• Proceedings of the KSME Conference
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• 2001.06a
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• pp.951-955
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• 2001

The experimental comparison between bonded and unbonded types stem-cement interface was carried out on axisymmetric stem-cement-aluminum model of the femoral component of a total hip replacement. Human femur was modeled in non-tapered and tapered($7.5^{\circ}$) aluminum hollow cylinders to emulate the diaphyseal and metaphyseal segments of the femur. For unbonded type, we tested stems with three different taper angles($5^{\circ},\;7.5^{\circ},\;10^{\circ}$). In every case, the cement-aluminum interface was designed to endure 8MPa shear strength. (a measured value at cement-bone interface) We tested aluminum models under axial loading for both cases. As an experimental result, it was found that unbonded stem sustained more axial load as bonded stem in both cases, diaphyseal and metaphyseal models. The unbonded types failed in cement mantle under axial compressive load, while the bonded ones failed in shear at cement-aluminum interface. These results suggest that a polished stem will sustain much higher axial load than a roughened stem. And a polished stem will make more stable cement-bone interface that may promote better osteosythesis around the stem.

• Journal of Korean Orthopaedic Sports Medicine
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• v.11 no.1
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• pp.51-56
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• 2012

Purpose: Golf is a popular sports activity after total knee arthroplasty in old age patients. We evaluated golf and implant loosening through the radiologic method. We also evaluated correlation of patterns of golf activity and clinical outcome to suggest guidelines to the patients. Materials and Methods: We carried out a retrospective case-control study of 80 patients (80 knees) who underwent TKR between 2005 and 2008, and followed up more than 3 years. We divided patients who played golf after TKR as a study group and who did not participate sports activities as a control group. We calculated the sum of width of radiolucent line in 7 sections around femoral component, 7 sections around tibial components and 5 sections in patella component using American Knee Society Roentgenographic Evaluation and Scoring system respectively. The inclusion criteria, was BMI (body mass index) was between 25 and $30kg/m^2$, and UCLA activity-level rating System score was between 5 and 8. We also got the information of patients' patterns of golf activities such as 1. the interval from surgery to return to golf activity. 2. the frequency of golf activities 3. using spike or cart. We obtained the information from patient's questionnaire and telephone interview. We compared with the VAS (visual analogue scale) respectively. And handicaps and driving distance was evaluated as well. Results: The study group's mean sum of radiologic score was 0.84 mm and 0.69 mm in control group. This is not statistically significant (p=0.22). Too early returning to golf (p=0.01) and left knee replacement (p<0.01) were statistically significant factors affecting clinical outcomes of golf activities after total knee arthroplasty. Conclusion: We concluded that golf activities after total knee arthroplasty is not correlated with radiographic loosening, and we need to give an explanation to the patients about increased pain when returing to golf too early and left side arthroplasties.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.896-902
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• 2005

An orthopedic surgeon normally gets the operational parameters of total knee arthroplasty from medical images(CT, MRI). Anatomical axis, mechanical axis, the width and height of femur, or tibia are the most important parameters related with accomplishment of TKA. This paper presents a methodology of simulation that virtually operates TKA according to 2D medical images. Using this simulator, some important parameters for operation can be achieved before hand. The simulator provides the 3D computational model of a knee joint and then derives the proper size of implant corresponding to the joint. The whole process of TKA can be simulated such as clipping a knee joint, assembling the joint and its implants, visualizing all the operation steps, deriving some crucial parameters such as anatomical axis and cutting thickness, and predicting the result of TKA. Some examples are given and discussed to validate the methodology.

• The Korean Journal of Nuclear Medicine
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• v.33 no.4
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• pp.413-421
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• 1999

Purpose: This study was performed to evaluate the usefulness of $^{99m}Tc$-HMPAO-labelled leucocyte scintigraphy for diagnosing prosthetic infection after total knee replacement arthroplasty without the aid of following bone marrow scintigraphy Materials and Methods: The study subjects were 25 prostheses of 17 patients (one man and 16 women, mean age. 65 years) who had total knee replacement arthroplasty. After injection of $^{99m}Tc$-HMPAO-labelled leucocyte, the whole body planar and knee SPECT images were obtained in all patients. The subjects were classified into three groups according to clinical suspicion of prosthetic infection. Group A (n=11) with high suspicion of infection; Group B (n=6) with equivocal suspicion of infection, and Group C (n=8) with asymptomatic contralateral prostheses. Final diagnosis of infection was based on surgical, histological and bacteriological data and clinical follow-up. Results: Infection was confirmed in 13 prostheses (11 in Group A and 2 in Group B). All prostheses in Group A were true positive. There were two true positives, one false positive and three true negatives in Group B, and six true negatives and two false positives in Group C. Overall sensitivity, specificity, and accuracy for diagnosis of the infected knee prosthesis were 100%, 75% and 88%, respectively Conclusion: $^{99m}Tc$-HMPAO-labelled leucocyte scintigraphy is a sensitive method for the diagnosis of infected knee prosthesis. However, false positive uptakes even in asymptomatic prosthesis suggest that bone marrow scintigraphy may be needed to achieve improved specificity.

