Discovery of (-)-epigallocatechin gallate, a novel olfactory receptor 2AT4 agonist that regulates proliferation and apoptosis in leukemia cells.

Olfactory receptors (ORs), the largest family of G protein-coupled receptors (GPCRs), are ectopically expressed in cancer cells and are involved in cellular physiological processes, but their function as anticancer targets is still potential. OR2AT4 is expressed in leukemia cells, influencing the proliferation and apoptosis, yet the limited number of known OR2AT4 agonists makes it challenging to fully generalize the receptor's function. In this study, we aimed to identify new ligands for OR2AT4 and to investigate their functions and mechanisms in K562 leukemia cells. After producing the recombinant OR2AT4 protein, immobilizing it on a surface plasmon resonance chip, and conducting screening to confirm binding activity using 258 chemicals, five novel OR2AT4 ligands were discovered. As a result of examining changes in intracellular calcium by five ligands in OR2AT4-expressing cells and K562 cells, (-)-epigallocatechin gallate (EGCG) was identified as an OR2AT4 agonist in both cells. EGCG reduced the viability of K562 cells and induced apoptosis in K562 cells. EGCG increased the expression of cleaved caspase 3/8 and had no effect on the expression of Bax and Bcl-2, indicating that it induced apoptosis through the extrinsic pathway. Additionally, the initiation of the extrinsic apoptosis pathway in EGCG-induced K562 cells was due to the activation of OR2AT4, using an OR2AT4 antagonist. This study highlights the potential of EGCG as an anti-cancer agent against leukemia and OR2AT4 as a target, making it a new anti-cancer drug.

Effect of surface matching mismatch of focal knee articular prosthetic on tibiofemoral contact stress using finite element analysis.

Aims: Focal knee arthroplasty is an attractive alternative to knee arthroplasty for young patients because it allows preservation of a large amount of bone for potential revisions. However, the mechanical behaviour of cartilage has not yet been investigated because it is challenging to evaluate in vivo contact areas, pressure, and deformations from metal implants. Therefore, this study aimed to determine the contact pressure in the tibiofemoral joint with a focal knee arthroplasty using a finite element model. Methods: The mechanical behaviour of the cartilage surrounding a metal implant was evaluated using finite element analysis. We modelled focal knee arthroplasty with placement flush, 0.5 mm deep, or protruding 0.5 mm with regard to the level of the surrounding cartilage. We compared contact stress and pressure for bone, implant, and cartilage under static loading conditions. Results: Contact stress on medial and lateral femoral and tibial cartilages increased and decreased, respectively, the most and the least in the protruding model compared to the intact model. The deep model exhibited the closest tibiofemoral contact stress to the intact model. In addition, the deep model demonstrated load sharing between the bone and the implant, while the protruding and flush model showed stress shielding. The data revealed that resurfacing with a focal knee arthroplasty does not cause increased contact pressure with deep implantation. However, protruding implantation leads to increased contact pressure, decreased bone stress, and biomechanical disadvantage in an in vivo application. Conclusion: These results show that it is preferable to leave an edge slightly deep rather than flush and protruding.

A herb mixture to ameliorate non-alcoholic fatty liver in rats fed a high-fat diet.

This study was performed to investigate the effects of an herb extract mixture (HM) in ameliorating non-alcoholic fatty liver disease (NAFLD). The HM contained equal amounts of 70% ethanol extracts from Zingiber officinale, Centella asiatica, and Boehmeria nivea. In vitro, the HM significantly inhibited lipid accumulation in oleic acid-stimulated HepG2 cells. We further evaluated the anti-NAFLD activities of the HM in vivo in an animal model. Rats were fed two different amounts of the HM (50 and 200 mg/kg body weight) along with a high-fat diet for 6 weeks. HM supplementation reduced liver weight; epididymal, peri-renal, and intra-abdominal fat content; and serum triglyceride, total cholesterol, and low-density lipoprotein cholesterol levels as well as increased high-density lipoprotein cholesterol levels in a dose-dependent manner. Histological evaluation of liver specimens further demonstrated that administration of HM significantly prevented hepatic lipid accumulation and subsequent development of hepatic steatosis. These findings suggest that HM can be used as an alternative nutraceutical for ameliorating NAFLD.

