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Orthopaedic Proceedings
Vol. 106-B, Issue SUPP_12 | Pages 21 - 21
10 Jun 2024
Gordon C Raglan M Dhar S Lee K
Full Access

Objective

The purpose of this study was to determine the outcomes of revision ankle replacements, using the Invision implant and impaction allograft for massive talar dome defects following primary ankle replacement failure. Outcomes were assessed in terms of bone graft incorporation; improvement in patient reported outcome measures (PROMs); and survivorship of the revision ankle arthroplasty.

Methods

A retrospective review of prospectively collected data identified eleven patients who had massive bone cysts and underwent revision of a failed primary total ankle replacement to the Invision revision system, combined with impaction grafting using morselized femoral head allograft. These revisions occurred at a single high volume ankle arthroplasty centre. Computed tomography (CT) scans were used to assess bone graft incorporation and the Manchester-Oxford Foot Questionnaire (MOXFQ) and EQ-5D scores were used pre and post operatively to assess PROMs.


The Bone & Joint Journal
Vol. 106-B, Issue 5 | Pages 475 - 481
1 May 2024
Lee M Lee G Lee K

Aims

The purpose of this study was to assess the success rate and functional outcomes of bone grafting for periprosthetic bone cysts following total ankle arthroplasty (TAA). Additionally, we evaluated the rate of graft incorporation and identified associated predisposing factors using CT scan.

Methods

We reviewed a total of 37 ankles (34 patients) that had undergone bone grafting for periprosthetic bone cysts. A CT scan was performed one year after bone grafting to check the status of graft incorporation. For accurate analysis of cyst volumes and their postoperative changes, 3D-reconstructed CT scan processed with 3D software was used. For functional outcomes, variables such as the Ankle Osteoarthritis Scale score and the visual analogue scale for pain were measured.


Orthopaedic Proceedings
Vol. 106-B, Issue SUPP_2 | Pages 101 - 101
2 Jan 2024
Firth A Lee K van Duren B Berber R Matar H Bloch B
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Stiffness is reported in up to 16% of patients after total knee replacement (TKR)1. Treatment of stiffness after TKR remains a challenge. Manipulation under anaesthesia (MUA) accounts for between 6%-36% of readmissions following TKR2,3. The outcomes of MUA remain variable/unpredictable. Post-operative CPM is used as an adjuvant to MUA, potentially offering improved ROM, however, remains the subject of debate. We report a retrospective study comparing MUA with and without post-operative CPM.

In our institution patients undergoing MUA to receive CPM post-operatively. Owing to the COVID-19 pandemic hospital admissions were limited. During this period MUA procedures were undertaken without CPM. Two cohorts were included: 1) MUA + post-operative CPM 2) Daycase MUA. Patients’ demographics, pre-manipulation ROM, post-MUA ROM, and ROM at final follow-up were recorded.

Between 2017-2022 126 patients underwent MUA and were admitted for CPM and 42 had daycase MUA. The median Age was 66.5 and 64% were female. 57% had extension deficit (>5o), 70% had flexion deficit (< 90o), and 37% had both. The mean Pre-operative ROM was 72.3o(SD:18.3o) vs. 68.5o(19.0o), ROM at MUA was 95.5o(SD:20.7o) vs 108.3o(SD:14.1o) [p< 0.01], and at final follow-up 87.4o(SD:21.9o) vs. 92.1o(SD:18.2o) for daycase and CPM groups respectively. At final follow-up for the daycase and CPM groups respectively 10% vs. 7% improved, 29% vs. 13% maintained, and 57% vs. 79% regressed from the ROM achieved at MUA. The mean percentage of ROM gained at MUA maintained at final follow-up was 92%(SD:17) and 85%(SD:14)[p=0.03] for daycase and CPM groups respectively.

There was no significant difference in ROM achieved at final follow-up despite the significantly greater improvement in ROM achieved at MUA for the CPM group. The CPM group lost a greater ROM after MUA (15% vs. 8%). We conclude that post-operative CPM does not improve ROM achieved after MUA.


