• Proceedings of the KOSOMBE Conference
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• v.1994 no.12
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• pp.71-74
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• 1994

In cementless total hip arthroplasty(THA), an initial stability of the femoral component is mandatory to achieve bony ingrowth and secondary long term fixation. Bone ingrowth depends strongly on relative micromotion and stress distributions at the interface. Primary stability of the femoral component can be obtained by minimizing the magnitude of relative micromotions at bone-prosthesis interface, Hence an accurate evaluation of interface behavior and stress/strain fields in the bone implant system may be relevant for better understanding of clinical situations and improving THA design. However, complete evaluation of load transfer in the bone remains difficult to assess experimentally, Hence, recently finite element method (FEM) was introduced in orthopaedic research field to fill the gap due to its unique capacity to evaluate stress in structure of complex shape, loading and material behavior. The authors developed the 3-dimensional numerical finite element model which is composed of totally 1179 elements off and 8 node blick. We also analyzed the micromotions at the bone-stem interface and mechanical behavior of existing bone prosthesis for a loading condition simulating the single leg stance. The result indicates that the values of relative motion for this well fit Multilock stem were $150{\mu}m$ in maximum, $82{\mu}m$ in minimum, and the largest relative motion developed in medial region of proximal femur with anterior-posterior direction. The proximal region of the bone was much larger in motion than the distal region and the stress pattern shows high stress concentration on the cortex near the tip of the stem. These findings indicates that the loading in the proximal femoral bone in the early postoperative situation can produce micromotions on the interface and clinically cementless TEA patient should not be allowed weight bearing strictly early in the postoperative period.

• 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 Chest Surgery
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• v.48 no.3
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• pp.214-216
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• 2015

Blunt abdominal trauma may cause peripheral vascular injuries. However, blunt abdominal trauma rarely results in injuries to the external iliac and common femoral arteries, which often stem from regional bone fractures. Here, we present the case of a patient who had experienced trauma in the lower abdominal and groin area three months before presenting to the hospital, but these injuries did not involve bone fractures and had been managed conservatively. The patient came to the hospital because of left lower leg claudication that gradually became severe. Computed tomography angiography confirmed total occlusion of the external iliac and common femoral arteries. The patient underwent femorofemoral bypass grafting and was discharged uneventfully.

• Hip & pelvis
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• v.34 no.2
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• pp.79-86
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• 2022

Purpose: The purpose of this study was to determine whether the direct anterior approach (DAA) can be applied to hemiarthroplasty for treatment of unstable femoral intertrochanteric fractures in elderly patients. Materials and Methods: We conducted a retrospective review of 34 cases (34 patients) who underwent bipolar hemiarthroplasty using a DAA from February 2019 to April 2020. The mean age of the patients was 82.68 years (range, 67-95 years). A cementless distal fixation hip system was used in all cases. Operation time, total amount of blood loss, intraoperative and postoperative fractures, infections, and reoperations were measured. The patients performed weight-bearing walking as tolerated immediately after surgery. Measurement of migration of the greater trochanter (GT) and progressive subsidence of the femoral stem was performed using follow-up radiographs. Results: The mean operative time was 83.50 minutes (range, 60-120 minutes). The mean amount of bleeding was 263.53 mL (range, 112-464 mL). Walking started a mean of 3.03 days (range, 3-4 days) after surgery. There was no case of progressive migration of the GT more than 5 mm even though it was not fixed. There were no cases of infection, dislocation, or reoperation. Conclusion: Bipolar hemiarthroplasty using the DAA for treatment of unstable femoral intertrochanteric fractures could be considered a useful option that provides many advantages in elderly patients.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.651-652
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• 2006

The choice of suitable hip implant is one of important factors in total hip replacement (THR). In clinical view points, improper adaptation of hip implant might cause abnormal stress distribution to the bone, which can shorten the lifespan of replaced hip implant. Currently, interest in custom-designed hip implants has increased as studies reveals the importance of geometric shape of patient's femur in modeling and designing custom hip implants. In this study, we have developed the custom-designed hip implant models with various sizes in hip implant, and the stress distribution in the bone was analyzed using Finite Elements methods. It was found that minimizing the gap between implant stem and femoral cavity is crucial to minimize stress concentration in the bone.

