Role of bone status in anterolateral portion of femoral head in the progression of osteonecrosis of the femoral head / 中国组织工程研究

BACKGROUND:Mechanical stress plays an important role in the progressive collapse in osteonecrosis of the femoral head.Therefore,the bone structure of weight-bearing area may be the risk factor for collapse.OBJECTIVE:To investigate the relationship between the bone preservation of weight-bearing area and collapse progression in necrotic femoral head.METHODS:Eighty-seven patients (102 hips) with ARCO stage Ⅱ osteonecrosis of the femoral head,diagnosed by MRI,were enrolled.All patients underwent a natural progression.Collapse and bone involvement of the weight-bearing area were viewed by anteroposterior and frog-leg lateral radiographs.According to the location of the necrotic lesion on the anterolateral portion of the femoral head,the necrosis was divided into three types:type 1,the posteromedial and central portions;type 2,part of the anterolateral portion;type 3,the entire anterolateral portion.The collapse rate and the time to collapse in different types were assessed.RESULTS AND CONCLUSION:(1) All patients were followed up for 3-58 months.(2) Of the 60 hips with collapse,46 (76.7％) hip collapse was identified on anteroposterior radiograph.On frog-leg lateral radiograph showing collapsed femoral head could be identified in 57 (95.0％) hips,which was significantly different (P ＜ 0.01).(3) In all 102 hips,the collapse rate in type 3 osteonecrosis of the femoral head was significantly higher than that of type 2 osteonecrosis of the femoral head (P ＜ 0.001),and the time to collapse was markedly shortened.None collapse occurred in all six hips with type Ⅰ osteonecrosis of the femoral head during follow-up.(4) In summary,preservation of anterolateral portion is associated with potential collapse progression in necrotic femoral head.

Preservación ósea femoral con tallos cortos de fijación cervicometafisaria. Estudio radiográfico comparativo con tallos no cementados de fijación metafisaria / Femoral bone presevation using short stems with metaphyseal fixation

Introducción: Los tallos no cementados recubiertos con hidroxiapatita de fijación metafisaria han logrado excelentes resultados a largo plazo. La segunda generación de tallos cortos de fijación cervicometafisaria ha surgido a principios de la década de 1990, con el objetivo de preservar capital óseo femoral. Sin embargo, la preservación ósea femoral teóricamente propuesta no ha sido comprobada. El objetivo de este trabajo es determinar radiográficamente la preservación del capital óseo femoral cuando se utilizó un tallo corto de fijación cervicometafisaria, comparando las radiografías posoperatorias con la programación del tallo que se debería haber utilizado en caso de ser un diseño convencional con fijación metafisaria. Materiales y Métodos: Los primeros 50 tallos cortos de fijación cervicometafisaria (MiniHip TM, Corin, Cirencester, Reino Unido) fueron analizados por dos observadores independientes, con radiografías de frente, en cuanto a nivel de resección cervical y longitud del tallo, comparándolos con las filminas de un tallo convencional de fijación metafisodiafisaria (MetaFix TM, Corin, Cirencester, Reino Unido). Resultados: Según el análisis radiográfico, los tallos cortos de fijación cervicometafisaria ocuparon una longitud femoral promedio de 79 mm (rango 68-102). Los tallos convencionales de fijación metafisaria hubiesen ocupado, en promedio, 73 mm más que los tallos cortos (rango 47-94). Esta distribución se observó en el corte de cuello (promedio 10 mm más distal) y en la longitud del implante (promedio 66 mm mayor longitud) (p <0,001). Esta diferencia permite preservar un 42% el capital óseo femoral. Conclusión: La preservación ósea relacionada con el uso de tallos cortos de fijación cervicometafisaria podría traer beneficios a largo plazo en pacientes jóvenes con alta demanda funcional.