Radical gastrectomy is safe for treatment of gastric cancer patients on immunosuppressive drugs after organ transplantation.

Background: De novo malignancies are major causes of death after organ transplantation because the recipients subsequently receive immunosuppressant drugs. When gastric cancer develops, the clinical course of the tumor may be particularly aggressive. However, there are few reliable studies of gastric cancer treatment after organ transplantation. This study examined the clinicopathological characteristics of gastric cancer patients after organ transplantation and evaluated treatment outcomes after gastrectomy. Methods: Clinical data were collected from 54 patients who were diagnosed with gastric cancer after organ transplantation. Of these, 30 who underwent surgery for gastric cancer while on immunosuppressant medications were compared with a control group of 625 gastric cancer patients. To compensate for clinical differences between the two groups, 1:1 propensity-score matching was performed. Results: Among the 30 gastric cancer patients on immunosuppressants, kidney transplantation was the most common procedure (19/30, 63.3%) followed by bone marrow (6) and liver transplantation (4); among all 54 patients, 45 were on one or two immunosuppressants. Up-migration to an advanced pathological stage was more frequent in the transplant group. In multivariate analysis, transplantation was a significant risk factor for up-migration from the T, M, and final stages after surgery. When the 30 patients on immunosuppressants who underwent gastric cancer surgery were compared with the matched controls, the total incidence (30.0 vs 40.0%, P = 0.417) and the number of severe postoperative complications (16.7 vs 13.4%, P = 0.417) did not differ significantly between groups after propensity score matching. In terms of overall survival, the transplant group showed significantly worse prognosis in stages I, II, and IV (P < 0.001, P = 0.039 and 0.007, respectively). Conclusion: Radical gastrectomy can be a safe oncological procedure for gastric cancer patients on immunosuppressants after transplantation. Considering their immunosuppressed condition and the possibility of underestimation of the stage of gastric cancer, early detection with endoscopic screening is needed to allow curative treatment.

Computational analysis of tibial slope adjustment with fixed-bearing medial unicompartmental knee arthroplasty in ACL- and PCL-deficient models.

AIMS: A functional anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL) has been assumed to be required for patients undergoing unicompartmental knee arthroplasty (UKA). However, this assumption has not been thoroughly tested. Therefore, this study aimed to assess the biomechanical effects exerted by cruciate ligament-deficient knees with medial UKAs regarding different posterior tibial slopes. METHODS: ACL- or PCL-deficient models with posterior tibial slopes of 1°, 3°, 5°, 7°, and 9° were developed and compared to intact models. The kinematics and contact stresses on the tibiofemoral joint were evaluated under gait cycle loading conditions. RESULTS: Anterior translation increased in ACL-deficient UKA cases compared with intact models. In contrast, posterior translation increased in PCL-deficient UKA cases compared with intact models. As the posterior tibial slope increased, anterior translation of ACL-deficient UKA increased significantly in the stance phase, and posterior translation of PCL-deficient UKA increased significantly in the swing phase. Furthermore, as the posterior tibial slope increased, contact stress on the other compartment increased in cruciate ligament-deficient UKAs compared with intact UKAs. CONCLUSION: Fixed-bearing medial UKA is a viable treatment option for patients with cruciate ligament deficiency, providing a less invasive procedure and allowing patient-specific kinematics to adjust posterior tibial slope. Patient selection is important, and while AP kinematics can be compensated for by posterior tibial slope adjustment, rotational stability is a prerequisite for this approach. ACL- or PCL-deficient UKA that adjusts the posterior tibial slope might be an alternative treatment option for a skilled surgeon. Cite this article: Bone Joint Res 2022;11(7):494-502.

Finite element analysis of femoral component sagittal alignment in mobile-bearing total knee arthroplasty.

