Publications by authors named "Myung Chul Lee"

339 Publications

Changes in the femoral varus and rotational profiles are correlated in women with varus osteoarthritic lower limbs.

Arch Orthop Trauma Surg 2021 Aug 2. Epub 2021 Aug 2.

Department of Orthopedic Surgery, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul, 110-744, Republic of Korea.

Introduction: Previous studies have reported the relationship between coronal alignment of the lower limbs and the rotational profile of the femur and tibia. However, the relationship between coronal alignment of the femur and tibia and their rotational profiles in patients with varus osteoarthritic knees is unclear.

Methods: One hundred women with varus osteoarthritic knees (varus OA group) and 50 women with neutrally aligned lower limbs without osteoarthritis (non-OA group) were evaluated retrospectively. The coronal alignment and rotational profile of the femur and tibia were evaluated, and the correlation between coronal alignment and rotational profile was analyzed, respectively.

Results: The femoral anteversion, posterior condylar angle of the distal femur, and tibial torsion were significantly smaller in the varus OA group than in the non-OA group. In the varus OA group, the femoral anteversion and rotational profile of the distal femur had significantly negative correlations with the degree of femoral varus, while tibial torsion was not related to the degree of tibial varus. In the non-OA group, there was no relationship between coronal alignment and rotational profiles of the femur and tibia in both the varus OA and non-OA groups.

Conclusion: Femoral anteversion and the rotational profile of the distal femur were negatively correlated with the degree of femoral varus in Asian women with varus osteoarthritic knees. This study enhanced the understanding of the relationship between changes in coronal alignment of the femur and tibia and their rotational profiles in patients with varus osteoarthritic lower limbs, although this study was limited by the small sample sizes and methodological quality.
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http://dx.doi.org/10.1007/s00402-021-04094-6DOI Listing
August 2021

Enhanced Osteogenesis of Dental Pulp Stem Cells In Vitro Induced by Chitosan-PEG-Incorporated Calcium Phosphate Cement.

Polymers (Basel) 2021 Jul 9;13(14). Epub 2021 Jul 9.

Department of Biosystems Engineering, Seoul National University, Seoul 08826, Korea.

The use of bone graft materials is required for the treatment of bone defects damaged beyond the critical defect; therefore, injectable calcium phosphate cement (CPC) is actively used after surgery. The application of various polymers to improve injectability, mechanical strength, and biological function of injection-type CPC is encouraged. We previously developed a chitosan-PEG conjugate (CS/PEG) by a sulfur (VI) fluoride exchange reaction, and the resulting chitosan derivative showed high solubility at a neutral pH. We have demonstrated the CPC incorporated with a poly (ethylene glycol) (PEG)-grafted chitosan (CS/PEG) and developed CS/PEG CPC. The characterization of CS/PEG CPC was conducted using Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The initial properties of CS/PEG CPCs, such as the pH, porosity, mechanical strength, zeta potential, and in vitro biocompatibility using the WST-1 assay, were also investigated. Moreover, osteocompatibility of CS/PEG CPCs was carried out via Alizarin Red S staining, immunocytochemistry, and Western blot analysis. CS/PEG CPC has enhanced mechanical strength compared to CPC, and the cohesion test also demonstrated in vivo stability. Furthermore, we determined whether CS/PEG CPC is a suitable candidate for promoting the osteogenic ability of Dental Pulp Stem Cells (DPSC). The elution of CS/PEG CPC entraps more calcium ion than CPC, as confirmed through the zeta potential test. Accordingly, the ion trapping effect of CS/PEG is considered to have played a role in promoting osteogenic differentiation of DPSCs. The results strongly suggested that CS/PEG could be used as suitable additives for improving osteogenic induction of bone substitute materials.
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http://dx.doi.org/10.3390/polym13142252DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8309336PMC
July 2021

Long-term Outcomes of Anterior Cruciate Ligament Reconstruction Using Quadriceps Tendon-Patellar Bone Autograft.

Orthop J Sports Med 2021 Jun 9;9(6):23259671211017474. Epub 2021 Jun 9.

Department of Orthopedic Surgery, Seoul National University Hospital, Seoul, Republic of Korea.

Background: To date, there have been few studies on the outcomes of anterior cruciate ligament reconstruction (ACLR) using quadriceps tendon-patellar bone (QTPB) autograft.

Purpose: To evaluate the long-term clinical outcomes of ACLR using QTPB autograft.

Study Design: Case series; Level of evidence, 4.

Methods: We retrospectively reviewed 139 patients who underwent primary ACLR with QTPB autografts and had at least 7 years of postoperative follow-up data. Instability, clinical scores, donor-site morbidity, radiographic progression of osteoarthritis, and any associated complications were assessed.

Results: The proportion of knees classified as grade >1 on the anterior drawer, Lachman, and pivot-shift tests decreased significantly postsurgically (from 47.4% to 5.0%, 48.9% to 4.3%, and 53.3% to 5.0%, respectively; < .001 for all). The mean clinical scores at the final follow-up were 89.8, 81.0, and 4.4 for the Lysholm, International Knee Documentation Committee, and Tegner Activity Scale, respectively. The results of the Cybex II dynamometer isokinetic test showed decreases in flexion and extension strength at both 60° and 180° per second, which persisted until the final follow-up visit. About one-fifth (19.4%) of the patients had osteoarthritis (Kellgren-Lawrence grade ≥1) before surgery, which increased to 33.8% at the final follow-up. The overall complication rate was 23.2%, and about one-third of the patients who experienced complications underwent revision surgery as a result of graft rupture and residual instability.

Conclusion: In the current study, ACLR using QTPB autograft provided satisfactory long-term clinical results, with acceptable rates of complication and donor-site morbidity.
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http://dx.doi.org/10.1177/23259671211017474DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8193668PMC
June 2021

A high degree of knee flexion after TKA promotes the ability to perform high-flexion activities and patient satisfaction in Asian population.

BMC Musculoskelet Disord 2021 Jun 21;22(1):565. Epub 2021 Jun 21.

Department of Orthopaedic Surgery, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul, 03080, South Korea.

Background: This study investigated whether achieving a higher degree of knee flexion after TKA promoted the ability to perform high-flexion activities, as well as patient satisfaction and quality of life.

Methods: Clinical data on 912 consecutive primary TKA cases involving a single high-flexion posterior stabilized fixed-bearing prosthesis were retrospectively analyzed. Demographic and clinical data were collected, including knee flexion angle, the ability to perform high-flexion activities, and patient satisfaction and quality of life.

Results: Of the cases, 619 (68%) achieved > 130° of knee flexion after TKA (high flexion group). Knee flexion angle and clinical scores showed significant annual changes, with the maximum improvement seen at 5 years and slight deterioration observed at 10 years postoperatively. In the high flexion group, more than 50% of the patients could not kneel or squat, and 35% could not stand up from on the floor. Multivariate analysis revealed that > 130° of knee flexion, the ability to perform high-flexion activities (sitting cross-legged and standing up from the floor), male gender, and bilateral TKA were significantly associated with patient satisfaction after TKA, while the ability to perform high-flexion activities (sitting cross-legged and standing up from the floor), male gender, and bilateral TKA were significantly associated with patient quality of life after TKA.

