Long-Term Mechanical Property Prediction of the Proximal Tibia after Knee Arthroplasty / 医用生物力学

Objective To study the short-term variation patterns of graft viscosity after anterior cruciate ligament reconstruction (ACLR) surgery. Methods Six male New Zealand rabbits were selected. The ACLR animal model of unilateral knee was made with Achilles tendon as the graft. The experimental rabbits were euthanized 15 days after ACLR surgery, with removal of the graft, healthy anterior cruciate ligament (ACL) and Achilles tendon. The cross-sectional area and viscosity coefficient of the graft were measured, and the creep experiments were carried out under equilibrium conditions of 0.1 MPa and 1 MPa, respectively. The viscosity coefficent was calculated. Variation patterns of graft viscosity were summarize. The grafts were compared with healthy ACL. Results The cross-sectional area of the graft increased slowly within 15 days after ACLR surgery. The viscosity of ACL and graft changed nonlinearly. The viscosity coefficient was quite different under different stresses. The viscosity coefficient of the graft decreased with the time after ACLR surgery, which was more obviously under the condition of low stress. Conclusions The results are helpful to guide the implementation of early postoperative rehabilitation plan after ACLR surgery .

Intercellular mediators in bone remodeling regulation in the experimental renal pathology / Mediadores intercelulares de la regulación de la remodelación ósea en un modelo experimental de patología renal

Bone metabolism disorders are characterized by an imbalance of bone resorption and formation in the bone remodeling process. Glucocorticoids that are used to treat kidney diseases exacerbate these disorders. P-selectin and galectin-3 are molecules involved in the sclerotic process in kidney, whereas bone resorption is regulated by the interaction between the nuclear factor activator kappa b receptor (RANK), its ligand (RANKL) and the RANKL decoy receptor osteoprotegerin (OPG). The aim of this study was to investigate the cellular and molecular mechanisms of disruption of bone remodeling regulation processes, reflected by intercellular mediators (RANKL, OPG, P-selectin and galectin-3) in chronic kidney disease experimental model treated with glucocorticoids. Rats were divided into four groups of 10 animals each. The first group, the control group, included intact animals. The second group consisted of rats with impaired bone remodeling resulting from chronic kidney disease (experimental group (CKD). The third group was a group of animals with impaired bone remodeling due to exposure to glucocorticoids (experimental group (GCs)). The fourth group consisted of rats with impaired bone remodeling in chronic kidney disease, followed by exposure to glucocorticoids (experimental group (CKD + GCs)). The effects of CKD and glucocorticoid were evaluated biochemically, histologically and by measuring bone density. An enzymelinked immunoassay was used to measure intercellular mediator levels in the serum. The bone density in the experimental groups was reduced compared to the control group. RANKL levels in animals of three experimental groups were higher than in intact animals. Serum levels of OPG were higher in CKD and GCs groups than in intact animals. At the same time, in the animals' blood serum of the CKD + GCs group, the levels of OPG were lower, than those in animals from the control group. The levels of galectin-3 in the serum of the experimental groups GCs and CKD + GCs were lower than in intact animals. The serum levels of galectin-3 in animals of the CKD group were higher than those in animals from the control group. The levels of P-selectin were lower in the serum of the GCs group than in intact animals. At the same time, the levels of P-selectin were higher in the CKD and CKD + GCs groups, than those in animals from the control group. In conclusion, the study of the complex system of bone remodeling regulation, which includes many factors and their interactions, may lead to the development of new methods for treating patients with chronic kidney disease in order to prevent osteoporosis in the future. (AU)

Las enfermedades metabólicas óseas se caracterizan por un desequilibrio en el proceso de remodelación ósea en los que participan mediadores tales como receptor del activador del factor nuclear- kappa- b (RANK), su ligando (RANKL) y la osteoprotegerina (OPG). Los glucocorticoides, recuentemente empleados en el tratamiento de la enfermedad renal crónica, exacerban este desequilibrio. En la enfermedad esclerótica renal, las moléculas de adhesión celular P-selectina and galectina-3 tienen un rol fundamental. El objetivo de esta trabajo fue estudiar las alteraciones en los mediadores de la remodelación ósea (RANKL, OPG, P-selectina and galectina-3) en un modelo de enfermedad renal crónica con tratamiento glucocorticoideo. Ratas Wistar hembras fueron divididos en 4 grupos: control (C); enfermedad renal crónica con afección de la remodelación ósea (ERC); animales con afección de la remodelación ósea expuestos a glucocorticoides (GC); enfermedad renal crónica con afección de la remodelación ósea tratados con glucocorticoides (ERC+GC). Los efectos de la ERC y los GC fueron evaluados bioquímicamente, histológicamente y por medición de la densidad ósea. RANKL, OPG, Pselectina and galectina-3 se cuantificaron en muestras de sangre venosa empleando enzimoinmuno análisis. En los 3 grupos experimentales la densidad ósea se evidenció reducida y los niveles séricos de RANKL elevados respecto al grupo control. Los niveles de OPG en los grupos ERC y GC fueron superiores mientras que en el grupo ERC+GC menores respecto a los animales controles. Galectina 3 plasmática en GC y ERC+GC se encontró reducida y aumentada en los animales ERC, en comparación con los animales controles. La concentración sérica de P-selectina sérica fue mayor en los grupos ERC y ERC+GC, y menor en los animales GC respecto a los niveles plasmáticos de los animales intactos. El avance del conocimiento sobre la regulación de la remodelación ósea a través de la interacción de mediadores sistémicos, en un futuro, puede conducir al desarrollo de nuevas estrategias terapéuticas para la prevención de la osteoporosis en pacientes con enfermedad renal crónica. (AU)