Orthopaedic Proceedings
Vol. 106-B, Issue SUPP_2 | Pages 4 - 4
2 Jan 2024
Han S Yoo Y Choi H Lee K Korhonen R Esrafilian A
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It is known that the gait dynamics of elderly substantially differs from that of young people. However, it has not been well studied how this age-related gait dynamics affects the knee biomechanics, e.g., cartilage mechanical response. In this study, we investigated how aging affects knee biomechanics in a female population using subject-specific computational models.

Two female subjects (ages of 23 and 69) with no musculoskeletal disorders were recruited. Korea National Institute for Bioethics Policy Review Board approved the study. Participants walked at a self-selected speed (SWS), 110% of SWS, and 120% of SWS on 10 m flat ground. Three-dimensional marker trajectories and ground reaction forces (Motion Analysis, USA), and lower limbs’ muscle activities were measured (EMG, Noraxon USA). Knee cartilage and menisci geometries were obtained from subjects’ magnetic resonance images (3T, GE Health Care). An EMG-assisted musculoskeletal finite element modeling workflow was used to estimate knee cartilage tissue mechanics in walking trials. Knee cartilage and menisci were modeled using a transversely isotropic poroviscoelastic material model.

Walking speed in SWS, 110%, and 120% of SWS were 1.38 m/s, 1.51 m/s, and 1.65 m/s for the young, and 1.21 m/s, 1.34 m/s and 1.46 m/s for the elderly, respectively. The maximum tensile stress in the elderly tibial cartilage was ~25%, ~33%, and ~32% lower than the young at SWS, 110%, and 120% of SWS, respectively. These preliminary results suggest that the cartilage in the elderly may not have enough stimulation even at 20% increases in walking speed, which may be one reason for tissue degeneration. To enhance these findings, further study with more subjects and different genders will investigate how age-related gait dynamics affects knee biomechanics.

Acknowledgments: Australian NHMRC Ideas Grant (APP2001734), KITECH (JE220006)


Orthopaedic Proceedings
Vol. 106-B, Issue SUPP_2 | Pages 111 - 111
2 Jan 2024
Wong S Lee K Razak H
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Medial opening wedge high tibial osteotomy (MOWHTO) is the workhorse procedure for correcting varus malalignment of the knee. There have been recent developments in the synthetic options to fill the osteotomy gap. The current gold standard for filling this osteotomy gap is autologous bone graft which is associated with donor site morbidity. We would like to introduce and describe the process of utilizing the novel Osteopore® 3D printed, honeycomb structured, Polycaprolactone and β-Tricalcium Phosphate wedge for filling the gap in MOWHTO. In the advent of additive manufacturing and the quest for more biocompatible materials, the usage of the Osteopore® bone wedge in MOWHTO is a promising technique that may improve the biomechanical stability as well the healing of the osteotomy gap.


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_17 | Pages 23 - 23
24 Nov 2023
Xie C Ren Y Weeks J Lekkala S Rainbolt J Xue T Shu Y Lee K de Mesy Bentley KL Yeh S Schwarz E
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Title

Longitudinal Intravital Imaging to Quantify the “Race for the Surface” Between Host Immune Cell and Bacteria for Orthopaedic Implants with S. aureus Colonization in a Murine Model

Aim

To assess S. aureus vs. host cell colonization of contaminated implants vis intravital multiphoton laser scanning microscopy (IV-MLSM) in a murine model.


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_16 | Pages 19 - 19
17 Nov 2023
Lee K van Duren B Berber R Matar H Bloch B
Full Access

Abstract

Objectives

Stiffness is reported in 4%–16% of patients after having undergone total knee replacement (TKR). Limitation to range of motion (ROM) can limit a patient's ability to undertake activities of daily living with a knee flexion of 83o, 93o, and 106o required to walk up stairs, sit on a chair, and tie one's shoelaces respectively. The treatment of stiffness after TKR remains a challenge. Many treatment options are described for treating the stiff TKR. In addition to physiotherapy the most employed of these is manipulation under anaesthesia (MUA). MUA accounts for up to 36% of readmissions following TKR. Though frequently undertaken the outcomes of MUA remain variable and unpredictable. CPM as an adjuvant therapy to MUA remains the subject of debate. Combining the use of CPM after MUA in theory adds the potential benefits of CPM to those of MUA potentially offering greater improvements in ROM. This paper reports a retrospective study comparing patients who underwent MUA with and without post-operative CPM.

