Mobile-bearing prosthesis suppresses the postoperative rotational mismatch and improves patient-reported outcome measurements better than fixed-bearing prosthesis: rotational analysis by 3D measurement in total knee arthroplasty.

INTRODUCTION: It is preferable to reduce postoperative excessive rotational mismatch between the femur and tibia that causes poor clinical results following total knee arthroplasty (TKA). The aim of this study is to compare postoperative rotational mismatches and clinical outcomes with mobile- and fixed-bearing prostheses. MATERIALS AND METHODS: This study classified 190 TKAs into two groups equally by propensity score matching: mobile-bearing group (n = 95) and fixed-bearing group (n = 95). Computed tomography images of the whole leg were taken at 2 weeks postoperatively. The component alignments, rotational mismatches between the femur and tibia, and rotations among components were measured three-dimensionally. The knee range of motion, New Knee Society Score (KSS) subjective sores, and Forgotten Joint Score (FJS-12) were assessed at the final follow-up. RESULTS: Rotational mismatch between the femur and tibia was significantly less in the mobile- (- 0.8° ± 7.3°) than in the fixed-bearing (3.3° ± 8.5°, p < 0.001) group. New KSS functional activity score was significantly poorer in patients with excessive rotational mismatch (61.3 ± 21.4) than in those without it (49.5 ± 20.6, p = 0.02). Comparing mobile-bearing prosthesis, the use of fixed-bearing prosthesis was a risk factor for postoperative excessive rotational mismatch (odds ratio: 2.32, p = 0.03). CONCLUSION: When compared to a fixed-bearing prosthesis, TKA using a mobile-bearing prosthesis could suppress the postoperative rotational mismatch between the femur and tibia that causes poor subjective functional activity score. However, since this study was conducted for PS-TKA, the results might not be applicable to other models.

A double tapered fully hydroxyapatite-coated stem has less contact area to femoral cortical bone than a tapered-wedge stem: a three-dimensional computed tomography-based density mapping analysis.

INTRODUCTION: It is clinically important to analyze the initial contact state between an implant and femoral cortical bone as it affects clinical outcomes, such as stress shielding, stem subsidence, thigh pain, and patient-reported outcomes after total hip arthroplasty. Whether the initial contact state of a double-tapered fully hydroxyapatite (HA)-coated stem is achieved with the preserved cancellous or cortical bone remains to be established. This study aimed to compare the contact area with the femoral cortical bone between a double-tapered fully HA-coated stem (HA group) and a tapered wedge cementless stem (TW group) using three-dimensional computed tomography (3DCT)-based templating software. MATERIALS AND METHODS: Forty-seven total hip arthroplasties in the HA and TW groups each were retrospectively analyzed. The contact area between the implant and femoral cortical bone in the whole stem and at each Gruen zone was measured using density mapping with 3DCT-based templating software. RESULTS: The demographic data were not significantly different between the two groups. The contact area in the whole stem area was lower in the HA group (HA 5.4 ± 1.8% vs. TW 9.0 ± 4.8%, p < 0.01). The HA group had a lower contact area in zone 2 (HA 6.7 ± 6.5% vs. TW 15.6 ± 10.8%, p < 0.01) and zone 6 (HA 1.8 ± 3.5% vs. TW 6.3 ± 3.6%, p < 0.01) than the TW group. The implant type (ß = 0.41, p < 0.01) and stem coronal alignment (ß = - 0.29, p < 0.01) were significant predictors of the contact area in the whole stem area in a multiple regression analysis (adjusted R2 = 0.27, p < 0.01). CONCLUSION: The contact area of the double-tapered fully HA-coated stem was significantly lower than that of the tapered wedge cementless stem.

Eldecalcitol regulates the gene expressions of articular cartilage markers and differentiation markers in chondrocytes.