Resposta tecidual à corticotomia alveolar seletiva após verticalização ortodôntica acelerada de molares inferiores em pacientes adultos / Tissue response to selective alveolar corticotomy after speedy orthodontics in uprighting lower molars in adult patients

O objetivo deste trabalho foi analisar e descrever histologicamente, o processo de remodelação óssea no momento da cirurgia e 90 dias após, em regiões submetidas ou não à corticotomia alveolar seletiva. Foram avaliados 8 pacientes adultos sem distinção de classe de maloclusão, e com necessidade de verticalização dos segundos molares inferiores bilateralmente. Neste estudo aleatório boca-dividida, a verticalização dos molares inferiores e coleta de osso mandibular aconteceu bilateralmente, enquanto que a corticotomia unilateralmente. As extrações dos blocos ósseos foram obtidas através de uma broca trefina acoplada ao contra ângulo, as peças continham aproximadamente 6 mm de osso cortical e trabecular, e foram armazenadas em formol tamponado a 10% até a data de envio ao laboratório do Instituto Forsyth (Boston, EUA). Após 90 dias da cirurgia, novas biopsias ósseas foram extraídas do segmento mandibular teste e controle. As avaliações histológicas foram realizadas no grupo teste e controle em dois momentos distintos: no momento da corticotomia (T0), e 90 dias após (T90). Os blocos ósseos foram corados com hematoxilina e eosina (HE) para análise descritiva das peças. A coloração com tricrômico de Masson (TM) foi utilizada com o intuito de identificar neoformação óssea e colágeno no tecido conjuntivo mineralizado e não mineralizado. Para descrição da remodelação óssea foram analisadas as seguintes características celulares: proporção entre os componentes de osso secundário e primário, quantificação do número de osteócitos, proporção entre os componentes inorgânicos e orgânicos do osso, e quantificação do número de linhas reversas. Os resultados foram comparados por meio do modelo de estimativa de equações generalizadas (GEE) clusterizado, ajustando pelas medidas basais. O grupo teste em T90 apresentou aumento de 0,16% na proporção de osso primário (p<0,001), aumento de 6,54 na quantidade de osteócitos (p=0,039), e aumento de 4,06 na quantidade de linhas reversas de remodelação óssea (p=0,924). Ambos os grupos apresentaram queda na proporção inorgânica, com um diminuição de 0,02% e 0,03% nos grupos teste e controle, respectivamente (p=0,105). Os dados sugerem que o processo de reabsorção óssea alveolar desencadeado pela corticotomia seja parcialmente revertido em 90 dias, pois foi possível observar características de formação e deposição óssea. O dano ósseo intencional realizado em pacientes adultos tratados ortodônticamente, pode ser considerado temporário e reversível, e as condições ósseas iniciais são restabelecidas.

The aim of this study was to analize and describe histological findings of bone remodeling at the time of surgery and 90 days later, at corticotomized and non-corticotomized sites. This randomized split mouth study included 8 adult patients, with bilaterally inclined mandibular molars, regardless their malocclusion type. A one-stage intervention was performed to corticotomize the test site, and harvest bone in both mandibular hemi-arches. Bone blocks were harvested using a trephine bur in a low speed hand piece. The specimens of aproximatelly 6 mm were stored in 10% buffered formalin at room temperature, until dispatch to Forsyth Institute lab (Boston, USA). After surgery, cantilevers were activated to upright inclined mandibular molars on both sides. Approximately 90 days post-surgery, new bone blocks were harvested from test and control sites located in the mandible. Histological analysis were performed in the control and test group at two time points: baseline (T0) and, ninety days post-surgery (T90). Bone blocks were stained with Hematoxylin & Eosin for descriptive analysis. Masson's trichrome staining protocol was used to identify new bone formation and collagen in mineralized and non-mineralized connective tissue. The following items were investigated to describe bone turnover: (1) ratio between secondary and primary bone, (2) ratio between inorganic and organic bone, (3) quantity of osteocytes and, (4) reversal lines of bone remodeling.The histologic analysis results were compared using clustered Generalized Estimating Equations (GEE) model, adjusted by baseline measures. The test group at T90 presented: increase of 0.16% in ratio of primary bone (p<0.001), increase of 6.54 in the quantity of osteocytes (p=0.039), and increase of 4.06 in the quantity of reversal lines (p=0.924). Both groups presented decay in inorganic proportions, with a decrease of 0.02% and 0.03% in test and control group, respectively (p=0.105). Data suggest that bone turnover provoked by corticotomy, might be partially reverted in 90 days, through bone formation and deposition. The intentional bone injury performed in adult patients undergoing orthodontic treatment, can be considered temporary and reversible, there is evidence to indicate baseline bone characteristics are restored.

