Concept model of atomic hydrogen dry developing process for photolithographic patterning

Atomic hydrogen dry etching was used for microstructure fabrication. Photolithography was proposed and achieved by a dry development process using atomic hydrogen irradiation. The reaction system of poly(methyl methacrylate) mixed with molecular benzophenone was examined as a model system for a proof-of-concept study. Optical patterning was experimentally made on a thin layer of poly(methyl methacrylate) with benzophenone by UV light exposure with a photomask. The reaction system acted as a negative tone resist in the proposed process. Thus, a model system for a new atomic hydrogen dry development process was proposed and successfully demonstrated.Yuki Takemori, Masao Gohdo, Yuta Koda, and Hideo Horibe, "Concept model of atomic hydrogen dry developing process for photolithographic patterning", AIP Advances 10, 105223 (2020) https://doi.org/10.1063/5.0027509

Musculo-cutaneous flap for reconstruction surgery for deep surgical site infection after total en bloc spondylectomy: A technical note

BackgroundTotal en bloc spondylectomy (TES) is potential radical resection surgery for spinal tumors. Surgical procedure of TES includes extremely wide detachment of surrounding soft tissue from pathological vertebra, resulting in impairment of blood supply. Moreover, massive dead space inevitably is made after vertebral body resection. Therefore deep surgical site infection (SSI) after TES could be intractable. To date, suitable treatment for deep SSI after TES has not been established.Case descriptionA 72 years old man underwent TES of 12th thoracic level via single posterior approach for primary leiomyosarcoma. Postoperative additional irradiation was performed. One year after surgery, late infection around the cage occurred. We removed the cage followed by autologous iliac bone grafting, we treat the wound by open therapy and daily irrigation, followed by negative pressure wound therapy. Four-month later, we performed musculo-cutaneous flap using latissimus dorsi muscle with plastic surgeons. At the follow-up visit one year after flap surgery, no evidence of recurrence of infection was observed.ConclusionMusculo-cutaneous flap is one of treatment options to fill the dead space and to control deep SSI after TES

Experimental rat model for cervical compressive myelopathy

Previously, a rat model of chronic compressive myelopathy that uses a water-absorbing polymer inserted under a spinal lamina was reported. However, the best size and coefficient of expansion of the polymer sheet have not yet been established. The aim of the present study was to optimize these properties in an ideal rat model of cervical compressive myelopathy. Thirty rats were used in this study. A sheet of water-absorbing polymer was inserted under the cervical laminae. Rats were divided randomly into five experimental groups by the expansion rate (350 or 200%) and thickness (0.5 or 0.7 mm) and the control. After the surgery, the severity of paralysis was evaluated for 12 weeks. At 12 weeks after the surgery, cresyl violet staining was performed to assess the number of motor neurons in the anterior horn at the C4/C5 segment and Luxol Fast Blue staining was performed to assess demyelination in the corticospinal tract at the C7 segment. ‘Slow-progressive’ paralysis appeared at 4–8 weeks postoperatively in rat models using sheets with 200% expansion. By contrast, only temporary paralysis was observed in rat models using sheets with 350% expansion. A loss of motor neurons in the anterior horn was observed in all groups, except for the control. Demyelination in the corticospinal tract was observed in rat models using sheets with 200% expansion, but not rat models using sheets with 350% expansion. A polymer sheet that expands its volume by 200% is an ideal material for rat models of cervical compressive myelopathy

Postoperative Increase in Occiput–C2 Angle Negatively Impacts Subaxial Lordosis after Occipito–Upper Cervical Posterior Fusion Surgery

Study DesignRetrospective case series.PurposeTo elucidate the impact of postoperative occiput–C2 (O–C2) angle change on subaxial cervical alignment.Overview of LiteratureIn the case of occipito–upper cervical fixation surgery, it is recommended that the O–C2 angle should be set larger than the preoperative value postoperatively.MethodsThe present study included 17 patients who underwent occipito–upper cervical spine (above C4) posterior fixation surgery for atlantoaxial subluxation of various etiologies. Plain lateral cervical radiographs in a neutral position at standing were obtained and the O–C2 angle and subaxial lordosis angle (the angle between the endplates of the lowest instrumented vertebra (LIV) and C7 vertebrae) were measured preoperatively and postoperatively soon after surgery and ambulation and at the final follow-up visit.ResultsThere was a significant negative correlation between the average postoperative alteration of O–C2 angle (DO–C2) and the average postoperative alteration of subaxial lordosis angle (Dsubaxial lordosis angle) (r=–0.47, p=0.03).ConclusionsThere was a negative correlation between DO–C2 and Dsubaxial lordosis angles. This suggests that decrease of mid-to lower-cervical lordosis acts as a compensatory mechanism for lordotic correction between the occiput and C2. In occipito-cervical fusion surgery, care must be taken to avoid excessive O–C2 angle correction because it might induce mid-to-lower cervical compensatory decrease of lordosis