1,721,078 research outputs found

    First-year experience with MICA technique: learning difficulties, mistakes, and results

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    BACKGROUND: Hallux valgus is a very common forefoot disorder, first named by Carl Hueter (1871) as a condition with a static subluxation of the first metatarsophalangeal joint with lateral deviation of the great toe and medial deviation of the first metatarsal. It usually leads to pain and functional impairment of the foot. With the continuous evolution of technology and the idea to shift open Austin Akin osteotomy to MIS surgery, more recently Redfern and Vernois developed the Minimally Invasive Chevron Akin (MICA) technique. The use of this technique has been vastly studied by the authors, but to our knowledge there is a scarce literature production by independent authors reporting their experience in the use of this technique. The aim of the present study was to show our preliminary results in the use of MICA technique performed by the same surgeon during his first year of use, underlining the learning difficulties, mistakes and results achieved during this frame of time. METHODS: The MICA procedure was performed on 60 feet from July 2018 to July 2019. A follow-up of at least 11 months was achieved. The clinical outcome was measured through AOFAS Score. RESULTS: The mean patients age was 51.5 years old (range: from 36 to 72 years old). The mean AOFAS Score was 90.4, interestingly 24 patients (40% of the total of 60 patients) had AOFAS Score set over 90. CONCLUSIONS: MICA osteotomy marries percutaneous surgery with the Austin Akin osteotomy, that have been and are widely used for the treatment of hallux valgus. It is possible to achieve the good results of a well know surgery with a stable fixation and obtain all the goals of percutaneous surgery, such has limited pain, good postoperative range of motion and an overall positive experience of the patient. The learning curve, if the surgeon is correctly instructed, is steep, but the results are good since the first procedures. On the other hand, the complications/surgical errors reported are limited, easily resolvable and do not impact the overall positive results. (Cite this article as: Marcolli D, Pichierri I, Minoli C, Mazzotti A, Compagnoni R, Randelli PS. First-year experience with MICA technique: learning difficulties, mistakes, and results. Minerva Orthop 2024;75:7-13. DOI: 10.23736/S2784-8469.23.04330-4

    Intermediate Alkali–Alumino-silicate Aqueous Solutions Released by Deeply Subducted Continental Crust: Fluid Evolution in UHP OH-rich Topaz–Kyanite Quartzites from Donghai (Sulu, China)

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    Minerals, fluid inclusions and stable isotopes have been studied in ultrahigh-pressure (UHP) OH-rich topaz^kyanite quartzites from Hushan (west of Dongai), in southern Sulu (China). The quartzites underwent a metamorphic evolution characterized by a peak stage (35 GPa and 730^8208C) with the anhydrous assemblage coesiteþkyanite I, followed by an early near-isothermal decompression stage (29GPa and 705^7808C) with growth of kyanite II, muscovite, and OH-rich topaz, and by decompressioncooling stages, represented by paragonite (19 GPa and 700^7808C) and pyrophyllite (03GPa and 4008C) on kyanite (I and II) and OH-rich topaz, respectively.These rocks may exhibit unusually low d18O and dD values acquired before undergoing UHP metamorphism. Five distinct fluid generations are recognized.Type I: concentrated peak solutions rich in Si, Al, and alkalis, present within multiphase inclusions in kyanite I. Type II: CaCl2-rich brines present during the growth of early retrograde OH-rich topaz. Type III, IV, and V: late aqueous fluids of variable salinity, and rare CO2 present during amphibolite- and late greenschistfacies conditions. A number of conclusions may be drawn from these relationships that have an effect on fluid evolution in deeply subducted continental rocks. (1) At a pressure of about 35GPa alkali^alumino-silicate aqueous solutions, with compositions intermediate between H2O fluid and melt (H2O425 and50 wt %) evolved from quartzites, probably generated by dehydration reactions. (2) During early decompression stages, at the transition from UHP to high-pressure (29 GPa) conditions, brines of external origin with higher water contents (82 wt % H2O) initiated the growth of OH-rich topaz and muscovite. (3) The subsequent decompression, at P52 GPa, was defined by a limited circulation of NaCl aqueous fluids, and CO2 infiltration. Overall, fluid inclusions and stable isotopes highlight a metamorphic fluid^rock interaction characterized by internally derived intermediate aqueous solutions at UHP, followed by infiltration of Cl-rich brines with higher water activities
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