Conclusions: High knee flexion angle (> 130°) after TKA increased the ease of high-flexion activities and patient satisfaction. The ease of high-flexion activities also increased quality of life after TKA in our Asian patients, who frequently engage in these activities in daily life.
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http://dx.doi.org/10.1186/s12891-021-04369-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8215776PMC
June 2021

Efficacy and Safety of Bioabsorbable Bone Hemostatic Agent in Total Knee Arthroplasty: A Prospective Randomized Controlled Trial.

Clin Appl Thromb Hemost 2021 Jan-Dec;27:10760296211023589

Department of Orthopedic Surgery, 37990Seoul National University College of Medicine, Jongno-gu, Seoul, South Korea.

Although a bioabsorbable bone hemostatic agent (BBHA) was developed approximately 20 years ago to overcome the shortcomings of conventional bone wax, its bleeding control capacity has not yet been studied. This study was aimed at investigating the efficacy and safety of BBHA in total knee arthroplasty (TKA). Sixty-two patients who underwent unilateral primary TKA for knee osteoarthritis were included and randomized to the control or BBHA group. Before releasing the tourniquet, BBHA was applied on the bone-cut surface that was not covered by implants. The primary variable was the drainage volume during the postoperative period. The secondary outcomes were total estimated blood loss (EBL), hemoglobin level, hematocrit level, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) level, range of motion (ROM), pain visual analog scale (VAS) score, and rate of complications. There were no significant differences in drainage volume or EBL between the 2 groups. Hemoglobin and hematocrit levels were higher in the BBHA group during the 4-week postoperative period; however, the intergroup differences were not significant. The ESR, CRP, ROM, and pain VAS scores in the BBHA group were not significantly different from the corresponding values in the control group. No specific complications were observed. Although BBHA was found to be safe without complications, it did not decrease bleeding after TKA in general cases. Further studies are necessary to evaluate the efficacy of BBHA in patients with coagulation problems.
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http://dx.doi.org/10.1177/10760296211023589DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8202333PMC
June 2021

Risk factors of de novo hyperextension developed after posterior cruciate ligament substituting total knee arthroplasty: a matched case-control study.

Knee Surg Sports Traumatol Arthrosc 2021 May 24. Epub 2021 May 24.

Department of Orthopaedic Surgery, Seoul National University Hospital, 101 Daehak-Ro Jongno-Gu, Seoul, 03080, Republic of Korea.

Purpose: To investigate factors contributing to the de novo hyperextension after posterior cruciate ligament substituting (PS) total knee arthroplasty (TKA).

Methods: Through a retrospective case-control study, de novo hyperextension patients were compared with patients without hyperextension after primary PS TKA. Eighty-five hyperextension patients were compared with 85 patients in a control group matched by age, sex, surgeon and implant. The clinical and radiographic parameters, including the mechanical axis (MA), joint line convergence angle (JLCA), posterior tibial slope angle (PTSA), posterior condylar offset (PCO), and the gamma angle, were evaluated preoperatively and immediate postoperatively. Comparisons between the two groups and logistic regression analysis were performed to investigate factors contributing to de novo hyperextension.

Results: Among the clinical factors, preoperative flexion contracture was less (5° ± 6° vs. 11° ± 6°, p < 0.001) and the range of motion was greater (125° ± 12° vs. 118° ± 5°, p = 0.041) in the de novo hyperextension group than in the control group. Among the radiographic parameters, preoperative and postoperative JLCA were greater (8.1° ± 4.4° vs. 6.1° ± 3.5°, p < 0.001, 1.0° ± 1.3° vs. 0.2° ± 0.8°, p = 0.002, respectively), postoperative PTSA was greater (3.7° ± 2.0° vs. 3.3° ± 1.6°, p < 0.001) and preoperative and postoperative PCO were less in the hyperextension group than in the control group (26.3 mm ± 3.3 mm vs. 29.1 mm ± 3.2 mm, p < 0.001, 26.4 mm ± 3.2 mm vs. 29.1 mm ± 3.0 mm, p < 0.001, respectively), whereas, change in PCO was greater in the hyperextension group (1.1 mm ± 7.7 mm vs. - 0.1 mm ± 3.3 mm, p < 0.001). In multivariate analysis, the degree of medial soft tissue release [odds ratio (OR) 2.83, p = 0.003], flexion contracture [OR 0.86, p = 0.028], postoperative JLCA [OR 2.45, p = 0.004], preoperative PCO and a change in PCO [OR 0.74, p = 0.002, OR 1.89, p = 0.001, respectively] were the factors associated with de novo hyperextension.

Conclusions: An increased degree of medial soft tissue release, small preoperative flexion contracture, increased postoperative JLCA, decreased preoperative PCO and increased change in PCO were risk factors of de novo hyperextension.

Level Of Evidence: III.
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http://dx.doi.org/10.1007/s00167-021-06618-4DOI Listing
May 2021

TGFβ1-Induced Transglutaminase-2 Triggers Catabolic Response in Osteoarthritic Chondrocytes by Modulating MMP-13.

Tissue Eng Regen Med 2021 Oct 20;18(5):831-840. Epub 2021 May 20.

Department of Orthopaedic Surgery, Seoul National University Hospital, Seoul National University College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul, 03080, Republic of Korea.

Background: Transforming growth factor beta 1 (TGFβ1) plays an essential role in maintaining cartilage homeostasis. TGFβ1 is known to upregulate anabolic processes in articular cartilage, but the role of TGFβ1 in chondrocyte catabolism remains unclear. Thus, we examined whether TGFβ1 increases catabolic processes in the osteoarthritic joint via transglutaminase 2 (TG2). In this study, we investigated whether interplay between TGFβ1 and TG2 mediates chondrocyte catabolism and cartilage degeneration in osteoarthritis.

Methods: To investigate the role of TGFβ1 and TG2 in osteoarthritis, we performed immunostaining to measure the levels of TGFβ1 and TG2 in 6 human non-osteoarthritic and 16 osteoarthritic joints. We conducted quantitative reverse transcription polymerase chain reaction and western blot analysis to investigate the relationship between TGFβ1 and TG2 in chondrocytes and determined whether TG2 regulates the expressions of matrix metalloproteinase (MMP)-13, type II, and type X collagen. We also examined the extent of cartilage degradation after performing anterior cruciate ligament transection (ACLT) and destabilization of the medial meniscus (DMM) surgery in TG2 knock-out mice.

Results: We confirmed the overexpression of TGFβ1 and TG2 in human osteoarthritic cartilage compared with non-osteoarthritic cartilage. TGFβ1 treatment significantly increased the expression of TG2 via p38 and ERK activation. TGFβ1-induced TG2 also elevated the level of MMP-13 and type X collagen via NF-κB activation in chondrocytes. Cartilage damage after ACLT and DMM surgery was less severe in TG2 knock-out mice compared with wild-type mice.