• Advances in biomechanics and applications
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• v.1 no.3
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• pp.187-210
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• 2014

With the goal of increasing the survivorship of the prosthesis and anticipating primary stability problems of new prosthetic implants, finite element evaluation of the micromotion, at an early stage of the development, is mandatory. This allows assessing and optimizing different designs without manufacturing prostheses. This study aimed at investigating, using finite element analysis (FEA), the difference in the prediction of the primary stability of cementless hip prostheses implanted into a $Sawbones^{(R)}$ 4th generation, using the manufacturer's mechanical properties and using mechanical properties close to that of human bone provided by the literature (39 papers). FEA was carried out on the composite $Sawbones^{(R)}$ implanted with a straight taper femoral stem subjected to a loading condition simulating normal walking. Our results show that micromotion increases with a reduction of the bone material properties and decreases with the augmentation of the bone material properties at the stem-bone interface. Indeed, a decrease of the cancellous Young modulus from 155MPa to 50MPa increased the average micromotion from $29{\mu}m$ up to $41{\mu}m$ (+42%), whereas an increase of the cancellous Young modulus from 155MPa to 1000MPa decreased the average micromotion from $29{\mu}m$ to $5{\mu}m$ (-83%). A decrease of cortical Young modulus from 16.7GPa to 9GPa increase the average global micromotion from $29{\mu}m$ to $35{\mu}m$ (+33%), whereas an increase of the cortical Young modulus from 16.7GPa to 21GPa decreased the average global micromotion from $29{\mu}m$ to $27{\mu}m$ (-7%). It can also be seen that the material properties of the cancellous structure had a greater influence on the micromotion than the material properties of the cortical structure. The present study shows that micromotion predicted at the stem-bone interface with material properties of the $Sawbones^{(R)}$ 4th generation is close to that predicted with mechanical properties of human femur.

• Hip & pelvis
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• v.30 no.4
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• pp.210-218
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• 2018

Purpose: This is a report on the outcomes associated with a consecutive series of 1,000 cementless hip arthroplasties utilizing the $Bencox^{(R)}$ hip stem-the first Korean-developed hip prosthesis. Materials and Methods: A consecutive series of 1,000 hip arthroplasties using the $Bencox^{(R)}$ hip stem were analyzed, starting from its initial release (September 2006) until June 2014. Patients in this consecutive series underwent surgery for fractures (n=552), arthritis (n=155), avascular necrosis (n=209), and revisions (n=84). Of these 1,000 cases, patients with a minimum follow-up of at least 1 year (n=616) were retrospectively analyzed for radiographic and clinical outcomes (i.e., Harris hip score). The stability of the prosthesis was evaluated by examining subsidence. Results: During the follow-up period (mean follow-up period of 54.8 months), there were 2 cases requiring revision of the femoral stem-both were caused by periprosthetic fractures and neither involved stem loosening. The mean Harris hip score during follow-up was 95.5. Bone ongrowth occurred in 95% of patients; no cases of subsidence or aseptic loosening of the stem were detected, and no cases of postoperative complications such as ceramic breakage were observed. Conclusion: Clinical and radiographic evaluations of hip arthroplasty using the $Bencox^{(R)}$ hip stem revealed excellent outcomes with an average of 54.8 month follow-up in a consecutive series of 1,000 cases.

• Hip & pelvis
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• v.34 no.4
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• pp.211-218
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• 2022

Purpose: We report on the 10-year clinical hip function and radiologic outcomes of patients who underwent hip arthroplasty using a COREN stem. Materials and Methods: A consecutive series of 224 primary cementless hip arthroplasty implantations were performed using a COREN stem between 2009 and 2011; among these, evaluation of 128 hips was performed during a minimum follow-up period of 10 years. The mean age of patients was 65.4 years (range, 40-82 years) and the mean duration of follow-up was 10.8 years (range, 10-12 years). Evaluation of clinical hip function and radiologic implant outcomes was performed according to clinical score, thigh pain, and radiologic analysis. Results: Dramatic improvement of the mean Harris hip score (HHS) from 59.4 preoperatively to 93.5 was observed at the final follow-up (P≤0.01). Stable fixation was demonstrated for all implants with no change in position except for one case of Vancouver type B2 periprosthetic femur fracture. A radiolucent line (RLL) was observed in 16 hips (12.5%). Thigh pain was observed in only two hips (1.6%) at the final follow-up. There were no cases of osteolysis around the stem. The survival rate for the COREN stem was 97.7%. Conclusion: Good long-term survival with excellent clinical and radiological outcomes can be achieved using the COREN femoral stem regardless of Dorr type.

