Knee Osteoarthritis Group Research Articles

Impact of Knee Osteoarthritis and Arthroplasty on Full Body Sagittal Alignment in Adult Spinal Deformity Patients.

Retrospective analysis of prospectively collected data. This study evaluates the impact of knee osteoarthritis (OA) and knee arthroplasty on alignments and patient-reported outcomes measures (PROMS) of patients undergoing adult spinal deformity (ASD) corrective surgery. The relationship between knee OA and spinal alignment in patients with ASD is incompletely understood. It is also unknown how patients with knee arthroplasty and ASD compare to ASD patients with native knees. Baseline full-body radiographs were used, and hip and knee OA were graded by two independent reviewers using the KL classification. Spinopelvic parameters and PROMs were compared across the different knee OA groups and compared between patients with knee replacement and native knees. 199 patients with bilateral non severe OA (G1), 31 patients with unilateral severe knee OA (G2), and 60 patients with bilateral severe knee OA (G3). Patients with severe knee OA presented with worse spinopelvic parameters. However, after multivariable regression analysis controlling for age, frailty, PI, T1PA, knee OA was an independent predictor of knee flexion (G1:-0.02±7.3, G2: 7.8±9.4, G3: 4.5±8.7, P<0.001), and ankle dorsiflexion (G1: 2.3±4.0, G2: 6.6±4.5, G3: 5.1±4.1, P<0.001). There was no difference in PROMs (P>0.05). Secondary analysis included 96 patients: 48 patients (50%) with non-severe knee OA, and 48 patients (50%) with knee replacement. There was no difference in radiographic parameters or PROMs between the groups. In this study of complex ASD patients, patients with worse spinal deformity were more likely to have concomitant knee OA. Knee OA was shown to be a predictor of knee flexion and ankle dorsiflexion angles, but was not associated with worse PROMs in this study population. Patients with knee arthroplasty, however, had comparable spinal alignment and PROMs relative to those with mild OA.

The volumes of amygdala subregions and peripheral programmed cell death protein-1 levels are associated with cognitive decline in individuals with knee osteoarthritis.

Persistent pain is a prominent symptom of knee osteoarthritis (KOA) and has been associated with cognitive decline in individuals with KOA. The amygdala, a complex structure consisting of nine subnuclei, and programmed cell death protein-1 (PD-1) levels play crucial roles in pain regulation and cognitive processing. This study aims to investigate the relationships among amygdala subregion volumes, cognitive function, and PD-1 levels to elucidate the underlying mechanism of cognitive decline in KOA. In this cross-sectional study, we recruited 36 patients with KOA and 25 age/gender-matched healthy controls for neuropsychological tests, structural magnetic resonance imaging scanning, and measurement of serum PD-1 levels. We used the atlas provided by FreeSurfer software to automatically segment the amygdala subnuclei. Subsequently, we compared the volumes of amygdala subregions between groups and explored their correlation with clinical scores and PD-1 levels. Compared to healthy controls, individuals with KOA exhibited significantly lower scores on global cognition tasks, such as long-delay free recall, short-delay free recall, and immediate recall tasks. Moreover, they displayed decreased volumes in lateral nucleus basal nucleus paralaminar nucleus while showing increased volumes in accessory basal nucleus, central nucleus, medial nucleus, and cortical nucleus. Within the KOA group specifically, paralaminar volume was negatively correlated with immediate recall scores; pain scores were negatively correlated with global cognition; basal volume was negatively correlated with PD-1 levels. Our findings highlight those alterations in amygdala subregion volumes along with changes in serum PD-1 levels may contribute to observe cognitive decline among individuals suffering from KOA.

Association of Hemogram Parameters with Body Mass Index in Knee Osteoarthritis

Objective: This study aims to investigate the relationship between hemogram parameters, which are low-cost, easy, routinely applied low-grade inflammation indicators, and severity of knee osteoarthritis (KOA) and obesity. Materials and Methods: This study involved 140 KOA patients aged 45 to 85 who underwent knee radiographs, weight and height measurements, and routine laboratory tests. Recorded data included demographic information (gender, age), body mass index (BMI), routine hemogram, and laboratory parameters. Patients were categorized into two groups based on their Kellgren-Lawrence (KL) scores (mild: KL 1-3, severe: KL 4) and four groups according to their BMI (BMI 35). Results: The findings revealed significantly elevated levels of serum Neutrophil-to-Lymphocyte Ratio (NLR) and C-reactive protein (CRP) in severe KOA compared to mild KOA (P30 in mild KOA groups, while mean blood NLR was notably higher in patients with BMI=30-35 in severe KOA groups. Conclusions: These results suggest that NLR and NMR could provide a new perspective on the relationship between obesity and mild KOA in clinical practice, presenting a cost-effective and easily applicable alternative for determining disease prognosis and progression.

