Osteonecrosis of the Femoral Head: Update Article / Osteonecrose da cabeça femoral: Artigo de atualização

Abstract Among the pathologies that affect the hip joint, osteonecrosis of the femoral head (ONFH) is probably the most intriguing and challenging. It consists of a multifactorial disease with a highly-variable spectrum in its clinical presentation. It has a devastating effect, due to disabling painful conditions, both for usual activities and sports. Given the huge range of risk factors, such as prolonged use of corticosteroids (especially in cases of rheumatologic diseases), trauma sequelae, sickle cell anemia, HIV, alcoholism, smoking, blood dyscrasias, and several other diseases that compromise the blood supply to the femoral head, ONFH has a varied clinical presentation and prognosis, which makes it difficult to determine a specific treatment, especially in cases in which chondral involvement has not yet occurred and the hip joint is still preserved. These are the main factors found in the literature that determine the classifications of this pathology. The range of treatments includes several options for cases in which an attempt is made to save the joint: conservative treatment, traditional decompression and/or combined with some type of adjuvant treatment (homologous grafting, synthetic grafting, vascularized grafts, tantalum screws, and bone marrow aspirate injection), and, for cases in which there is already a subchondral fracture and/or collapse of the femoral head and/or a reduction in the joint space, femoral osteotomies or total hip arthroplasty are commonly performed.

Resumo Entre as patologias que acometem a articulação coxofemoral, a osteonecrose da cabeça femoral (ONCF) é provavelmente a mais intrigante e desafiadora. Consiste em uma doença multifatorial, com um espectro muito variável em sua apresentação clínica. Tem efeito devastador, devido a quadros dolorosos incapacitantes tanto para atividades habituais quanto esportivas. Dada a gama enorme de fatores de risco, tais como uso prolongado de corticoides (principalmente em casos de doenças reumatológicas), sequelas de trauma, anemia falciforme, HIV, etilismo, tabagismo, discrasias sanguíneas, e várias outras doenças que comprometem a irrigação sanguínea da cabeça femoral, a ONCF tem apresentação clínica e prognósticos bem variados, o que dificulta a determinação de um tratamento específico, especialmente em casos nos quais ainda não houve acometimento condral e a articulação do quadril ainda se mantém preservada, sendo estes os principais fatores encontrados na literatura que determinam as classificações desta patologia. No leque de tratamentos, encontramos diversas opções para os casos em que setenta salvar a articulação: tratamento conservador, descompressão simples e/ou associada a algum tipo de tratamento adjuvante (enxertia homóloga, enxertia sintética, enxertos vascularizados, parafusos de tântalo, e injeção de aspirado de medula óssea), e, para casos nos quais já há fratura subcondral e/ou colapso da cabeça femoral e/ou diminuição do espaço articular, reserva-se, comumente, a realização de osteotomias femorais ou artroplastia total do quadril.

Análisis experimental del desgaste entre UHMWPE y acero inoxidable 316l empleados en la manufactura de prótesis coxofemorales / Experimental wear analysis of UHMWPE and stainless 316l used in the manufacturing of coxofemoral prosthesis

La causa más común de falla en prótesis coxofemorales es el aflojamiento entre los componentes que conforman el sistema, de manera específica la copa acetabular y la cabeza femoral. En esta investigación se presenta un análisis tribológico del desgaste en los componentes mencionados, ya que cuando las superficies en contacto se desgastan, la funcionalidad mecánica del sistema se compromete, debido al cambio de geometría de los mismos, dando como resultado un juego mecánico entre la copa y la cabeza. Los materiales considerados en este estudio son el polietileno de ultra elevado peso molecular (UHMWPE, por sus siglas en inglés) para la copa acetabular, y acero inoxidable 316L para la cabeza femoral. Esta combinación de materiales representa hoy en día la recomendación más usual por parte de los cirujanos para pacientes de la tercera edad. La tasa anual de desgaste se determinó de manera experimental y se cuantificó la cantidad de material desprendido durante el contacto. Se establecieron las condiciones de carga de forma analítica, considerando las que actúan sobre la cabeza femoral a lo largo del área de desgaste durante la marcha humana. Posteriormente, se realizó el análisis experimental de desgaste utilizando una máquina tribológica de configuración perno-sobre-disco (pin-on-disk), diseñada de manera específica para este estudio. Las pruebas para determinar la pérdida volumétrica de los componentes se realizaron bajo tres condiciones de operación: en seco, lubricada con agua destilada y lubricada con suero bovino. El marco experimental considerado consistió en pernos de UHMWPE sobre discos de acero inoxidable 316l simulando el desgaste equivalente a diez años de uso de la prótesis. Finalmente, de los resultados obtenidos se puede establecer que el desgaste y la cantidad de partículas desprendidas disminuyen considerablemente cuando se utiliza suero bovino como lubricante para replicar las condiciones reales de operación del sistema...

The most common cause of failure in coxofemoral prostheses is the loosening between the components of the system, namely the acetabular cup and the femoral head. In this work a tribologic analysis of wear suffered in the components is presented, due to when the surfaces in contact are worn, the mechanical function of the system is compromised as the wearing implies a change in the geometry of the components, thus in their dimensions, resulting on a looseness between the cup and the head. The materials considered in this study are Ultra High Molecular Weight Polyethylene (UHMWPE) for the cup and 316L Stainless Steel for the femoral head, which represent the surgeons choice for elderly patients. The annual wearing rate between these components was experimentally determined, as well as the amount of debris produced during contact. Firstly, the loading conditions were determined analytically considering those acting on the femoral head taking into consideration the wearing area during human walk. Secondly, the experimental analysis consisted in wearing tests using a tribology pin-on-disk machine, specifically built for this study. The tests to determine the volumetric loss of the components were performed under three different operational conditions: dry, lubricated with bovine serum and lubricated with destilated water. The experimental set up consisted on UHMWPE pins and 316L Stainless steel discs simulating the equivalent wear of ten years of usage of the prostheses. Lastly, the obtained results proved that using the bovine serum as lubricant the wear and debris of the components was significantly reduced when compared with other cases, being the dry scenario where more damage was produced. It is important to point out that the bovine serum was chosen to simulate the synovial fluid in which the system is embedded.

