Accuracy of total knee arthroplasty using the modified gap technique based on the bone gap: an evaluation of the bone gap with a distal femoral trial component

BACKGROUND

In total knee arthroplasty (TKA) using the modified gap technique, the soft-tissue balance is measured after osteotomy of the distal femur and proximal tibia (conventional bone gap). However, after osteotomy, the flexion gap size during 90° knee flexion may be larger than that observed after implantation. The tension of the lateral compartment during 90° flexion may also be reduced after osteotomy of the distal femur. We manufactured a distal femoral trial component to reproduce the condition after implantation and prior to posterior condyle osteotomy. This study aimed to evaluate the effect of the trial component on the flexion gap.

METHODS

This prospective study included 21 consecutive patients aged 78 years with medial osteoarthritis who underwent cruciate-retaining TKA between February 2017 and March 2018. The postoperative flexion gap size and inclination during 90° flexion were compared between cases with and without the trial component.

RESULTS

The mean joint gap size with the trial component (13.4 ± 0.80 mm) was significantly smaller than that without the trial component (14.7 ± 0.84 mm). The mean gap inclination angle with the trial component (3.7° ± 0.62°) was significantly smaller than that without the trial component (5.5° ± 0.78°).

CONCLUSIONS

In the present study, the joint gap size and medial tension were significantly reduced after the trial component had been set. Accurate measurement of the soft-tissue balance is an important factor in the modified gap technique, and this method using a distal femoral trial component can offer better outcomes than those achieved with conventional methods.

Autologous meniscus fragments embedded in atelocollagen gel enhance meniscus repair in a rabbit model

Aims

Meniscal injuries are common and often induce knee pain requiring surgical intervention. To develop effective strategies for meniscus regeneration, we hypothesized that a minced meniscus embedded in an atelocollagen gel, a firm gel-like material, may enhance meniscus regeneration through cell migration and proliferation in the gel. Hence, the objective of this study was to investigate cell migration and proliferation in atelocollagen gels seeded with autologous meniscus fragments in vitro and examine the therapeutic potential of this combination in an in vivo rabbit model of massive meniscus defect.

Methods

A total of 34 Japanese white rabbits (divided into defect and atelocollagen groups) were used to produce the massive meniscus defect model through a medial patellar approach. Cell migration and proliferation were evaluated using immunohistochemistry. Furthermore, histological evaluation of the sections was performed, and a modified Pauli’s scoring system was used for the quantitative evaluation of the regenerated meniscus.

Results

In vitro immunohistochemistry revealed that the meniscus cells migrated from the minced meniscus and proliferated in the gel. Furthermore, histological analysis suggested that the minced meniscus embedded in the atelocollagen gel produced tissue resembling the native meniscus in vivo. The minced meniscus group also had a higher Pauli’s score compared to the defect and atelocollagen groups.

Conclusion

Our data show that cells in minced meniscus can proliferate, and that implantation of the minced meniscus within atelocollagen induces meniscus regeneration, thus suggesting a novel therapeutic alternative for meniscus tears.

Cite this article: Bone Joint Res 2021;10(4):269–276.

The evaluation of degeneration of posterior cruciate ligament using CT Hounsfield unit in knee osteoarthritis

Background

Posterior cruciate ligament (PCL) degeneration is often seen in knee osteoarthritis (OA); however, there is no established method for its evaluation. The purpose of this study is to investigate whether the Hounsfield unit (HU) using computed tomography (CT) could be a useful scale to evaluate the degeneration of PCL in knee OA.

Methods

Knee OA treated with total knee arthroplasty (21 patients, 21 knees) and non-osteoarthritic knees (21 patients, 21 knees) were retrospectively observed and studied. All PCLs in the knees were analyzed using CT. The PCL in the sagittal section was divided into three regions: proximal, middle, and distal sections. The HU value of the PCL at each area was measured. In osteoarthritic knees, tissues from the PCL were collected and histologically graded. The correlation between the radiological classification by Kellgren and Lawrence and the histological grade was analyzed. The average CT HU values for each degenerative grade were also calculated and compared.