Association of ADAMTS-5 gene polymorphisms with the susceptibility to knee osteoarthritis in a Chinese Han population

BackgroundOsteoarthritis (OA) is the most prevalent type of arthritis and the main reason for progressive disability in middle-aged and older people. Studies of candidate genes may provide a novel insight and treatment strategy for knee osteoarthritis (KOA). The aim of this study was to investigate the relationship between KOA susceptibility and single-nucleotide polymorphism (SNP) of the ADAMTS-5 gene.Materials and methodsThe case group included 188 patients from Luoyang Orthopedic Hospital with clinically and radiographically diagnosed primary KOA, and the control group included 100 age-matched individuals without KOA. Fifteen ADAMTS-5 SNPs were assayed using MALDI-TOF MS. Allelic and haplotypic frequencies were compared between the groups. The relationship between genotype distribution and risk of KOA was analyzed by multivariate logistic regression.ResultsThe frequency of A allele in rs2249350 site in the KOA group was significantly lower (odds ratio [OR]: 0.761; 95% confidence interval [95% CI]: 0.612–0.947; P = 0.016), while that of C allele was higher than that in the control group (OR: 1.176; 95% CI: 1.025–1.351; P = 0.016). AA genotype and gene model, especially recessive gene model at rs2249350 locus, negatively correlated with KOA risk after adjustment for sex, body mass index, age, and occupation (AA vs. CC: OR: 0.288; 95% CI: 0.124–0.669; P = 0.004; AA vs. CA + CC: OR: 0.348; 95% CI: 0.162–0.749; P = 0.007). Meanwhile, one protective haplotype, GA (rs229054, rs2249350) (OR: 0.763; 95% CI: 0.614–0.949; P = 0.017), and one high-risk haplotype, GC (rs229054, rs2249350) (OR: 1.259; 95% CI: 1.032–1.537; P = 0.019), were found in this study.ConclusionDespite a limited sample size, our study suggests that the rs2249350 polymorphism in the ADAMTS-5 gene is one of the genetic factors influencing the risk of KOA. The A allele and AA genotype of rs2249350 may protect from KOA, whereas C allele and CC genotype increase the risk of KOA. In addition, the GA haplotype (rs229054, rs2249350) might be associated with a decreased risk of KOA, whereas the GC haplotype (rs229054, rs2249350) may be a risk factor for KOA. Additional larger-sized studies in more ethnically diverse populations are needed to confirm these findings.

The association between patella alignment and morphology and knee osteoarthritis

ObjectiveThis study aims to quantitatively assess the relationship between the patella alignment and morphology and knee osteoarthritis (KOA), as well as the kinematics and kinetics of the knee, using gait analysis.MethodsEighty age-matched patients with KOA and control subjects were evaluated. Incident radiographic osteoarthritis (iROA) was identified using a Kellgren-Lawrence (KL) grade of ≥ 2. The modified Insall-Salvati ratio (Mod-ISR), patellar tilt angle (PTA), and patella index (PI) were utilized to evaluate the sagittal and transverse alignment of the patella and its morphology, respectively. Regression analyses were conducted to explore associations between patellar measurements and KOA, iROA, kinematics, and kinetics.ResultsSignificant differences were observed between the control and KOA groups in terms of KL grade, patella alta, abduction angle, and reaction force to the ground (P < 0.05, respectively). Following adjustment for covariates, a significant positive association was found between patella alta and KOA (OR = 0.307, 95%CI: 0.103 to 0.918, P = 0.035). Additionally, a significant negative association was observed between PTA and abduction angle (B = -0.376, 95%CI: -0.751 to -0.002; P = 0.049). The PI exhibited a statistically significant association with log-transformed vertical ground reaction force (B = 0.002, 95%CI: 0.001 to 0.003, P = 0.002). Furthermore, adjustment for covariates did not reveal any significant correlations with other indicators (P > 0.05, respectively).ConclusionThis study provides further evidence that proper alignment and morphology of the patella might be associated with maintaining normal biomechanical function. In addition, intervention measures targeting relevant patellar parameters, such as Mod-ISR, PTA, and PI, may positively impact KOA treatment outcomes.

