Vaena Michel L H T, Sinnecker João P, Vargas Thiago J S, Serra-Guimarães Fernando, Marques Ruy G
Hospital Universitário Pedro Ernesto, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil.
CBPF - Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro, Brazil.
J Surg Res. 2017 Dec;220:139-146. doi: 10.1016/j.jss.2017.06.081. Epub 2017 Jul 26.
Magnetic subdermal implants have never been studied in the context of magnetic fixation of an external device to the body's surface. Excessive attractive force between the implant and the external device may compromise local circulation due to mechanical compression, leading to necrosis.
To evaluate the feasibility of transcutaneous magnetic fixation and assess secondary skin changes when subjected to a continuous static magnetic field.
Using the pig as an animal model, 72 implants were introduced in 12 animals. After wound healing, ultrasonography was performed to measure implant depths. Computer simulations were applied to allow magnetic attachment between implants and external devices without impairing local blood flow. External devices of different magnetic strengths were applied over the skin for 7 days. Local skin was examined and collected for analysis. A senior dermatopathologist blindly examined skin specimens and controls for abnormal findings, measuring dermal and epidermal thickness. Statistical analysis (P <0.05) was performed over the data.
Nineteen implants presented extrusion. The remaining 53 skin sites underwent magnetic compression, of which 43 (81%) evolved uneventfully. Implant depth varied between 4.6 mm and 8.3 mm (5.8 mm; ± 8.6 mm) with estimated pressure levels between 13.28 mmHg and 37.04 mmHg (27.6 mmHg; ±6.0 mmHg). Stronger magnets were associated with an increase in dermal thickness (P = 0.011) and neovascularization (P = 0.045).
Transcutaneous magnetic fixation is compatible with skin viability in vivo, under experimental conditions. Skin interposition between two permanent magnets resulted in a continuous static magnetic field stimulation, which showed similar effects to pulsed electromagnetic fields reported on scientific literature.
磁性皮下植入物从未在外部装置与身体表面磁固定的背景下进行过研究。植入物与外部装置之间过大的吸引力可能会因机械压迫而损害局部血液循环，导致坏死。
评估经皮磁固定的可行性，并评估在连续静磁场作用下的继发性皮肤变化。
以猪作为动物模型，在12只动物体内植入72个植入物。伤口愈合后，进行超声检查以测量植入物深度。应用计算机模拟使植入物与外部装置之间实现磁附着，同时不损害局部血流。将不同磁场强度的外部装置置于皮肤上7天。检查并收集局部皮肤进行分析。一位资深皮肤病理学家对皮肤标本和对照进行盲法检查，以寻找异常发现，测量真皮和表皮厚度。对数据进行统计学分析（P<0.05）。
19个植入物出现挤出。其余53个皮肤部位受到磁压迫，其中43个（81%）进展顺利。植入物深度在4.6毫米至8.3毫米之间（5.8毫米；±8.6毫米），估计压力水平在13.28毫米汞柱至37.04毫米汞柱之间（27.6毫米汞柱；±6.0毫米汞柱）。更强的磁体与真皮厚度增加（P=0.011）和新生血管形成增加（P=0.045）相关。
在实验条件下，经皮磁固定与体内皮肤活力相容。两个永久磁体之间的皮肤置入导致连续静磁场刺激，其显示出与科学文献中报道的脉冲电磁场相似的效果。