Results

The HU values in OA and non-OA were 70.7 and 88.4 HU (p < 0.05) at the proximal region, 75.7 and 85.3 HU (p < 0.05) in the central region, and 82.3 and 86.5 HU (p > 0.05) in the distal region, respectively. The degeneration of PCL was graded as follows: one, three, and 17 mild, moderate, and severe cases at the proximal portion, and 16, 4, and one mild, moderate, and severe cases at the distal portion, respectively. The radiological classification and the grade of degeneration were not correlated in either the proximal (r = 0.047, p = 0.84) or the distal (r = − 0.21, p = 0.35) portions. The HU value was 84.5, 72.1, and 70.6 HU for mild, moderate, and severe grades, respectively (mild versus moderate: p < 0.05, mild versus severe: p < 0.05, moderate versus severe: p > 0.05).

Conclusions

In knee OA, a lower HU value in the PCL indicates the progression of degeneration. The CT HU value could be a useful measurement to predict the grade of PCL degeneration.

Evaluation of the degenerative pattern of PCL in osteoarthritis patients using UTE-T2 mapping

Background

The posterior cruciate ligament (PCL) is one of the essential stabilizers of the knee joint and it was demonstrated that its degenerative change related to the knee osteoarthritis (OA). We aimed to evaluate signal of the PCL in OA patients in comparison with healthy young and elderly volunteers using the ultra-short echo timeenhanced (UTE)-T2∗ mapping, and to validate these findings with histology.

Methods

Thirty asymptomatic volunteers, 13 young people (younger group) and 17 elderly people (elder group), and 27 patients who had undergone total knee arthroplasty (OA group) were enrolled in this study. UTE-T2∗ maps of PCL were obtained from all participants. The PCL was divided into proximal, middle, and distal parts and the UTET2∗ values obtained from each part were compared among the groups. In OA group, the sacrificed PCLs were evaluated histologically in each part corresponding to the part of UTE-T2∗ maps and compared.

Results

The UTE-T2∗ values in OA group were significantly higher than those in other groups except in distal part. In elder group, the UTE-T2∗ values were significantly higher than those in younger group only in the proximal part. Moreover, in OA group, the UTE-T2∗ values in proximal and middle parts were significantly higher than those in distal part. There was a moderate correlation between the UTE-T2∗ values and histological scores.

Conclusions

The specific signal intensity pattern of the PCL in patients with OA was demonstrated using UTE-T2∗ mapping, and these findings were related to histological degenerated status of the PCL.

Quantification of Oscillatory Shear Stress from Reciprocating CSF Motion on 4D Flow Imaging

BACKGROUND AND PURPOSE

Oscillatory shear stress could not be directly measured in consideration of direction, although cerebrospinal fluid has repetitive movements synchronized with heartbeat. Our aim was to evaluate the important of oscillatory shear stress in the cerebral aqueduct and foramen magnum in idiopathic normal pressure hydrocephalus by comparing it with wall shear stress and the oscillatory shear index in patients with idiopathic normal pressure hydrocephalus.

MATERIALS AND METHODS

By means of the 4D flow application, oscillatory shear stress, wall shear stress, and the oscillatory shear index were measured in 41 patients with idiopathic normal pressure hydrocephalus, 23 with co-occurrence of idiopathic normal pressure hydrocephalus and Alzheimer-type dementia, and 9 age-matched controls. These shear stress parameters at the cerebral aqueduct were compared with apertures and stroke volumes at the foramen of Magendie and cerebral aqueduct.