BACKGROUND: Recently, there has been an increasing interest in mobile-bearing total knee arthroplasty (TKA). However, changes in biomechanics for femoral component alignment in mobile-bearing TKA have not been explored in depth. OBJECTIVE: This study aims to evaluate the biomechanical effect of sagittal alignment of the femoral component in mobile-bearing TKA. METHODS: We developed femoral sagittal alignment models with -3°, 0°, 3°, 5°, and 7° flexion. We also examine the kinematics of the tibiofemoral (TF) joint, contact point on the TF joint, contact stress on the patellofemoral (PF) joint, collateral ligament force, and quadriceps force using a validated computational model under a deep-knee-bend condition. RESULTS: Posterior kinematics of the TF joint increases as the femoral component flexes. The contact stress on the PF joint, collateral ligament force, and the quadriceps force decreases as the femoral component flexes. CONCLUSIONS: Our results show that a slight, approximately 0°âˆ¼3°, flexion of the implantation could be an effective substitute technique. However, excessive flexion should be avoided because of the potential loosening of the TF joint.

Astigmatic correction of simultaneous femtosecond laser-assisted cataract surgery (FLACS) with intrastromal arcuate keratotomy (ISAK) versus Toric intraocular Lens Impantation with conventional phacoemulsification.

BACKGROUND: To compare the efficacies in astigmatic correction of simultaneous femtosecond laser-assisted cataract surgery (FLACS) with intrastromal arcuate keratotomy (ISAK) versus toric intraocular lens (IOL) implantation with conventional phacoemulsification in moderate astigmatism. METHODS: A retrospective chart review was conducted for patients who had undergone cataract surgery by one surgeon. We identified patients with preoperative corneal astigmatism from + 0.75 to + 2.00 diopters (D) who had undergone astigmatic correction with FLACS with ISAK or toric IOL implantation with conventional phacoemulsification. We measured the visual acuity, intraocular pressure, automated keratometer, manifest refraction, and topography preoperatively and 1-day, 1-month, 3-month, and 6-month postoperatively. The vector analysis of refractive astigmatism was performed. RESULTS: Of a total of 48 eyes of 48 patients, 27 eyes of 27 patients had FLACS with ISAK (AK group), and 21 eyes of 21 patients had conventional cataract surgery with toric IOL implantation (toric IOL group). Refractive astigmatism was significantly decreased in both groups. The mean preoperative and 6-month postoperative refractive astigmatism were 1.85 ± 1.07 and 0.99 ± 0.51 D, respectively, in the AK group (P = 0.028), and 1.84 ± 0.81 and 0.68 ± 0.21 D, respectively, in the toric IOL group (P < 0.001). There was no significant difference in refractive astigmatism between the two groups at 6-month postoperatively (0.99 ± 0.51 vs 0.68 ± 0.21 D, P = 0.057). At 6-month postoperatively, parameters for vector analysis of refractive astigmatism showed no statistical difference between the two groups. Corneal astigmatism was significantly decreased in the AK group. Corneal astigmatism from topography and the automated keratometer were significantly lower in the AK group 6-month postoperatively compared to toric IOL group (0.94 ± 0.40 vs. 1.53 ± 0.46 D, P = 0.018 for topography; and 0.98 ± 0.69 vs. 1.37 ± 0.41 D, P = 0.032 for the automated keratometer). CONCLUSIONS: FLACS with ISAK could be an effective procedure for reducing astigmatism as well as toric IOL implantation in cataract surgery.

N-Dopant-Mediated Growth of Metal Oxide Nanoparticles on Carbon Nanotubes.