Vitamin D has been shown to reduce symptoms in patients with osteoarthritis (OA). In a previous study, local administration of eldecalcitol, an active vitamin D3 analog, reduced degenerative changes in articular cartilage in the early phase of experimental OA. However, the target of vitamin D in OA remains unknown. Here, we investigated the effect of eldecalcitol treatment on chondrocytes, which were divided into superficial zone chondrocytes (SZC), deep zone chondrocytes (DZC), and differentiated chondrocytes. SZC and DZC were cultured in monolayer and 3D pellet cultures treated with eldecalcitol. The gene expressions of articular cartilage and chondrocyte differentiation markers were evaluated. Histological analysis of SZC and DZC 3D pellet cultures was performed. The results showed that the articular cartilage markers ETS-related gene (Erg) and lubricin/proteoglycan 4 (PRG4) were significantly increased in SZC, but not in DZC, in the monolayer culture treated with eldecalcitol. The chondrocyte differentiation markers type X collagen and alkaline phosphatase (ALP) were significantly decreased in the DZC pellet culture treated with eldecalcitol. Immunochemical analysis also showed that Erg and lubricin/PRG4 expressions were elevated in the SZC pellet culture treated with eldecalcitol, while type X collagen and ALP expressions were decreased in the DZC pellet culture treated with eldecalcitol. In conclusion, this study showed that eldecalcitol upregulated articular cartilage markers in SZC and suppressed differentiation markers in DZC. Such regulation of chondrocytes by eldecalcitol could be potentially effective against OA progression.

Four-Millimeter Additional Bone Resection in the Distal Femur Does Not Result in an Equivalent Increase in the Extension Joint Gap in Total Knee Arthroplasty.

BACKGROUND: Additional bone resection in the distal femur is performed to increase the extension joint gap in total knee arthroplasty (TKA). The present study aimed to analyze the relationship between the amount of additional bone resection in the distal femur and the increase in the extension joint gap in TKA. METHODS: Fifty knees undergoing TKA for varus osteoarthritis were evaluated. Two femoral trial component models were prepared: (1) a normal model with 9-mm-thick distal and posterior femoral components and (2) an additional bone resection model with a 5-mm-thick distal femoral component (9 mm to 4 mm) and a 9-mm-thick posterior femoral component, which simulated an additional bone cut in the distal femur of 4 mm. The femoral trial component models were set before implantation, and the extension joint gap was measured using a tensor device that had a shape identical to that of the fixed-bearing tibial insert. RESULTS: The additional bone resection model had a larger joint gap than the normal model (P < .01). The mean extension gap increase in the additional bone resection model was 2 (standard deviation 1) mm, which was less than the thickness of the additional bone resection (4 mm) (P < .01). CONCLUSION: The amount of additional bone resection in the distal femur was not equal to the increase in the extension joint gap. Additional bone resection of 4 mm in the distal femur only increased the extension joint gap by a mean of 2 mm.

Joint line elevation is not associated with mid-flexion laxity in patients with varus osteoarthritis after total knee arthroplasty.

PURPOSE: Previous cadaver studies showed that the additional bone cuts in the distal and posterior femur and joint line elevation resulted in laxity at mid-flexion after total knee arthroplasty (TKA). However, these results are not always applicable to TKA candidates because the related studies used cadaver knees with no osteoarthritis. It was hypothesized that the joint line elevation results in mid-flexion laxity after TKA in patients with knee osteoarthritis. The purpose of this study was to analyze the relationship between joint line elevation and mid-flexion laxity in patients with knee osteoarthritis. METHODS: 30 knees with varus osteoarthritis undergoing TKA were evaluated. Two femoral trial component models were prepared: (1) normal model with a thickness of the distal and posterior femoral components of 9 mm, and (2) 2-mm joint line elevation model with a thickness of the distal and posterior femoral components of 9 - 2 = 7 mm. This 2-mm joint line elevation model simulated an additional bone cut in the distal and posterior femur, and joint line elevation, without an additional bone cut. The femoral trial component models were set before implantation and measured the joint gap kinematics using a tensor device through the full knee range of motion. RESULTS: The differences in joint gap change from 30° to 90° were not statistically significant between the two models. However, the joint line elevation model decreased the joint gap laxity at 120° (p = 0.02) and at 145° (p = 0.01). CONCLUSIONS: This study showed that a 2-mm joint line elevation was not associated with mid-flexion laxity in patients with varus osteoarthritis in the knee. The results of this study differed from the results in previous cadaver studies. LEVEL OF EVIDENCE: Therapeutic study, level II, prospective comparative study.