RESULTS

Two wall shear stress magnitude peaks during a heartbeat were changed to periodic oscillation by converting oscillatory shear stress. The mean oscillatory shear stress amplitude and time-averaged wall shear stress values at the dorsal and ventral regions of the cerebral aqueduct in the idiopathic normal pressure hydrocephalus groups were significantly higher than those in controls. Furthermore, those at the ventral region of the cerebral aqueduct in the idiopathic normal pressure hydrocephalus group were also significantly higher than those in the co-occurrence of idiopathic normal pressure hydrocephalus with Alzheimer-type dementia group. The oscillatory shear stress amplitude at the dorsal region of the cerebral aqueduct was significantly associated with foramen of Magendie diameters, whereas it was strongly associated with the stroke volume at the upper end of the cerebral aqueduct rather than that at the foramen of Magendie.

CONCLUSIONS

Oscillatory shear stress, which reflects wall shear stress vector changes better than the conventional wall shear stress magnitude and the oscillatory shear index, can be directly measured on 4D flow MR imaging. Oscillatory shear stress at the cerebral aqueduct was considerably higher in patients with idiopathic normal pressure hydrocephalus.

The correlation between osteoarthritis stage and the effect of the lateral wedge insole for 3 months on medial meniscus extrusion in the knee joint

BACKGROUND

Medial meniscus extrusion (MME) leads to symptomatic knee osteoarthritis (OA) due to increased mechanical stress. MME increases with weight-bearing, and the difference in MME between non-weight-bearing and weight-bearing status (ΔMME) is a factor that causes greater MME. The lateral wedge insole (LWI) is an ideal approach for decreasing the amount of ΔMME associated with the reduction of medial loading stress in the early stage of knee OA. However, the effect of the LWI for 3 months on the ΔMME and its response to OA stage have not been elucidated.

OBJECTIVE

To investigate the effects of the LWI for 3 months on MME and the ΔMME in each stage of OA.

METHODS

Participants were divided into three groups: no intervention with the LWI (control group; n = 9) and intervention with the LWI in early OA (early OA group: Kellgren-Lawrence (K/L) stage = 2, n = 17) and late OA (late OA group: K/L stage > 2, n = 13). MME was evaluated using ultrasound, and the ΔMME was obtained as the difference in MME from non-weight-bearing and weight-bearing conditions. These measurements were performed at two time points: the initial office visit as a baseline and post-3 months.

RESULTS

The weight-bearing MME and ΔMME values post-3 months were significantly decreased compared with those at baseline in the early OA group but not in the control or late OA groups.

CONCLUSIONS

The use of the LWI for 3 months decreased weight-bearing MME and ΔMME values, and its effectiveness was more pronounced in the early stage of knee OA.

The Benefit of Minced Cartilage Over Isolated Chondrocytes in Atelocollagen Gel on Chondrocyte Proliferation and Migration

OBJECTIVE

Autologous chondrocyte implantation is a necessary procedure for the repair of articular cartilage defects; however, isolated chondrocyte implantation requires a 2-step procedure (for harvesting and implantation) and is limited by cytotoxicity due to enzymatic digestion. Therefore, in this in vitro study, we evaluated the possible benefit of using minced cartilage embedded in a 3-dimensional culture scaffold and fixed with fibrin glue, in comparison with isolated chondrocytes in atelocollagen, to induce cell migration, proliferation, and matrix production, using cartilage from patients with knee joint osteoarthritis.

DESIGN

Cartilage fragments were obtained from 7 female patients with knee osteoarthritis (OA) and embedded in atelocollagen gels. As a control, chondrocytes were isolated and embedded in gels in the same manner. These composites were cultured for 3 weeks, and cell proliferation and matrix production were evaluated using histology and immunochemistry.

RESULTS

Histologically, minced cartilage showed cell migration from the cartilage fragments into the gel, with the Bern score and cell count in the minced cartilage group being significantly higher than those in the control group. Immunohistochemistry revealed that the number of Ki67-positive cells, the expression of LECT-1 and TGF-β, and the glycosaminoglycan content were significantly higher in the minced cartilage than in the control group. Minced cartilage exhibited superior cell migration, proliferation, and glycosaminoglycan content than isolated chondrocytes.

CONCLUSION

Our findings support that minced cartilage has a favorable potential for cell proliferation and matrix production compared with the isolated chondrocytes after enzymatic treatment.