Conclusion: TGFβ1 modulated catabolic processes in chondrocytes in a TG2-dependent manner. TGFβ1-induced TG2 might be the therapeutic target for treating cartilage degeneration and osteoarthritis.
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http://dx.doi.org/10.1007/s13770-021-00342-3DOI Listing
October 2021

Effect of Posterior Tibial Slope Change on Postoperative Range of Motion and Clinical Outcomes after Posterior Cruciate-Substituting Total Knee Arthroplasty.

J Knee Surg 2021 May 15. Epub 2021 May 15.

Department of Orthopedic Surgery, Seoul National University Hospital, Seoul, Korea (the Republic of).

The posterior tibial slope (PTS) is usually adjusted by less than 5 degrees, without considering its individual difference, during posterior cruciate-substituting (PS) total knee arthroplasty (TKA). The effect of these individual changes of PTS would be important because clinical results depending on postoperative PTS were reported conflictingly. We investigated the effect of the change in PTS on the postoperative range of motion (ROM) and clinical scores after PS TKA. We retrospectively reviewed 164 knees from 107 patients who underwent PS TKA with a 2-year follow-up. We analyzed the preoperative and postoperative PTS, ROM, visual analog scale pain scale, Western Ontario and McMaster University Index (WOMAC), Hospital for Special Surgery Knee Score, Knee Society Score, and Forgotten Joint Score (FJS). The association of the absolute change in PTS with ROM and clinical scores was analyzed using correlation analysis and multiple regression analysis. As a result, the mean PTS and mean ROM changed from 9.6 ±  3.4 and 120.1 ±  15.4 degrees preoperatively to 2.0 ±  1.3 and 128.4 ±  9.3 degrees postoperatively, and the mean PTS change was 7.6 ±  3.5 degrees. The PTS change had no statistically significant association with the postoperative ROM and clinical scoring systems, although it did have a weak positive correlation with WOMAC function, No 10 (difficulty in rising from sitting) (correlation coefficient = 0.342,  = 0.041), and moderate positive correlation with the FJS, No. 6 (awareness when climbing stairs) (correlation coefficient = 0.470,  = 0.001). The authors concluded that the amount of change in PTS did not affect the postoperative ROM and clinical scores, although proximal tibial resection with a constant target of PTS resulted in individually different changes in the PTS after PS TKA.
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http://dx.doi.org/10.1055/s-0041-1729967DOI Listing
May 2021

Federated Learning for Thyroid Ultrasound Image Analysis to Protect Personal Information: Validation Study in a Real Health Care Environment.

JMIR Med Inform 2021 May 18;9(5):e25869. Epub 2021 May 18.

Institute of Medical & Biological Engineering, Medical Research Center, Seoul National University College of Medicine, Seoul, Republic of Korea.

Background: Federated learning is a decentralized approach to machine learning; it is a training strategy that overcomes medical data privacy regulations and generalizes deep learning algorithms. Federated learning mitigates many systemic privacy risks by sharing only the model and parameters for training, without the need to export existing medical data sets. In this study, we performed ultrasound image analysis using federated learning to predict whether thyroid nodules were benign or malignant.

Objective: The goal of this study was to evaluate whether the performance of federated learning was comparable with that of conventional deep learning.

Methods: A total of 8457 (5375 malignant, 3082 benign) ultrasound images were collected from 6 institutions and used for federated learning and conventional deep learning. Five deep learning networks (VGG19, ResNet50, ResNext50, SE-ResNet50, and SE-ResNext50) were used. Using stratified random sampling, we selected 20% (1075 malignant, 616 benign) of the total images for internal validation. For external validation, we used 100 ultrasound images (50 malignant, 50 benign) from another institution.

Results: For internal validation, the area under the receiver operating characteristic (AUROC) curve for federated learning was between 78.88% and 87.56%, and the AUROC for conventional deep learning was between 82.61% and 91.57%. For external validation, the AUROC for federated learning was between 75.20% and 86.72%, and the AUROC curve for conventional deep learning was between 73.04% and 91.04%.

Conclusions: We demonstrated that the performance of federated learning using decentralized data was comparable to that of conventional deep learning using pooled data. Federated learning might be potentially useful for analyzing medical images while protecting patients' personal information.
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http://dx.doi.org/10.2196/25869DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8170555PMC
May 2021

Which orally administered antithrombotic agent is most effective for preventing venous thromboembolism after total knee arthroplasty? A propensity score-matching analysis.

Knee Surg Relat Res 2021 Mar 20;33(1):10. Epub 2021 Mar 20.

Department of Orthopedic Surgery, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul, 110-744, South Korea.

Purpose: Even today, total knee arthroplasty (TKA) is associated with venous thromboembolism (VTE). The purpose of our study is to report the incidence of postoperative VTE and to compare the efficacy of commonly used orally administered antithrombotic agents.

Materials And Methods: Seven hundred ad ninety-nine patients who underwent primary TKA were retrospectively reviewed. The patients were prescribed one of three antithrombotic agents: aspirin (n = 168), rivaroxaban (n = 117), or apixaban (n = 514). Before surgery, patient demographics and risk factors were matched via propensity scoring. After surgery, all three groups took the agent for 7 days and underwent ultrasonography to check for VTE.

Results: The overall incidence of postoperative VTE was 15.4% (123/799). Only one patient developed symptomatic VTE. Female sex and staged bilateral TKA were risk factors for postoperative VTE. The postoperative VTE rates in the aspirin, rivaroxaban, and apixaban groups were 16.2%, 6.0%, and 17.1%, respectively, significantly lower in the rivaroxaban group (p <  0.02). The majority of VTEs in all three groups were calf-vein thromboses.

Conclusions: All agents showed enough efficacy as antithrombotic agents. Considering that aspirin is inexpensive, aspirin is a cost-effective option for preventing postoperative VTE.
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http://dx.doi.org/10.1186/s43019-021-00093-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7981904PMC
March 2021

Development of novel gene carrier using modified nano hydroxyapatite derived from equine bone for osteogenic differentiation of dental pulp stem cells.

Bioact Mater 2021 Sep 13;6(9):2742-2751. Epub 2021 Feb 13.

Department of Biosystems Engineering, Seoul National University, Seoul, 08826, Republic of Korea.

