSIONS: If literature offers well-established guidelines to femoral revision of conventional stems, there is, on the other hand, a lack of data about revision strategies in presence of failed conservative implants. Although the mean follow-up of our procedures is still too short (4.5 years) to give final conclusions, we would leave a message: a conservative hip arthroplasty is not a "one-time" opportunity for young and active people. A "conservative revision" is a valid option for at least a part of them, when an early failure of primary procedure occurred.

Bone quality evaluation of experimental osteometabolic disease in Pantanal alligators (Caiman yacare) by High Resolution Computerized Microtomography (µCT) / Avaliação da qualidade óssea de doença osteometabólica experimental em jacarés do pantanal (Caiman yacare) por Microtomografia Computadorizada (µCT)

Computerized microtomography is the gold standard examination for the evaluation of the three-dimensional bone structure. This experiment was developed to evaluate the structure and bone quality of Caiman yacare with metabolic bone disease using high resolution computerized microtomography (μCT). The animals were distributed into four groups: G1 - hyperphosphatemic diet with sun exposure deprivation (n=4), G2 - hyperphosphatemic diet with sun exposure (n=4), G3 - balanced diet with sun exposure deprivation (n=4), and G4 - balanced diet with exposure to sunlight (n=4). The parameters for the trabecular bone (Trabecular Number, Trabecular Thickness, Trabecular Separation, Bone Pattern Factor, Fractal Dimension, Euler Number, Structural Model Index, Degree of Anisotropy, Eigenvalues 1, 2 and 3, and Centroides X, Y and Z), and cortical bone (Number of Closed Pores, Volume of Closed Pores, Surface of Closed Pores, Closed Porosity, Volume of Open Pores, Open Porosity and Total Porosity). The overall results showed that the structure and bone quality of group G3 and G4 were better than those of groups G1 and G2, and that the diet factor influenced more than the sun exposure factor. The computerized microtomography allowed to evaluate the quality of the cortical and trabecular bones of the Pantanal alligator tibia with osteometabolic disease. The diet and sun exposure factors influenced individually the results of the μCT parameters between the groups, demonstrating the functional and structural complexity. Thus, these parameters can contribute to the interpretation of the mechanical behavior of bones and correlate them with the risk of lesions and fractures associated with osteometabolic diseases.(AU)

Microtomografia computadorizada é o exame padrão-ouro para a avaliação da estrutura tridimensional do osso. Este estudo experimental foi desenvolvido para avaliar a estrutura e a qualidade óssea de jacarés-do-pantanal (Caiman yacare) com doença óssea metabólica utilizando a microtomografia computadorizada (μCT) de Alta Resolução. Os animais foram distribuídos em quatro grupos, G1 - dieta hiperfosfatêmica com privação de luz solar (n=4), G2 - dieta hiperfosfatêmica com exposição à luz solar (n=4), G3 - dieta balanceada com privação de luz solar (n=4) e G4 - dieta balanceada com exposição à luz solar (n=4). Avaliaram-se os parâmetros para o osso trabecular (Número de Trabéculas, Espessura Trabecular, Separação Trabecular, Fator do Padrão Ósseo, Dimensão Fractal, Número de Euler, Índice do Modelo Estrutural, Grau de Anisotropia, Autovalores 1, 2 e 3 e Centroides X, Y e Z) e osso cortical (Número de Poros Fechados, Volume dos Poros Fechados, Superfície de Poros Fechados, Porosidade Fechada, Volume de Poros Abertos, Porosidade Aberta e Porosidade Total). Os resultados gerais evidenciaram que a estrutura e a qualidade óssea dos grupos G3 e G4 foram superiores aos dos grupos G1 e G2, sendo que o fator dieta influenciou mais do que o fator exposição solar. A Microtomografia Computadorizada permitiu avaliar a qualidade dos ossos cortical e trabecular da tíbia de jacarés do pantanal com doença osteometabólica. Os fatores dieta e exposição solar influenciaram individualmente no resultado dos parâmetros do μCT entre os grupos, demonstrando a complexidade funcional e estrutural. Assim, esses parâmetros podem contribuir na interpretação do comportamento mecânico dos ossos e correlacioná-los com o risco de lesões e fraturas associadas às doenças osteometabólicas.(AU)

Caracterización de pacientes con enfermedades genéticas del esqueleto en un centro colombiano de remisión / Characterization of patients with skeletal genetic diseases in a Colombian referral center