Hyperuricemia impaired nitric oxide bioavailablity and deteriorated pulmonary arterial hypertension via a uric acid transporter, URATv1 in xanthine oxidoreductase (XOR)-independent manner

Background

Hyperuricemia occurs in approximately 80% in patients with pulmonary arterial hypertension (PAH) and is positively correlated with pulmonary arterial pressure (PAP). It has been reported that uric acid (UA) reduced endothelium derived nitric oxide (NO) production in porcine pulmonary arterial endothelial cells (PAEC). However, the effects of UA and xanthine oxidoreductase (XOR), catalytic enzyme of UA, on the development of PAH have not been fully elucidated.

Purpose

We examined the followings; (1) the effects of hyperuricemia on the endothelial function and the development of PAH in rats (2) the therapeutic effects of UA transporter inhibitor on PAH in rats, and (3) the role of XOR in PAH in mice.

Methods

We used normal and 5-wk Sugen5416/Hypoxia/Normoxia-exposed (SU/Hx/Nx) rats. Gene expression levels of URATv1, a UA transporter, were measured by RT-PCR. We determined the isometric tension of PA rings isolated from normal rats. The study with the isolated perfused lung preparation was performed in SU/HX/Nx rats. To investigate the chronic effect of UA on the development of PAH, hyperuricemia was induced by the administration of 2% oxonic acid (OA) in diet for 6-wk. Benzbromarone (BBR, 10mg/kg/day, diet, from weeks 0 to 5), a URATv1 transporter inhibitor, was administered in the SU/Hx/Nx-rats with or without 2%OA. To examine the role of XOR in PAH, XOR+/− and wild type (WT) mice were exposed to 3-wk Nx or Hx (10% O2).

Results

The mRNA of URATv1 was detected in the normal lungs. Isometric tension study showed that UA (8 mg/dl) inhibited acetylcholine-induced vasorelaxation. In perfused lung preparations, UA acutely increased estimated PVR in a dose-dependent manner (1.6–16.0mg/dl) with reducing cGMP levels in the lungs. BBR significantly attenuated the pressor response to UA. UA levels in the plasma and the lung tissues were significantly elevated in SU/Hx/Nx-rats with 2%OA (normal vs. vehicle vs. 2%OA, plasma: 0.24±0.01 vs. 0.80±0.14 and 1.44±0.17 mg/dl; lung tissues: 68±3 vs. 142±3 and 377±46 pmol/g tissue). They exhibited further elevation of right ventricle systolic pressure (RVSP) (31±2 vs. 72±6 vs. 101±3 mmHg) and Ea (a marker of RV afterload) (0.24±0.04 vs. 0.97±0.15 vs. 2.36±0.49 mmHg/μL) with the exacerbation of occlusive lesions of PAs. BBR had no changes in the UA levels in the plasma (1.93±0.30 mg/dL), but significantly reduced the UA levels in the lung tissues (101±10 pmol/g tissue) and attenuated the increase in RVSP (53±8mmHg) and Ea (0.21±0.05 mmHg/mL) in the SU/Hx/Nx-rats with 2%OA. On the other hand, BBR had no effects on RVSP (76±7 mmHg) and Ea (0.91±0.15 mmHg/mL) in the SU/Hx/Nx-rats without 2%OA. There were no significant differences in RVSP between XOR+/− mice with Hx and WT with Hx (26±2 vs. 26±2 mmHg).

Conclusions

Hyperuricemia itself impairs endothelial function and deteriorates PAH via URATv1 in a XOR-independent manner. UA can be a novel therapeutic target for PAH.

Funding Acknowledgement

Type of funding source: None

Comparison between optical frequency domain imaging and intravascular ultrasound in PCI guidance for Biolimus A9 eluting stent implantation

Background

It has been reported that intravascular ultrasound (IVUS) guided PCI reduced a risk of major adverse cardiac event compared to conventional angiography guided PCI, while comparison between IVUS-guided and optical frequency domain imaging (OFDI)-guided PCI specifically in long-term clinical outcomes (&gt;1 year) has been unexplored.

