Symptoms of Knee Instability as Risk Factors for Recurrent Falls

Hamstrings-quadriceps strength ratio could be related to falls in community-living older adults

A prior study reported that the concentric strength imbalance between hamstrings and quadriceps is associated with falls in older adults. Given that the concentric strength may not be measured as conveniently as the isometric strength, it is meaningful to test whether the isometric hamstring-quadricep strength imbalance is related to falls among older adults. This study sought to explore whether the hamstrings-quadriceps ratio could differentiate fallers from non-fallers in community-dwelling older adults. One hundred and eleven older adults were included in this cross-sectional study. Their isometric knee joint strength capacity (extensors and flexors) was measured. Based on their fall history in the past year, they were classified as fallers (at least one fall) or non-fallers (no fall). The hamstrings-quadriceps ratio was compared between the faller and non-faller groups. The receiver operating characteristic analysis was used to determine the cutoff value of the hamstrings-quadriceps ratio able to best classify fallers and non-fallers. Fallers showed a significantly lower hamstrings-quadriceps ratio than non-fallers (p = 0.008). The receiver operating characteristic analysis identified 0.733 as the best ratio to differentiate fallers from non-fallers with an accuracy of 64.0 %. A 0.1-unit reduction in the hamstrings-quadriceps ratio increases the probability of falling by a factor of 1.30. The hamstrings-quadriceps ratio could be used as an additional fall risk factor when assessing the risk of falls among older adults. A smaller than 0.733 hamstring-quadriceps ratio may indicate a high risk of falls.

Effectiveness of Yijinjing exercise in the treatment of early-stage knee osteoarthritis: a randomized controlled trial protocol

INTRODUCTION

Knee osteoarthritis (KOA) is still a challenging degenerative joint disease with high morbidity and disease burden. Early-stage KOA, the focus of this study, could present a Window of Opportunity to arrest the disease process and reduce the disease burden. Yijinjing exercise is an important part of physical and psychological therapies in Traditional Chinese Exercise and may be an effective treatment. However, there is no clinical efficacy assessment of Yijinjing exercise for patients with early-stage KOA. Therefore, we designed a randomised controlled trial to evaluate the effectiveness of Yijinjing exercise on patients with early-stage KOA.

METHODS AND ANALYSIS

This is a parallel-design, two-arm, analyst assessor-blinded, randomised controlled trial. In total, 60 patients with early-stage KOA will be recruited and randomly assigned to the Yijinjing exercise group (n=30) and health education group (n=30) at a ratio of 1:1, receiving 12 weeks of Yijinjing exercise or health education accordingly. The primary outcome will be measured with the Western Ontario and McMaster Universities Osteoarthritis Index, and the secondary outcomes will include the Visual Analogue Scale, Short-Form 36 Item Health Survey Questionnaire, Beck Depression Inventory, Perceived Stress Scale, Berg Balance Scale, and Gait Analysis for a comprehensive assessment. Outcome measures are collected at baseline, at 12 week ending intervention and at the 12 week, 24 week and 48 week ending follow-up. The primay time point will be 12 weeks postintervention. Adverse events will be recorded for safety assessment.

ETHICS AND DISSEMINATION

This study has been approved by the ethical application of the Shanghai Municipal Hospital of Traditional Chinese Medicine Ethics Committee (2021SHL-KY-78).

TRIAL REGISTRATION NUMBER

ChiCTR2200065178.

Knee biomechanics variability before and after total knee arthroplasty: an equality of variance prospective study

This study evaluated gait variability in patients before and after total knee arthroplasty (TKA) using the equality of variance method to determine where variability differences occur in the movement cycle. Twenty-eight patients underwent TKA with cruciate-sacrificed implants. Patients underwent motion analysis which measured knee biomechanics as they walked overground at their preferred pace before and 12 months after TKA. Equality of variance results were compared with 14 healthy controls of similar age. Before surgery, patients had reduced knee extension moment variability throughout the early stance phase (4-21% gait cycle, p < 0.05) compared to controls. Knee power variability was lower preoperatively compared to controls for most of the stance phase (0-13% and 17-60% gait cycle, p < 0.05). Sagittal knee moment and power variability further decreased following TKA. Knee extension moment variability was lower postoperatively throughout stance phase compared to preoperatively (4-22% and 36-60% gait cycle, p < 0.05) and compared to controls (4-30% and 45-60% gait cycle, p < 0.05). Knee power variability remained lower following TKA throughout stance phase compared to preoperatively (10-24% and 36-58% gait cycle, p < 0.05) and controls (3-60% gait cycle, p < 0.05). TKA patients may be less stable, and this may be in part due to an unresolved adaptation developed while awaiting TKA surgery and the cruciate sacrificing design of the implants utilized in this study.