• Journal of the Korean Arthroscopy Society
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• v.16 no.2
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• pp.190-194
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• 2012

The role of arthroscopy for the diagnosis of polyethylene wear after total knee arthroplasty has been reported previously. In this report, we demonstrate a case of wear of meniscal bearing in unicompartmental knee arthroplasty (UKA) and recurrent meniscal bearing subluxation which was diagnosed by arthroscopy. Arthroscopic examination has its role in diagnosing the wear and subluxation of polyethylene bearing after UKA.

• Journal of the Korean Orthopaedic Association
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• v.53 no.6
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• pp.490-497
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• 2018

Purpose: To evaluate the utility of ceramic-on-polyethylene articular bearing surface when cementless total hip arthroplasty is performed in patients older than 65 years through an analysis of the minimum five-year follow-up results using the ceramic femoral head and cross-linked polyethylene liner. Materials and Methods: From March 2010 to September 2012, 51 patients (56 hips) who were older than 65 years were enrolled in this retrospective study. The mean age at surgery was $70.9{\pm}5.1years$ old. A clinical assessment was analyzed using the Harris hip score. For the radiographic assessment, the cup inclination and anteversion, stem alignment, and wear amount were measured. The postoperative complications were also determined. Results: The mean Harris hip score was improved from preoperative 48 points to postoperative 87 points (p<0.05). The mean cup inclination was $40.9^{\circ}{\pm}6.4^{\circ}$ and the mean cup anteversion was $20.3^{\circ}{\pm}8.1^{\circ}$. The mean cup anteversion of the elevated liner-used group (16 cases) was $14.3^{\circ}{\pm}7.9^{\circ}$ and the mean cup anteversion of the neutral liner used group (40 cases) was $22.4^{\circ}{\pm}9.1^{\circ}$ (p<0.05). The mean stem alignment angle was $0^{\circ}$ (range, varus $4^{\circ}$-valgus $4^{\circ}$). The mean linear wear amount was $0.458{\pm}0.041mm$ and the average annual linear wear rate was $0.079{\pm}0.032mm/yr$. Six cases (10.7%) of intraoperative periprosthetic femoral fractures were encountered. Conclusion: Based on these results, the use of a ceramic-on-polyethylene articular bearing surface in elderly patients with cementless total hip arthroplasty is beneficial. On the other hand, careful effort is needed to prevent intraoperative periprosthetic femoral fractures.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.7 no.1
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• pp.39-44
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• 2014

The patellar clunk syndrome is one of the patellofemoral complication, caused by formation of the fibrous nodule at the suprapatellar region after total knee arthroplasty. The symptom involves painful catching, crepitus and clunk during knee extension. It has been mainly but not exclusively associated with the posterior stabilized total knee system. The fibrous nodule is entrapped in the femoral intercondylar notch of the femoral component during flexion and as the knee is extended, it displaces back to the trochlear groove abruptly and the typical symptoms occur. The risk of developing this complication is primarily related to the design of the femoral component and higher incidence was noted with earlier designs of posterior stabilized knee prosthesis. Modifications have been made to the femoral component to optimize the kinematics of the patellofemoral joint and thereby reduced the incidence of patellar clunk syndrome but did not eliminate the problem completely. Clinical examination is the gold standard of diagnosis and imaging study has been used as a possible adjunct to diagnosis. Especially ultrasonography is an imaging modality, which can be easily performed to detect the fibrous nodule on the quadriceps tendon. We report a case of patellar clunk syndrome which was diagnosed with ultrasonography.