Purpose

We sought to compare imaging surrogates at 8 months and clinical outcomes beyond 1 year after drug-eluting stent implantation between IVUS and OFDI guidance.

Methods

The MISTIC-1 is a prospective, multi-centre, single-blinded, randomised-controlled, non-inferiority trial comparing OFDI-guided and IVUS-guided PCI using Biolimus A9 eluting Nobori stent. We enrolled patients with stable coronary artery disease who have symptoms or clinically relevant myocardial ischemia. Stent landing zones were selected in the most normal looking sites with largest lumen and without percentage plaque area &gt;50% in IVUS group while without lipidic plaque of &gt;2 quadrants or suggestive thin-cap fibroatheroma in OFDI group. Stent sizing was based on external elastic lamina (EEL) in IVUS group, while by taking 10% or 0.25mm larger than mean lumen diameter at reference sites in OFDI group. Stent optimisation with in-stent minimum lumen area ≥80% of the average lumen area at proximal and distal reference sites was encouraged in both groups. Primary efficacy endpoint is in-segment minimum lumen area (MLA) assessed by OFDI at 8 months. Secondary safety endpoint is a composite of cardiovascular death, target vessel myocardial infarction, or target lesion revascularisation. Based on the assumption that mean in-segment MLA at follow-up was 4.5mm2 with a standard deviation of 2.0mm2 in the control (IVUS) group and a non-inferiority limit of 1.2mm2 for OFDI group, sample size was estimated as 48 cases in each group with 5% type I error and 90% statistical power.

Results

Since June-2014 and August-2016, we prospectively enrolled 109 patients (mean age 70 years, male 78%) with 126 lesions. Baseline patient and lesion characteristics were well balanced and average nominal size and length of stent used did not differ between OFDI-guided and IVUS-guided PCI (3.0 and 19.1mm vs. 3.1 and 19.3mm, respectively). Post-procedural minimum stent area was 6.24mm2 in OFDI group and 6.72mm2 in IVUS group (p=0.20). At 8-month follow-up, in-segment MLA was 4.56mm2 in OFDI group and 4.13mm2 in IVUS group (P for non-inferiority &lt;0.001). During the follow-up (median 4.5 years [1654 days]), incidence rates of major adverse cardiac event were comparable between the two groups (7.4% in OFDI group and 7.3% in IVUS group, hazard ratio 0.96, 95% CI 0.24–3.83, p=0.95). No definite or probable stent thrombosis were documented in both groups.

Conclusion

OFDI-guided PCI demonstrated comparable results in achieving satisfactory imaging surrogates as well as long-term clinical outcomes after newer generation DES implantation as compared to IVUS-guided PCI.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Suzuken Memorial Foundation

Conceptual design of a collimator for the neutron emission profile monitor in JT-60SA using Monte Carlo simulations

Materials and structures of a collimator for a new neutron emission profile monitor in JT-60SA are examined through Monte Carlo simulations using the Monte Carlo N-Particle transport code. First, the shielding properties of various material combinations are compared in order to determine a combination with high shielding performances against both neutrons and gamma-rays. It is found that a collimator consisting of borated polyethylene and lead has a high shielding performance against neutrons. Moreover, a high shielding performance against gamma-rays is obtained when a lead pipe with a radial thickness of 0.01 m is inserted into a collimation tube. Second, we demonstrate that it is possible to improve the spatial resolution to a desired level by installing a thin tubular extension structure that fits into the limited space available between the main collimator block and the tokamak device. Finally, the collimator structures that meet both the targeted spatial resolutions (<10% of the plasma minor radius) and the targeted counting rate (10⁵ cps order) are discussed.