Fall experiences from the perspectives of people with osteoarthritis: in their own words

PURPOSE

To explore real-life experiences of people with osteoarthritis (OA) to increase understanding of how they perceive contributing factors to falls, circumstances at time of falls, and consequences of falls.

MATERIALS AND METHODS

Four focus groups of 3-7 people with OA from the Chicago, IL, USA, and neighboring areas were conducted remotely via web-based videoconferencing. Inclusion criteria included history of falls in previous 12 months and hip and/or knee OA. Focus group transcripts were coded and analyzed using a modified grounded theory approach to identify themes.

RESULTS

Focus group participants (n = 17) described experiences associated with fall-related events that resulted in the identification of four themes: (1) perception of falls and fall risks can be influenced by OA symptoms, (2) ability to remember circumstances of falls are influenced by consequences, (3) behaviors and attitudes that address OA symptoms and avoidance of falls are similar and (4) OA symptoms and falls have common psychological impacts on lives.

CONCLUSION

Our study highlights how people with OA define falls, perceive contributing factors to falls, and describe general and OA-related factors that contributed to their fall experiences. The shared experiences contributed to the creation of themes that represented various aspects of the circumstances and impact of falls. Consideration for the identified themes may enhance recording and reporting of falls, contribute to development of improved fall risk assessment tools, and prioritize research into the biopsychosocial effects of falls in people with OA.IMPLICATIONS FOR REHABILITATIONInformation about circumstances of a fall such as location, activity, and symptoms of osteoarthritis may be beneficial in creating tailored fall prevention training and education.Falls are a common problem for people with lower limb osteoarthritis that can lead to negative changes in activity and quality of life.The psychological impact of osteoarthritis symptoms may be contributing to fear of falling and decrease participation in daily activities.Awareness of the perceptions people with osteoarthritis have about their symptoms may provide educational and training opportunities to address the benefits of different therapeutic treatments.Awareness of perceptions people with osteoarthritis have about their risk of falling may provide educational and training opportunities to address the benefits of different therapeutic treatments.

Influence of Self-Reported Knee Instability on Outcomes Following Education and Exercise: A Cohort Study of 2,466 Patients With Knee Osteoarthritis

OBJECTIVE

To study the influence of self-reported knee instability on changes in knee pain and gait speed following patient education and supervised exercise therapy in patients with knee osteoarthritis (OA).

METHODS

We included patients enrolled in the Good Life With Osteoarthritis in Denmark (GLA:D) program, an 8-week education and supervised neuromuscular exercise program. Patients were classified into 4 groups according to their level of self-reported knee instability (never; rarely; sometimes; most of the time or all the time). Knee pain intensity was evaluated on a 0-100 mm scale and gait speed from the 4 × 10 meters fast-paced walk test at baseline and after the program. Using linear regression, we examined the association between knee instability and the change in pain and gait speed, respectively. Sex, age, body mass index, physical activity level, and previous knee surgery were covariates in adjusted models.

RESULTS

Among 2,466 patients with knee OA, mean baseline pain and gait speed varied between 38-59 mm and 1.39-1.56 meters/second in patients experiencing no instability and patients experiencing instability most or all the time, respectively. All instability groups improved in pain and gait speed. Compared to the no instability group, patients reporting instability most or all the time experienced larger improvements in pain (4.3 mm [95% confidence interval 1.2, 7.5]), while no difference between instability groups was found for gait speed.

CONCLUSION

Knee OA patients with self-reported instability seem to benefit even more from a patient education and supervised exercise therapy program than OA patients without instability.