Hydroxyapatite (HA) is a representative substance that induces bone regeneration. Our research team extracted nanohydroxyapatite (EH) from natural resources, especially equine bones, and developed it as a molecular biological tool. Polyethylenimine (PEI) was used to coat the EH to develop a gene carrier. To verify that PEI is well coated in the EH, we first observed the morphology and dispersity of PEI-coated EH (pEH) by electron microscopy. The pEH particles were well distributed, while only the EH particles were not distributed and aggregated. Then, the existence of nitrogen elements of PEI on the surface of the pEH was confirmed by EDS, calcium concentration measurement and fourier transform infrared spectroscopy (FT-IR). Additionally, the pEH was confirmed to have a more positive charge than the 25 kD PEI by comparing the zeta potentials. As a result of pGL3 transfection, pEH was better able to transport genes to cells than 25 kD PEI. After verification as a gene carrier for pEH, we induced osteogenic differentiation of DPSCs by loading the BMP-2 gene in pEH (BMP-2/pEH) and delivering it to the cells. As a result, it was confirmed that osteogenic differentiation was promoted by showing that the expression of osteopontin (OPN), osteocalcin (OCN), and runt-related transcription factor 2 (RUNX2) was significantly increased in the group treated with BMP-2/pEH. In conclusion, we have not only developed a novel nonviral gene carrier that is better performing and less toxic than 25 kD PEI by modifying natural HA (the agricultural byproduct) but also proved that bone differentiation can be effectively promoted by delivering BMP-2 with pEH to stem cells.
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http://dx.doi.org/10.1016/j.bioactmat.2021.01.020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7895645PMC
September 2021

Faster bone union progression and less sclerosis at the osteotomy margin after medial opening-wedge high tibial osteotomy using highly porous β-tricalcium phosphate granules versus allogeneic bone chips: A matched case-control study.

Knee 2021 Mar 4;29:33-41. Epub 2021 Feb 4.

Department of Orthopedic Surgery, Seoul National University Hospital, Seoul, South Korea. Electronic address:

Background: This study compared bone union progression using highly porous (80% porosity) β-tricalcium phosphate (β-TCP) granules or allogeneic bone chips in the gap created by medial opening-wedge high tibial osteotomy (MOWHTO).

Methods: The study population consisted of 54 patients who received MOWHTO with locking plate fixation: 27 patients using highly porous β-TCP granules, and 27 age- and sex-matched patients using allogeneic bone chips. Bone union progression was evaluated 1, 3, 6, and 12 months postoperatively. The presence of radiographic sclerosis at the osteotomy margin was also assessed.

Results: Among all patients, the highest degree of bone union observed 12 months postoperatively was grade 4. As postoperative time passed, bone union progression of highly porous β-TCP granules increased linearly and was statistically significant compared with that of cancellous allogeneic bone chips (P = 0.014). The presence of radiographic sclerosis at the osteotomy margin was significantly less common in the β-TCP group than in the allograft group (P = 0.003) and was the strongest predictor of delayed progress of bone union (odds ratio = 6.16, P = 0.006).

Conclusions: Patients who underwent MOWHTO using highly porous β-TCP granules had faster new bone remodeling, less radiographic sclerosis at the osteotomy margin, and no inferior clinical outcome compared with allogeneic bone chips, as determined at the 1-year follow up. The presence of radiographic sclerosis at the osteotomy margin in patients undergoing MOWHTO using allogeneic bone or synthetic bone substitute may indicate delayed progress of bone union.
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http://dx.doi.org/10.1016/j.knee.2021.01.017DOI Listing
March 2021

A Flexible Intramedullary Guide Can Reduce the Anteroposterior Oversizing of Femoral Components Used in Total Knee Arthroplasty in Patients with Osteoarthritis and Severe Distal Femoral Sagittal Bowing.

J Knee Surg 2021 Feb 5. Epub 2021 Feb 5.

Department of Orthopedic Surgery, Seoul National University Hospital, Seoul, South Korea.

Traditionally, a rigid intramedullary rod has been used as the reference guide for femoral cutting in total knee arthroplasty (TKA). However, correct positioning of this rigid rod is difficult, especially in the knees with severe distal femoral sagittal bowing. A flexible intramedullary rod has been developed to address this problem. This study was performed to compare the sagittal alignment and clinical outcomes of TKAs performed with flexible and rigid femoral intramedullary guides. Thirty-eight knees that underwent primary TKAs with flexible intramedullary rods as femoral cutting guides were matched according to patient height and sex with 38 knees that underwent TKAs using conventional rigid rods. Clinical outcomes, including the range of motion and functional scores, and radiological variables, including the distal femoral bowing angle (DFBA), femoral component flexion angle (FFA), and mediolateral overhang and anteroposterior (AP) oversizing of femoral components, were evaluated. Clinical and radiological outcomes did not differ significantly between the flexible rod and conventional rigid rod groups. A subgroup analysis of knees with severe distal femoral sagittal bowing (DFBA >4 degrees) showed that the FFA was significantly larger in the flexible rod group than in the rigid rod group, with an average difference of 3 degrees (5.2 ± 2.4 vs. 2.2 ± 1.6 degrees, respectively,  = 0.022). In addition, the incidence of AP oversizing of femoral components was lower in the flexible rod group than in the rigid rod group (11.1 vs. 60.0%, respectively,  = 0.027). Relative to TKA with a rigid rod, TKA performed with a flexible femoral intramedullary guide resulted in more flexed sagittal alignment of femoral components in patients with severe distal femoral sagittal bowing. This greater flexion of the femoral component resulted in less AP oversizing. However, the use of a flexible rod had no impact on short-term clinical outcomes.
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http://dx.doi.org/10.1055/s-0040-1722325DOI Listing
February 2021

3D-Printed Poly(ε-Caprolactone)/Hydroxyapatite Scaffolds Modified with Alkaline Hydrolysis Enhance Osteogenesis In Vitro.

Polymers (Basel) 2021 Jan 14;13(2). Epub 2021 Jan 14.

Division of Agro-System Engineering, College of Agriculture and Life Science, Gyeongsang National University, Jinju 52828, Korea.

The 3D-printed bioactive ceramic incorporated Poly(ε-caprolactone) (PCL) scaffolds show great promise as synthetic bone graft substitutes. However, 3D-printed scaffolds still lack adequate surface properties for cells to be attached to them. In this study, we modified the surface characteristics of 3D-printed poly(ε-caprolactone)/hydroxyapatite scaffolds using O2 plasma and sodium hydroxide. The surface property of the alkaline hydrolyzed and O2 plasma-treated PCL/HA scaffolds were evaluated using field-emission scanning microscopy (FE-SEM), Alizarin Red S (ARS) staining, and water contact angle analysis, respectively. The in vitro behavior of the scaffolds was investigated using human dental pulp-derived stem cells (hDPSCs). Cell proliferation of hDPSCs on the scaffolds was evaluated via immunocytochemistry (ICC) and water-soluble tetrazolium salt (WST-1) assay. Osteogenic differentiation of hDPSCs on the scaffolds was further investigated using ARS staining and Western blot analysis. The result of this study shows that alkaline treatment is beneficial for exposing hydroxyapatite particles embedded in the scaffolds compared to O2 plasma treatment, which promotes cell proliferation and differentiation of hDPSCs.
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http://dx.doi.org/10.3390/polym13020257DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7830212PMC
January 2021

The Influence of Non-Linear Frequency Compression on the Perception of Speech and Music in Patients with High Frequency Hearing Loss.

J Audiol Otol 2021 Apr 19;25(2):80-88. Epub 2021 Jan 19.