RESUMEN Introducción. La prevalencia de talla baja en Colombia es de 10 %, aproximadamente. En el 2009, la International Skeletal Dysplasia Society incluyó 456 condiciones clínicas en su clasificación, con base en criterios bioquímicos, radiológicos y moleculares para su diagnóstico. Objetivo. Analizar las variables demográficas, epidemiológicas y clínicas en un grupo de pacientes con enfermedades genéticas del esqueleto, remitidos al Instituto de Ortopedia Infantil Roosevelt. Materiales y métodos. Se analizaron pacientes remitidos entre el 2008 y el 2014, con 167 diagnósticos relacionados con enfermedades genéticas del esqueleto según la Clasificación Internacional de Enfermedades, versión 2010 (CIE-10). Se exploraron las variables demográficas, epidemiológicas y clínicas empleando estadística descriptiva. Se generó una puntuación para las intervenciones que contempló las combinaciones de tratamientos, y se analizaron las variables mediante la prueba t de Student. Resultados. El motivo de consulta más frecuente fue por sospecha de enfermedad genética del esqueleto. Entre los tipos de tratamiento, se consideraron los de soporte, los quirúrgicos, el farmacológico y la 'ortesis', y se pudo establecer que los pacientes con enfermedades genéticas del esqueleto obtenían puntajes mayores en la variable de intervención y menores en las de talla alta y baja. Conclusiones. El diagnóstico de la mayoría de los pacientes remitidos respondía a enfermedades genéticas del esqueleto, talla baja y otras enfermedades genéticas monogénicas. Se encontraron diferencias significativas entre la edad de inicio de los síntomas y la de diagnóstico, así como diversos enfoques terapéuticos. Hubo menos intervenciones en los pacientes con talla alta y baja, lo cual podría alertar sobre la necesidad de reevaluar las necesidades terapéuticas de este grupo.

ABSTRACT Introduction: Short height in Colombia has an estimated prevalence of 10%. The 2009 Nosology and Classification of Skeletal Genetic Diseases described 456 clinical conditions using biochemical, molecular and radiological criteria for diagnosis. Objective: To analyze demographic, epidemiological and clinical variables in a group of patients with skeletal genetic diseases referred to the Instituto de Ortopedia Infantil Roosevelt. Materials and methods: Patients referred between 2008 and 2014 were analyzed filtering 167 diagnoses of the International Classification of Diseases, 10th revision (ICD 10), related to skeletal genetic diseases. Demographic, epidemiological and clinical variables were explored using descriptive statistics. An intervention score was generated contemplating different combinations of treatments. An inferential statistical analysis using Student's t test was performed on such variables. Results: The most frequent reason for consultation was suspicion of a genetic skeletal disorder. The types of treatments considered included support, surgical, pharmacological and orthotics, and it was established that genetic skeletal disorders were associated with higher intervention scores while tall and short height showed a lower score. Conclusions: Most referred patients were classified with genetic bone diseases, short stature and other monogenic genetic diseases. Significant differences were found between the age at symptoms onset and the age of diagnosis. Diversity was found in the therapeutic approach among different groups of pathologies. Patients with tall and short height showed lower intervention scores, which may warn on the need to reassess the therapeutic requirements of these groups.

[Characterization of patients with skeletal genetic diseases in a Colombian referral center].

INTRODUCTION: Short height in Colombia has an estimated prevalence of 10%. The 2009 Nosology and Classification of Skeletal Genetic Diseases described 456 clinical conditions using biochemical, molecular and radiological criteria for diagnosis. OBJECTIVE: To analyze demographic, epidemiological and clinical variables in a group of patients with skeletal genetic diseases referred to the Instituto de Ortopedia Infantil Roosevelt. MATERIALS AND METHODS: Patients referred between 2008 and 2014 were analyzed filtering 167 diagnoses of the International Classification of Diseases, 10th revision (ICD 10), related to skeletal genetic diseases. Demographic, epidemiological and clinical variables were explored using descriptive statistics. An intervention score was generated contemplating different combinations of treatments. An inferential statistical analysis using Student's t test was performed on such variables. RESULTS: The most frequent reason for consultation was suspicion of a genetic skeletal disorder. The types of treatments considered included support, surgical, pharmacological and orthotics, and it was established that genetic skeletal disorders were associated with higher intervention scores while tall and short height showed a lower score. CONCLUSIONS: Most referred patients were classified with genetic bone diseases, short stature and other monogenic genetic diseases. Significant differences were found between the age at symptoms onset and the age of diagnosis. Diversity was found in the therapeutic approach among different groups of pathologies. Patients with tall and short height showed lower intervention scores, which may warn on the need to reassess the therapeutic requirements of these groups.