Musculoskeletal adaptation of young and older adults in response to challenging surface conditions

Over 36 million adults over 65 years of age experience accidental falls each year. The underlying neuromechanics (whole-body function) and driving forces behind accidental falls, as well as the effects of aging on the ability of the musculoskeletal system to adapt, are poorly understood. We evaluated differences in kinematics (lower extremity joint angles and range of motion), kinetics (ground reaction force), and electromyography (muscle co-contraction), due to changes in surface conditions during gait in 14 older adults with a history of falling and 14 young adults. We investigated the impact of challenging surfaces on musculoskeletal adaptation and compared the mechanisms of adaptation between age-groups. Older adults displayed greater hip and knee flexion and range of motion during gait, reduced initial vertical loading, and 13 % greater knee muscle co-contraction during early stance compared to young adults. Across age groups, the presence of an uneven challenging surface increased lower-limb flexion compared to an even surface. On a slick surface, older adults displayed 30 % greater ankle muscle co-contraction during early stance as compared to young adults. Older adults respond to challenging surfaces differently than their younger counterparts, employing greater flexion during early stance. This study underscores the need for determining lower-limb musculoskeletal adaptation strategies during gait and assessing how these strategies change with age, risk of accidental falls, and environmental surfaces to reduce the risk of accidental falls.

The effect of self-reported knee instability on plantar pressure and postural sways in women with knee osteoarthritis

BACKGROUND

Giving way and knee instability are common problems in patients with knee osteoarthritis, disrupting the daily activities and balance of the affected individual. The present study aimed to evaluate the postural control status of women with knee osteoarthritis with and without self-report knee instability (KI).

METHODS

This cross-sectional, single-blind study was conducted on 57 female patients with knee osteoarthritis. The patients were selected based on the inclusion and exclusion criteria and divided into two groups of with KI (n = 26) and without KI (n = 31). Fear of movement was assessed using the Tampa questionnaire, the degree of knee instability was measured based on the Fitzgard scale, the static and dynamic balance of the subjects were evaluated with open and closed eyes using a Biodex balance device, and foot pressure distribution situation was measured using a FDM-S-Zebris device.

RESULTS

Mean comparison showed a significant difference between the subjects with and without KI in static balance only in anterior-posterior direction with open eyes (p = 0.01) and closed eyes (p = 0.0001). In the dynamic balance test, the subjects in both groups had significant differences in terms of all the indicators of anterior-posterior stability (p = 0.001), medial-lateral stability (p = 0.0001), and overall stability (p = 0.0001) with closed eyes. However, no significant difference was observed with open eyes (p > 0.05). Multiple regression also indicated significant positive correlations between pain intensity and disease duration with the degree of KI (p < 0.05).

CONCLUSIONS

According to the results, there were significant differences between the mean pain scores, static and dynamic balance, and the rate of fall between the women with knee osteoarthritis with and without the KI index. Therefore, patients with knee osteoarthritis, which also has an index of KI, are more susceptible to falls, and proper strategies are required to reduce the level of KI in these patients.

A Methodology to Evaluate the Effects of Kinematic Measurement Uncertainties on Knee Ligament Properties Estimated From Laxity Measurements

Ligaments are important joint stabilizers but assessing their mechanical properties remain challenging. We developed a methodology to investigate the effects of kinematic measurement uncertainty during laxity tests on optimization-based estimation of ligament properties. We applied this methodology to a subject-specific knee model with known ligament properties as inputs and compared the estimated to the known knee ligament properties under the influence of noise. Four different sets of laxity tests were simulated with an increasing number of load cases, capturing anterior/posterior, varus/valgus, and internal/external rotation loads at 0 deg and 30 deg of knee flexion. 20 samples of uniform random noise ([-0.5,0.5] mm and degrees) were added to each set and fed into an optimization routine that subsequently estimated the ligament properties based on the noise targets. We found a large range of estimated ligament properties (stiffness ranges of 5.97 kN, 7.64 kN, 8.72 kN, and 3.86 kN; reference strain ranges of 3.11%, 2.53%, 1.88%, and 1.58% for anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medical collateral ligament (MCL), and lateral collateral ligament (LCL), respectively) for three sets of laxity tests, including up to 22 load cases. A set of laxity tests with 60 load cases kept the stiffness and reference strain ranges below 470 N per unit strain and 0.85%, respectively. These results illustrate that kinematic measurement noise have a large impact on estimated ligament properties and we recommend that future studies assess and report both the estimated ligament properties and the associated uncertainties due to kinematic measurement noise.