Impacts of asymmetric hip rotation angle on gait biomechanics in patients with knee osteoarthritis

BackgroundKnee Osteoarthritis (OA) is a highly prevalent age-related disease. The altered kinematic pattern of the knee joint as well as the adjacent joints affects to progression of knee OA. However, there is a lack of research on how asymmetry of the hip rotation angle affects the gait pattern in knee OA patients.Research questionWhat are the impacts of asymmetric hip rotation range on gait biomechanical characteristics and do the gait patterns differ between patients with knee OA and healthy elderly people?MethodsTwenty-nine female patients with knee OA and 15 healthy female elders as control group were enrolled in this study. The spatiotemporal parameters, kinematic and kinetic data during walking were measured using a three-dimensional motion capture system. The differences between knee OA and control group were analyzed using an independent t-test.ResultsThe knee OA group exhibited a significant reduction in hip internal rotation range and internal/external rotation ratio on more affected side (p < 0.05). Significant differences were found in spatiotemporal parameters except to the step width. Significant reductions were also found in kinematic parameters (pelvic lateral tilt range, sagittal angle ranges in hip, knee and ankle, knee adduction mean angle). There were also significant differences in vertical ground reaction force and knee adduction moment (p < 0.05).ConclusionsKnee OA patients have asymmetric hip rotation ranges. Especially limited hip internal rotation could lead to the reduction of pelvic lateral tilt, which may cause greater knee joint loading. Therefore, it is necessary to pay attention to recovery of hip rotation after knee surgery.

The effect of foot orientation modifications on knee joint biomechanics during daily activities in people with and without knee osteoarthritis

BackgroundAltered gait could influence knee joint moment magnitudes and cumulative damage over time. Gait modifications have been shown to reduce knee loading in people with knee osteoarthritis during walking, although this has not been explored in multiple daily activities. Therefore, this study investigated the effect of different foot orientations on knee loading during multiple daily activities in people with and without knee osteoarthritis. MethodsThirty people with knee osteoarthritis and twenty-nine without (control) performed walking, stair ambulation and sit-to-stand across a range of foot progression angles (neutral, toe-in, toe-out and preferred). Peak knee adduction moment, knee adduction moment impulse and knee pain were compared across a continuous range of foot orientations, between activities, and groups. FindingsIncreased foot progression angle (more toe-in) reduced 1st peak knee adduction moment across all activities in both knee osteoarthritis and control (P < 0.001). There was a greater reduction in knee adduction moment in the control group during walking and stair ambulation (P ≤ 0.006), where the knee osteoarthritis group already walked preferably less toe-out than the control group. Under preferred condition, stair descent had the greatest knee loading and knee pain compared to other activities. InterpretationAlthough increased foot progression angle (toward toe-in) appeared to be more effective in reducing knee loading for all activities, toe-in modification might not benefit stair ambulation. Future gait modification should likely be personalised to each patient considering the individual difference in preferred gait and knee alignment required to shift the loading medially or laterally.

Balance Control is Sequentially Correlated with Proprioception, Joint Range of Motion, Strength, Pain, and Plantar Tactile Sensation Among Older Adults with Knee Osteoarthritis

BackgroundPatients with knee osteoarthritis (KOA) are at high risk for falls, which is attributed to their impaired balance control. Identifying factors associated with balance control facilitates the development of precise KOA rehabilitation programs. This study was to investigate the correlations of balance control with proprioception, plantar tactile sensation (PTS), pain, joint range of motion (ROM), and strength among older adults with and without KOA, as well as the magnitudes and sequence of correlation of these factors to balance control.MethodsA total of 240 older adults with (n = 124, female: 84, age: 68.8 ± 4.0 years) and without (n = 116, female: 64, age: 67.9 ± 3.5 years) KOA were recruited and assigned to the KOA and control groups. Their proprioception, PTS, pain, ROM, and strength were measured. Pearson or Spearman correlations were used to test whether they were significantly related to their Berg Balance Scale (BBS), and factor analysis and multivariate linear regression were used to determine the degrees of correlation between each factor and the BBS.ResultsCompared to the control group, the KOA group had lower BBS score, larger proprioception and PTS thresholds, smaller ROM, and less strength (p: 0.008, < 0.001–0.016, < 0.001–0.005, < 0.001–0.014, and < 0.001–0.002, respectively). In the KOA group, the BBS was weakly to moderately correlated with proprioception, PTS, pain, ROM, and strength (r: 0.332–0.501, 0.197–0.291, 0.340, 0.212–0.508, and 0.236–0.336, respectively). While in the control group, the BBS was correlated with proprioception and strength (r: 0.207–0.379, and 0.212–0.410). In the KOA group, BBS = 54.41+ (0.668*strength) - (0.579*PTS) - (1.141*proprioception) + (1.054* ROM) - (0.339*pain). While in the control group, BBS = 53.85+ (0.441*strength) - (0.677*proprioception).ConclusionWorse proprioception and PTS, smaller ROM, and less strength were detected among older adults with KOA, and their proprioception, PTS, pain, ROM, and strength were all related to balance control. Proprioception had the strongest correlations, followed by ROM, strength, pain, and PTS. Precise KOA rehabilitation programs may be proposed following the sequence of improving the five factors.