Malrotation of the fixed-bearing posterior stabilized total knee prosthesis causes a postoperative rotational mismatch between the femur and tibia.

PURPOSE: This study aimed to identify factors associated with rotational mismatch after total knee arthroplasty (TKA) using fixed-bearing posterior stabilized prosthesis and to evaluate the impact of the rotational mismatch on clinical outcomes. METHODS: This retrospective cohort study included 159 cases that underwent TKA. Whole-leg computed tomography images were obtained 2 weeks after TKA, with three-dimensional measures of alignment. Rotational alignment of the femoral and tibial components and rotational mismatch between components and between the femur and tibia bones were evaluated. The new Knee Society Score (KSS) was obtained at the final outpatient visit, which was defined as the final follow-up timepoint. Predictive factors were identified for rotational mismatch of the lower extremity and poor new KSS. RESULTS: The mean follow-up period was 42 ± 16 months. Rotational mismatch ≥ 10° between bones was identified in 56 cases (35%), with a mean mismatch angle of 5.0° ± 9.1° of external rotation of the tibia relative to the femur. Rotational mismatch ≥ 10° between components was identified in three cases (2%; mean 0.3° ± 3.6° of internal tibial rotation). A multivariate regression analysis showed that component malrotation was predictive of post-operative rotational mismatch between bones (p < 0.01) and rotational mismatch ≥ 10° associated with poor new KSS (odds ratio 4.22; p < 0.01). CONCLUSION: Malrotation of the fixed-bearing posterior stabilized TKA causes a rotational mismatch between the femur and tibia bones. Excessive rotational mismatch between bones greater than 10° is a risk factor for poor postoperative functional outcome. Precise component positioning is essential for improving TKA outcomes. LEVEL OF EVIDENCE: III.

Two-dimensional measurement misidentifies alignment outliers in total knee arthroplasty: a comparison of two- and three-dimensional measurements.

PURPOSE: Two-dimensional (2D) and three-dimensional (3D) measurements of prosthetic alignment and "outliers" after total knee arthroplasty (TKA) might not necessarily be comparable. The aim of this study was to compare the use of 2D and 3D measurements in the identification of prosthetic alignment and outliers after TKA. METHODS: This cross-sectional study included 159 consecutive TKAs. All patients underwent plain radiography, fluoroscopy-guided radiography, and computed tomography after TKA. The same baseline was used for 2D and 3D measurements. The reliability of prosthetic alignment and outlier identification (> 3° from neutral alignment) was compared between the 2D and 3D measurements. RESULTS: The mean prosthetic alignment and rate of outliers were not significantly different the between 2D and 3D measurements. The inter- and intra-observer reliabilities were higher for the 3D measurements than for the 2D measurements. The agreement between 2D and 3D measurements in outlier identification was poor, except for femoral coronal alignment. Cohen's κ coefficients were 0.19 in femoral sagittal (poor), 0.02 in tibial coronal (poor), and 0.10 in tibial sagittal (poor) on plain radiography. The values were 0.23 in tibial coronal (poor) and 0.002 in tibial sagittal (poor) on fluoroscopy-guided radiography. CONCLUSIONS: The agreement between 2D and 3D measurements in the identification of outliers was poor, even on fluoroscopy-guided radiography. Since 2D measurements have an inherent risk of misidentifying alignment outliers, this finding is clinically relevant. To properly analyze the correlation between outliers and clinical results, such as longevity, patient satisfaction, and patient-reported outcome, 3D measurements for prosthetic alignment are desirable. LEVEL OF EVIDENCE: III.

An accelerometer-based portable navigation system improved prosthetic alignment after total knee arthroplasty in 3D measurements.