Analysis of the Associations between Arthritis and Fall Histories in Korean Adults

(1) Background: the purpose of the present study was to analyze the associations between arthritis and fall histories in Korean adults. (2) Methods: data from the 2015 and 2017 Korean Community Health Survey were analyzed. In total, 322,962 participants aged ≥40 years were included. The participants were divided into two different groups. First, the participants were divided into the ‘arthritis (osteoarthritis or rheumatoid arthritis) for entire life’ and ‘nonarthritis for entire life (comparison I)’ groups. Subsequently, the participants were divided into the ‘current arthritis’ and ‘noncurrent arthritis (comparison II)’ groups. Afterwards, we analyzed the prevalence odds ratios (pORs) of the fall histories of the participants using a logistic regression analysis with the 95% confidence interval (CI). The variables of income, education level, region of residence, smoking status, alcohol consumption, obesity, subjective health status, stress level, physical activity, and sleep hours were adjusted for as covariates. (3) Results: both the arthritis for entire life and current arthritis groups had higher prevalence rates of falls than the comparison I and comparison II groups, respectively (each p < 0.001). The pORs of falling ≥1 time and ≥2 times per year in the arthritis for the entire life group were 1.42 (95% CI = 1.38–1.46) and 1.69 (95% CI = 1.62–1.76), respectively. The adjusted pORs for falling ≥1 time and ≥2 times per year in the current arthritis group were 1.35 (95% CI = 1.31–1.39) and 1.56 (95% CI = 1.50–1.63), respectively. (4) Conclusions: previous arthritis has a significant impact on the risk of falling.

The influence of resistance training on neuromuscular function in middle-aged and older adults: A systematic review and meta-analysis of randomised controlled trials

BACKGROUND

Deterioration of neuromuscular function is a major mechanism of age-related strength loss. Resistance training (RT) improves muscle strength and mass. However, the effects of RT on neuromuscular adaptations in middle-aged and older adults are unclear.

METHODS

Randomised controlled RT interventions (≥2 weeks) involving adults aged ≥50 years were identified. Primary outcome measures were voluntary activation (VA), electromyographic (EMG) activity during maximal voluntary contraction (MVC), and antagonist coactivation. Data were pooled using a weighted random-effect model. Sub-analyses were conducted by muscle or muscle group and health status of participants. Sensitivity analysis was based on study quality. P < 0.05 indicated statistical significance.

RESULTS

Twenty-seven studies were included. An effect was found for VA (standardised mean difference [SMD] 0.54, 0.01 to 1.07, P = 0.04), This result remained significant following sensitivity analysis involving only studies that were low risk of bias. Subgroup analyses showed an effect for plantar flexor VA (SMD 1.13, 0.20 to 2.06, P = 0.02) and VA in healthy participants (SMD 1.04, 0.32 to 1.76, P = 0.004). There was no effect for EMG activity or antagonist coactivation of any muscle group (P > 0.05).

DISCUSSION

Resistance training did not alter EMG activity or antagonist coactivation in older adults. Sensitivity analysis resulted in the effect for VA remaining significant, indicating that this finding was not dependent on study quality. Studies predominantly involved healthy older adults (78%), limiting the generalisability of these findings to clinical cohorts. Future research should determine the effects of RT on neuromuscular function in people with sarcopenia and age-related syndromes.

