• 한국CDE학회논문집
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• 제16권5호
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• pp.315-322
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• 2011

The goal of total knee replacement (TKR) surgery is to replace patient's knee joint with artificial implants in order to restore normal knee joint functions. Since mismatched knee implants often cause a critical balancing problem and short durability, designing a well-fitted implant to a patient's knee joint is essential to improve surgical outcomes. We developed a software system that three-dimensionally (3D) simulates TKR surgery based upon 3D knee models reconstructed from computed tomography (CT) imaging. The main task of the system was to extract precise 3D anatomical parameters of a patient's knee that were directly used to determine a custom fit implant and to virtually perform TKR surgery. The virtual surgery was simulated by amputating a 3D knee model and positioning the determined implant components on the amputated knee. The test result shows that it is applicable to derive surgical parameters, determine individualized implant components, rehearse the whole surgical procedure, and train medical staff or students for actual TKR surgery. The feasibility and verification of the proposed system is described with examples.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.207-208
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• 2007

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1473-1474
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• 2008

In the total knee arthroplasty (TKA), kinematic benefic of a mobile-bearing total knee prosthesis is still arguing. Main reasons for implant failure are loosening and polyethylene wear and should be solved with new designs with mob ile bearings. The kinematics of the knee prosthesis also affects the implant failure. Recently, a second generation of p rostheses with a mobile-bearing was developed. The current study aimed to assess the kinematic path of the 2nd generation mobile knee prosthesis compared to the normal knees. Using 3D/2D registration method, CT-derived 3D knee models were fitted to sequential 2D X-ray images during knee flexion. 3D kinematics of the femur and the tibia were analyzed. The 2nd generation mobile-bearing TKA prosthesis (e.motion, Aesculap, Germany) knees showed less external rotation and knee flexion range compared to the normal knee, but the trend of external rotation was similar each other.

• Journal of Yeungnam Medical Science
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• 제21권1호
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• pp.1-11
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• 2004

Total knee arthroplasty has become a common procedure for treatment of severe osteoarthritis, rheumatoid arthritis and post-traumatic arthritis. In the past, failure of total knee arthroplasty was commonly attributable to aseptic loosening, often associated with component malalignment, soft tissue imbalance. With improved surgical instrumentation and soft tissue balancing techiniques, failure secondary to mechanical loosening has been minimal. But surgeons are still dissatisfied with implant malalignment. Correct tibiofemoral alignment seems to be particularly important since it is generally agreed that axial deviation and imprecise implantation may lead to loosening of the implant component. Navigation systems and robotic techniques could potentially solve problems of imprecision in traditional total knee arthroplasty. It is expected that the success rate and longevity of total knee arthroplasty will be improved during the twenty first century.

• 대한의용생체공학회:의공학회지
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• 제28권1호
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• pp.108-116
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• 2007

Recently, it has been reported that the posterior stabilized implant, which is clinically used for the total knee replacement (TKR), may have failure risk such as wear or fracture by the contact pressure and stress on the tibial post. The purpose of this study is to investigate the influence of the mal alignment of the posterior stabilized implant on the tibial post by estimating the distributions of contact pressure and von-Mises stress on a tibial post and to analyze the failure risk of the tibial post. Finite element models of a knee joint and an implant were developed from 1mm slices of CT images and 3D CAD software, respectively. The contact pressure and the von-Mises stress applying on the implant were analyzed by the finite element analysis in the neutral alignment as well as the 8 malalignment cases (3 and 5 degrees of valgus and varus angulations, and 2 and 4 degrees of anterior and posterior tilts). Loading condition at the 40% of one whole gait cycle such as 2000N of compressive load, 25N of anterior-posterior load, and 6.5Nm of torque was applied to the TKR models. Both the maximum contact pressure and the maximum von-Mises stress were concentrated on the anterior-medial region of the tibial post regardless of the malalignment, and their magnitudes increased as the degree of the malalignment increased. From present result, it is shown that the malalignment of the implant can influence on the failure risk of the tibial post.

• 대한의용생체공학회:의공학회지
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• 제24권4호
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• pp.363-367
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• 2003

인공무릎관절의 수명에 직접적인 영향을 주는 인자는 접촉면에 대한 접촉면적과 압력분포이다 따라서. 이에 대한 실험적인 평가가 필요하였고 knee simulator 혹은 K-scan sensor를 포함한 시스템과 같은 많은 연구가 진행되어 왔다. 그러나 지금까지 보행주기에 따른 연속적인 인공관절 운동에 대한 접촉면의 압력분포를 실시간으로 분석한 연구는 미흡하다 따라서 본 연구의 목적은 보행주기를 모사하는 simulator와 I-scan을 이용하여 연속적인 동작에 따른 접촉면의 압력분포를 분석함에 있다. 본 연구의 목적을 이루기 위해서 생체내 인공관절 환경을 정확히 표현할 수 있는 knee simulator를 제작하였다. 네 방향의 자유도를 갖고 있는 본 simulator는 soft tissue의 기능을 포함하고 있고 PC Program을 통하여 압축하중과 femoral component의 굴곡각을 조절할 수 있다. 본 시스템의 I-scan sensor는 보행주기에 따른 압력분포를 분석할 수 있다. 보행주기에 대한 압력분포는 압축하중곡선에 따라 주요하게 변화함을 알 수 있고 운동성에 영향을 쿠는 압력중심의 위치도 변한다는 것을 알 수 있다. 따라서 본 연구에서 제작한 knee simulator는 보행주기 같은 특정의 운동정보를 이용하여 접촉면의 압력분포 및 운동성 같은 기계적 성능을 평가할 수 있고 형상 설계를 위한 기초 자료를 제공할 수 있다.