Methods

Standard practice in our institution is for patients undergoing MUA for stiff TKR to receive CPM for between 12–24hours post-operatively. Owing to the COVID-19 pandemic hospital admissions were limited. During this period several MUA procedures were undertaken without subsequent inpatient CPM. We retrospectively identified two cohorts of patients treated for stiff TKR: group 1) MUA + post-operative CPM 2) Daycase MUA. All patients had undergone initial physiotherapy to try and improve their ROM prior to proceeding to MUA. In addition to patients’ demographics pre-manipulation ROM, post-MUA ROM, and ROM at final follow-up were recorded for each patient.


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_8 | Pages 110 - 110
11 Apr 2023
Lee K Lin J Lynch J Smith P
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Variations in pelvic anatomy are a major risk factor for misplaced percutaneous sacroiliac screws used to treat unstable posterior pelvic ring injuries. A better understanding of pelvic morphology improves preoperative planning and therefore minimises the risk of malpositioned screws, neurological or vascular injuries, failed fixation or malreduction. Hence a classification system which identifies the clinically important anatomical variations of the sacrum would improve communication among pelvic surgeons and inform treatment strategy.

300 Pelvic CT scans from skeletally mature trauma patients that did not have pre-existing posterior pelvic pathology were identified. Axial and coronal transosseous corridor widths at both S1 and S2 were recorded. Additionally, the S1 lateral mass angle were also calculated. Pelvises were classified based upon the sacroiliac joint (SIJ) height using the midpoint of the anterior cortex of L5 as a reference point. Four distinct types could be identified:

Type-A – SIJ height is above the midpoint of the anterior cortex of the L5 vertebra.

Type-B – SIJ height is between the midpoint and the lowest point of the anterior cortex of the L5 vertebra.

Type-C – SIJ height is below the lowest point of the anterior cortex of the L5 vertebra.

Type-D – a subgroup for those with a lumbosacral transitional vertebra, in particular a sacralised L5.

Differences in transosseous corridor widths and lateral mass angles between classification types were assessed using two-way ANOVAs.

Type-B was the most common pelvic type followed by Type-A, Type-C, and Type-D. Significant differences in the axial and coronal corridors was observed for all pelvic types at each level. Lateral mass angles increased from Types-A to C, but were smaller in Type-D.

This classification system offers a guide to surgeons navigating variable pelvic anatomy and understanding how it is associated with the differences in transosseous sacral corridors. It can assist surgeons’ preoperative planning of screw position, choice of fixation or the need for technological assistance.


The Bone & Joint Journal
Vol. 103-B, Issue 2 | Pages 353 - 359
1 Feb 2021
Cho C Min B Bae K Lee K Kim DH

Aims

Ultrasound (US)-guided injections are widely used in patients with conditions of the shoulder in order to improve their accuracy. However, the clinical efficacy of US-guided injections compared with blind injections remains controversial. The aim of this study was to compare the accuracy and efficacy of US-guided compared with blind corticosteroid injections into the glenohumeral joint in patients with primary frozen shoulder (FS).

Methods

Intra-articular corticosteroid injections were administered to 90 patients primary FS, who were randomly assigned to either an US-guided (n = 45) or a blind technique (n = 45), by a shoulder specialist. Immediately after injection, fluoroscopic images were obtained to assess the accuracy of the injection. The outcome was assessed using a visual analogue scale (VAS) for pain, the American Shoulder and Elbow Surgeons (ASES) score, the subjective shoulder value (SSV) and range of movement (ROM) for all patients at the time of presentation and at three, six, and 12 weeks after injection.


Aims

The aim of this study was to compare patient-reported outcome measures (PROMs) and the Single Assessment Numerical Evaluation (SANE) score in patients treated with a volar locking plate for a distal radial fracture.

Methods

This study was a retrospective review of a prospective database of 155 patients who underwent internal fixation with a volar locking plate for a distal radial fracture between August 2014 and April 2017. Data which were collected included postoperative PROMs (Disabilities of the Arm, Shoulder, and Hand questionnaire (DASH) and Patient-Rated Wrist Evaluation (PRWE)), and SANE scores at one month (n = 153), two months (n = 155), three months (n = 144), six months (n = 128), and one year (n = 73) after operation. Patients with incomplete data were excluded from this study. Correlation and agreement between PROMs and SANE scores were evaluated. Subgroup analyses were carried out to identify correlations according to variables such as age, the length of follow-up, and subcategories of the PRWE score.