[Safety aspects of the treatment with glucocorticoids for rheumatoid arthritis]

Glukokortikoide (GC) werden für die initiale Therapie der RA nach wie vor empfohlen – zeitlich befristet und in geringstmöglicher Dosierung. Ihre komplexe Wirkweise geht mit Nebenwirkungen einher, die v. a. in der Dauertherapie oberhalb von 5 mg Prednisolon pro Tag eine Rolle spielen. In diesem Dosisbereich begünstigen sie Osteoporose, Diabetes/Hyperglykämie, kardiovaskuläre Ereignisse und Infektionen und tragen damit zu einer vermehrten Frühsterblichkeit bei. Dabei sind die Risiken der GC-Therapie von patientenbezogenen Faktoren abhängig wie Alter, Komorbidität und Begleitmedikation. Ein negativer Einfluss sehr niedriger Steroiddosen auf das Gesamtüberleben ist möglicherweise bei hoher kumulativer Dosis nachweisbar, die Datenlage ist hier jedoch widersprüchlich. Das Monitoring einer GC-vermittelten Toxizität mithilfe eines validierten Index sollte in Zukunft dazu beitragen, die Vorteile einer steroidsparenden Behandlungsstrategie besser zu beschreiben. Selektiver wirkende Substanzen könnten in Zukunft eine Abkopplung der erwünschten Wirkungen von den Nebenwirkungen ermöglichen.

Perceptions of falls risk and falls prevention among people with osteoarthritis

PURPOSE

To understand the perceptions of falls risk and falls prevention, and the perceived enablers and barriers to engaging in falls prevention strategies/activities among people with doctor-diagnosed hip and/or knee osteoarthritis.

METHODS

A qualitative study utilising semi-structured telephone interviews. Researchers independently analysed qualitative data using an inductive method guided by the COM-B framework. Interviews were analysed thematically using open, axial, and selective coding. Recruitment ceased at 20 interviews, once data saturation was evident.

RESULTS

Participants were 18 women and two men aged 52-84 years and half had fallen in the last 12 months. Main themes were the absence of recommendations to access activities after having a fall, inconsistencies between perceptions of the relationship between OA and falls, and individual beliefs of not being at risk of falling because of taking precautions. Knowledge about falls prevention programs was limited, the term "falls prevention" was considered stigmatising and only applicable to older frail people. Home modifications were perceived as broadcasting negativity; participants felt falls terminology should be changed from a negative to a positive focus.

CONCLUSIONS

Falls were often seen as inevitable consequence of keeping active. Re-framing the language used to discuss falls is recommended to promote uptake of falls prevention activities.Implications for rehabilitationDespite growing evidence that osteoarthritis (OA) is an independent risk factor for falls, people with OA do not perceive themselves to be at risk and falls prevention is for those who are "old and frail".Re-framing the language used to discuss falls and falls prevention to focus on positive messages may promote the uptake of falls prevention activities in this population.Improving the awareness of falls and falls risk among people with OA through effective health education is needed in order to foster the uptake of, and engagement with, falls prevention activities.

Modeling of cumulative effects of time-varying drug exposures on within-subject changes in a continuous outcome

An accurate assessment of the safety or effectiveness of drugs in pharmaco-epidemiological studies requires defining an etiologically correct time-varying exposure model, which specifies how previous drug use affects the outcome of interest. To address this issue, we develop, and validate in simulations, a new approach for flexible modeling of the cumulative effects of time-varying exposures on repeated measures of a continuous response variable, such as a quantitative surrogate outcome, or a biomarker. Specifically, we extend the linear mixed effects modeling to estimate how past and recent drug exposure affects the way individual values of the outcome change throughout the follow-up. To account for the dosage, duration and timing of past exposures, we rely on a flexible weighted cumulative exposure methodology to model the cumulative effects of past drug use, as the weighted sum of past doses. Weights, modeled with unpenalized cubic regression B-splines, reflect the relative importance of doses taken at different times in the past. In simulations, we evaluate the performance of the model under different assumptions concerning (i) the shape of the weight function, (ii) the sample size, (iii) the number of the longitudinal observations and (iv) the intra-individual variance. Results demonstrate the accuracy of our estimates of the weight function and of the between- and within-patients variances, and good correlation between the observed and predicted longitudinal changes in the outcome. We then apply the proposed method to re-assess the association between time-varying glucocorticoid exposure and weight gain in people living with rheumatoid arthritis.