• Archives of Plastic Surgery
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• 제45권3호
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• pp.280-283
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• 2018

Knee revision arthroplasty following peri-prosthetic joint infections is a formidable challenge. Patients are at a high risk of recurrent infection, and the soft tissue over the revised implant is often of questionable quality. Flap reconstruction has improved the salvage rates of infected arthroplasties, and should be considered in all cases of revision arthroplasty. We present a challenging case requiring staged reconstruction with two free latissimus dorsi flaps after the initial use of a medial gastrocnemius flap.

• 한국전산구조공학회논문집
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• 제31권1호
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• pp.23-29
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• 2018

무릎 임플란트에서 접촉압력이 마모에 큰 영향을 미친다. 본 연구에서는 본 연구기관에서 개발한 무릎 임플란트 모델을 이용하여 유한요소해석을 하였다. 연구와 산업에서 실제로 사용하는 조합을 이용하여 총 10가지의 무릎 임플란트의 재료조합에 대한 접촉압력을 분석하였다. 무릎이 30도, 45도 60도 기울어져있을 때의 하중을 가하여 접촉압력을 구하였다. 접촉압력을 계산한 결과 티타늄합금-UHMWPE 조합에서 가장 작은 접촉압력이 나왔다. UHMWPE의 경우 대퇴골부에 어떠한 재료를 사용하여도 접촉압력이 크게 변하지 않았다. 접촉압력이 가장 큰 조합과 작은 조합을 비교하였을 때 0.77% 차이를 보였다. 반면에 Carbon/PEEK 복합재료의 경우 접촉압력이 가장 큰 경우와 작은 경우를 비교하였을 때 5.3% 차이를 보였다. 이를 통해 Carbon/PEEK 복합재료를 베어링부로 사용할 경우 대퇴골부의 재료가 마모에 영향을 미침을 알 수 있다. 본 연구는 무릎 임플란트 마모예측과 마모를 최소화 연구에 도움이 될 것이라 생각한다.

• 대한방사선기술학회지:방사선기술과학
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• 제41권5호
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• pp.413-419
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• 2018

Magnetic Resonance Imaging for patients with metallic implant has poor image quality, and signal loss and artifacts including distortion can occur. The purpose of this study is to carry out a comparative evaluation on high receive bandwidth(hiBW), O-MAR, O-MAR XD to reduce artifacts in knee implant. To take MRI, 3.0T scanner and dual-source radiofrequency transmission were used. O-MAR XD technique's strong option showed a significant difference (p<0.001) with O-MAR XD technique's weak option, O-MAR and hiBW excluding the medium option. O-MAR XD's medium option had a significant difference (p<0.01) with O-MAR XD's weak, O-MAR and hiBW. O-MAR XD technique's weak option had a significant difference (p<0.01) with O-MAR XD's strong and medium options, O-MAR and hiBW. O-MAR technique had a significant difference (p<0.001) with strong, medium, weak options of O-MAR XD technique except for hiBW. HiBW had a significant difference (p<0.001) with strong, medium and weak options of O-MAR XD technique except for O-MAR. The results showed that O-MAR XD technique was more useful for MRI scan for patients with knee replacement surgery than traditional techniques such as hiBW or O-MAR, and susceptibility artifacts decreased more when O-MAR XD technique's strong or medium option was applied. Based on the results above, it is considered that it will be possible to acquire images whose susceptibility artifacts were highly decreased by using O-MAR XD technique's strong or medium option when conducting MRI for artificial knee joint and it will be helpful for checking and monitoring patients with knee joint replacement.

• Archives of Plastic Surgery
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• 제44권2호
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• pp.124-135
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• 2017

Background In cases of total knee arthroplasty (TKA) threatened by potential hardware exposure, flap-based reconstruction is indicated to provide durable coverage. Historically, muscle flaps were favored as they provide vascular tissue to an infected wound bed. However, data comparing the performance of muscle versus fasciocutaneous flaps are limited and reflect a lack of consensus regarding the optimal management of these wounds. The aim of this study was to compare the outcomes of muscle versus fasciocutaneous flaps following the salvage of compromised TKA. Methods A systematic search and meta-analysis were performed to identify patients with TKA who underwent either pedicled muscle or fasciocutaneous flap coverage of periprosthetic knee defects. Studies evaluating implant/limb salvage rates, ambulatory function, complications, and donor-site morbidity were included in the comparative analysis. Results A total of 18 articles, corresponding to 172 flaps (119 muscle flaps and 53 fasciocutaneous flaps) were reviewed. Rates of implant salvage (88.8% vs. 90.1%, P=0.05) and limb salvage (89.8% vs. 100%, P=0.14) were comparable in each cohort. While overall complication rates were similar (47.3% vs. 44%, P=0.78), the rates of persistent infection (16.4% vs. 0%, P=0.14) and recurrent infection (9.1% vs. 4%, P=0.94) tended to be higher in the muscle flap cohort. Notably, functional outcomes and ambulation rates were sparingly reported. Conclusions Rates of limb and prosthetic salvage were comparable following muscle or fasciocutaneous flap coverage of compromised TKA. The functional morbidity associated with muscle flap harvest, however, may support the use of fasciocutaneous flaps for coverage of these defects, particularly in young patients and/or high-performance athletes.