Metal oxide nanoparticles supported on heteroatom-doped graphitic surfaces have been pursued for several decades for a wide spectrum of applications. Despite extensive research on functional metal oxide nanoparticle/doped carbon nanomaterial hybrids, the role of the heteroatom dopant in the hybridization process of doped carbon nanomaterials has been overlooked. Here, the direct growth of MnOx and RuOx nanoparticles in nitrogen (N)-doped sites of carbon nanotubes (NCNTs) is presented. The quaternary nitrogen (NQ) sites of CNTs actively participate in the nucleation and growth of the metal nanoparticles. The evenly distributed NQ nucleation sites mediate the generation of uniformly dispersed <10 nm diameter MnOx and RuOx nanoparticles, directly decorated on NCNT surfaces. The electrochemical performance of the resultant hybridized materials was evaluated using cyclic voltammetry. This novel hybridization method using the dopant-mediated nucleation and growth of metal oxides suggests ways that heteroatom dopants can be utilized to optimize the structure, interface and corresponding properties of graphitic carbon-based hybrid materials.

Effect of post-cam design on the kinematics and contact stress of posterior-stabilized total knee arthroplasty.

BACKGROUND: The post-cam mechanism in the posterior-stabilized (PS) implant plays an important role, such as durability and kinematic performances, in total knee arthroplasty (TKA). OBJECTIVE: The purpose of this study was to evaluate the difference in the kinematics and contact stress of five post-cam designs, which are flat-and-flat, curve-and-curve (concave), curve-and-curve (concave and convex), helical, and asymmetrical post-cam designs, using three-dimensional finite element models. METHODS: We designed the post-cam model with five different geometries. The kinematics, contact stress, and contact area were evaluated in the five post-cam designs under gait cycle loading conditions using the finite element method. RESULTS: There were no differences in the contact stress and area on the tibial insert in all designs. The largest internal rotation was shown in the swing phase for the helical design, and the largest tibial posterior translation was observed for the curve-and-curve (concave) design. The curve-and-curve (concave) design showed the lowest contact stress and the largest posterior tibial translation during the gait cycle. CONCLUSIONS: Considering the kinematics and contact stress, we found that the curve-and-curve (concave) design was more stable than other designs. From the results, we found the important factors of TKA implant considering stability and kinematics.

The influence of the number of holes in the open wedge high tibial osteotomy on knee biomechanics using finite element analysis.

BACKGROUND: The most significant differences of high tibial osteotomy (HTO) were found in terms of plate length, and this was related to number of holes distal region of the plate below wedge. The purpose of this study is to evaluate the biomechanical effects of three different designs medial opening wedge plates. HYPOTHESIS: The design of the HTO plate influenced the outcome of the biomechanics. METHODS: The HTO model was simulated using finite element (FE) model. This FE investigation included three types of loading conditions corresponding to the loads used in the experimental study for model validation and model predictions for clinically relevant loading scenarios. The average stress and contact stress were evaluated. RESULTS: The highest average stress was observed in the TomoFix. Conversely, the stress on the bone declined in the order of Puddu, Maxi and TomoFix plates. The micromotion in the wedge displayed a similar trend to the stress on bone. The highest and lowest contact stresses on the medial meniscus were observed in the Puddu and TomoFix plate, respectively. However, an opposite trend was observed in the lateral meniscus. The contact stress on medial and lateral menisci decreased and increased, respectively, in all three different plates when compared to those in the intact model. DISCUSSION: The TomoFix plate exhibited the highest stability relative to the micromotions of the wedge. However, in terms of the stress on the bone and plates, a stress-shielding effect could exist in the TomoFix plate. Additionally, the contact stress on the articular surface suggested that a complicated relationship could exist with respect to the plate design. LEVEL OF EVIDENCE: IV.

Effects of contact stress on patellarfemoral joint and quadriceps force in fixed and mobile-bearing medial unicompartmental knee arthroplasty.