Five-year major adverse cardiac and cerebrovascular events of patients with lipid core abutting lumen (LCAL) on integrated-backscatter intravascular ultrasound undergoing PCI with current DES

Background

Percutaneous Coronary Intervention (PCI) using the new generation drug-eluting stent (DES) has been extremely reduced target lesion revascularization (TLR) in recent years. However, a high incidence of non-target lesion-related cardiovascular events in patients undergoing PCI is an important problem to be solved. According to the previous findings, patients with vulnerable plaques particularly have a high recurrence of cardiovascular events. Little studies, however, has been done to examine the relationship between plaque characteristics on intravascular imaging in a target lesion and non-target lesion-related cardiovascular events.

Purpose

The main objective of this study is to investigate the five-year major adverse cardiac and cerebrovascular events (MACCE) of patients with lipid core abutting lumen (LCAL) on integrated backscatter intravascular ultrasound (IB-IVUS) in a target lesion undergoing PCI with current DES.

Methods and results

Between February 2010 and September 2013, in total 780 patients with ischemic heart disease undergoing PCI, 166 target lesions in 166 consecutive patients with non-ST segment elevation acute coronary syndrome (NSTE-ACS) and stable angina pectoris (SAP) undergoing IVUS-guided PCI were studied.

Plaque characteristics in all target lesions were analyzed by three-dimensional IB-IVUS system using the mechanical IVUS catheter. Our previous study has found that LCAL which is defined as a lipid pool directly in contact with the lumen visualizes the thin fibrous cap of less than 75μm on optical coherence tomography (OCT). On the basis of this data, LCAL at minimal lumen area (MLA) site was identified.

In total, 39 patients had lesions with LCAL at MLA site (LCAL(+)), and 127 patients had those without LCAL (LCAL(−)).

The primary endpoint was defined as MACCE, including cardiovascular death, non-fatal myocardial infarction, non-fatal stroke and non-TLR for the new lesion during a median follow up of five years. The MACCE occurred significantly higher in the LCAL(+) than in the LCAL(−) (38.5% vs. 17.3%; p&lt;0.005). And the Kaplan-Meier estimates have shown that the cumulative incidence of MACCE was significantly higher in the LCAL(+) than in the LCAL(−) (log rank test, p=0.041). Additionally, after adjustment for confounders, gender, prior PCI and LCAL was the independent predictors for the MACCE of patients undergoing PCI with current DES.

Furthermore, after adding LCAL to a baseline model with established factors consisting of age, gender, diabetes mellitus, prior PCI and percentage lipid volume on IB-IVUS, the net reclassification (p&lt;0.002) and integrated discrimination improvement (p&lt;0.004) significantly improved compared to baseline model alone.

Conclusions

In this study, it has become clear that LCAL on IB-IVUS is likely to be a surrogate marker of MACCE in patients undergoing PCI with current DES.

Funding Acknowledgement

Type of funding source: None

Role of vasoactive intestinal peptide in the progression of osteoarthritis through bone sclerosis and angiogenesis in subchondral bone

OBJECTIVE

Osteoarthritis (OA) is a progressive joint disorder, with abnormal remodeling of subchondral bone linked to the disruption of cartilage metabolism. Nerves also play an important role in bone remodeling in OA progression, and vasoactive intestinal peptide (VIP), one of the neuropeptides, plays an important role in bone metabolism. The aim of this study was to analyze the expression pattern of VIP in subchondral bone, and its potential as a therapeutic target for OA progression.

DESIGN

The pattern of VIP expression in the human tibia was histologically evaluated. The effect of VIP on angiogenesis was investigated using human umbilical vein endothelial cells (HUVECs). Knee OA was induced by the resection of the medial meniscotibial ligament in C57BL/6 mice. A VIP receptor antagonist was intraperitoneally administered postoperatively, and therapeutic effects were analyzed at 4 and 8 weeks.

RESULTS

VIP expression in the subchondral bone increased as OA progressed in human tibia. VIP was also expressed in the vascular channels into the cartilage layer. The total length and branch points were significantly increased, due to the VIP receptor agonist in HUVECs. In OA mice, the VIP receptor antagonist could prevent cartilage degeneration and subchondral bone sclerosis. The Osteoarthritis Research Society International score in the VIP receptor antagonist group was significantly lower than in the control group.