Department of Otorhinolaryngology-Head and Neck Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.

Background And Objectives: Non-linear frequency compression (NLFC) technology compresses and shifts higher frequencies into a lower frequency area that has better residual hearing. Because consonants are uttered in the high-frequency area, NLFC could provide better speech understanding. The aim of this study was to investigate the clinical effectiveness of NLFC technology on the perception of speech and music in patients with high-frequency hearing loss.

Subjects And Methods: Twelve participants with high-frequency hearing loss were tested in a counter-balanced order, and had two weeks of daily experience with NLFC set on/off prior to testing. Performance was repeatedly evaluated with consonant tests in quiet and noise environments, speech perception in noise, music perception and acceptableness of sound quality rating tasks. Additionally, two questionnaires (the Abbreviated Profile of Hearing Aid Benefit and the Korean version of the International Outcome Inventory-Hearing Aids) were administered.

Results: Consonant and speech perception improved with hearing aids (NLFC on/off conditions), but there was no significant difference between NLFC on and off states. Music perception performances revealed no notable difference among unaided and NLFC on and off states. The benefits and satisfaction ratings between NLFC on and off conditions were also not significantly different, based on questionnaires, however great individual variability preferences were noted.

Conclusions: Speech perception as well as music perception both in quiet and noise environments was similar between NLFC on and off states, indicating that real world benefits from NLFC technology may be limited in Korean adult hearing aid users.
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http://dx.doi.org/10.7874/jao.2020.00276DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8062242PMC
April 2021

Aligned Nanofiber-Guided Bone Regeneration Barrier Incorporated with Equine Bone-Derived Hydroxyapatite for Alveolar Bone Regeneration.

Polymers (Basel) 2020 Dec 25;13(1). Epub 2020 Dec 25.

Department of Biosystems Engineering, Seoul National University, Seoul 08826, Korea.

Post-surgery failure of dental implants due to alveolar bone loss is currently critical, disturbing the quality of life of senior dental patients. To overcome this problem, bioceramic or bone graft material is loaded into the defect. However, connective tissue invasion instead of osteogenic tissue limits bone tissue regeneration. The guided bone regeneration concept was adapted to solve this problem and still has room for improvements, such as biochemical similarity or oriented structure. In this article, an aligned electrospun-guided bone regeneration barrier with xenograft equine bone-derived nano hydroxyapatite (EBNH-RB) was fabricated by electrospinning EBNH/PCL solution on high-speed rotating drum collector and fiber characterization, viability and differentiation enhancing properties of mesenchymal dental pulp stem cell on the barrier was determined. EBNH-RB showed biochemical and structural similarity to natural bone tissue electron microscopy image analysis and x-ray diffractometer analysis, and had a significantly better effect in promoting osteogenesis based on the increased bioceramic content by promoting cell viability, calcium deposition and osteogenic marker expression, suggesting that they can be successfully applied to regenerate alveolar bone as a guided bone regeneration barrier.
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http://dx.doi.org/10.3390/polym13010060DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7796229PMC
December 2020

Is a Titanium Implant for Total Knee Arthroplasty Better? A Randomized Controlled Study.

J Arthroplasty 2021 04 12;36(4):1302-1309. Epub 2020 Nov 12.

Department of Orthopedic Surgery, Seoul National University College of Medicine, Seoul, South Korea.

Background: Lighter weight and lower modulus are potential advantages of titanium (Ti) implants over cobalt chrome (CoCr) implants in total knee arthroplasty (TKA). This study was conducted to determine whether Ti implants in TKA resulted in better clinical outcomes and radiologic results.

Methods: One hundred and eight patients (216 knees) with knee arthritis warranting bilateral primary TKA were randomly allocated to undergo Ti rotating-platform TKA in one knee and CoCr rotating-platform TKA in the contralateral knee. The mean follow-up period was 5.3 years (range, 1-7 years). The weight of Ti implants was one-third lighter than that of CoCr implants (133.9 g vs 390.1 g, P < .01). Clinical outcomes were evaluated using clinical scores, patient preferences (lightness, comfort, naturalness, and satisfaction), gait analysis (kinetic and kinematic data), range of motion, and degree of pain. Radiologic results were evaluated based on the radiolucent line (RLL), degree of medial tibial bone loss, and loosening as seen on X-ray.

Results: No significant differences were observed in clinical scores or patient preference. Regarding implant weight, approximately 70% of patients did not perceive the Ti implant as lighter. No significant differences were observed in gait analysis, range of motion, or degree of pain. The RLL was seen in 9% of the Ti implant group and 19% of the CoCr implant group.

Conclusion: The lighter Ti implant did not show any clinical benefit over CoCr implants. The lightness of the Ti implant is not sufficient to matter or be noticeable. However, the Ti implant showed lower rate of RLL than the CoCr implant.

Level Of Evidence: level I, randomized controlled trial.
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http://dx.doi.org/10.1016/j.arth.2020.11.010DOI Listing
April 2021

Isoflavones, anthocyanins, phenolic content, and antioxidant activities of black soybeans (Glycine max (L.) Merrill) as affected by seed weight.

Sci Rep 2020 11 17;10(1):19960. Epub 2020 Nov 17.

National Agrobiodiversity Center, National Institute of Agricultural Sciences, Rural Development Administration, Jeonju, 54874, Korea.

Seed weight is regulated by several genes which in turn could affect the metabolite contents, yield, and quality of soybean seeds. Due to these, seed weight is receiving much attention in soybean breeding. In this study, seeds of 24 black soybean varieties and a reference genotype were grown in Korea, and grouped as small (< 13 g), medium (13-24 g), and large (> 24 g) seeds based on their seed weight. The contents of six anthocyanins, twelve isoflavones, and total phenolic, and the antioxidant activities were determined, and the association of each with seed weight was analyzed. The total anthocyanin (TAC) and total isoflavone (TIC) contents were in the ranges of 189.461-2633.454 mg/100 g and 2.110-5.777 mg/g, respectively and were significantly different among the black soybean varieties. By comparison, the average TAC and TIC were the highest in large seeds than in small and medium seeds while the total phenolic content (TPC) was in the order of small seeds > large seeds > medium seeds. Besides, large seeds showed the maximum 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging activity, whereas small seeds showed the maximum ferric reducing antioxidant power (FRAP) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS) scavenging activities. FRAP activity was positively associated with TIC and TAC, the former association being significant. On the other hand, ABTS and DPPH activities were positively correlated to TPC, the later association being significant. Overall, our findings demonstrated the influence of seed weight on anthocyanin, isoflavone, and phenolic contents and antioxidant activities in black soybeans. Besides, the dominant anthocyanins and isoflavones were the principal contributors to the variations observed in the black soybean varieties, and hence, these components could be selectively targeted to discriminate a large population of black soybean genetic resources.
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http://dx.doi.org/10.1038/s41598-020-76985-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7673111PMC
November 2020

Combination treatment utilizing fractional ablative and continuous wave CO lasers for hypertrophic burn scars.

