• Biomaterials Research
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• v.22 no.4
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• pp.259-270
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• 2018

Background: Total hip arthroplasty (THA) is probably one of the most successful surgical interventions performed in medicine. Through the revolution of hip arthroplasty by principles of low friction arthroplasty was introduced by Sir John Charnley in 1960s. Thereafter, new bearing materials, fixation methods, and new designs has been improved. The main concern regarding failure of THA has been the biological response to particulate polyethylene debris generated by conventional metal on polyethylene bearing surfaces leading to osteolysis and aseptic loosening of the prosthesis. To resolve these problems, the materials of the modern THA were developed since then. Methods: A literature search strategy was conducted using various search terms in PUBMED. The highest quality articles that met the inclusion criteria and best answered the topics of focus of this review were selected. Key search terms included 'total hip arthroplasty', 'biomaterials', 'stainless steel', 'cobalt-chromium', 'titanium', 'polyethylene', and 'ceramic'. Results: The initial search retrieved 6921 articles. Thirty-two articles were selected and used in the review. Conclusion: This article introduces biomaterials used in THA and discusses various bearing materials in currentclinical use in THA as well as the newer biomaterials which may even further decrease wear and improve THA survivorship.

• Clinics in Shoulder and Elbow
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• v.26 no.3
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• pp.312-322
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• 2023

Background: Silicone radial head prostheses (SRHP) are considered obsolete due to reports of frequent failure and destructive silicone-induced synovitis. Considering the good outcomes of modern non-radial silicone joint implants, the extent of scientific evidence for this negative view is unclear. The aim of this research was to systematically analyze the clinical evidence on complications and outcomes of SRHP and how SRHP compare to both non-SRHP and silicone prostheses of other joints. Methods: A systematic literature review was conducted through the Cochrane, PubMed, and Embase databases. Results: Eight cohort studies were included, consisting of 142 patients and follow-up periods ranging from 23 months to 8 years. Average patient satisfaction was 86%, range of 71%-100%, and 58 complications were seen, but no cases of synovitis. These outcomes were in line with non-SRHP. Four case series with 11 cases of synovitis were found, all due to implant fractures years to decades after implantation. Six systematic reviews of currently used non-radial silicone joint implants showed excellent outcomes with low complication rates. Conclusions: Since SRHP have satisfactory clinical results and an acceptable complication rate when selecting a patient group in suitable condition for surgical indications, it is considered that SRHP can still be chosen as a potential surgical treatment method in current clinical practice.

• Structural Engineering and Mechanics
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• v.91 no.3
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• pp.251-262
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• 2024

Numerical modeling using the finite element method (FEM) offers crucial insights into the mechanical behavior of prostheses, including stress and strain distribution, load transfer, and stress intensity factors. Analyzing cracking in PMMA surgical cement (polymethylmethacrylate) for total hip prostheses (THP) is essential for understanding the loosening phenomenon, as the rupture of orthopedic cement is a primary cause. By understanding various failure mechanisms, significant advancements in cemented total prostheses can be achieved. This study performed a numerical analysis using a 3D FEM model to evaluate stress levels in different THP models, aiming to model damage in the orthopedic cement used in total hip arthroplasty. Utilizing ABAQUS software, FEM, and XFEM, the damage in three types of THPs-Charnley (CMK3), Osteal (BM3), and THOMPSON was modeled under stumbling loading conditions. XFEM allowed for the consideration of crack propagation between the cement and bone, while the GEARING criterion employed a user-defined field subroutine to model damage parameters. The study's findings can contribute to improving implant fixation techniques and preventing postoperative complications in orthopedic surgery.

• Journal of Technologic Dentistry
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• v.33 no.4
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• pp.299-306
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• 2011

Purpose: This study aimed to investigate the shear bond strength by manufacturing the veneering porcelain on the IPS e.max $ZirCAD^{(R)}$ zirconia core, using the layering technique and heat-pressing technique, and to evaluate the clinical stability by comparing to the conventional metal ceramic system. Methods: The Schmitz-Schulmeyer test method was used to evaluate the core-veneer shear bond strength of zirconia core ceramic(IPS e.max $ZirCAD^{(R)}$) and their manufacture recommended two veneering ceramic systems(IPS e.max $ceram^{(R)}$, IPS e. max $ZirPress^{(R)}$). A metal ceramic system(Bellabond $plus^{(R)}$, VITA $VM13^{(R)}$) was used as a control group for the two all ceramic system test groups. The maximum loading and shear bond strength was measured. The average shear strength(MPa) was analyzed with the one-way ANOVA and the Tukey's test(${\alpha}$=.05). The fracture specimens were examined using Microscope to determine the failure pattern. Results: The mean shear bond strengths(SD) in MPa were MBSB control 43.62(2.13); ZBSB 18.65(1.76); ZPSB 18.89(1.54). The shear strengths of the zirconia cores were not significantly different(P>.05). Microscope examination showed that zirconia specimens presented mixed failure, and base metal alloy specimens showed adhesive failure. Conclusion: There was no siginificant different between the layering technique and the heat pressing technique in the veneering methods on the zirconia cores. None of the zirconia core and veneering ceramics could attain the high bond strength values of the metal ceramic combination.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.23 no.1
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• pp.34-40
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• 2014