PURPOSE: This study aimed to compare prosthetic alignment using three-dimensional (3D) measurements following total knee arthroplasty (TKA) performed using an accelerometer-based portable navigation system (KneeAlign2) versus the conventional technique. METHODS: A total of 159 patients who had primary osteoarthritis of the knee with varus deformity underwent TKA. The KneeAlign2 system was used for distal femoral resection and tibial resection in 78 knees, and the conventional instrumentation (intramedullary for the femur and extramedullary for the tibia) was used in 81 knees. 3D computed tomography (CT) scans of the whole leg were taken after TKA. Femoral and tibial prosthetic alignments in the coronal, sagittal, and axial planes were measured using computer software. The operation time and estimated blood loss were calculated. Deep venous thrombosis (DVT) and pulmonary embolism (PE) were evaluated using the contrast-enhanced multi-detector row CT at 1 week after TKA. RESULTS: In the femoral coronal plane, the mean and standard deviation of prosthetic alignment from neutral alignment were 1.2° [95% confidence interval (CI) 1.0°-1.4°) in the navigation group and 1.6° (95% CI 1.3°-2.0°) in the conventional group (p = 0.03). The femoral component outliers (> 3° away from the goal alignment) using the navigation system and the conventional technique were 3 and 15%, respectively, in the coronal plane (p < 0.01), and 15 and 43%, respectively, in the sagittal plane (p < 0.01). The outliers in tibial coronal and tibial sagittal planes were not statistically different between the two groups. There were no statistically significant differences between the two groups in operation time, blood loss, DVT, and PE. CONCLUSION: Using an accelerometer-based portable navigation system decreased the outliers of prosthetic alignment in femoral coronal and sagittal planes, and did not increase the complications such as operation time, blood loss, DVT, and PE. To our knowledge, this study is the first to investigate the usefulness of an accelerometer-based portable navigation system using the validated 3D measurement. LEVEL OF EVIDENCE: III.

Simultaneous Post and Cone Fractures of a Polyethylene Insert in a Mobile-Bearing Posterior-Stabilized Total Knee Arthroplasty.

We report a novel case of the simultaneous post and cone fractures of a polyethylene (PE) insert in a mobile-bearing posterior-stabilized total knee arthroplasty. Twelve years after the primary total knee arthroplasty, the 72-year-old male patient presented with a recurring right knee instability and was diagnosed with the wear of the PE insert based on physical and radiological examinations. Revision surgery was performed. The post and cone of the PE insert had fractured simultaneously. Moreover, the femoral and tibial components were in direct contact with each other. One year post-revision, knee function had improved. To diagnose a PE breakage, such as a post or cone fracture, surgeons should consider the possibility of PE breakage even in the absence of pain since patients might complain of subjective instability only.

Improvement of rotational arc during deep flexion range of a novel designed polyethylene insert for posterior-stabilised total knee arthroplasty.

BACKGROUND: One of the remaining issues in total knee arthroplasty (TKA) is achieving sufficient rotational arc during deep flexion range of the knee for specific postures such as the 'seiza' or cross-legged sitting. This study aimed to evaluate whether there was a change in the actual in vivo rotational arc during deep flexion range before and after a design change of polyethylene (PE) inserts. METHODS: In 50 posterior-stabilised TKA cases, knee kinematics, including rotational movement, were measured intraoperatively using an image-free navigation system to compare a newly designed PE insert with reduced the posterior lip with a conventional PE insert. Femoral-tibial rotational angles at 30°, 45°, 60°, 90°, 120°, and 130° knee flexion were evaluated. Varus/valgus instability, knee range of motion, and femoral rollback were also measured. Obtained parameters were compared between new and conventional PE inserts. The independent factors associated with rotational arc during deep flexion range (120° and 130° knee flexion) were analysed using multivariate analysis. RESULTS: The newly designed PE insert demonstrated a significant increase in the rotational arc at 120° (22.9 ± 8.7° vs. 30.1 ± 11.9°, P < 0.001) and 130° (24.3 ± 9.5° vs. 32.5 ± 12.4°, P < 0.001) knee flexion compared with that with the conventionally designed posterior-stabilised insert. Multivariate analysis demonstrated that using the newly designed PE insert was an independent predictor of improved rotational arc during deep flexion range: regression coefficient was 11.2 (95% confidence interval 7.1-15.3, P < 0.001). CONCLUSION: The design change, which reduced the posterior lip of the PE insert, contributed to improved rotational arc in 120° and 130° deep flexion ranges.

Photoluminescence characterization of polythiophene films incorporated with highly functional molecules such as metallophthalocyanine.