Acupotomy ameliorates knee osteoarthritis-related collagen deposition and fibrosis in rabbit skeletal muscle through the TGF-β/Smad pathway

ObjectiveTo investigate the effects of acupotomy on skeletal muscle fibrosis and collagen deposition in a rabbit knee osteoarthritis (KOA) model. MethodsRabbits (n = 18) were randomly divided into control, KOA, and KOA + acupotomy (Apo) groups (n = 6). The rabbits in the KOA and Apo groups were modeled using the modified Videman's method for 6 weeks. After modeling, the Apo group was subjected to acupotomy once a week for 3 weeks on the vastus medialis, vastus lateralis, rectus femoris, biceps femoris, and anserine bursa tendons around the knee. The behavior of all animals was recorded, rectus femoris tissue was obtained, and histomorphological changes were observed using Masson staining and transmission electron microscopy. The expression of transforming growth factor-β1 (TGF-β1), Smad 3, Smad 7, fibrillar collagen types I (Col-I) and III (Col-III) was detected using Western blot and real-time polymerase chain reaction (RT-PCR). ResultsHistological analysis revealed that acupotomy improved the microstructure and reduced the collagen volume fraction of rectus femoris, compared with the KOA group (P = .034). Acupotomy inhibited abnormal collagen deposition by modulating the expression of fibrosis-related proteins and mRNA, thus preventing skeletal muscle fibrosis. Western blot and RT-PCR analysis revealed that in the Apo group, Col-I, and Col-III protein levels were significantly lower than those in the KOA group (both P < .01), same as Col-I and Col-III mRNA levels (P = .0031; P = .0046). Compared with the KOA group, the protein levels of TGF-β1 and Smad 3 were significantly reduced (both P < .01), as were the mRNA levels of TGF-β1 and Smad 3 (P = .0007; P = .0011). Conversely, the levels of protein and mRNA of Smad 7 were significantly higher than that in the KOA group (P < .01; P = .0271). ConclusionAcupotomy could alleviate skeletal muscle fibrosis and delay KOA progress by inhibiting collagen deposition through the TGF-β/Smad pathway in the skeletal muscle of KOA rabbits.

Acupotomy alleviates knee osteoarthritis in rabbit by regulating chondrocyte mitophagy Pink1-Parkin pathway.

To investigate the effect of acupotomy, on mitophagy and the Pink1-Parkin pathway in chondrocytes from rabbits with knee osteoarthritis (KOA). A KOA model was established via the modified Videman method. Rabbits were randomly divided into a control group (CON), KOA group and KOA + acupotomy group (Acu). Rabbits in the acupotomy group were subjected to acupotomy for 4 weeks after model establishment. The behavior of the rabbits before and after intervention was recorded. Cartilage degeneration was evaluated by optical microscopy and fluorescence microscopy. The level of mitophagy was evaluated by transmission electron microscopy, immunofluorescence and enzyme-linked immunosorbent assay (ELISA). The expression of phosphatase and tensin homolog (PTEN)-induced kinase 1 (Pink1)-Parkin mitophagy pathway components was evaluated by immunofluorescence, Western blotting and real-time polymerase chain reaction. In rabbits with KOA, joint pain, mobility disorders and cartilage degeneration were observed, the Mankin score was increased, collagen type Ⅱ (Col-Ⅱ) expression was significantly decreased, mitophagy was inhibited, mitochondrial function was impaired, and factors associated with the Pink1-Parkin pathway were inhibited. Acupotomy regulated the expression of Pink1-Parkin pathway-related proteins, the mitophagy-related protein microtubule-associated protein-1 light chain-3, the translocase of the outer membrane, and the inner mitochondrial membrane 23; increased the colocalization of mitochondria and autophagosomes; promoted the removal of damaged mitochondria; restored mitochondrial adenosine-triphosphate (ATP) production; and alleviated cartilage degeneration in rabbits with KOA. Acupotomy played a role in alleviating KOA in rabbits by activating mitophagy in chondrocytes via the regulation of proteins that are related to the Pink1-Parkin pathway.