The Bone & Joint Journal
Vol. 101-B, Issue 6 | Pages 695 - 701
1 Jun 2019
Yang H Wang S Lee K

Aims

The purpose of this study was to determine the functional outcome and implant survivorship of mobile-bearing total ankle arthroplasty (TAA) performed by a single surgeon.

Patients and Methods

We reviewed 205 consecutive patients (210 ankles) who had undergone mobile-bearing TAA (205 patients) for osteoarthritis of the ankle between January 2005 and December 2015. Their mean follow-up was 6.4 years (2.0 to 13.4). Functional outcome was assessed using the Ankle Osteoarthritis Scale, American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, 36-Item Short-Form Health Survey (SF-36) score, visual analogue scale, and range of movement. Implant survivorship and complications were also evaluated.


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_5 | Pages 29 - 29
1 Apr 2018
Kim S Han S Rhyu K Yoo J Oh K Lim S Suh D Yoo J Lee K
Full Access

Introduction

In recent years, there has been an increase in hip joint replacement surgery using short bone-preserving femoral stem. However, there are very limited data on postoperative periprosthetic fractures after cementless fixation of these stem although the periprosthetic fracture is becoming a major concern following hip replacement surgery. The purpose of this study is to determine incidence of postoperative periprosthetic femoral fractures following hip arthroplasty using bone preserving short stem in a large multi-center series.

Materials & Methods

We retrospectively reviewed 897 patients (1089 hips) who underwent primary total hip arthroplasty (THA) or bipolar hemiarthroplasty (BHA) during the same interval (2011–2016) in which any other cementless, short bone-preserving femoral stem was used at 7 institutions. During the study, 1008 THAs were performed and 81 BHAs were performed using 4 different short femoral prostheses. Average age was 57.4 years (range, 18 – 97 years) with male ratio of 49.7% (541/1089). Postoperative mean follow-up period was 1.9 years (range, 0.2 – 7.9 years).


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_5 | Pages 62 - 62
1 Apr 2018
Lee K Min B Bae K Jung J
Full Access

Purpose

Two-stage revision with the removal of all prosthesis has been considered to be the gold standard for treatment of periprosthetic joint infection. However, removal of well-fixed femoral stem is technically challenging and may cause excessive bone loss. The aim of this study was to compare the results between retention and removal of femoral stem when performing two-stage revision total hip arthroplasty for periprosthetic joint infection.

Materials & Methods

From 2007 to 2014, ninety-four patients with infection after hip arthroplasty were treated by using two-stage exchange protocol with temporary articulating spacers. Among them, 38 patients completed the planned second stage reimplantation. Stem was exchanged in 15 patients (group I) and retained in 23 patients (group II). We retrospectively investigated the clinical and radiographic results after an average 39.9 months follow up


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_5 | Pages 30 - 30
1 Apr 2018
Jeong H Kong B Rhee S Nam K Park J Yeo J Lee K Oh J
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Introduction

Previous hemodynamics studies in shoulder arthroplasty only evaluated Western population and mainly focused on risk factors of transfusion. However, Asians are relatively small, and have higher bleeding risk due to prothrombin-clotting-factor polymorphisms. Therefore, it is not appropriate to apply the results of previously studies directly to Asians. Authors compare different hemodynamics depending on the types of shoulder arthroplasties, and evaluate predictors for transfusion in Asian population.

Methods

Total 212 shoulder arthroplasties (26 fracture hemiarthroplasty (fHA), 49 anatomical total shoulder arthroplasty (aTSA), 132 reverse total shoulder arthroplasty (rTSA), and 5 revision surgery) from August 2004 to January 2016 were retrospectively reviewed. Demographics, surgical factors and perioperative hemodynamic factors were compared for each type of arthroplasty. Multivariate regression analysis was conducted to determine predictors for transfusion.