A Definition of Significant Instability and a Scoring System for Predicting Meniscal Tears in ACL-Deficient Knees

Background:

Patients with anterior cruciate ligament (ACL)–deficient knees risk recurrent instability of the affected knee, which may predispose to meniscal injuries. Various studies have correlated the incidence of meniscal tear with elapsed time from ACL tear and number of instability events. However, it is not clear how significant an instability event needs to be to contribute to a meniscal tear.

Purpose/Hypothesis:

The purpose of this study was to (1) define a significant instability episode and (2) develop a checklist and scoring system for predicting meniscal tears based on significant instability episode. We hypothesized that patients with ACL-deficient knees who met the scoring threshold for a significant instability episode would have a higher incidence of meniscal tears compared with those who did not meet the threshold.

Study Design:

Cohort study (prognosis); Level of evidence, 2.

Methods:

This retrospective study included patients with magnetic resonance imaging (MRI)–confirmed isolated ACL tear for longer than 3 months. We determined parameters for assessing instability episodes and defined any instability events between the MRI and ACL reconstruction as significant or insignificant. Patients were then grouped into a significant instability group (≥1 significant episode) and an insignificant instability group, and the incidence and types of meniscal tears found during surgery were compared between groups.

Results:

There were 108 study patients: 62 in the significant instability group and 46 in the insignificant instability group. During surgery, 58 meniscal tears (46 medial, 12 lateral) were recorded, for an overall meniscal injury rate of 53.70%. In the significant instability group, 47 patients (75.81%) had a meniscal tear and 15 (24.19%) had intact menisci (P < .001). In the insignificant instability group, 11 patients (23.91%) had a meniscal tear and 35 (76.08%) had intact menisci (P < .001). Regarding the 58 patients with a meniscal tear, 47 (81.03%) had ≥1 significant episode of instability before surgery, as compared with 11 (18.97%) who had insignificant or no instability. The odds of having a medial meniscal tear at ACL reconstruction was 10 times higher in the significant instability group versus the insignificant instability group.

Conclusion:

The incidence of a medial meniscal tear was 10 times greater in patients with a significant episode of instability versus those with insignificant instability, as defined using a predictive scoring system. The incidence of lateral meniscal tear did not change with instability episodes.

Knee Osteoarthritis and the Risk of Medically Treated Injurious Falls Among Older Adults: A Community-Based US Cohort Study

OBJECTIVE

The risk of falls among adults with knee osteoarthritis (OA) has been documented, yet, to our knowledge no studies have examined knee OA and the risk of medically treated injurious falls (overall and by sex), which is an outcome of substantial clinical and public health relevance.

METHODS

Using data from the Health Aging and Body Composition Knee Osteoarthritis Substudy, a community-based study of white and African American older adults, we tested associations between knee OA status and the risk of injurious falls among 734 participants with a mean ± SD age of 74.7 ± 2.9 years. Knee radiographic OA (ROA) was defined as having a Kellgren-Lawrence grade of ≥2 in at least 1 knee. Knee symptomatic ROA (sROA) was defined as having both ROA and pain symptoms in the same knee. Injurious falls were defined using a validated diagnosis code algorithm from linked Medicare fee-for-service claims. Cox regression modeling was used to estimate hazard ratios (HRs) and 95% confidence intervals (95% CIs).

RESULTS

The mean ± SD follow-up time was 6.59 ± 3.12 years. Of the 734 participants, 255 (34.7%) had an incident injurious fall over the entire study period. In the multivariate model, compared with those without ROA or pain, individuals with sROA (HR 1.09 [95% CI 0.73-1.65]) did not have a significantly increased risk of injurious falls. Compared with men without ROA or pain, men with sROA (HR 2.57 [95% CI 1.12-5.91]) had a significantly higher risk of injurious falls. No associations were found for women or by injurious fall type.

CONCLUSION

Knee sROA was independently associated with an increased risk of injurious falls in older men, but not in older women.