CONCLUSION

VIP is involved in the progression of OA through its effect on subchondral bone sclerosis and angiogenesis. Inhibition of VIP signaling has the potential to be a therapeutic target to prevent OA progression.

Dynamic ultrasonography of the medial meniscus during walking in knee osteoarthritis

BACKGROUND

Medial meniscal extrusion (MME) is a risk factor for the progression of knee osteoarthritis (OA). MME evaluation is crucial and it is commonly performed using magnetic resonance imaging (MRI) or static ultrasonography. We developed a prototype flat-shaped ultrasound transducer to visualize the actual meniscal movements during walking.

OBJECTIVE

The aim of this study was to investigate whether it is feasible to visualize and evaluate the meniscal movements during walking using the novel flat-shaped ultrasound transducer for dynamic ultrasonography.

METHODS

Six participants who were diagnosed with primary unilateral or bilateral tibiofemoral knee OA on radiography (mean age, 67.1 ± 9.9 years; males/females, 4/2) and six healthy volunteers without any symptoms in their knees (mean age, 26.3 ± 4.0 years; males/females, 4/2) were enrolled in this study. The movement of the medial meniscus during walking was visualized using the novel transducer and the gait motion was recorded as video images that were synchronized with the ultrasonogram. MME and ΔMME (the difference between the minimum and maximum MME during the stance phase of the gait cycle) were evaluated in those with OA and compared with those in healthy volunteers.

RESULTS

In both groups, MME was visualized clearly in the stance phase. The mean values of MME and ΔMME in the knee OA group were significantly greater than those in the control group (P < .01).

CONCLUSIONS

Dynamic meniscal movement during gait can be evaluated with the specially developed novel ultrasound transducer. Our approach will be helpful in unveiling unknown pathological mechanisms in knee OA.

The understanding of congruent and incongruent referential gaze in 17-month-old infants: an eye-tracking study comparing human and robot

Several studies have shown that the human gaze, but not the robot gaze, has significant effects on infant social cognition and facilitate social engagement. The present study investigates early understanding of the referential nature of gaze by comparing-through the eye-tracking technique-infants' response to human and robot's gaze. Data were acquired on thirty-two 17-month-old infants, watching four video clips, where either a human or a humanoid robot performed an action on a target. The agent's gaze was either turned to the target (congruent) or opposite to it (incongruent). The results generally showed that, independent of the agent, the infants attended longer at the face area compared to the hand and target. Additionally, the effect of referential gaze on infants' attention to the target was greater when infants watched the human compared to the robot's action. These results suggest the presence, in infants, of two distinct levels of gaze-following mechanisms: one recognizing the other as a potential interactive partner, the second recognizing partner's agency. In this study, infants recognized the robot as a potential interactive partner, whereas ascribed agency more readily to the human, thus suggesting that the process of generalizability of gazing behaviour to non-humans is not immediate.

Increase in medial meniscal extrusion in the weight-bearing position observed on ultrasonography correlates with lateral thrust in early-stage knee osteoarthritis

BACKGROUND

Lateral thrust is known to be risk factors for knee osteoarthritis progression. Medial meniscus extrusion is also known to be risk factors for knee osteoarthritis progression; moreover, the amount of change in medial meniscus extrusion from non-weight bearing to weight bearing is an important factor for the progression of knee osteoarthritis. This study aimed to investigate the correlation between lateral thrust and the change in medial meniscus extrusion.

METHODS

In total, 44 knees from 44 patients (mean age, 68.9 years) with knee osteoarthritis were divided into two groups according to the Kellgren-Lawrence grade: early-stage osteoarthritis (Kellgren-Lawrence = 2) and severe osteoarthritis (Kellgren-Lawrence = 3 or 4). The lateral thrust during gait, represented as the lateral acceleration peak immediately after heel strike, was recorded by an inertial sensor. The amount of change in medial meniscus extrusion, which was the difference between weight-bearing (unipedal standing) and non-weight-bearing (supine) conditions, was evaluated using ultrasonography.