The photoluminescence (PL) of conducting polymer polythiophene (PT) films incorporated with metallophthalocyanines (PcMs) such as CuPc, MgPc, FePc, Li2Pc, and CoPc was studied by PL and time-correlated single photon counting (TCSPC) measurements. Polymer films were prepared by electrochemical polymerization and PcMs migrated into the polymer films by a diffusion method using acetonitrile or toluene as a solvent to dissolve the PcMs. The wavelength of PL emission peaks changed significantly depending on the solvent used in the doping process. Using acetonitrile, the observed PL emission peaks originated from the Q band, whereas they were assigned to the Soret band in the case of toluene. TCSPC measurements showed that PL emission took place through a ligand-ligand transition process when using acetonitrile because the average lifetimes were comparable and independent of the central metal ions for CoPc-, Li2Pc-, and MgPc-doped polymer films. Conversely, using toluene, it was found that ligand-ligand emission occurred for Li2Pc-, MgPc-, and FePc-doped films. To identify the cause of the drastic change in PL emission pattern, x-ray photoelectron spectroscopy measurements were obtained. A lower binding energy component appeared in the C 1s core-level spectra of acetonitrile-processed PcM-doped PT films, whereas this component shifted to higher energy and overlapped with the main peak for toluene-processed PcM-doped PT films. The lower binding energy component corresponded to photoelectrons due to the C atoms in the benzene rings of the ligand. Lower binding energy components also appeared in the N 1s core-level spectra of acetonitrile-processed PcM-doped PT films, and this component shifted to higher energy for toluene-processed PcM-doped PT films. These lower energy components were assigned to the core-level peaks due to the N atoms at the meso position bridging between pyrrole rings. This suggests that the electron charge at the N sites of the meso positions in toluene-processed films was smaller than in acetonitrile-processed ones. The changes in energy at benzene C sites and meso N sites suggest that the electronic states of the phthalocyanine in the toluene-processed films were porphyrin-like, so the Soret band became dominant in the PL emission spectrum.

Medial peg position of cementless porous tantalum tibial component affects bone mineral density around the prosthesis after total knee arthroplasty: 2-year follow-up study.

BACKGROUND: Use of a porous tantalum tibial component for total knee arthroplasty (TKA) was reported to have beneficial effects on periprosthetic bone mineral density (BMD). In some cases, hexagonal peg is placed close to or in contact with the tibial cortex, which may result in stress-shielding around the peg. However, no studies have analyzed the relationship between peg position and BMD. The aim of this study was to compare the peg position and BMD around the peg in a porous tantalum tibial component after TKA. METHODS: Twenty-seven patients (27 knees) who underwent primary TKA with a cementless porous tantalum tibial component were investigated. BMD was measured by dual-energy X-ray absorptiometry for 2 years after the operation. The distance between the peg and the tibial cortex (peg distance) was measured on the medial and lateral sides. RESULTS: BMD was decreased in the medial region after the operation (p < 0.01). Relative change in BMD was lower in the medial region than in the central and lateral regions (p < 0.01). Multiple regression analysis showed that medial peg distance was negatively correlated with relative change of BMD in the medial part of the tibia (p = 0.04, R = 0.402). CONCLUSIONS: The medial peg position affected the postoperative relative change of BMD in the medial part of the tibia, but did not affect the longevity of the implant. As the tibial medial peg became closer to the medial tibial cortex, the BMD loss became larger in the medial part of the tibia at 2 years postoperatively.

Differences in the setting of acetabular component alignment guides between the supine and lateral positions for total hip arthroplasty.

The acetabular component orientation in total hip arthroplasty is of critical importance to clinical results. Although navigation systems and surgical robots have been introduced, most surgeons still use acetabular component alignment guides. This study aimed to compare the accuracy between modern acetabular component alignment guides for the lateral position and those for the supine position. Thirteen alignment guides for the lateral position and 10 for the supine position were investigated. All the lateral position alignment guides indicated cup alignment in operative definition, and the supine position alignment guides indicated cup alignment in radiographic definition. For lateral position alignment guides, the anteversion actually indicated by the alignment guide itself was smaller than that indicated by the manufacturer by a mean of 6° (maximum, 9°), and the inclination actually indicated by alignment guides themselves was larger than that by the manufacturer (p < 0.01) by a mean of 2° (maximum, 4°). For supine position alignment guides, the inclination and anteversion indicated by the alignment guide itself were identical with those indicated by the manufacturer. The current study showed that the angles actually indicated and those stated by manufacturers were not identical for lateral position alignment guides.