Effect of isometric quadriceps exercise on local microcirculation of the infrapatellar fat pad in female patients with knee osteoarthritis

ObjectiveTo elucidate the local microcirculation of the infrapatellar fat pad (IFP) in patients with knee osteoarthritis (KOA) by determining the changes in IFP hardness and hemoglobin concentration during isometric quadriceps exercise (IQE). DesignIn this observational cross-sectional study, patients diagnosed with bilateral KOA were included in the KOA group (30 knees), healthy older adults in the control group (20 knees), and younger adults in the young group (20 knees). Ultrasonography was performed at rest and during IQE to measure IFP hardness based on shear wave velocity. Near-infrared spectroscopy was performed to measure oxygenated hemoglobin (O2Hb), deoxygenated hemoglobin (HHb), and total hemoglobin (cHb) in the IFP before (Baseline), during (IQE task), and after IQE (Post). IFP hardness and O2Hb, HHb, and cHb concentration were analyzed using a linear mixed model for the groups and measurement points. ResultsDuring IQE, IFP hardness changes were significantly less in the KOA group than in the other groups (KOA: 95% confidence intervals (CIs) [−0.854, 0.028]; control: 95% CI [−0.941, −0.341]; and young: 95% CI [−2.305, −1.706]). In the KOA group, O2Hb concentration exhibited no significant changes at Post compared with Baseline; however, significant changes were observed in the other groups (KOA: 95% CI [−1.176, 0.423]; control: 95% CI [−1.452, −0.276]; and young: 95% CI [−4.062, −2.102]). ConclusionsDuring IQE, changes in hardness and hemoglobin concentration in the IFP were not significant in the KOA group, suggesting impaired local microcirculation of the IFP.

The impact of sericin on inflammation, oxidative stress, and lipid metabolism in female rats with experimental knee osteoarthritis.

This study investigated the effects of sericin on inflammation, oxidative stress, and lipid metabolism in female rats with experimental knee osteoarthritis (KOA), focusing on evaluating its effectiveness via the sterol regulatory protein (SREBP)-1C and SREBP-2 pathways. The rats were randomly assigned to three experimental groups: the C group (control), the KOA group (KOA control), and the sericin group (KOA + sericin). The KOA model was created by injecting monosodium iodoacetate (MIA) into the knee joint. Sericin was administered intra-articularly to rats on days 1, 7, 14, and 21 (0.8g/kg/mL, 50 µL). After 21days, the rats were sacrificed, and serum samples were analyzed using an ELISA to measure tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), IL-10, SREBP-1c, SREBP-2, acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), cholesterol, triglyceride, and total oxidant-antioxidant status (TOS-TAS) levels. The KOA group exhibited higher serum TNF-α, IL-1β, TOS, SREBP-1C, ACC, FAS, triglyceride, SREBP-2, and cholesterol levels than the C group (P < 0.05). However, the levels of these cytokines, except cholesterol, were significantly lower in the sericin group than in the KOA group. The KOA group exhibited significantly lower serum TAS and IL-10 levels than the C group (P < 0.05). In the sericin group, there was a statistically significant increase (P < 0.05). Sericin shows promising potential for reducing inflammation, oxidative stress, and lipid metabolism in experimental models of KOA in rats. However, further clinical research is necessary to validate the potential of sericin as a therapeutic agent for treating KOA. Key Points • Sericin can reduce knee osteoarthritis (KOA) symptoms in an experimental rat model. • In particular, in the serum of an experimental KOA rat model, sericin specifically reduces the levels of proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α) and interleukin-1beta (IL-1β), and increases the levels of anti-inflammatory cytokines, such as IL-10. • Sericin reduced lipid metabolism via the sterol regulatory protein (SREBP)-1C and SREBP-2 pathways and oxidative stress in the serum of the experimental KOA rat model. • The intra-articular administration of sericin has been shown to significantly reduce lipid metabolism, oxidative stress, and inflammation, as supported by biochemical analysis. These findings suggest its promising potential as an alternative treatment option for KOA.