BACKGROUND: Unicompartmental knee arthroplasty (UKA) is an effective treatment for end-stage, symptomatic unicompartmental osteoarthritis of the knee joint. However, patellofemoral joint degeneration is a contraindication to medial UKA. Therefore, the objective of this study was to evaluate the biomechanical effect of medial UKA using fixed-bearing (FB) and mobile-bearing (MB) design prostheses on the patellofemoral joint. METHODS: A three-dimensional finite-element model of a normal knee joint was developed using medical image data. We performed statistical analysis for each model. The differences in contact stress on the patellofemoral joint and the quadriceps force between the FB and MB designs were evaluated under a deep-knee-bend condition. RESULTS: At an early flexion angle, the results of contact stress showed no significant difference between the FB and MB medial UKA models compared with the intact model. However, at high flexion angles, we observed a significant increase in contact stress with the FB models compared with the intact model. On the contrary, in the case of the MB models, we found no statistically significant increment compared with the intact model. A larger quadriceps force was needed to produce an identical flexion angle for both the FB and MB UKA designs than for the intact model. At high flexion angles, a significant increase quadriceps force whit the FB model compared with the intact model. CONCLUSIONS: Our results indicate that with medial UKA, the contact stress increased and greater quadriceps force was applied to the patellofemoral joint. However, performing UKA on a patellofemoral joint with osteoarthritis should not be difficult, unless anterior knee pain is present, because the increase in contact stress is negligible.

Biomechanical effect of tibial slope on the stability of medial unicompartmental knee arthroplasty in posterior cruciate ligament-deficient knees.

AIMS: Unicompartmental knee arthroplasty (UKA) has become a popular method of treating knee localized osteoarthritis (OA). Additionally, the posterior cruciate ligament (PCL) is essential to maintaining the physiological kinematics and functions of the knee joint. Considering these factors, the purpose of this study was to investigate the biomechanical effects on PCL-deficient knees in medial UKA. METHODS: Computational simulations of five subject-specific models were performed for intact and PCL-deficient UKA with tibial slopes. Anteroposterior (AP) kinematics and contact stresses of the patellofemoral (PF) joint and the articular cartilage were evaluated under the deep-knee-bend condition. RESULTS: As compared to intact UKA, there was no significant difference in AP translation in PCL-deficient UKA with a low flexion angle, but AP translation significantly increased in the PCL-deficient UKA with high flexion angles. Additionally, the increased AP translation became decreased as the posterior tibial slope increased. The contact stress in the PF joint and the articular cartilage significantly increased in the PCL-deficient UKA, as compared to the intact UKA. Additionally, the increased posterior tibial slope resulted in a significant decrease in the contact stress on PF joint but significantly increased the contact stresses on the articular cartilage. CONCLUSION: Our results showed that the posterior stability for low flexion activities in PCL-deficient UKA remained unaffected; however, the posterior stability for high flexion activities was affected. This indicates that a functional PCL is required to ensure normal stability in UKA. Additionally, posterior stability and PF joint may reduce the overall risk of progressive OA by increasing the posterior tibial slope. However, the excessive posterior tibial slope must be avoided.Cite this article: Bone Joint Res 2020;9(9):593-600.

Effects of the material properties of a focal knee articular prosthetic on the human knee joint using computational simulation.

BACKGROUND: Localized cartilage defects are related to joint pain and reduced function to the development of osteoarthritis. The mechanical properties of the implant for treatment do influence its longevity. Therefore, we aimed to evaluate the effect of material properties' variations of anatomically shaped focal knee implants in the knee joint using numerical finite element analysis. METHODS: Computational simulations were performed for different cases including an intact knee, a knee with a focal cartilage defect, and a knee fitted with a focal articular prosthetic having three distinct mechanical properties: cobalt-chromium, pyrolytic carbon, and polyethylene. Femoral cartilage, tibial cartilage, and menisci contact pressures were evaluated under the load. In addition, bone stress was evaluated to investigate the stress shielding effect. RESULTS: Compared with the intact model, the contact stress of the focal implant model was increased; on the femoral lateral cartilage by 14%, on medial and lateral tibial cartilages by nine percent and 10%, on medial and lateral menisci by 23% and 20%. In contrast, the focal implant model had no effect on the menisci but contact stress on the tibial cartilage increased compared with the intact model. The BioPoly model showed the lowest contact stress on femoral and tibial cartilages. Additionally, the cobalt-chromium model showed the lowest bone stress that improved the load-sharing effect. CONCLUSIONS: The results suggested that implant material properties are an important parameter in the design of a focal implant. The polyethylene model potentially restored the intact knee contact mechanics and it reduced the risk of physiological damage to the articular cartilage.