There are several treatment options for rehabilitation of partial edentulism including the use of conventional or implant-retained fixed prostheses. However, such prosthetic options cannot always be possible because of compromised general and oral health (i.e. loss of supporting tissues, medical reasons, extensive surgical protocol and osseointegration failure of dental implant) as well as the affordability of patients. In some cases, removable partial denture provides easier access for oral hygiene procedures and the ability to correct discrepancies in dental arch relationships than implant fixed prosthesis. Recently, Implant Supported Removable Partial Denture (ISRPD) where to place dental implant in strategic position has been suggested to improve the limitation and shortcomings of conventional RPD. ISPRD can overcome mechanical limition of conventional RPD by placing implant in a favorable position and can be cost-effective, prosthetic solution for partially edentulous patients who are not immediate candidates for extensive, fixed implant supported restorations. Incorporation of dental implants to improve the RPD support and retention and to enhance patient acceptance should be considered when treatment planning for RPD. In this case, 59 years old male patient who received dental treatment of implant fixed prosthesis on both side of the upper jaw and implant overdenture on lower jaw showed implant abutment screw fracture on #15i and osseointegration failure on multiple number of implants. After removing failed implants, we planned ISRPD using #15i,24i,25i,26i and #23 natural tooth for RPD abutment. We fabricated #23 surveyed crown,#24i=25i=26i surveyed bridge and #15i gold coping for support,retention and stability for RPD. Periodic follow up check for 2years has been performed since the ISRPD delivery to the patient. No sign of screw loosening, fracture or bone resorption around abutment implants were detected.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.1
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• pp.28-40
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• 2010

Purpose: The aim of this retrospective study was to provide long-term data about the correlation between multifactorial local factors and the survival of implants. Material and methods: During 19 years (1991 to 2009), 2796 implants were placed in 879 patients. From dental charts and radiographs, the following data were collected: patient's age at implant placement, gender, implant system, surface, length, diameter, location of implant placement, bone quality, primary stability, type of prosthesis. The correlations between these data and implant survival were analyzed. Statistical analysis was performed using Kaplan-Meier survival analysis, Chi-square test, odds ratio. Results: 1. Among the 2796 implants, 150 implants failed that resulted in a cumulative survival rate of 94.64%. The cumulative survival rate of smooth surface implants (91.76%) was lower than rough surface implants (96.02%). 2. Anatomic location, implant surface, diameter of smooth surface implant, primary stability, type of prosthesis, patient's age and gender were significantly associated with implant survival (P < .05). 3. No significant difference in implant survival was found in relation to the following factors: implant length, bone quality, diameter of rough surface implants and type of rough surface according to implant manufacturer (P < .05). Conclusions: Local factors such as anatomic location, implant surface, diameter of smooth surface implant, primary stability and type of prosthesis have a significant effect on implant survival.

• Journal of the Korean Orthopaedic Association
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• v.54 no.1
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• pp.37-44
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• 2019

Purpose: Tumor infiltration around the knee joint or skip metastasis, repeated infection sequelae after tumor prosthesis implantation, regional recurrence, and mechanical failure of the megaprosthesis might require combined distal femur and proximal tibia replacement (CFTR). Among the aforementioned situations, there are few reports on the indication, complications, and implant survival of CFTR in temporarily arthrodesed patients who had a massive bony defect on either side of the knee joint to control infection. Materials and Methods: Thirty-four CFTR patients were reviewed retrospectively and 13 temporary arthrodesed cases switched to CFTR were extracted. All 13 cases had undergone a massive bony resection on either side of the knee joint and temporary arthrodesis state to control the repeated infection. This paper describes the diagnosis, tumor location, number of operations until CFTR, duration from the index operation to CFTR, survival of CFTR, complications, and Musculoskeletal Tumor Society (MSTS) score. Results: According to Kaplan-Meier plot, the 5- and 10-year survival of CFTR was 69.0%±12.8%, 46.0%±20.7%, respectively. Six (46.2%) of the 13 cases had major complications. Three cases underwent removal of the prosthesis and were converted to arthrodesis due to infection. Two cases underwent partial change of the implant due to loosening and periprosthetic fracture. The remaining case with a deep infection was resolved after extensive debridement. At the final follow-up, the average MSTS score of 10 cases with CFTR was 24.6 (21-27). In contrast, the MSTS score of 3 arthrodesis cases with failed CFTR was 12.3 (12-13). The average range of motion of the 10 CFTR cases was 67° (0°-100°). The mean extension lag of 10 cases was 48° (20°-80°). Conclusion: Although the complication rates is substantial, conversion of an arthrodesed knee to a mobile joint using CFTR in a patient who had a massive bony defect on either side of the knee joint to control infection should be considered. The patient's functional outcome was different from the arthrodesed one. For successful conversion to a mobile joint, thorough the eradication of scar tissue and creating sufficient space for the tumor prosthesis to flex the knee joint up to 60° to 70° without soft tissue tension.