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_6 | Pages 15 - 15
1 Apr 2018
Lee K
Full Access

Anterior cruciate ligament (ACL) reconstruction is the current standard of care for ACL tears. However, the results are not consistently successful, autografts or allografts have certain disadvantages, and synthetic grafts have had poor clinical results. The aim of this study was to determine the efficacy of tissue engineering decellularized tibialis tendons by recellularization and culture in a dynamic tissue bioreactor. To determine if recellularization of decellularized tendons combined with mechanical stimulation in a bioreactor could replicate the mechanical properties of the native ACL and be successfully used for ACL reconstruction in vivo.

Porcine tibialis tendons were decellularized and then recellularized with human adult bone marrow-derived stem cells. Tendons were cultured in a tissue bioreactor that provided biaxial cyclic loading for up to 7 days. To reproduce mechanical stresses similar to hose experienced by the ACL within the knee joint, the tendons were subjected to simultaneous tension and torsion in the bioreactor. Expression of tendon-specific genes, and newly synthesized collagen and glycosaminoglycan (GAG) were used to quantify the efficacy of recellularization and dynamic bioreactor culture. The mechanical strength of recellularized constructs was measured after dynamic stimulation. Finally, the tissue-engineered tendons were used to reconstruct the ACL in mini-pigs and mechanical strength was assessed after three months.

Dynamic bioreactor culture significantly increased the expression of tendon-specific genes, the quantity of newly synthesized collagen and GAG, and the tensile strength of recellularized tendons. After in vivo reconstruction, the tensile strength of the tissue-engineered tendons increased significantly up to 3 months after surgery and were within 80% of the native strength of the ACL.

Our translational study indicates that the recellularization and dynamic mechanical stimuli can significantly enhance matrix synthesis and mechanical strength of decellularized porcine tibialis tendons. This approach to tissue engineering can be very useful for ACL reconstruction and may overcome some of the disadvantages of autografts and allografts.


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_6 | Pages 16 - 16
1 Apr 2018
Lee K
Full Access

Meniscus tears in adult patients do not heal spontaneously and represent a risk factor for OA development. PDGF is well known as an enhancer of meniscal cell biosynthetic activity and also has chemotactic activity for mesenchymal cells. PDGF incorporation into scaffolds should be efficient for recruitment of cells to initiate repair in the injured meniscus. We recently developed decellularized meniscus sheet for use in the treatment of meniscus tears. The aim of this study is to examine the potential of PDGF-coated decellularized meniscus scaffold in mediating integrative healing by endogenous cell migration.

Fresh bovine meniscus was chemically decellularized. Round sheets were made from the decellularized tissue. Heparin was covalently conjugated with decellularized meniscus scaffold (DMS). PDGF-BB was immobilized by binding to the heparin-conjugated DMS. In vitro, PDGF release kinetics was analyzed by ELISA. DMS was transplanted into the injured meniscus explants and cultured for 2 and 4 weeks. The numbers of migrated cells at the border between DMS and injured explant were counted on DAPI stained sections and PDGFRb expressing cells were counted after immunohistochemical staining. The newly produced ECM and collagen fiber alignment was detected by histology on Safranin-O and picrosirius red stained sections. The explants were also tested for tensile properties.

PDGF release kinetics showed sustained slow release in heparin-conjugated DMS, with 11.2% release at day- 16th compared to 26.1% release from the DMS without heparin. Insertion of the PDGF-treated DMS into the meniscus tears in bovine meniscus explants led to the migration of endogenous meniscus cells to the defect zone. The migrated cells expressed PDGFRb and produced new ECM in the defect area. Safranin-O and pircrosirius red staining showed tissue integration between DMS and injured explants. Moreover, the higher concentration of PDGF promoted cell integration into the DMS. Tensile properties of injured explants treated with PDGF coated DMS were significantly higher than in DMS without PDGF.

Heparin-conjugated DMS showed strong immobilization of PDGF, which was released slowly. PDGF coated DMS promoted migration of endogenous meniscus cells to the defect area and into the scaffold. New matrix was formed that bridged the space between the native meniscus and the scaffold and this was associated with improved biomechanical properties. The PDGF coated DMS is a novel, feasible and efficient approach for the treatment of meniscus tears.


Aims

The purpose of this study was to compare the clinical and radiographic outcomes of total ankle arthroplasty (TAA) in patients with pre-operatively moderate and severe arthritic varus ankles to those achieved for patients with neutral ankles.