Restoration of normal knee kinematics with respect to tibial insert design in mobile bearing lateral unicompartmental arthroplasty using computational simulation.

AIMS: Mobile-bearing unicompartmental knee arthroplasty (UKA) with a flat tibial plateau has not performed well in the lateral compartment, leading to a high rate of dislocation. For this reason, the Domed Lateral UKA with a biconcave bearing was developed. However, medial and lateral tibial plateaus have asymmetric anatomical geometries, with a slightly dished medial and a convex lateral plateau. Therefore, the aim of this study was to evaluate the extent at which the normal knee kinematics were restored with different tibial insert designs using computational simulation. METHODS: We developed three different tibial inserts having flat, conforming, and anatomy-mimetic superior surfaces, whereas the inferior surface in all was designed to be concave to prevent dislocation. Kinematics from four male subjects and one female subject were compared under deep knee bend activity. RESULTS: The conforming design showed significantly different kinematics in femoral rollback and internal rotation compared to that of the intact knee. The flat design showed significantly different kinematics in femoral rotation during high flexion. The anatomy-mimetic design preserved normal knee kinematics in femoral rollback and internal rotation. CONCLUSION: The anatomy-mimetic design in lateral mobile UKA demonstrated restoration of normal knee kinematics. Such design may allow achievement of the long sought normal knee characteristics post-lateral mobile UKA. However, further in vivo and clinical studies are required to determine whether this design can truly achieve a more normal feeling of the knee and improved patient satisfaction.Cite this article: Bone Joint Res 2020;9(7):421-428.

Clinical outcomes after mix-and-match implantation of diffractive multifocal intraocular lenses with + 2.75 and + 4.00 diopter add powers.

BACKGROUND: To evaluate the clinical outcomes of bilateral mix-and-match implantation of diffractive multifocal intraocular lenses (IOLs) with different add powers. METHODS: We retrospectively reviewed the medical records of 18 patients who underwent bilateral mix-and-match implantation of diffractive multifocal IOLs with different add powers. Multifocal IOLs with add powers of + 2.75 diopters (D) and + 4.00 D were implanted into the patients' dominant and nondominant eyes, respectively. At 1 and 3-month postoperatively, monocular and binocular visual acuity was measured using logMAR charts and manifest refraction was performed. Specifically, logMAR charts were used to measure uncorrected distance visual acuity (UDVA), uncorrected intermediate visual acuity (UIVA), uncorrected near visual acuity (UNVA), and corrected distance visual acuity (CDVA). Defocus curves, contrast sensitivity, and patient satisfaction were assessed at 3-month postoperatively. RESULTS: Binocular logMAR measurements (mean ± standard deviation) at 3-month postoperatively were 0.01 ± 0.04 (UDVA), 0.16 ± 0.05 (UIVA), and 0.11 ± 0.07 (UNVA). Postoperative spherical equivalent was - 0.43 ± 0.35 D and - 0.39 ± 0.21 D in the dominant and nondominant eyes, respectively. Defocus curves showed significant differences between - 1.50 and - 4.00 D among binocular, dominant, and nondominant eye measurements, except between - 2.50 and - 3.00 D. Eyes implanted with + 2.75 and + 4.00 D IOLs showed good contrast sensitivity under photopic and mesopic conditions. Over 80% of patients reported high satisfaction with their near vision. CONCLUSIONS: Bilateral mix-and-match implantation of diffractive multifocal IOLs with add powers of + 2.75 D and + 4.00 D showed good near, intermediate, and far vision.

Biomechanical and Clinical Effect of Patient-Specific or Customized Knee Implants: A Review.