• Journal of Korean Neurosurgical Society
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• v.62 no.4
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• pp.450-457
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• 2019

Objective : Anterior cervical discectomy and fusion (ACDF) is commonly used surgical procedure for cervical degenerative disease. Among the various intervertebral spacers, the use of allografts is increasing due to its advantages such as no harvest site complications and low rate of subsidence. Although subsidence is a rare complication, graft collapse is often observed in the follow-up period. Graft collapse is defined as a significant graft height loss without subsidence, which can lead to clinical deterioration due to foraminal re-stenosis or segmental kyphosis. However, studies about the collapse of allografts are very limited. In this study, we evaluated risk factors associated with graft collapse. Methods : We retrospectively reviewed 33 patients who underwent two level ACDF with anterior plating using allogenous bone graft from January 2013 to June 2017. Various factors related to cervical sagittal alignment were measured preoperatively (PRE), postoperatively (POST), and last follow-up. The collapse was defined as the ratio of decrement from POST disc height to follow-up disc height. We also defined significant collapses as disc heights that were decreased by 30% or more after surgery. The intraoperative distraction was defined as the ratio of increment from PRE disc height to POST disc height. Results : The subsidence rate was 4.5% and graft collapse rate was 28.8%. The pseudarthrosis rate was 16.7% and there was no association between pseudarthrosis and graft collapse. Among the collapse-related risk factors, pre-operative segmental angle (p=0.047) and intra-operative distraction (p=0.003) were significantly related to allograft collapse. The cut-off value of intraoperative distraction ${\geq}37.3%$ was significantly associated with collapse (p=0.009; odds ratio, 4.622; 95% confidence interval, 1.470-14.531). The average time of events were as follows: collapse, $5.8{\pm}5.7months$; subsidence, $0.99{\pm}0.50months$; and instrument failure, $9.13{\pm}0.50months$. Conclusion : We experienced a higher frequency rate of collapse than subsidence in ACDF using an allograft. Of the various preoperative factors, intra-operative distraction was the most predictable factor of the allograft collapse. This was especially true when the intraoperative distraction was more than 37%, in which case the occurrence of graft collapse increased 4.6 times. We also found that instrument failure occurs only after the allograft collapse.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.3
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• pp.272-278
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• 2017

Purpose: The aim of the present prospective clinical study was to assess the cumulative survival rate (CSR) of Neobiotech implants restored with fixed partial prosthesis in relation to its potential risk factors. Materials and methods: Thirty six partially edentulous patients received Neobiotech implants and implant supported fixed partial prosthesis at Korea University Guro Hospital Dental Center from November 2009 until November 2011. The observation period was set from the implant placement and the last clinical visit until December 2015. Implant survival rate was determined using the Kaplan-Meier method. The relationship between implant survival rate and the potential risk factors were analysed using the multi Cox proportional analysis (P<.05). Results: A total of 69 implants were placed in 36 patients after a mean observation period of 45.9 months. Two out of 69 implants failed before loading, yielding a 5-year cumulative survival rate of 97.1%. The maxillary implants have a lesser CSR than the mandibular implants based on log rank test analysis (maxilla=91.3%; mandible=100% P<.05). However, the multi Cox proportional analysis showed that implant location has no significant correlation with implant failure (P>.05). Conclusion: Neobiotech implants showed predictable results with a 5 year cumulative survival rate of 97.1%.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.5
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• pp.507-524
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• 2002

Load transfer of implant overdenture varies depending on anchorage systems that are the design of the superstructure and substructure and the choice of attachment. Overload by using improper anchorage system not only will cause fracture of the framework or screw but also may cause failure of osseointegration. Choosing anchorage system in making prosthesis, therefore, can be considered to be one of the most important factors that affect long-term success of implant treatment. In this study, in order to determine the effect of anchorage systems on load transfer in mandibular implant overdenture in which 4 implants were placed in the interforaminal region, patterns of stress distribution in implant supporting bone in case of unilateral vertical loading on mandibular left first molar were compared each other according to various types of anchorage system using three-dimensional photoelastic stress analysis. The five photoelastic overdenture models utilizing Hader bar without cantilever using clips(type 1), cantilevered Hader bar using clips(type 2), cantilevered Hader bar with milled surface using clips(type 3), cantilevered milled-bar using swivel-latchs and frictional pins(type 4), and Hader bar using clip and ERA attachments(type 5), and one cantilevered fixed-detachable prosthesis(type 6) model as control were fabricated. The following conclusions were drawn within the limitations of this study, 1. In all experimental models. the highest stress was concentrated on the most distal implant supporting bone on loaded side. 2. Maximum fringe orders on ipsilateral distal implant supporting bone in a ascending order is as follows: type 5, type 1, type 4, type 2 and type 3, and type 6. 3. Regardless of anchorage systems. more or less stresses were generated on the residual ridge under distal extension base of all overdenture models. To summarize the above mentioned results, in case of the patients with unfavorable biomechanical conditions such as not sufficient number of supporting implants, short length of the implant and unfavorable antero-posterior spread. selecting resilient type attachment or minimizing distal cantilever bar is considered to be appropriate methods to prevent overloading on implants by reducing cantilever effect and gaining more support from the distal residual ridge.