Patients and Methods

A total of 105 patients (105 ankles), matched for age, gender, body mass index, and follow-up duration, were divided into three groups by pre-operative coronal plane tibiotalar angle; neutral (< 5°), moderate (5° to 15°) and severe (> 15°) varus deformity. American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, a visual analogue scale (VAS), and Short Form (SF)-36 score were used to compare the clinical outcomes after a mean follow-up period of 51 months (24 to 147).


The Bone & Joint Journal
Vol. 98-B, Issue 12 | Pages 1656 - 1661
1 Dec 2016
Kim S Park J Lee K Lee B

Aims

The aim of the study was to develop a quantitative scoring system to predict whether a large-to-massive rotator cuff tear was arthroscopically reparable prior to surgery.

Patients and Methods

We conducted a retrospective review of the pre-operative MR imaging and surgical records of 87 patients (87 shoulders) who underwent arthroscopic repair of a large-to-massive rotator cuff tear. Patients were divided into two groups, based on the surgical outcome of the repair. Of the 87 patients, 53 underwent complete repair (Group I) and 34 an incomplete repair (Group II). Pre-operative MR images were reviewed to quantify several variables. Between-group differences were evaluated and multiple logistic regression analysis was used to calculate the predictive value of significant variables. The reparability index (RI) was constructed using the odds ratios of significant variables and a receiver operating characteristic curve analysis performed to identify the optimal RI cutoff to differentiate between the two groups.


Bone & Joint Research
Vol. 5, Issue 9 | Pages 412 - 418
1 Sep 2016
Ye S Ju B Wang H Lee K

Objectives

Interleukin 18 (IL-18) is a regulatory cytokine that degrades the disc matrix. Bone morphogenetic protein-2 (BMP-2) stimulates synthesis of the disc extracellular matrix. However, the combined effects of BMP-2 and IL-18 on human intervertebral disc degeneration have not previously been reported. The aim of this study was to investigate the effects of the anabolic cytokine BMP-2 and the catabolic cytokine IL-18 on human nucleus pulposus (NP) and annulus fibrosus (AF) cells and, therefore, to identify potential therapeutic and clinical benefits of recombinant human (rh)BMP-2 in intervertebral disc degeneration.

Methods

Levels of IL-18 were measured in the blood of patients with intervertebral disc degenerative disease and in control patients. Human NP and AF cells were cultured in a NP cell medium and treated with IL-18 or IL-18 plus BMP-2. mRNA levels of target genes were measured by real-time polymerase chain reaction, and protein levels of aggrecan, type II collagen, SOX6, and matrix metalloproteinase 13 (MMP13) were assessed by western blot analysis.


Introduction

Ultra high molecular weight polyethylene (UHMWPE) has been used successfully as a bearing material in hip, knee, and shoulder joint replacements. However, there are problems to cause a failure in UHMWPE component, which are wear behavior and creep deformation. Continuous bearing motion and dynamic load have occurred to UHMWPE wear debris caused osteolysis in periprosthetic tissue and to plastic deformation of joint component, and subsequent aseptic loosening of components. Therefore, many studies have being carried out in order to reduce wear debris and to improve mechanical strength from UHMWPE, and there is tremendous improvement of mechanical property in UHMWPE from gamma irradiated conventional UHMWPE (GIPE), highly crosslinked PE (XLPE), and XLPE with vitamin E1, 2. Friction has a significant one of the factors effect on the wear and creep deformation. In this study, the short-term frictional behaviors of three typical types of GIPE, remelted XLPE (R-XLPE), and s annealed XLPE (A-XLPE), and XLPE with Vitamin E against Co-Cr alloy were compared under three levels of contact pressures which occured in hip, knee, and shoulder joints.

Methods

Friction tests were conducted with UHMWPE against Co-Cr alloy by using pin-on-disk type triboteter. For test, tribotester performed in a repeat pass rotational slidintg motion with a velocity of 60rpm. Applied contact pressure selected three kinds of levels, 5, 10, and 20MPa which were within the range of maximum contact pressures for total hip, knee, and shoulder joint replacements. To analyze the frictional effect of UHMWPE type, it conducted t-test and p-values less than 0.05 were used to determine the statistically significant difference.