(1) Background: Although knee arthroplasty or knee replacement is already an effective clinical treatment, it continues to undergo clinical and biomechanical improvements. For an increasing number of conditions, prosthesis based on an individual patient's anatomy is a promising treatment. The aims of this review were to evaluate the clinical and biomechanical efficacy of patient-specific knee prosthesis, explore its future direction, and summarize any published comparative studies. (2) Methods: We searched the PubMed, MEDLINE, Embase, and Scopus databases for articles published prior to February 1, 2020, with the keywords "customized knee prosthesis" and "patient-specific knee prosthesis". We excluded patient-specific instrument techniques. (3) Results: Fifty-seven articles met the inclusion criteria. In general, clinical improvement was greater with a patient-specific knee prosthesis than with a conventional knee prosthesis. In addition, patient-specific prosthesis showed improved biomechanical effect than conventional prosthesis. However, in one study, patient-specific unicompartmental knee arthroplasty showed a relatively high rate of aseptic loosening, particularly femoral component loosening, in the short- to medium-term follow-up. (4) Conclusions: A patient-specific prosthesis provides a more accurate resection and fit of components, yields significant postoperative improvements, and exhibits a high level of patient satisfaction over the short to medium term compared with a conventional prosthesis. However, the tibial insert design of the current patient-specific knee prosthesis does not follow the tibial plateau curvature.

Biomechanical effect of a lateral hinge fracture for a medial opening wedge high tibial osteotomy: finite element study.

BACKGROUND: This study aimed to investigate the biomechanical effect on the Takeuchi classification of lateral hinge fracture (LHF) after an opening wedge high tibial osteotomy (HTO). METHODS: We performed an FE simulation for type I, type II, and type III in accordance with the Takeuchi classification. The stresses on the bone and plate, wedge micromotion, and forces on ligaments were evaluated to investigate stress-shielding effect, plate stability, and biomechanical change, respectively, in three different types of LHF HTO and with the HTO without LHF model (non-LHF) models. RESULTS: The greatest stress-shielding effect and wedge micromotion were observed in type II LHF (distal portion fracture). The type II and type III (lateral plateau fracture) models exhibited a reduction in ACL force and an increase in PCL force compared with the HTO without LHF model. However, the type I (osteotomy line fracture) and HTO without LHF models did not exhibit a significant biomechanical effect. This study demonstrates that Takeuchi type II and type III LHF models provide unstable structures compared with the type I and HTO without LHF models. CONCLUSIONS: HTO should be performed while considering a medial opening wedge HTO to avoid a type II and type III LHF as a potential complication.

Anatomy-mimetic design preserves natural kinematics of knee joint in patient-specific mobile-bearing unicompartmental knee arthroplasty.

PURPOSE: This study aims to evaluate whether different tibial-femoral conformities for patient-specific mobile-bearing unicompartmental knee arthroplasties (UKAs) preserve natural knee kinematics, using computational simulations. METHODS: Different designs for patient-specific mobile-bearing UKAs were evaluated using finite element analysis. Three designs for the identical femoral component were considered: flat (non-conforming design), anatomy-mimetic, and conforming for the tibial insert. RESULTS: The conforming design for the patient-specific mobile-bearing UKAs exhibited a 1.2 mm and 0.7° decrease in the translation and rotation, respectively, in the swing phase compared with those of the natural knee. In addition, the femoral rollback and internal rotation were 2.6 mm and 1.2° lower, respectively, than those of the natural knee, for the conforming design under the deep-knee-bend condition. The flat design for the patient-specific mobile-bearing UKAs exhibited a 2.2 mm and 1.4° increase in the femoral rollback and rotation compared with the natural knee under the deep-knee-bend condition. The anatomy-mimetic patient-specific mobile-bearing UKAs best preserved the natural knee kinematics under the gait and deep-knee-bend loading conditions. CONCLUSIONS: The kinematics of the loading conditions in patient-specific mobile-bearing UKAs was determined to closely resemble those of a native knee. In additional, by replacing the anatomy-mimetic design with a mobile-bearing, natural knee kinematics during gait and deep-knee-bend motions is preserved. These results confirm the importance of tibiofemoral conformity in preserving native knee kinematics in patient-specific mobile-bearing UKA.