• Journal of the Korean Orthopaedic Association
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• v.55 no.1
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• pp.62-70
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• 2020

Purpose: External tibia torsion and proximal tibial vara have been reported in severe varus deformed osteoarthritis, which is a tibio-femoral angle of more than 20°. The radiology measurements were compared with those of control group and the preoperative and follow-up radiology and clinical results were examined. Materials and Methods: From January 2007 to March 2016, 43 knees from 37 persons, who underwent total knee arthroplasty for a severe varus deformity of more than 20° on the tibio-femoral angle on the standing radiographs and had a follow-up period more than two years, were examined. The mean follow-up period was 45.7 months. The control group, who underwent conservative treatments, had Kellgren-Lawrence grade three osteoarthritis and a tibio-femoral angle of less than 3° varus. The external tibial torsion of enrolled patients and control group were estimated using the proximal tibio-fibular overlap length and the tibial torsion values on computed tomography. The proximal tibia vara was measured using the proximal tibial tilt angle. The preoperative and postoperative proximal tibio-fibular overlap length, tibial torsion value, proximal tibial tilt angle, and hospital for special surgery (HSS) score were evaluated. Results: The mean proximal tibio-fibular overlap length was 18.6 mm preoperatively and 11.2 mm (p=0.031) at the follow-up. The control group had a mean proximal tibio-fibular overlap length of 8.7 mm (p=0.024). The mean tibial torsion value was 13.8° preoperatively and 14.0° (p=0.489) at the follow-up. The control group had a mean tibial torsion value of 21.9° (p=0.012). The mean proximal tibial tilt angle was 12.2° preoperatively and 0° (p<0.01) at the follow-up. The control group had a mean proximal tilt angle of 1.2° (p<0.01). The preoperative tibiofemoral angle and mechanical axis deviation were corrected from preoperative 28.3° and medial 68.4 mm to postoperative 0.7° and medial 3.5 mm (p<0.01, p<0.01), respectively. The HSS scores increased from 34 points of preoperatively to 87 points at the last follow-up (p=0.028). Conclusion: Patients with advanced osteoarthritis with a severe varus deformity of more than 20° had significant increases in the external tibial torsion and varus of the proximal tibia. The tibial torsion value before and after surgery in the enrolled patients was not changed statistically, but good clinical results without complications were obtained.

• Journal of Biomedical Engineering Research
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• v.23 no.2
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• pp.119-130
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• 2002

The nonlinear finite element program has been developed to analyze the design performance of an artificial hip prosthesis and long term behavior of a treated femur with stems made of composite material after cementless total hip arthroplasty(THA). The authors developed the three dimentional FEM models of femoral bone with designed composite stem which was taken with elliptic cross section of 816 brick elements under hip contact load and muscle farce in simulating single leg stand. Using the program, density changes, stress distributions and micromotions of the material femoral bone were evaluated by changing fiber orientation of stems for selected manufacturing method such as plate cut and bend mold. The results showed that the composite materials such as AS4/PEEK and T300/976 gave less bone resorption than the metallic material such as cobalt chrome alloy, titanium alloy and stainless steal. It was found that increasing the long term stability of the prosthesis in the femur could be obtained by selecting the appropriate ply orientation and stacking sequence of composite.

• Journal of the Korean Orthopaedic Association
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• v.54 no.2
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• pp.110-119
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• 2019

Proximal humerus fracture can be defined as a fracture that occurs in the surgical neck or proximal part of the humerus. Despite the appropriate treatment, however, various complications and sequelae can occur, and the treatment is quite difficult often requiring surgical treatment, such as a shoulder replacement. The classification of sequelae after a proximal humerus fracture is most commonly used by Boileau and can be divided into two categories and four types. Category I is an intracapsular impacted fracture that is not accompanied by important distortions between the tuberosities and humeral head. An anatomic prosthesis can be used without greater tuberosity osteotomy. In category I, there are type 1 with cephalic collapse or necrosis with minimal tuberosity malunion and type 2 related to locked dislocation or fracture-dislocation. Category II is an extracapsular dis-impacted fracture with gross distortion between the tuberosities and the humeral head. To perform an anatomic prosthesis, a tuberosity osteotomy should be performed. In category II, there are type 3 with nonunion of the surgical neck and type 4 with severe tuberosity malunion. In type 1, non-constrained arthroplasty (NCA) without a tuberosity osteotomy should be considered as a treatment. On the other hand, reverse shoulder arthroplasty (RSA) should be considered if types 1C or 1D accompanied by valgus or varus deformity or severe fatty degeneration of the rotator cuff. In general, the results are satisfactory when NCA is performed in type 2 sequelae. On the other hand, RSA can be considered as an option when there is no bony defect of the glenoid and a defect of the rotator cuff is accompanied. In type 3, it would be effective to perform internal fixation with a bone wedge graft rather than shoulder replacement arthroplasty. Recent reports on the results of RSA are also increasing. On the other hand, recent reports suggest that good results are obtained with RSA in type 3. In type 4, RSA should be considered as a first option.