• Journal of the Korean Orthopaedic Association
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• v.54 no.3
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• pp.244-253
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• 2019

Purpose: Total hip arthroplasty was performed using a direct anterior approach (DAA) on an ordinary operation table and a short femoral stem. The clinical radiographic results were evaluated by a comparison with those performed using the modified hardinge (anterolateral approach, ALA) method. Materials and Methods: From January 2013 to November 2015, 102 patients who underwent total hip arthroplasty using DAA (DAA group) and the same number of patients using ALA (ALA group), both performed by a single surgeon, were compared and analyzed retrospectively. The operation time and amounts of bleeding were compared, and the improvement in post-operative pain, ambulatory capacity and functional recovery of the hip joint were checked. The location of insertion of the acetabular cup and femoral stem were evaluated radiologically, and the complications that occurred in the two groups were investigated. Results: The amount of bleeding was significantly smaller in the DAA group (p=0.018). Up to 3 weeks postoperatively, recovery of hip muscle strength was significantly higher in the DAA group (flexion/extension strength p=0.023, abduction strength p=0.031). The Harris hip score was significantly better in the DAA group for up to 3 months (p<0.001) and the Koval score showed significantly better results in the DAA group up to 6 weeks (p≤0.001). The visual analogue scale score improvement was significantly higher in the DAA group by day 7 (p=0.035). The inclination angle (p<0.001) and anteversion angle (p<0.001) of the acetabular cup were located in the safe zone of the DAA group more than in the ALA group, and there was no statistically significant difference in the position of the femur stem and leg length difference. During surgery, two cases of greater trochanter fracture occurred in the DAA group (p=0.155). Conclusion: The DAA performed in the ordinary operation table using a short femoral stem showed post-operative early functional recovery. Because a simple to use fluoroscope was used during surgery with an anatomical position familiar to the surgeon, it is considered to be useful for the insertion of implants into the desired position and for an approach that is useful for the prevention of leg length differences.

• Journal of the Korean Orthopaedic Association
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• v.55 no.6
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• pp.503-510
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• 2020

Purpose: Bipolar hemiarthroplasty is used as an alternative to open reduction and internal fixation for unstable intertrochanteric fractures in elderly patients. Recent advances in medical systems and technologies have resulted in increased survival rates after intertrochanteric fractures of the femur, requiring selection of the appropriate femoral stems considering the mid- to long-term duration of survival. Hemiarthroplasty was performed for unstable intertrochanteric fractures using a double tapered quadrilateral femoral stem (C2 stem), and the clinical and radiological results were evaluated as a five-year follow-up post-surgery. Materials and Methods: From January 2004 to December 2013, 43 patients (43 hips) who underwent hemiarthroplasty with a C2 stem were enrolled in this study. Their mean age was 78.6 years (range, 70-84 years), and the mean follow-up period was 85.4 months (range, 60-96 months). During the follow-up period, clinical parameters, such as the changes in pain, walking ability, and functional status, were examined. Radiologically, changes in the proximal femur, such as osteoporosis and bone resorption of cortical bone, were noted. Complications that occurred during the follow-up period, such as dislocation and prosthetic features, were also reviewed. Results: Initially, the pain was relieved postoperatively, but it increased four years after surgery. The walking ability was reduced by two steps in nine patients after 60 months, and the Harris hip score was reduced significantly postoperatively after two to three years. Radiologically, cortical osteoporosis occurred in 14 patients. Five patients developed cortical bone resorption. Four of them showed nonunion of the trochanteric fracture fragments, and three of them suffered reverse oblique fractures. Conclusion: Careful selection considering the general health condition and remaining lifespan of the patient would be necessary for primary hip hemiarthroplasty using a 3C type cementless femoral stem for unstable intertrochanteric fractures in elderly patients with osteoporosis.