A novel non-invasive method for measuring knee joint laxity in four dof: In vitro proof-of-concept and validation

Knee joint laxity or instability is a common problem that may have detrimental consequences for patients. Unfortunately, assessment of knee joint laxity is limited by current methodologies resulting in suboptimal diagnostics and treatment. This paper presents a novel method for accurately measuring non-invasive knee joint laxity in four degrees-of-freedom (DOF). An arthrometer, combining a parallel manipulator and a six-axis force/moment sensor, was developed to be used in combination with a low-dose biplanar x-ray system and 3D image data to reconstruct tibiofemoral position and orientation of laxity measurements. As proof-of-concept, four cadaveric knees were tested in the device. Each cadaveric knee was mounted in the device at approximately 30° of flexion and twelve monoplanar anteroposterior, mediolateral and internal/external load cases were applied. Additionally, four biplanar load cases were applied, consisting of different combinations of anteroposterior and internal/external loads. The arthrometer was limited to four DOF to address the specific measurements. For validation purposes, the pose reconstructions of tibia and femur were compared with pose reconstructions of bone pin marker frames mounted on each bone. The measurements from the arthrometer in terms of translation and rotations displayed comparable values to what have previously been presented in the literature. Furthermore, the measurements revealed coupled motions in multiple planes, demonstrating the importance of multi DOF laxity measurements. The validation displayed an average mean difference for translations of 0.08 mm and an average limit of agreement between -1.64 mm and 1.80 mm. The average mean difference for rotations was 0.10° and the limit of agreement was between -0.85° and 1.05°. The presented method eliminates several limitations present in current methods and may prove a valuable tool for assessing knee joint laxity.

Self-reported Instability in Knee Osteoarthritis: A Scoping Review of Literature

BACKGROUND

Knee Osteoarthritis (OA) is a disabling musculoskeletal condition among the elderly. Self-reported instability is one of the impairments associated with osteoarthritis. A complete understanding of the self-reported instability in knee OA is essential, to identify the best strategies for overcoming this impairment. The focus of this scoping review is to provide an overview of evidence supported information about the prevalence and other associated features of selfreported instability in Knee OA. A broad search of the database PubMed with keywords such as knee osteoarthritis and instability resulted in 1075 articles. After title abstract and full-text screening, 19 relevant articles are described in the review. Overall, there is less amount of published literature on this topic. Studies reported prevalence rates of more than 60% for self-reported instability in knee osteoarthritis, which causes functional deterioration and high fear of falls. The most probable causative factors for self-reported instability in knee OA were altered sensory mechanisms and decreased muscle strength.

CONCLUSION

To conclude, self-reported knee instability in knee OA requires thorough evaluation and directed treatment with further studies providing rationalistic evidence-based management strategies. The current literature regarding self-reported knee instability is summarized, highlighting the research gaps.

A phase I/II randomized, controlled, clinical trial for assessment of the efficacy and safety of β-D-mannuronic acid in rheumatoid arthritis patients

BACKGROUND

Following the potent efficacy of β-D-mannuronic acid (M2000) in phase I/II trial in ankylosing spondylitis patients, the present clinical trial was conducted to evaluate the efficacy, safety, and tolerability of this novel drug in rheumatoid arthritis (RA) patients who had inadequate response to conventional therapy.

METHOD

The study was a 12-week randomized, controlled, phase I/II clinical trial with two treatment arms: M2000 and conventional treatment. Patients who had RA according to the modified American College of Rheumatology (ACR) criteria, with active disease at baseline also inadequate response to conventional therapy, were enrolled in this study. M2000 was administrated at a dose of two capsules (500 mg) per day orally during a period of 12 weeks. The primary endpoint was the proportion of patients fulfilling the ACR 20% improvement criteria after 12 weeks of M2000 therapy. Moreover, the patients were also followed up for safety.

RESULTS

There were no statistically significant differences between treatment and conventional groups at baseline characteristics. The ACR20 response rate was significantly higher among M2000-treated patients than conventional-treated control, so that 74% of patients in treatment group showed an ACR20 response after 12 weeks of M2000 therapy (74 versus 16%; P = 0.011). 10% of M2000-treated patients and 57.1% of conventional-treated patient's adverse events occurred during this study.

CONCLUSION

Treatment with M2000 in combination with conventional therapy showed a significantly superior efficacy along with a high safety profile compared to conventional-treated patients. Thereby, M2000 might be suggested as a suitable option in the treatment of RA.