RESULTS

The mean value of the lateral acceleration peak in the severe osteoarthritis group was higher than that of the early-stage osteoarthritis group (p < 0.05). The non-weight-bearing and weight-bearing medial meniscus extrusion in the severe OA group were significantly higher than those of the early-stage osteoarthritis group (p < 0.001). However, the amount of change in medial meniscus extrusion in severe osteoarthritis group was significantly lower than in the early-stage osteoarthritis group (p < 0.05). The amount of change in medial meniscus extrusion showed a significant correlation with the lateral acceleration peak in the early-stage osteoarthritis group (r = 0.56, p < 0.001). On the other hand, there was no significant correlation in the severe osteoarthritis group.

CONCLUSION

The lateral thrust shows a positive correlation with the amount of change in medial meniscus extrusion by weight bearing in patients with early-stage knee osteoarthritis.

New standardization method of tibial tubercle-posterior cruciate ligament distance according to patient size in patients with patellofemoral instability

BACKGROUND

Large differences in tibial tubercle-posterior cruciate ligament (TT-PCL) distance were described in several reports between countries, suggesting that abnormal TT-PCL distance is variable due to individual patient size. This study aimed to clarify the relationship between TT-PCL distance and patient size, and to determine a method for describing individualized TT lateralization.

METHODS

We analyzed 41 patients with recurrent patellar dislocation (RPD) and 41 age-matched patients without patellar instability who underwent primary anterior cruciate ligament reconstruction (control). TT-PCL distance and tibia width (TW) were measured based on preoperative T2-weighted magnetic resonance imaging. Then, TT-PCL distance was standardized based on TW (TT-PCL ratio), and TT-PCL distance and ratio were compared between groups. Correlations were investigated among TT-PCL distance, TT-PCL ratio and each measurement (patient height, weight, TW).

RESULTS

Strong positive correlations were observed between TW and patient height, and weak or moderate positive correlations were found between TT-PCL distance and each parameter. The mean TT-PCL distance was 21.2 and 20.6 mm (P = .39), while the mean TT-PCL ratio was 31.6% and 29.0% (P = .0093) in the RPD and control groups, respectively. The TT-PCL ratio was <34% in 39 of 41 knees (95.1%) in the control group. No correlation was indicated between the TT-PCL ratio and patient size.

CONCLUSIONS

Our findings demonstrate that the TT-PCL ratio is not affected by patient size, although the TT-PCL distance is associated with knee size and patient height. The TT-PCL ratio could be an important index for identifying patients for whom distal realignment surgery should be considered.

A self-reported measurement scale on a potential component of competency in the healthcare staff engaged in the prevention and control of non-communicable disease in Fiji

Background

According to the World Health Organization, an estimated 80% or more deaths in Pacific island countries, including Fiji, were related to non-communicable diseases (NCDs). Although competency-based approaches have been effective for developing healthcare workers’ capabilities, there are only a few reports on competency scales of healthcare workers for NCD prevention. We aimed to develop a self-reported measurement scale on a potential component of competency in the healthcare staff engaged in the prevention and control of NCDs in Fiji.

Methods

There were 378 Ministry of Health and Medical Services staff members working on NCD prevention and control in Fiji included in this study, which was a cross-sectional survey of social factors, working situation factors, and competency. Exploratory factor analysis was conducted to assess potential competency components, whereas Cronbach’s α coefficient and analysis of variance were used to assess the validity and reliability of the scale items, respectively. Multivariate regression analyses were conducted to analyze the respondents’ factor scores relative to social status and work situations.

Results

The factor analysis revealed 16 items that identified competency in four work types: 1) work management, 2) monitoring and evaluation, 3) community partnership, and 4) community diagnosis. The monitoring and evaluation roles were related to ethnic background, community partnership was related to religion, and community diagnosis was related to academic qualifications.

Conclusions

Based on the results, we developed a competency scale for the four work types. This scale can help healthcare workers engage in better management of residents with NCDs in Fiji.