[Benign tumours and tumour-like lesions of the bone : General treatment principles]. / Benigne Tumoren und tumorähnliche Läsionen des Knochens : Allgemeine Behandlungsprinzipien.

BACKGROUND: Benign bone lesions are much more common than malignant lesions. Some benign bone tumors have a characteristic and typical radiographic appearance, while others are more challenging. Therapy of benign bone tumors differs greatly. While the majority of benign bone tumors do not require surgical therapy, other specific lesions, e. g. aneurysmal bone cysts or giant cell tumors (GCT) of the bone require surgery due to their locally aggressive behavior. DIAGNOSTICS: The major challenge for the radiologist and/or pathologist is the differentiation between a benign and low-grade malignant lesion (e. g. enchondroma versus low-grade chondrosarcoma) for which all available clinical and radiographic information is mandatory. Therefore, surgical therapy is rather more often performed than necessary due to uncertainty in many cases. THERAPY: Novel systemic therapies are available for fibrous dysplasia and GCT of the bone: Fibrous dysplasia can be treated with bisphosphonates, and GCT responds to denosumab. In fact, denosumab has been approved for the treatment of irresectable GCT. Osteoid osteoma is fairly easy to recognize and also to treat given the characteristic clinical presentation and rapid and effective response to local therapy (possible as percutaneous thermo-/laser ablation). In summary, several therapeutic options exist for benign bone tumors, and the choice depends upon the tendency/risk of local recurrence, the rate of surgical complications, options for defect reconstruction, postoperative functional deficits, and specific patient characteristics.

The Diagnosis and Initial Treatment of Patellofemoral Disorders.

Our purpose is to provide simple guidelines for the diagnosis and early care of patellofemoral disorders. Any clinician who treats knee problems, including family practitioners, rheumatologists, orthopedic surgeons, or physical therapists, must know how to make the correct diagnosis, or at least a presumptive diagnosis, at the initial visit. This can avoid unneeded and costly tests, ineffective treatment, and even damaging exercises and unnecessary surgery. The diagnosis of patellofemoral disorders is confusing because they can have many causes. That is, the etiology of patellofemoral disorders is multifactorial. To dispel this confusion and simplify the process, we use a clinical classification based on etiology. Within that framework are 7 key abnormalities or factors that can cause both patellofemoral pain and instability: vastus medialis obliquus deficiency, medial patellofemoral ligament laxity, lateral retinaculum tightness, increased quadriceps angle, hip abductor weakness, patella alta, and trochlear dysplasia. At the initial evaluation, the clinician can assess for these abnormalities through history-taking, physical examination, and standard radiography. Any abnormalities identified, along with their severity, can be used to arrive at a diagnosis, or a presumptive diagnosis, and begin early nonoperative treatment. The clinician does not need magnetic resonance imaging at this point, unless a presumptive diagnosis cannot be made or a more complex problem is suggested.

Interobserver Variability in the Differential Diagnosis of Benign Bone Tumors and Tumor-like Lesions.