Burns 2021 Aug 7;47(5):1084-1093. Epub 2020 Nov 7.

Department of Plastic and Reconstructive Surgery, Konkuk University School of Medicine, Seoul, South Korea. Electronic address:

Background: Hypertrophic scars are devastating outcomes of severe burn injuries, producing physical and mental burdens. Adequate treatment is of benefit to relieve these burdens. Laser therapy has shown scar reducing effects. In this study, we compared outcomes after combination of two different lasers or single laser treatment to treat severe hypertrophic burn scars.

Methods: Forty patients with hypertrophic burn scars were included in one of two therapeutic groups: continuous wave CO laser and fractional ablative CO laser group (group 1, n = 20) or fractional ablative CO laser alone group (group 2, n = 20). Hypertrophic scars were evaluated by the observer-rated Vancouver Scar Scale (VSS) before and after treatment and by patient-completed questionnaires after treatment. Comparative analyses were performed before and after treatment, and time-dependent improvement was also analyzed.

Results: Forty patients (54 hypertrophic scars) completed the laser treatment protocols. Group 1 exhibited significantly more improvement in VSS vascularity, pliability, and height indices than group 2 (p < 0.05). Time-dependent analysis of total VSS scores suggested that group 1 experienced more improvement during a shorter treatment period (p < 0.05). For patient-reported outcomes, group 1 noted better grades than group 2 in four indices, namely scar appearance, scar thickness, pain, and pruritus (p < 0.05).

Conclusion: Effective scar reduction was achieved using combination laser treatment, with significant improvement in multiple observer- and patient-reported outcomes. The shorter treatment period of the combination method can be a merit, as prolonged hypertrophic scars may increase morbidity. Nonetheless, cautious treatment protocols are necessary to avoid undesirable sequelae related to laser application.
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http://dx.doi.org/10.1016/j.burns.2020.10.015DOI Listing
August 2021

Enhancement of Cartilage Regeneration of Synovial Stem Cells/Hydrogel by Using Transglutaminase-4.

Tissue Eng Part A 2021 06 7;27(11-12):761-770. Epub 2020 Dec 7.

Department of Orthopedic Surgery, Seoul National University College of Medicine, Seoul, Republic of Korea.

Although mesenchymal stem cells (MSCs) transplantation is reportedly a promising strategy for repairing damaged articular cartilage, MSCs-based cartilage tissue engineering has numerous limitations, including poor implanted cell adhesion, phenotypic alteration of cells, regulation of mechanical properties, and engraftment rates after implantation. This study aimed to investigate the efficacy of transplantation of synovium-derived mesenchymal stem cells (SDSCs) encapsulated in a hyaluronic acid/collagen/fibrinogen (HA/COL/FG) composite gel by supplementing recombinant human transglutaminase 4 (rhTG-4) in treating osteochondral defects. RhTG-4 treatment induced the expression of integrin β1 and dynamic actin fiber, enhancing SDSCs adhesion to fibronectin. Supplementation of rhTG-4 significantly induced the proliferation of SDSCs encapsulated in the HA/COL/FG composite gel and increased the hardness of the extracellular matrix. Furthermore, supplementation of rhTG-4 significantly upregulated aggrecan and type II collagen mRNA. Pretreatment with integrin β1 siRNA markedly suppressed TG4-induced actin remodeling, activation mitogen-activated protein kinase (MAPK), and eventually the chondrogenesis-related genes. Moreover, transplantation of SDSCs encapsulated in HA/COL/FG/rhTG-4 composite gel yielded reconstructed tissue resembling native hyaline cartilage. These data suggest that rhTG-4 enhances cartilage regeneration of the SDSCs encapsulated in hydrogel in rabbits. Impact statement In this study, we investigated the effects of recombinant human transglutaminase 4 on the ability of synovium-derived mesenchymal stem cells encapsulated in a hyaluronic acid/collagen/fibrinogen composite gel to repair osteochondral defects. We believe that our study makes a significant contribution to the literature because it explores a method of improving an existing modality to mediate tissue repair.
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http://dx.doi.org/10.1089/ten.TEA.2020.0271DOI Listing
June 2021

Rotational Changes in the Tibia After High Tibial Valgus Osteotomy: A Comparative Study of Lateral Closing Versus Medial Opening Wedge Osteotomy.

Am J Sports Med 2020 12 22;48(14):3549-3556. Epub 2020 Oct 22.

Department of Orthopaedic Surgery, College of Medicine, Seoul National University, Seoul, Republic of Korea.

Background: After high tibial valgus osteotomy (HTO), rotational changes in the tibia may occur, which can affect the biomechanics of the patellofemoral joint and may lead to anterior knee pain.

Purpose: To compare the rotational changes in the tibia between closing wedge HTO (CWHTO) and opening wedge HTO (OWHTO).

Study Design: Cohort study; Level of evidence, 3.

Methods: Among the patients who underwent HTO between May 2012 and August 2015, 53 (28 CWHTO and 25 OWHTO) who had computed tomography scans before and at 1 year after the HTO were included. The following parameters were compared between CWHTO and OWHTO: (1) tibial torsion angle, (2) knee rotation angle, and (3) tibial tuberosity-trochlear groove (TT-TG) distance. During the last follow-up, patients were asked to rate their anterior knee pain when climbing the stairs, using the visual analog scale.

Results: The tibial torsion angle significantly decreased (internal rotation of the distal fragment) after CWHTO (mean ± SD, -2.1°± 4.1°; = .019) and OWHTO (-1.8°± 3.3°; = .029). The knee rotation angle significantly decreased (external rotation of the proximal fragment) after OWHTO (-1.8°± 3.4°; = .039) but was not changed after CWHTO (0.1°± 3.1°; = .859). The mean TT-TG distance significantly decreased after CWHTO (-3.1 ± 3.0 mm; < .001) but increased after OWHTO (2.0 ± 4.3 mm; = .012). At the final follow-up (minimum, 4 years), the visual analog scale pain score during stair climbing was significantly higher after OWHTO than after CWHTO (3.1 ± 1.4 vs 2.2 ± 1.3, = .024).

Conclusion: Internal rotation of the distal fragment occurred after both CWHTO and OWHTO. However, external rotation of the proximal fragment and increased TT-TG distance occurred after OWHTO. Because such rotational changes could affect anterior knee pain, further studies are warranted to investigate the definite relationship between tibial rotational changes and anterior knee pain after HTO.
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http://dx.doi.org/10.1177/0363546520960114DOI Listing
December 2020

A machine learning-based diagnostic model associated with knee osteoarthritis severity.

Sci Rep 2020 09 25;10(1):15743. Epub 2020 Sep 25.

Department of Orthopedic Surgery, Seoul National University Hospital, Seoul National University College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul, 110-744, Korea.