Primary knee osteoarthritis increases the risk of falling

OBJECTIVES

The aim of this study was to investigate the effect of primary knee osteoarthritis on the risk of falling.

MATERIALS AND METHODS

One hundred participants (50 with knee osteoarthritis and 50 healthy controls) were included in this study. Primary knee osteoarthritis was diagnosed according to the American College of Rheumatology (ACR) criteria. Patients who were grade 2 or 3 by Kellgren-Lawrence criteria according to weight-bearing knee radiographs were included in this study. The risk of falling was evaluated by the interactive balance and coordination device both in the osteoarthritis and control groups. The functional status and pain were evaluated with respectively Lequesne Index and Visual Analogue Scale.

RESULTS

No statistically significant differences were found between the group of primary knee osteoarthritis and control in terms of age, BMI, and gender. The median falling index was 52 in the group with knee OA, whereas it was 31 in the control group. It was determined that primary knee osteoarthritis increased the risk of falling significantly and grade 3 primary knee osteoarthritis was statistically significantly higher than grade 2 (p < 0.001). The pain and functional status did not appear to be effective on the risk of falling in those patients (p > 0.05).

DISCUSSION

Falling is among the important causes of mortality and morbidity in advanced age. Therefore, assessment of risk factors for falling and the strategies to prevent it are important. Primary knee osteoarthritis is one of the risk factors associated with falling. Therefore, medical approaches, proprioception training, balance-gait training, muscle strengthening exercises, and arrangements to prevent domestic injurious falling should be planned to reduce the risk of falling in the presence of primary knee osteoarthritis.

Competing risks modeling of cumulative effects of time-varying drug exposures

An accurate assessment of drug safety or effectiveness in pharmaco-epidemiology requires defining an etiologically correct time-varying exposure model, which specifies how previous drug use affects the hazard of the event of interest. An additional challenge is to account for the multitude of mutually exclusive events that may be associated with the use of a given drug. To simultaneously address both challenges, we develop, and validate in simulations, a new approach that combines flexible modeling of the cumulative effects of time-varying exposures with competing risks methodology to separate the effects of the same drug exposure on different outcomes. To account for the dosage, duration and timing of past exposures, we rely on a spline-based weighted cumulative exposure modeling. We also propose likelihood ratio tests to test if the cumulative effects of past exposure on the hazards of the competing events are the same or different. Simulation results indicate that the estimated event-specific weight functions are reasonably accurate, and that the proposed tests have acceptable type I error rate and power. In real-life application, the proposed method indicated that recent use of antihypertensive drugs may reduce the risk of stroke but has no effect on the hazard of coronary heart disease events.

Using Multiple Pharmacovigilance Models Improves the Timeliness of Signal Detection in Simulated Prospective Surveillance

INTRODUCTION

Prospective pharmacovigilance aims to rapidly detect safety concerns related to medical products. The exposure model selected for pharmacovigilance impacts the timeliness of signal detection. However, in most real-life pharmacovigilance studies, little is known about which model correctly represents the association and there is no evidence to guide the selection of an exposure model. Different exposure models reflect different aspects of exposure history, and their relevance varies across studies. Therefore, one potential solution is to apply several alternative exposure models simultaneously, with each model assuming a different exposure-risk association, and then combine the model results.

METHODS

We simulated alternative clinically plausible associations between time-varying drug exposure and the hazard of an adverse event. Prospective surveillance was conducted on the simulated data by estimating parametric and semi-parametric exposure-risk models at multiple times during follow-up. For each model separately, and using combined evidence from different subsets of models, we compared the time to signal detection.

RESULTS

Timely detection across the simulated associations was obtained by fitting a set of pharmacovigilance models. This set included alternative parametric models that assumed different exposure-risk associations and flexible models that made no assumptions regarding the form/shape of the association. Times to detection generated using a simple combination of evidence from multiple models were comparable to those observed under the ideal, but unrealistic, scenario where pharmacovigilance relied on the single 'true' model used for data generation.

CONCLUSIONS

Simulation results indicate that, if the true model is not known, an association can be detected in a more timely manner by first fitting a carefully selected set of exposure-risk models and then generating a signal as soon as any of the models considered yields a test statistic value below a predetermined testing threshold.