Background: Uncemented hydroxyapatite-coated stems with methaphyseal fixation have demonstrated excellent long-term results. Second generation of short stems has been developed in the 90’s with the purpose to preserve femoral bone at the femoral neck and diaphysis. However, the amount of bone that would be theoretically saved has not been well-established. To radiographically determine femoral bone preservation in a series of patients operated on with a short, neck preserving stem, we compared these results with the length of a templated conventional length, uncemented hydroxyapatite-coated stem. Methods: The first 50 short hydroxyapatite-coated uncemented stems (MiniHip TM, Corin, Cirencester, UK) were radiographically analyzed by two independent observers measuring the level of neck cut and the stem length. Then, these results were compared with the level of neck cut and stem length when a conventional, metaphysodiaphyseal stem (MetaFix TM, Corin, Cirencester, UK) was implanted using templates. Results: According to the radiographic results, short stems measured an average length of 79 mm (range 68-102). Conventional stems would have required 78 mm (range 47-94) more bone for fixation than short stems. This difference was observed in the neck cut (average 10 mm more distal with a conventional stems), as well as in the diaphysis (average 66 mm more distal with a conventional stems) (p <0.001). Conclusion: Femoral bone preservation may be related to long-term benefits especially in young patients.

Crestal bone preservation: A review of different approaches for successful implant therapy.

The level of bone crest surrounding the implant is of utmost significance to determine osseointegrated implant success, as preservation of marginal bone height is highly important for long-term dental implant survival. Various approaches have been described in the literature to prevent the crestal bone loss, including platform switching, non-submerged approach, scalloped implants, implant design modifications, progressive loading, immediate implant placement, etc. The purpose of this paper is to review all the possible methods to preserve the crestal bone, when each method should be used and their success rates in an attempt to address this complex problem of crestal bone resorption. "PubMed" and "Google Scholar" were used to find out any studies involving platform switching concept from 1990 up to 2009. Twenty-four studies involving methods for preservation of crestal bone were evaluated, which included 26% studies on platform switching, 22% on non-submerged approach, 17% on scalloped implants, 13% on progressive loading and 22% on immediate implant placement. Crestal bone preservation should be thought of starting from the design of the implant to be placed. The technique to be followed in a given case will depend upon the density of bone, force factors by the patient, bone volume and amount of soft tissues, etc. The best possible method or the combination of the methods should be used to preserve the crestal bone for the long-term success of the implants.

Técnica de conservación de huesos en peróxido de hidrógeno / Técnica de conservación de huesos en peróxido de hidrógeno

Se presenta la Osteotecnia en peróxido de hidrógeno y ácido acético como una herramienta para la conservacón de material óseo para fines docentes en colegios y universidades o de exhibición en museos o instituciones afines. Esta técnica de conservación de material óseo permite además rescatar piezas y estructuras óseas de difícil adquisición. Es un método rápido y muy baja toxicidad, fácil de aplicar y de un costo relativamente bajo en comparación con otros descritos en la literatura.

An Osteotechnique is presented on hidrogen peroxide and acetic acid as a tool for the conservation of bone material with teaching purposes on high schools and colleges, museum exhibitions or similar institutions. This bone preservation technique allowds to rescue pieces and bone structures that are difficult to adquire. It`s a simple and low toxicity method, easy to apply and with relatively low cost compared to other techniques described on the literature.

Variação da força de resistência à micro-tração de fragmentos de ossos corticais preservados em diversos meios e a fresco: estudo experimental em coelhos / Variation of the resistance force to the micro-traction of fragments of cortical bones preserved in several means and fresh: Experimental study in rabbits