Knee osteoarthritis (KOA) is characterized by pain and decreased gait function. We aimed to find KOA-related gait features based on patient reported outcome measures (PROMs) and develop regression models using machine learning algorithms to estimate KOA severity. The study included 375 volunteers with variable KOA grades. The severity of KOA was determined using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). WOMAC scores were used to classify disease severity into three groups. A total of 1087 features were extracted from the gait data. An ANOVA and student's t-test were performed and only features that were significant were selected for inclusion in the machine learning algorithm. Three WOMAC subscales (physical function, pain and stiffness) were further divided into three classes. An ANOVA was performed to determine which selected features were significantly related to the subscales. Both linear regression models and a random forest regression was used to estimate patient the WOMAC scores. Forty-three features were selected based on ANOVA and student's t-test results. The following number of features were selected from each joint: 12 from hip, 1 feature from pelvic, 17 features from knee, 9 features from ankle, 1 feature from foot, and 3 features from spatiotemporal parameters. A significance level of < 0.0001 and < 0.00003 was set for the ANOVA and t-test, respectively. The physical function, pain, and stiffness subscales were related to 41, 10, and 16 features, respectively. Linear regression models showed a correlation of 0.723 and the machine learning algorithm showed a correlation of 0.741. The severity of KOA was predicted by gait analysis features, which were incorporated to develop an objective estimation model for KOA severity. The identified features may serve as a tool to guide rehabilitation and progress assessments. In addition, the estimation model presented here suggests an approach for clinical application of gait analysis data for KOA evaluation.
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http://dx.doi.org/10.1038/s41598-020-72941-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7519044PMC
September 2020

A web-based machine-learning algorithm predicting postoperative acute kidney injury after total knee arthroplasty.

Knee Surg Sports Traumatol Arthrosc 2020 Sep 3. Epub 2020 Sep 3.

Department of Orthopedic Surgery, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul, 110-744, Korea.

Purpose: Acute kidney injury (AKI) is a deleterious complication after total knee arthroplasty (TKA). The purposes of this study were to identify preoperative risk factors and develop a web-based prediction model for postoperative AKI, and assess how AKI affected the progression to ESRD.

Method: The study included 5757 patients treated in three tertiary teaching hospitals. The model was developed using data on 5302 patients from two hospitals and externally validated in 455 patients from the third hospital. Eighteen preoperative variables were collected and feature selection was performed. A gradient boosting machine (GBM) was used to predict AKI. A tenfold-stratified area under the curve (AUC) served as the metric for internal validation. Calibration was performed via isotonic regression and evaluated using a calibration plot. End-stage renal disease (ESRD) was followed up for an average of 41.7 months.

Results: AKI develops in up to 10% of patients undergoing TKA, increasing the risk of progression to ESRD. The ESRD odds ratio of AKI patients (compared to non-AKI patients) was 9.8 (95% confidence interval 4.3-22.4). Six key predictors of postoperative AKI were selected: higher preoperative levels of creatinine in serum, the use of general anesthesia, male sex, a higher ASA class (> 3), use of a renin-angiotensin-aldosterone system inhibitor, and no use of tranexamic acid (all p < 0.001). The predictive performance of our model was good (area under the curve 0.78 [95% CI 0.74-0.81] in the developmental cohort and improved in the external validation cohort (0.89). Our model can be accessed at https://safetka.net .

Conclusions: A web-based predictive model for AKI after TKA was developed using a machine-learning algorithm featuring six preoperative variables. The model is simple and has been validated to improve both short- and long-term prognoses of TKA patients. Postoperative AKI may lead to ESRD, which surgeons should strive to avoid.

Level Of Evidence: Diagnostic level II.
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http://dx.doi.org/10.1007/s00167-020-06258-0DOI Listing
September 2020

Optimal dose of topical tranexamic acid considering efficacy and safety in total knee arthroplasty: a randomized controlled study.

Knee Surg Sports Traumatol Arthrosc 2021 Oct 31;29(10):3409-3417. Epub 2020 Aug 31.

Department of Orthopedic Surgery, Seoul National University College of Medicine, Seoul, South Korea.

Purpose: This study aimed to evaluate the optimal dosage of topical tranexamic acid (TXA) considering the efficacy and safety for controlling bleeding after total knee arthroplasty (TKA).

Methods: This prospective randomized double-blinded placebo-controlled comparative study included 325 patients scheduled to undergo TKA, who were randomly assigned to five groups based on the topical TXA injection (n = 65 per group): control; group 1, 0.5 g TXA; group 2, 1.0 g TXA; group 3, 2.0 g TXA; and group 4, 3.0 g TXA. The primary outcome was decrease in postoperative hemoglobin levels. The secondary outcomes were blood loss calculated using Good's method, drainage volume, frequency of transfusion, and range of motion (ROM). Plasma TXA levels and complications were also evaluated.

Results: Significant differences were noted in the decrease in hemoglobin levels between the control group and groups 2 (p = 0.0027), 3 (p = 0.005), and 4 (p = 0.001). No significant differences were shown among the experimental groups. Significant differences in total blood loss and frequency of transfusion were noted between the control group and groups 2 (p = 0.004, 0.002, respectively), 3 (p = 0.007, 0.001, respectively), and 4 (p = 0.001, 0.009, respectively) without showing significant differences among the experimental groups. With respect to drainage volume, no significant differences were observed among the groups. The serum TXA levels increased proportionally with the applied dose of topical TXA immediately and at 3 and 6 h postoperatively. Symptomatic deep vein thrombosis or pulmonary embolism was not observed in any group. Other complications related to TXA administration were not detected.

Conclusion: Topical application of 1.0 g or more of TXA shows significant bleeding control without a dose-response relationship. Blood TXA levels increase with the TXA dose following topical TXA application. Therefore, to prevent overdosing and reduce potential complications with ensuring the effectiveness, 1.0 g of TXA is recommended as a topical application.

Level Of Evidence: I.
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http://dx.doi.org/10.1007/s00167-020-06241-9DOI Listing
October 2021

Retroauricular thyroidectomy with a single-arm robotic surgical system: Preclinical cadaveric study.

Head Neck 2020 12 27;42(12):3663-3669. Epub 2020 Aug 27.

Department of Otorhinolaryngology, Severance Hospital, Yonsei University Health System, Yonsei University College of Medicine, Seoul, Republic of Korea.

Background: In this study, we evaluate a new flexible, single-arm robotic system in performing thyroidectomy via a retroauricular approach.

Methods: Four fresh cadavers were used. Technical details of the new system are discussed, and the comprehensive surgical procedures are described step by step.

Results: This single-port flexible system could be used to successfully perform retroauricular thyroidectomy. The ideal angle to dock the patient-side cart was at a 90° angle to the operating table. When the cannula tip was placed 10 to 15 cm away from the skin incision, positioning and full movement of all four instruments without collisions were possible. Three flexible instruments and an endoscope made the robotic dissection more efficient.

Conclusions: We describe the first preclinical evaluation of an innovative, flexible, single-arm robotic surgical system for retroauricular thyroidectomy.
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http://dx.doi.org/10.1002/hed.26436DOI Listing
December 2020

Elastic pneumatic tourniquet cuff can reduce postoperative thigh pain after total knee arthroplasty: a prospective randomized trial.

