Structural interaction between bone and implants due to arthroplasty of the first metatarsophalangeal joint.

BACKGROUND: Currently, the metatarsophalangeal joint replacement through a restorative arthroplasty, where implants are used, is a viable invasive surgical medical procedure in the treatment of severe cases of osteoarthritis in this joint, better known as hallux rigidus. However, few things are known about the postoperative complications that implants can cause on the joint, like Swanson and Tornier implants.Research in this field can provide a valuable information that would help the specialist surgeon in the decision-making during the selection of the more suitable joint implant in each patient, as well as the redesign of the devices, to make them more efficient, durable and biocompatible with the human body. METHODS: The aim of this work is to perform a structural biomechanical analysis of a restorative arthroplasty of the first metatarsophalangeal joint, and to analyze the interaction between bone and medical grade silicone implants. For that, a simulation of a foot with Swanson and Tornier joint implants were performed to evaluate the stress/strain distribution during a critical stage (toe-off). RESULTS AND CONCLUSIONS: Principal stresses obtained for the first metatarsal with both implants suggest that failure is induced in this bone because, values exceed (up to 136.84% for Swanson model) the tensile strength reported for phalange trabecular bone, which may be related to osteolysis. Stress and strain values obtained in this work suggest that arthroplasty surgery with Swanson implant is more likely to cause postoperative complications versus Tornier implant.

Effect of sterilization on 3-point dynamic response to in vitro bending of an Mg implant.

BACKGROUND: The aim of the study is to characterize a biomedical magnesium alloy and highlighting the loss of mechanical integrity due to the sterilization method. Ideally, when using these alloys is to delay the onset of degradation so that the implant can support body loads and avoid toxicological effects due to the release of metal ions into the body. METHODS: Standardized procedures according to ASTM F-1264 and ISO-10993-5 were used, respecting detailed methodological controls to ensure accuracy and reproducibility of the results, this testing methodology is carried out in accordance with the monographs of the Pharmacopoeia for the approval of medical devices and obtaining a health registration. An intramedullary implant (IIM) manufactured in magnesium (Mg) WE43 can support loads of the body in the initial period of bone consolidation without compromising the integrity of the fractured area. A system with these characteristics would improve morbidity and health costs by avoiding secondary surgical interventions. RESULTS: As a property, the fatigue resistance of Mg in aggressive environments such as the body environment undergoes progressive degradation, however, the autoclave sterilization method drastically affects fatigue resistance, as demonstrated in tests carried out under in vitro conditions. Coupled with this phenomenon, the relatively poor biocompatibility of Mg WE43 alloys has limited applications where they can be used due to low acceptance rates from agencies such as the FDA. However, Mg alloy with elements such as yttrium and rare earth elements (REEs) have been shown to delay biodegradation depending on the method of sterilization and the physiological solution used. With different sterilization techniques, it may be possible to keep toxicological effects to a minimum while still ensuring a balance between the integrity of fractured bone and implant degradation time. Therefore, the evaluation of fatigue resistance of WE43 specimens sterilized and tested in immersion conditions (enriched Hank's solution) and according to ASTM F-1264, along with the morphological, crystallinity, and biocompatibility characterization of the WE43 alloy allows for a comprehensive evaluation of the mechanical and biological properties of WE43. CONCLUSIONS: These results will support decision-making to generate a change in the current perspective of biomaterials utilized in medical devices (MDs), to be considered by manufacturers and health regulatory agencies. An implant manufactured in WE43 alloy can be used as an intramedullary implant, considering keeping elements such as yttrium-REEs below as specified in its designation and with the help of a coating that allows increasing the life of the implant in vivo.

Bio-inspired biomaterial Mg-Zn-Ca: a review of the main mechanical and biological properties of Mg-based alloys.

The toxicity of alloying elements in magnesium alloys used for biomedical purposes is an interesting and innovative subject, due to the great technological advances that would result from their application in medical devices (MDs) in traumatology. Recently promising results have been published regarding the rates of degradation and mechanical integrity that can support Mg alloys; this has led to an interest in understanding the toxicological features of these emerging biomaterials. The growing interest of different segments of the MD market has increased the determination of different research groups to clarify the behavior of alloying elements in vivo. This review covers the influence of the alloying elements on the body, the toxicity of the elements in Mg-Zn-Ca, as well as the mechanical properties, degradation, processes of obtaining the alloy, medical approaches and future perspectives on the use of the Mg in the manufacture of MDs for various medical applications.

Follow-up care of women with an abnormal cytology in a low-resource setting.

STUDY PURPOSE: We ascertained the follow-up care after an abnormal cytology (Papanicolaou) screening in the San Marti;n region of Perú and assessed the status of women who had not received adequate care. BASIC PROCEDURES: We identified women with an abnormal cytology and assessed their medical records, laboratory registries, death certificates and interviewed them at home. Re-screening, diagnosis and treatment were offered. MAIN FINDINGS: Only 46 (25%) of the 183 women identified received appropriate follow-up care. At re-screening 31 (34%) had a normal result, 9 (10%) were diagnosed with CIN1 and 50 (56%) had CIN2 or worse. PRINCIPAL CONCLUSIONS: In this setting, follow-up care after an abnormal cytology was very poor and could explain the lack of impact of cervical cancer screening. Women with an abnormal cytology constitute a high-risk group that should be a priority for health services.

Efecto antimicrobiano de la Óleo-resina de Copaifera officinalis sobre principales cepas bacterianas periodontópatogenas de la cavidad bucal / Antimicrobial effect of Copaifera officinalis oil-resin on major periodontopathogenic bacterial strains of the oral cavity

La fitoterapia busca alternativas de solución a enfermedades bucales, con hierbas medicinales, como productos económicos y prácticos.La Copaifera es uno de los géneros de plantas medicinales más importantes en la región amazónica y Brasil y puede tener efecto antimicrobiano sobre las principales bacterias causantes de la enfermedad gingival y periodontal. Objetivo: Determinar el efecto antimicrobiano de la óleo-resina de Copaifera officinalis sobre las principales cepas bacterianas periodontopatógenas (ATCC) Porphyromona gingivalis y Fusobacterium nucleatum a diversas concentraciones. Material y método: Se empleó la técnica de dilución en agar que permite hallar la concentración inhibitoria mínima. Se emplearon cepas ATCC de Porphyromona gingivalis y Fusobacterium nucleatum y la óleo-resina de Copaifera officinalis a 10 concentraciones: 100%, 50%, 25%, 12.5%, 6.25%, 3.12%, 1.56%, 0.78%. 0.39%, 0.19%. Se empleó la clorhexidina al 0.12% como control positivo, al agar schaedler puro y Tween 80 como controles negativos. Se emplearon 13 placas y se duplicó el ensayo. Resultados: La concentración inhibitoria mínima para Porphyromona gingivalis corresponde a 1.56%. Asimismo, la concentración inhibitoria mínima para el Fusobacterium nucleatum corresponde a 50% de óleo-resina.La clorhexidina mostró mayor efectividad al tener efecto a una menor concentración. Conclusiones:La óleo-resina de Copaifera officinalis presentó efecto antimicrobiano frente a la cepa ATCC de Porphyromona gingivalis y Fusobacterium nucleatum, siendo el primero más sensible a su acción y el segundo más resistente.