Anatomía de la cabeza femoral humana: consideraciones en ortopedia, Parte I: anatomía y relaciones antropométricas del fémur proximal / Anatomy of the human femoral head: orthopedic issues, Part I: proximal femur anatomy and anthropometric measures

Las variantes antropométricas son aspectos que han servido como sustento científico para el entendimiento de la vasta patología que afecta a la articulación coxofemoral y para el desarrollo tanto de implantes de reemplazo articular como de técnicas de reconstrucción ósea. En esta revisión se planea exponer los aspectos morfológicos macroscópicos de la cabeza femoral en relación al extremo proximal del fémur, para describir las características anatómicas y funcionales que hacen de ésta, uno de los sitios anatómicos de mayor importancia en la cirugía ortopédica.

The femoral head macroscopic and anthropometric anatomical variations are issues that have been used as scientific support for the understanding of the pathology which affects the hip joint and for the development of joint replacement implants and bone reconstruction techniques. The aim of this review is to expose the morphological macroscopic characteristics of the femoral head in relation to the proximal femur, in order to describe the functional and anatomical characteristics, which have made of this structure one of the most important anatomical areas in orthopedic surgery.

Femoral head-neck junction deformity is related to osteoarthritis of the hip.

BACKGROUND: Primary or idiopathic osteoarthritis (OA) of the hip has increasingly been attributed to the presence of presumably minor femoral or acetabular deformities that are not routinely identified. The alpha angle reflects one such deformity of the femoral neck and reflects a risk for femoroacetabular impingement, which in turn reportedly is associated with OA. If impingement is in fact associated with OA, then one might expect the mean alpha angle to be greater in patients with presumed idiopathic hip OA. QUESTIONS/PURPOSES: We therefore compared the alpha angle among a group of elderly patients with idiopathic OA with that in a control group of elderly individuals without OA. PATIENTS AND METHODS: We measured the alpha angles in 50 individuals (72 hips) with a mean age of 70 years (range, 60-84 years) with apparently idiopathic OA and compared their angles with those from a control group of 56 individuals without OA. The alpha angle was measured by means of radiographs of their hips using the Dunn view at 45 degrees flexion. RESULTS: The patients with OA had a greater percentage with abnormal alpha angles than did the normal subjects: 82% versus 30%, respectively. The mean alpha angle in the group with OA was larger than in the control subjects: 66.4 masculine (range, 28 degrees -108 degrees ) versus 48.1 masculine (range, 34 degrees -68 degrees ). CONCLUSIONS: Hips with presumably idiopathic OA had more abnormalities at the femoral head-neck junction than did the control hips without OA and may relate to the risk of OA developing. LEVEL OF EVIDENCE: Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Importância do diagnóstico da fratura subcondral da cabeça do fêmur, suas diferenças com a necrose avascular e seu tratamento / The importance of the diagnosis of subchondral fracture of the femoral head, how to differentiate it from avascular necrosis and how to treat it

A fratura subcondral da cabeça femoral é afecção pouco conhecida e, consequentemente, pouco diagnosticada. O quadro clínico de dor aguda ou insidiosa com piora progressiva na região inguinal, exacerbada com carga e com alívio em repouso, deve levar à suspeita diagnóstica. O erro comumente feito com o diagnóstico de necrose avascular da cabeça do fêmur pode induzir a indicação de procedimentos invasivos desnecessários no quadril. Com o advento da ressonância nuclear magnética, o diagnóstico dessa afecção pode ser realizado observando os diferentes padrões de edema medular na cabeça do fêmur, possibilitando o tratamento precoce correto.

Subchondral fracture of the femoral head is an uncommon and underdiagnosed affection. The abrupt or gradual onset of groin pain with functional disability on weight-bearing that improves with a resting period should alert the orthopedic surgeon to the possibility of this diagnosis. The differential diagnosis from osteonecrosis of the femoral head can be provided by assessing the different patterns of bone edema on MRI studies of the hip, thus avoiding unnecessary invasive operations on the hip.

Koilonychia, dome-shaped epiphyses, and vertebral platyspondylia.

A 2.5-year-old girl presented with koilonychia since birth and was subsequently found to have dome-shaped femoral epiphyses and platyspondylia with anterior central tongues on a skeletal survey.

Deficiência focal proximal femoral (DFPF) / Proximal focal femoral deficiency

Os autores fazem uma revisäo dos aspectos radiológicos encontrados em exames de dois pacientes com deficiência focal proximal do fêmur (DFPE). A DFPF é uma anomalia congênita rara, caracterizada por ausência parcial da estremidade proximal do fêmur, e necessita de classificaçäo radiológica precoce para planejamento e tratamento cirúrgico adequados. Vários esquemas de classificaçäo têm sido propostos com base na relaçäo anatômica entre o acetábulo e o fêmur proximal. Säo discutidos o sistema Aitken e a classificaçäo de Amstutz