The posterior tibial slope does not influence the flexion angle in posterior-stabilized mobile-bearing total knee arthroplasty.

BACKGROUND: It remains uncertain whether an increase in the tibial slope leads to better flexion in posterior-stabilized (PS) total knee prostheses. PURPOSE: To compare the intra-operative flexion angle between standard and an additional 10° posterior slope inserts. PATIENTS AND METHODS: Between December 2014 and February 2015, 22 patients (25 knees) who underwent PS mobile-bearing primary total knee arthroplasty (TKA) were included. Flexion angles were measured using either standard or specially-made inserts. Differences in flexion angles between the two situations were analyzed to determine the relationship between changes in flexion angle and pre-operative flexion angle or body mass index (BMI), and between intra- and post-operative flexion angle. RESULTS: The difference between the average flexion angle of standard inserts and specially-made inserts was not statistically significant. Although the correlations between changes in flexion angle due to insert difference and flexion angle, pre-operative flexion angle or BMI were not significant, there was a positive correlation between intra-operative and post-operative flexion at 2 years. CONCLUSION: The results showed an additional posterior tibial slope by 10° did not affect the intra-operative flexion angle. Surgeons performing PS mobile-bearing TKA do not need to excessively slope the tibial bone cutting to improve the post-operative flexion angle. LEVEL OF EVIDENCE: I, Experimental study.

Vitamin E-infused highly cross-linked polyethylene did not reduce the number of in vivo wear particles in total knee arthroplasty.

AIMS: Vitamin E-infused highly cross-linked polyethylene (E1) has recently been introduced in total knee arthroplasty (TKA). An in vitro wear simulator study showed that E1 reduced polyethylene wear. However there is no published information regarding in vivo wear. Previous reports suggest that newly introduced materials which reduce in vitro polyethylene wear do not necessarily reduce in vivo polyethylene wear. To assist in the evaluation of the newly introduced material before widespread use, we established an in vivo polyethylene wear particle analysis for TKA. The aim of this study was to compare in vivo polyethylene wear particle generation between E1 and conventional polyethylene (ArCom) in TKA. METHODS: A total of 34 knees undergoing TKA (17 each with ArCom or E1) were investigated. Except for the polyethylene insert material, the prostheses used for both groups were identical. Synovial fluid was obtained at a mean of 3.4 years (SD 1.3) postoperatively. The in vivo polyethylene wear particles were isolated from the synovial fluid using a previously validated method and examined by scanning electron microscopy. RESULTS: The total number of polyethylene wear particles obtained from the knees with E1 (mean 6.9, SD 4.0 × 107 counts/knee) was greater than that obtained from those with ArCom (mean 2.2, SD 2.6 × 107 counts/knee) (p = 0.001). The particle size (equivalent circle of diameter) from the knees with E1 was smaller (mean 0.5 µm, SD 0.1) than that of knees with ArCom (mean 1.5, SD 0.3 µm) (p = 0.001). The aspect ratio of particles from the knees with E1 (mean 1.3, SD 0.1) was smaller than that with ArCom (mean 1.4, SD 0.1) (p < 0.001 ). CONCLUSION: This is the first report of in vivo wear particle analysis of E1. E1 polyethylene did not reduce the number of in vivo polyethylene wear particles compared with ArCom in early clinical stage. Further careful follow-up of newly introduced E1 for TKA should be carried out. Cite this article: Bone Joint J 2020;102-B(11):1527-1534.

Peri-prosthetic bone mineral density after simultaneous bilateral total knee arthroplasty under oral bisphosphonate therapy - A comparison between mobile- and fixed-bearing prostheses.

