• Design & Manufacturing
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• 제11권2호
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• pp.51-56
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• 2017

Nitinol, a shape memory alloy (SMA), is manufactured from titanium and nickel and it used in various fields such as electrical applications, micro sensors. It is also recommended as a material in medical for implant because it has excellent organic compatibility. Nitinol is intended to be inserted into the human body, products require a high-quality surface and low residual stress. To overcome this problems, explore electrolyte polishing (EP) is being explored that may be appropriate for use with nitinol. EP is a particularly useful machining method because, as a non contact machining method, it produces neither machining heat nor internal stress in the machined materials. Sandpaper polishing is also useful machining method because, as a contact machining method, it can easily good surface roughness in the machined materials. The electrolyte polishing (EP) process has an effect of improving the surface roughness as well as the film polishing process, but has a characteristic that the residual stress is hardly generated because the work hardened layer is not formed on the processed surface. The sandpaper polishing process has the effect of improving the surface roughness but the residual stress remains in the surface. We experimented with three conditions of polishing process. First condition is the conventional polishing. Second condition is the electrochemical polishing(EP). And Last condition is a mixing process with the conventional polishing and the EP. Surface roughness and residual stress of the nitinol before a polishing process were $0.474{\mu}mRa$, -45.38MPa. Surface roughness and residual stress of the nitinol after mixing process of the conventional polishing and the EP were $1.071{\mu}mRa$, -143.157MPa. Surface roughness and residual stress of the nitinol after conventional polishing were $0.385{\mu}mRa$ and -205.15MPa. Surface roughness and residual stress of sandpaper and EP nitinol were $1.071{\mu}mRa$, -143.157MPa. The result shows that the EP process is a residual stress free process that eliminates the residual stress on the surface while eliminating the deformed layer remaining on the surface through composite surface machining rather than single surface machining. The EP process can be used for biomaterials such as nitinol and be applied to polishing of wafers and various fields.

• Journal of Periodontal and Implant Science
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• 제48권6호
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• pp.347-359
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• 2018

Purpose: Periodontitis and rheumatoid arthritis (RA) share a similar inflammatory pathogenesis. Porphyromonas gingivalis (Pg) can induce anticyclic-citrullinated peptide autoantibodies (anti-CCP antibodies), a key factor in the development of RA. This study aimed at evaluating the relationships between the 2 diseases and identifying the clinical implications thereof, with a focus on periodontal pathogens in Korean adults. Methods: A total of 260 RA patients and 86 age- and sex-matched control patients without arthritis were enrolled in this prospective cross-sectional study. Periodontal indices and the prevalence and amount of periodontal pathogens were compared between the groups. Correlations between periodontal and RA indices were examined, as were correlations between 9 periodontal pathogens and RA indices. Results: The RA group had significantly higher values than the control group for all investigated periodontal indices (P<0.05) except the number of teeth. The gingival index (GI) was correlated with the disease activity score 28 (DAS28) (r=0.125, P=0.049), RA disease duration (r=0.253, P<0.001), erythrocyte sedimentation rate (ESR) (r=0.162, P=0.010), and anti-CCP antibody titer (r=0.205, P=0.004). Probing pocket depth (PPD) was correlated with ESR (r=0.139, P=0.027) and anti-Pg antibody titer (r=0.203, P=0.001). Bleeding on probing (BOP) was correlated with DAS28 (r=0.137, P=0.030), RA disease duration (r=0.202, P=0.001), ESR (r=0.136, P=0.030), anti-Pg antibody titer (r=0.177, P=0.005), and anti-CCP antibody titer (r=0.188, P=0.007). Clinical attachment level (CAL) and periodontitis severity were correlated with anti-Pg antibody titer (the former r=0.201, P=0.002; the latter r=0.175, P=0.006). The quantity of Pg was positively correlated with the serum anti-Pg antibody titer (r=0.148, P=0.020). Conclusions: The GI, BOP, and PPD showed positive relationships with several RA indices. The anti-Pg antibody titer had positive relationships with PPD, BOP, CAL, and periodontitis severity. Thus, increasing values of periodontal indices could be used as a risk indicator of disease development in RA patients, and an increasing anti-Pg antibody titer could be considered as a warning sign in RA patients suffering with periodontitis.

• Clinics in Shoulder and Elbow
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• 제26권4호
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• pp.343-350
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• 2023