Devido ao crescente uso dos aloenxertos nas cirurgias ortopédicas, há a necessidade do conhecimento de suas características biomecânicas ao longo do tempo de preservação. O presente trabalho consistiu na análise da força de resistência à micro-tração de amostras de ossos corticais de coelho preservadas em diversos meios por até 180 dias e a fresco. Os resultados revelaram que a resistência e o tempo de preservação apresentaram uma relação inversamente proporcional, significando que, quanto maior o tempo de preservação, menor a resistência física avaliada no ensaio biomecânico de resistência à micro-tração. Dos meios utilizados, a glicerina apresentou menores valores quanto ao teste de resistência, demonstrando, após 30 dias de preservação, apenas 24,58 por cento da força presente no osso a fresco e, aos 180 dias, 1,76 por cento. As amostras submetidas à autoclavagem também demonstraram baixos valores ao final do experimento, quando permaneceram com apenas 12,31 por cento da força presente no osso a fresco. Os ossos preservados em plasma homólogo, líquido de dakin e aqueles criopreservados apresentaram os melhores índices de resistência ao final do experimento, permanecendo, respectivamente, com 82,47; 70,34 e 66,72 por cento da força máxima quando comparados com a resistência dos ossos frescos. Concluiu-se que a escolha do método e o tempo de preservação interferiu diretamente na biomecânica dos ossos corticais, promovendo a diminuição da capacidade de resistência à tração ao longo do período de preservação.

Due to the increasing use of cortical bone allografts in orthopedic surgeries, de knowledge of its biomechanics characteristics during preservation time is needed. The present study consisted in the analyses of the resistance power to the micro-traction of samples of rabbit cortical bones preserved in several means for up to 180 days and fresh. The results showed that the resistance and the preservation time presented an inversely proportional relation, meaning that, the longer the time of preservation, the shorter the physical resistance evaluated in the biomechanical rehearsal of resistance to the micro-traction. The glycerin has presented lower values in relation to the resistance test, showing, after 30 days, only 24.58 percent of the present power in the fresh bone, and by 180 days, 1.76 percent. The samples submitted to autoclavation also showed low values by the end of the experiment, while they remained with just 12.31 percent of the power present in the fresh bone. The bones preserved in homologous plasma, Dakin liquid and the ones cryopreserved showed the best levels of resistance at the end of the experiment, remaining, respectively with 82.47, 70.34 and 66.72 percent of the maximum power, while compared with the resistance of the fresh bones. The conclusion is that the choice of methodology and time of preservation interfered directly in the biomechanics of the cortical bones, promoting decrease of the resistance capacity to the traction along the period of preservation.

The little master-results of proxima hip replacement / 中国矫形外科杂志

[Objective] Total hip replacement has given good results in the elderly population but with an increasing number of younger patients requiring hip replacement,soft tissue and bone preservation has become important.Studies have shown that a more natural loading of the proximal femur leads to preservation of bone stock and aids remodeling.Proxima hip was developed keeping these requirements in mind.[Methods] Twenty nine Proxima hip replacements were performed on twenty one patients between July 2006 and March 2008 by the senior author.The average age of the patients at the time of surgery was 44 years.Eight of the patients had bilateral hip replacement in the same sitting.The implant used was a Proxima stem with a large diameter metal on metal XL head.Particular care was taken in preserving the full length of femoral neck and the trechanteric muscles.The patients were assessed by Harris hip acore,return to normal and advanced hip functions and satisfaction levels.All patients were followed up with serial X rays and clinical examination.[Results] Average duration of follow up was 1 year.The mean Harris hip score pre surgery was 48 and at last follow up was 88.All patients at 3 to 4 months achieved full weight bearing.One patient had an intra-operation fracture of the lateral cortex which recovered without any sequelae.Another patient had persistent thigh pain without any apparent cause and a poor result.One stem was revised because of aseptic loosening after 9 months.None of the hips showed any sign of acetabular cup loosening or migration.[Conclusions] Early results in this young group of patients are very encouraging.This small implant relies on the preserved neck and the lateral flare for its stability,ensuring a more natural loading of the proximal femur and preserving bone stock and facilitating remodeling.As our results show the Proxima stem as an implant that stands the test of biomechanics and holds a promising future.