PURPOSE: The interobserver-variability of radiological diagnosis of benign bone tumors (BBT) and tumor-like lesions (TLL) was examined in order to identify difficult-to-diagnose entities, to examine the frequency of advanced diagnostics and to describe the number of interdisciplinary tumor center diagnoses (IDT) in comparison with diagnoses upon referral (ED) and radiologists´ diagnoses (RD). MATERIALS AND METHODS: We retrospectively reviewed 413 patients with 272 BBT and 141 TLL, classified either histologically or through interdisciplinary consultation. Discrepancies between groups were analyzed and rates of additional imaging and biopsy to establish diagnosis were assessed. RESULTS: In BBT the number of identical radiological diagnoses was 56 (ED) and 81 % (RD) compared to the IDT, while in the latter additional imaging were obtained in 30 % cases. In 21 % (12 % to establish diagnosis) BBT were biopsied, the ED matching the histology 40 %, the RD 60 % and the IDT 76 % of the time. For TLL diagnosed through radiology, ED and RD matched IDT 31 % and 61 % of the time, with additional imaging being obtained in 21 % of cases (IDT). In 36 % (27 % to establish diagnosis) biopsy was performed, with histological diagnosis matching the IDT, RD and ED in 51, 27 and 20 %. Diagnostic challenges were apparent in enchondromas, non-ossifying fibromas (NOF), solitary (SBC) and aneurysmal bone cysts (ABC). Ganglia can be misinterpreted as a tumor. CONCLUSIONS: Establishing a definitive diagnosis for BBT and TLL can be challenging with the latter posing greater difficulties. An interdisciplinary approach involving radiologists, orthopedics and pathologists was found to improve diagnostic accuracy. KEY POINTS: • Benign bone tumors (BBT) and tumor-like lesions (TLL) present a diagnostic challenge, while enchondroma, NOF, SBC and ABC were difficult to diagnose, and ganglia can be misinterpreted as a tumor• Additional imaging studies were required for diagnosis in 29 % and 21 % of cases for BBT and TLL, respectively, biopsies in 12 % of cases for BBT and 27 % for TLL• Sound diagnoses can be made through interdisciplinary case discussion, while reducing the risk of overtreatment Citation Format: • Scheitza P, Uhl M, Hauschild O et al. Interobserver Variability in the Differential Diagnosis of Benign Bone Tumors and Tumor-like Lesions. Fortschr Röntgenstr 2016; 188: 479 - 487.

Nosology and classification of genetic skeletal disorders: 2015 revision.

The purpose of the nosology is to serve as a "master" list of the genetic disorders of the skeleton to facilitate diagnosis and to help delineate variant or newly recognized conditions. This is the 9th edition of the nosology and in comparison with its predecessor there are fewer conditions but many new genes. In previous editions, diagnoses that were phenotypically indistinguishable but genetically heterogenous were listed separately but we felt this was an unnecessary distinction. Thus the overall number of disorders has decreased from 456 to 436 but the number of groups has increased to 42 and the number of genes to 364. The nosology may become increasingly important today and tomorrow in the era of big data when the question for the geneticist is often whether a mutation identified by next generation sequencing technology in a particular gene can explain the clinical and radiological phenotype of their patient. This can be particularly difficult to answer conclusively in the prenatal setting. Personalized medicine emphasizes the importance of tailoring diagnosis and therapy to the individual but for our patients with rare skeletal disorders, the importance of tapping into a resource where genetic data can be centralized and made available should not be forgotten or underestimated. The nosology can also serve as a reference for the creation of locus-specific databases that are expected to help in delineating genotype-phenotype correlations and to harbor the information that will be gained by combining clinical observations and next generation sequencing results.

Does bony increased-offset reverse shoulder arthroplasty decrease scapular notching?

BACKGROUND: The purpose of this cohort study was to compare scapular notching rates, range of motion, and functional outcomes between patients who underwent a standard Grammont-style reverse shoulder arthroplasty (RSA) and patients who underwent bony increased-offset reverse shoulder arthroplasty (BIO-RSA) at a minimum of 2 years' follow-up. We hypothesized that the BIO-RSA cohort would have lower notching rates and improved rotational range of motion; however, validated outcome scores between cohorts would be no different. METHODS: A comparative cohort study was designed after a sample size calculation. A total of 40 patients were studied with 20 in each cohort (RSA vs BIO-RSA). All patients underwent an interview and physical examination. Outcomes included range of motion; shoulder strength; Disabilities of the Arm, Shoulder and Hand (DASH) score; American Shoulder and Elbow Surgeons score; Simple Shoulder Test score; Constant score; and Global Rating of Change scale score. Radiographs were obtained for all patients and examined for scapular notching. RESULTS: When we compared demographic characteristics between the standard RSA and BIO-RSA cohorts, including age, sex, and follow-up duration, there were no significant differences between groups (P > .05). In addition, there were no significant differences between cohorts when we compared forward elevation (P = .418); external rotation (P = .999); internal rotation (P = .071); strength (P > .376); Disabilities of the Arm, Shoulder and Hand score (P = .229); American Shoulder and Elbow Surgeons score (P = .579); Simple Shoulder Test score (P = .522); Constant score (P = .917); or Global Rating of Change scale score (P = .167). The frequency of scapular notching, however, was significantly higher (P = .022) in the RSA cohort than in the BIO-RSA cohort: 75% versus 40%. CONCLUSIONS: Although the scapular notching rate was significantly higher in the standard RSA group, no other outcome measures were statistically different, including range of motion, strength, and validated outcome scores.