Background: Our purpose was to evaluate a custom reverse total shoulder arthroplasty glenoid baseplate for severe glenoid deficiency, emphasizing the challenges with this approach, including short-term clinical and radiographic outcomes and complications. Methods: This was a single-institution, retrospective series of 29 patients between January 2017 and December 2022 for whom a custom glenoid component was created for extensive glenoid bone loss. Patients were evaluated preoperatively and at intervals for up to 5 years. All received preoperative physical examinations, plain radiographs, and computed tomography (CT). Intra- and postoperative complications are reported. Results: Of 29 patients, delays resulted in only undergoing surgery, and in three of those, the implant did not match the glenoid. For those three, the time from CT scan to implantation averaged 7.6 months (range, 6.1-10.7 months), compared with 5.5 months (range, 2-8.6 months) for those whose implants fit. In patients with at least 2-year follow-up (n=9), no failures occurred. Significant improvements were observed in all patient-reported outcome measures in those nine patients (American Shoulder and Elbow Score, P<0.01; Simple Shoulder Test, P=0.02; Single Assessment Numeric Evaluation, P<0.01; Western Ontario Osteoarthritis of the Shoulder Index, P<0.01). Range of motion improved for forward flexion and abduction (P=0.03 for both) and internal rotation up the back (P=0.02). Pain and satisfaction also improved (P<0.01 for both). Conclusions: Prolonged time (>6 months) from CT scan to device implantation resulted in bone loss that rendered the implants unusable. Satisfactory short-term radiographic and clinical follow-up can be achieved with a well-fitting device. Level of evidence: III.

• Journal of Yeungnam Medical Science
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• 제13권1호
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• pp.116-133
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• 1996

생체합금의 생체적합성을 검증하기위해, 표면처리가 되지 않은 타이타늄 봉과 표면처리를 시행한 타이타늄 봉을 실험용토끼의 대퇴골 근위부에 삽입하여 6주, 12주 및 26주후 방사선 관찰 후 광학현미경적 검사를 통한 골 반응을 비교 관찰하였다. 전 례에서 부식에 의한 반응은 관찰되지 않았으며, 신생골의 증식은 타이타늄의 삽입 후 26주까지 경도의 골증식이 관찰되었으나, 표면처리여부에는 관계가 없었다. 표면처리를 시행하지 않은 타이타늄의 삽입한 11례 중 1례의 경우 삽입 후 12주에 경도의 골괴사반응이 관찰되었으며 표면처리를 시행한 타이타늄을 삽입한 후 전 례에서 골괴사가 관찰되지 않았다. 이는 수술적 조작에 의한 것으로 사료되었다. 섬유원세포의 증식은 시기에 관계없이 전 례에서 관찰되었으며, 표면처리 여부 혹은 시간의 경과 정도와 관계가 없었다. 표면처리를 시행하지 않은 타이타늄의 삽입 후 6주에는 침윤정도 및 조직반응정도는 표면처리한 타이타늄의 삽입에 비해 통계적으로 유의하게 증가하였다. 그러나, 12주 및 26주 후에는 유의한 차이가 없었다. 다중회귀분석법의 단계별 투입방식을 이용하여 세포의 침윤율을 시간의 경과와 표면 처리여부에 따라 상관관계를 분석한결과, 세포 침윤율은 시간의 경과 및 표면처리를 하게 됨에 따라 감소하는 경향이 있었다. 조직 반응율의 정도도 침윤율과 유사한 양상을 나타내었다. 이상의 결과, 생체합금의 표면처리에 따라 골반응의 정도가 유의한 차이가 있었으므로 내고정 기구의 제작을 위해서는 보다 생체 적합성이 양호한 제작방법의 개발이 요구될 것으로 사료되었다.

• 대한정형외과학회지
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• 제52권1호
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• pp.25-32
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• 2017

목적: 고령 환자에서 발생한 불안정성 대퇴골 전자간부 골절의 치료 시 골수강내 금속정의 길이에 따른 방사선적, 임상적 치료 결과를 비교 분석하고자 한다. 대상 및 방법: 2009년 8월부터 2014년 12월까지 방사선 영상상 AO/OTA 분류 31-A2 대퇴골 전자간부 골절로 진단되어 골수강 내 금속정을 이용한 내고정을 시행한 뒤 최소 1년 이상 추시가 가능하였던 65세 이상의 환자 139예를 대상으로 후향적 대조군 연구를 시행하였다. 대상군을 짧은 골수정(I군)과 긴 골수정(II군)을 사용한 군으로 분류하였으며 각각 106예, 33예로 조사되었다. 방사선적인 평가로 골절의 정복 정도, 골유합까지의 기간, 합병증 발생을 조사하였으며 수술 전 혈색소, 수술 시간, 수술 중 출혈량, 수혈 유무, 입원 기간 및 최종 추시 시 Charnley 고관절 점수를 통한 임상적 평가를 시행하였다. 결과: 수술 후 단순 방사선 검사상 전 예에서 good 또는 acceptable한 정복 상태를 얻었다. 골유합까지 평균 4.8개월이 걸렸으며 두 군 간의 차이는 없었다. II군(57.87분)이 I군(45.65분)보다 수술 시간이 길었던 것으로 확인되었다(p=0.003). 수술 중 출혈량의 경우 II군(288.78 ml)이 I군(209.90 ml)보다 많은 것으로 확인되었다(p=0.046). 최종 추시 시 임상적 결과는 두 군 모두 만족스러웠다. 결론: 고령의 환자에서 발생한 후내측 골편을 동반한 불안정성 대퇴골 전자간부 골절의 치료 시 골절 부위의 정복을 잘 시행한 경우 긴 골수정과 짧은 골수정 모두 만족스러운 방사선적, 임상적 결과를 보였다.