Saucerização: um mecanismo natural de adaptação peri-implantar cervical / Saucerization: a natural mechanism of peri-implant cervical adaptation

A Saucerização Óssea Peri-implantar Cervical, ou simplesmente Saucerização, deve ser considerada uma adaptação morfológica e funcional dos tecidos cervicais peri-implantares. O homem conseguiu imitar a natureza, e os implantes osseointegráveis simulam o dente: parte dentro do meio interno e parte no meio externo. O epitélio juncional peri-implantar leva o EGF próximo ao osso vizinho, que se reabsorve de forma inclinada. Esse processo é inevitável e independe do design, tipo ou marca comercial dos implantes osseointegráveis. Tridimensionalmente, o formato final do osso cervical peri-implantar imita um pires e pode sofrer influências de fatores cirúrgicos, bem como do tipo ósseo, designs, carga oclusal, tempo de uso, grau de higienização e muitos outros fatores. Porém, negar o processo implica em ignorar alguns aspectos da biopatologia óssea. Todos os 206 ossos humanos são arredondados e suas funções não permitem ângulos retos em suas margens e limites.

Cervical periimplant bone saucerization, or simply saucerization, should be considered a morphological and functional adaptation of peri-implant cervical tissues. Humans were able to mimic nature. Osseointegrated implants imitate natural teeth: half inside the alveolar bone and half in the oral environment. Peri-implant junctional epithelium takes the epidermal growth factor near neighboring bones which is reabsorbed in an inclined manner. his process is unavoidable and occurs regardless of implant design, type and commercial brand. hree-dimensionally, peri-implant cervical bone resembles a saucer and might be afected by surgery, the type of bone, implant design, occlusal load, time of use, sanitization and several other factors. Nevertheless, denying the process means ignoring some features of bone biopathology. All 206 human bones are round-shaped and, for this reason, do not allow straight angles at their borders and limits.

The early results of total hip replacement with a proximally hydroxyapatite-coated femoral component / 中华创伤骨科杂志

Objective To summarize the early results of total hip replacement with a proximally hydroxyapatite-coated femoral component. Methods From February 2000 to October 2003, 65 cases (70 hips) underwent uncemented total hip replacement with a proximally hydroxyapatite-coated femoral component (U2, United Orthopedic Corporation, Taiwan, China). The diagnosis included femoral neck fractures in 30 cases, osteoarthritis in 15 cases, avascular necrosis of the femoral head in 9 cases, loosening of artificial femoral head in 8 cases, rheumatoid arthritis in 2 cases, and arthrodesis in 1 case. Clinical and radiographic evaluations were performed at 1 week, 3 and 6 months postoperatively, and yearly afterwards. Bone mineral density (BMD) of the proximal femur was measured with dual-energy X-ray Absorptiometry (DEXA) for 44 cases. Results Postoperative X-ray films showed that the initial fixation was excellent or good in all the stems. The follow-ups averaged 3 years (2 to 5.5 years). The mean preoperative Harris hip score was 32 (25 to 52) points, which were improved to 96 points at the latest follow-ups. There was no reported incidence of thigh pain at any time throughout our study. And no case needed revision. By the measurements on the X-ray films taken within 1 year postoperatively, 7 of the 70 stems had subsidence of less than 1.5 mm. No hip experienced extensive proximal end osteolysis, intramedullary osteolysis, or loosening. DEXA showed that the BMD values decreased after operation, and then returned rapidly to the normal or near normal ones 3 to 6 months after operation, especially in zones Ⅱand Ⅵwhere the increase was even more significant than at the control side. All the stems were radiographically stable with evidence of osseous ingrowth typically seen in HA-coated zones, according to the criteria proposed by Engh et al. Conclusions Since HA-coating on femoral implants can enhance the initial fixation of implants, accelerate bone ingrowth and osseous fixation of the femoral component, and seal the interface between the implant and bone to prevent ingress of polyethylene particles, it is helpful in improving clinical results of the cementless total hip replacement.