BACKGROUND: Peri-prosthetic bone mineral density (BMD) decreases after total knee arthroplasty (TKA). We aimed to specifically compare peri-prosthetic BMD changes between mobile- and fixed-bearing prostheses in patients undergoing oral bisphosphonate therapy, hypothesizing that mobile-bearing components would have a favorable effect on postoperative peri-prosthetic BMD. METHODS: This prospective cohort study investigated 30 patients who underwent simultaneous bilateral TKA for primary knee osteoarthritis between December 2007 and September 2012. All patients underwent mobile-bearing TKA in one knee and fixed-bearing TKA in the other and received oral alendronate therapy at a dosage of 35 mg/week. Peri-prosthetic and lumbar spine BMDs were measured using dual X-ray absorptiometry scans, with peri-prosthetic BMD changes being compared between the two prostheses in each patient at six months and one, two, three, and five years post-operation. RESULTS: Clinical results did not significantly differ between two prostheses. Relative change of lumbar spine BMD was significantly greater at five years post-operation than at one year post-operation (p = 0.01), and was significantly correlated at five years post-operation with peri-prosthetic BMD in the central femur (r = 0.39, p = 0.002), posterior femur (r = 0.39, p = 0.002), and medial tibia (r = 0.42, p = 0.007). CONCLUSIONS: There was no difference in peri-prosthetic BMD changes between two prostheses in patients undergoing oral bisphosphonate therapy. Our results suggest that the influence of oral bisphosphonate therapy might offset the influence of prosthetic design. Thus, oral bisphosphonate therapy may be more effective than prosthetic design selection in preventing post-TKA peri-prosthetic BMD loss. LEVEL OF EVIDENCE: II.

Clinical results of alumina medial pivot total knee arthroplasty at a minimum follow-up of 10years.

BACKGROUND: The medial pivot total knee prosthesis with alumina ceramic femoral components was introduced to reproduce physiological knee kinematics and reduce polyethylene wear. The five-year clinical outcomes of alumina medial pivot total knee arthroplasties (TKA) have previously been reported. The purpose of this study was to provide the longer-term clinical results at a minimum follow-up of 10years. METHODS: The clinical results of 70 alumina medial pivot TKA in 51 consecutive patients, with a minimum follow-up period of 10years, were evaluated. RESULTS: Mean follow-up was 11.8years (range 10 to 13). Alumina medial pivot TKAs improved the patients' Knee Society knee scores, function scores, and postoperative ranges of motion compared with their pre-operative statuses (P<0.05 for each). Revision surgery was required in one knee due to a postoperative fracture of the tibial plateau after a fall that occurred two years postoperatively. Osteolysis and femoral component loosening was identified in one case after the initial five-year time point of analysis. The survival rate was 99.1% at 10years. CONCLUSIONS: This study demonstrated excellent clinical results for patients receiving the alumina medial pivot prosthesis at a minimum follow-up period of 10years.

Fabrication and Characterization of Electronic and Optical Properties of Polyaniline Nanopatterns.

The authors conducted polyaniline (HA) polymerization on a micro-scale patterned Si water and nano-scale patterned Al surface. Polymerization was performed using a microliter solution droplet made of aniline, HCI and oxidation agent ammonium peroxodisulfate (APS). The droplet was dropped on a flat Si wafer, a micro-patterned Si wafer and a nanostructured Al surface. The SEM image showed that PA was densely polymerized on the circle edge of the dropped 1 mm sized droplet on the flat Si wafer because of large surface tension due to the flat surface. On the other hand, a droplet was broken on a circular trench pattern of 100 µm in diameter fabricated on a Si wafer. The width and depth of the trench were 1 µm and 1 µm, respectively. Tree-like polymer was intensively polymerized along the circular trench. Droplet was also dropped on a lattice trench pattern whose pitch was 10 µm. The width and the depth of the trench were 1 µm and 1 µm, respectively. The SEM image showed that dots of PA were fabricated along the trenches. Far smaller dots of PA were also observed on the flat area of the lattice. Thus, micro-scale structure affects the shape and size of PA in polymerization. Nanoscopic polymerization of PA was conducted locally in a nanoscale highly-oriented line pattern with nanoscale trenches formed on an Al surface. One of the characteristic fabricated patterns was a highly conductive PA line pattern whose pitch was 100 nm. In this case, point-contact IV characteristic measurement, step-like curve was observed. PL spectra of the PA line-pattern exhibited significantly enhanced emission peaks at 380, 450 anc 550 nm due to PA which were overlapped by the rippled PL pattern due to the Al nanostructure.