BMC Musculoskelet Disord 2020 Aug 21;21(1):565. Epub 2020 Aug 21.

Department of Orthopedic Surgery, Seoul National University College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul, 03080, Republic of Korea.

Background: Tourniquet use is associated with complications such as thigh pain, skin problems, and deep vein thrombosis (DVT). This prospective study aimed to evaluate the efficacy and safety of the pneumatic tourniquet system using an elastic cuff and limb occlusion pressure (LOP) in total knee arthroplasty (TKA). The hypothesis of this study was that an elastic cuff tourniquet would result in less postoperative thigh pain after TKA.

Methods: This prospective randomized controlled trial involved a total of 98 patients who underwent primary TKA. They were randomized into two groups: tourniquet system using an elastic cuff and LOP group (Group E) and tourniquet system using a conventional-cuff and LOP group (Group C). Outcomes including postoperative thigh pain assessed using a visual analog scale (VAS), serum muscle enzymes, recommended tourniquet pressure (RTP), bloodlessness of surgical field, surgical time, incidence of DVT, and the frequency of rescue analgesic use after surgery, were compared between groups.

Results: Patients in Group E experienced significantly less thigh pain compared to those in Group C on postoperative day 4 (P = 0.01) and day 7 (P = 0.04). The difference between RTP and systolic blood pressure was significantly lower in Group E (P = 0.045). One case of thigh DVT was found in Group E, while no such cases were found in Group C. One and two cases of poor bloodless surgical fields were observed in Group E and Group C, respectively. There was no significant difference in surgical time, levels of serum muscle enzymes, and the frequency of rescue analgesic use between the two groups.

Conclusions: The pneumatic tourniquet system using an elastic cuff and LOP reduced early postoperative thigh pain more effectively than did the tourniquet system using a conventional cuff and LOP.

Trial Registration: # KCT0003149 . Registered August 17, 2018 - Retrospectively registered.
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http://dx.doi.org/10.1186/s12891-020-03579-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7442977PMC
August 2020

Change in intersegmental foot and ankle motion after a high tibial osteotomy in genu varum patients.

J Orthop Res 2021 01 28;39(1):86-93. Epub 2020 Aug 28.

Department of Orthopedic Surgery, Seoul National University Hospital, Seoul, Korea.

High tibial osteotomy (HTO) is a well-established treatment for medial compartment knee osteoarthritis (OA), which shifts the weight-bearing axis from the medial to the lateral side of the knee. As the adjacent ankle joint may be directly affected by the change in biomechanics, this study aimed to evaluate the change in the intersegmental foot and ankle motion after HTO in patients with genu varum. The study included 24 patients who underwent HTO, and 48 older healthy participants as a control group. Segmental foot kinematics were evaluated using a 3D multisegment foot model, and gait data of temporal and spatial parameters were obtained. After HTO, normalized stride length significantly increased with a tendency for increases in gait speed. In hallux kinematics relative to the forefoot, the sagittal motions of both the patients and the control group were similar throughout the majority of the gait cycle. In forefoot kinematics relative to the hindfoot, the pre-HTO state revealed significant pronation throughout the gait cycle, while the post-HTO state showed a similar position and motion to the control group. In hindfoot kinematics relative to the tibia, coronal motions of the pre-HTO state showed supination throughout the gait cycle, while supination during the stance phase decreased after HTO. Genu varum patients with medial compartment knee OA showed different gait parameters and intersegmental motion during gait when compared with age- and gender-matched controls. The effect of HTO was demonstrated by the normalization of midfoot compensation in patients with genu varum.
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http://dx.doi.org/10.1002/jor.24834DOI Listing
January 2021

Ultrasonographic Thyroid Nodule Classification Using a Deep Convolutional Neural Network with Surgical Pathology.

J Digit Imaging 2020 10;33(5):1202-1208

Department of Otorhinolaryngology, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences (KIRAMS), 75 Nowon-gil, Nowon-gu, Seoul, 139-706, South Korea.

Ultrasonography with fine-needle aspiration biopsy is commonly used to detect thyroid cancer. However, thyroid ultrasonography is prone to subjective interpretations and interobserver variabilities. The objective of this study was to develop a thyroid nodule classification system for ultrasonography using convolutional neural networks. Transverse and longitudinal ultrasonographic thyroid images of 762 patients were used to create a deep learning model. After surgical biopsy, 325 cases were confirmed to be benign and 437 cases were confirmed to be papillary thyroid carcinoma. Image annotation marks were removed, and missing regions were recovered using neighboring parenchyme. To reduce overfitting of the deep learning model, we applied data augmentation, global average pooling. And 4-fold cross-validation was performed to detect overfitting. We employed a transfer learning method with the pretrained deep learning model VGG16. The average area under the curve of the model was 0.916, and its specificity and sensitivity were 0.70 and 0.92, respectively. Positive and negative predictive values were 0.90 and 0.75, respectively. We introduced a new fine-tuned deep learning model for classifying thyroid nodules in ultrasonography. We expect that this model will help physicians diagnose thyroid nodules with ultrasonography.
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http://dx.doi.org/10.1007/s10278-020-00362-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7572950PMC
October 2020

Factors that Predicts the Size of Autologous Hamstring Tendon Graft for Double-Bundle ACL Reconstruction.

Indian J Orthop 2020 Jul 12;54(4):444-453. Epub 2020 Feb 12.

Department of Orthopedic Surgery, Hyundae General Hospital, Chung-Ang University College of Medicine, Seoul, South Korea.

Background: To evaluate the effectiveness of demographic data and radiographic measurements for predicting the diameter and length of autologous semitendinosus (ST) and gracilis (GR) graft.

Materials And Methods: Fifty-four cases were included to measure the size of 3 or 4 strands of ST and GR tendons retrospectively. The hamstring length on radiograph was defined as the length from the lowest point of ischial tuberosity to intercondylar notch of the femur. The linear and logistic regression analysis was used to assess the roles of the predictor variables, as demographic and radiologic data, in the outcome variables, as diameter of tendon grafts. The cross-validation with hold-out samples and concordance correlation coefficient (CCC) were also calculated.

Results: The hamstring and leg length measurement and gender were associated with the diameter of 4-stranded ST tendon graft. The hamstring length measurement, age and BMI were the factors associated with the diameter of 3-stranded ST tendon graft. The hamstring length measurement was found as a common factor for predicting diameters of hamstring tendon with reliable predictability. Moreover, the equation of multivariate regression analysis for the diameter of 4-stranded ST tendon graft showed the most validated power of prediction. All of the cross-validated values were calculated as similar results of multivariate model, but CCC between the measured diameter and estimated value on the predictive equation showed moderate agreement only (CCC = 0.694).

Conclusions: Combining radiographic length measurements with demographic data showed reliable prediction in identifying the risk of inappropriate graft diameters.

Level Of Evidence: Level IV retrospective cohort study.
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http://dx.doi.org/10.1007/s43465-019-00014-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7270234PMC
July 2020
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