Analysing Pre-Operative Gait Patterns Using Inertial Wearable Sensors: An Observational Study of Participants Undergoing Total Hip and Knee Replacement

Background. Knee and hip arthroplasty are two of the most frequently performed procedures in orthopaedic surgery. They are associated with positive patient-reported outcomes and significant improvements in quality of life for patients. Despite this, there may be room for further progress by quantifying functional improvements with gait analysis. Our study therefore aims to characterise the disease-specific gait pattern of participants with knee and hip osteoarthritis undergoing total joint replacement using a single chest-based wearable sensor. Methods. Twenty-nine participants awaiting total hip replacement and 28 participants awaiting total knee replacement underwent three-dimensional motion analysis with inertial wearable sensors. These gait metrics were then compared with 28 healthy controls of similar ages. Differences in gait metrics were evaluated using a T-test. The participants were recruited through a single centre to participate in this cross-sectional observational study. Participants with osteoarthritis severity sufficient to warrant surgical intervention were considered for inclusion in our study. The participants were instructed to walk 15–120 m in a hospital environment while fitted with a chest-based wearable sensor. Results. In total, three domains were evaluated, including spatiotemporal, variability and asymmetry parameters. There were marked variations in the gait asymmetry parameters and step length variation in both the hip and knee osteoarthritis patients compared with the healthy controls. The magnitude of gait deterioration in terms of step length asymmetry was greater on average in the hip osteoarthritis group than the knee group. The hip osteoarthritis (+180%, p &lt; 0.001) and knee osteoarthritis (+129%, p = 0.001) groups demonstrated marked differences in step length asymmetry. Discussion. A single chest-based sensor was found to be capable of detecting pathological gait signatures in osteoarthritis patients when compared with age-matched controls. Future studies should compare pre- and postoperative changes to disease-specific gait impairments to validate the use of wearable sensors as a clinical adjunct.

Role of Serum Micro-RNA-122-5p Expression as a Circulatory Biomarker in People Having Both Knee Osteoarthritis and Osteoporosis: A Case-Control Study.

Background Although knee osteoarthritis (KOA) and osteoporosis (OP) manifest distinct pathophysiologies, they share numerous similarities. These health conditions are commonly found in older individuals, particularly among women. The objective of this study is to explore the expression of micro-RNA (miRNA) 122-5p (miR-122-5p) in people affected by both KOA and OP. The main aim is to identify diagnostic biomarkers and potential therapeutic targets, which could help develop personalized treatment approaches. Methods As part of the study, a total of 268 serum samples were collected from the participants, who were divided into four groups: KOA, OP, KOA and OP, and controls, with 67 subjects per group. The miRNA species-containing total RNA was isolated from the serum samples using an miRNeasy serum/plasma kit by QIAGEN (Hilden, Germany). The expression of miR-122-5p was examined in each group using real-time quantitative polymerase chain reaction. Results Expression of miR-122-5p in all three groups (KOA, OP, and common group of KOA and OP) was significantly upregulated, and the fold change value was much higher in the group having both diseases. Conclusions These results might contribute to the identification of cases at risk, early diagnosis, and development, and might also contribute to the development of therapeutic targets in subjects having both KOA and OP.

People with painful knee osteoarthritis hold negative implicit attitudes towards activity.

Negative attitudes/beliefs surrounding osteoarthritis, pain, and activity contribute to reduced physical activity in people with knee osteoarthritis (KOA). These attitudes/beliefs are assessed using self-report questionnaires, relying on information one is consciously aware of and willing to disclose. Automatic (ie, implicit) assessment of attitudes does not rely on conscious reflection and may identify features unique from self-report. We developed an implicit association test that explored associations between images of a person moving/twisting their knee (activity) or sitting/standing (rest), and perceived threat (safe vs dangerous). We hypothesised that people with KOA would have greater implicit threat-activity associations (vs pain-free and non-knee pain controls), with implicit attitudes only weakly correlating with self-reported measures (pain knowledge, osteoarthritis/pain/activity beliefs, fear of movement). Participants (n = 558) completed an online survey: 223 had painful KOA (n = 157 female, 64.5 ± 8.9 years); 207 were pain free (n = 157 female, 49.3 ± 15.3 years); and 99 had non-KOA lower limb pain (n = 74 female, 47.5 ± 15.04 years). An implicit association between "danger" and "activity" was present in those with and without limb pain (KOA: 0.36, 95% CI 0.28-0.44; pain free: 0.13, 95% CI 0.04-0.22; non-KOA lower limb pain 0.11, 95% CI -0.03 to 0.24) but was significantly greater in the KOA group than in the pain free ( P < 0.001) and non-KOA lower limb pain ( P = 0.004) groups. Correlations between implicit and self-reported measures were nonsignificant or weak (rho = -0.29 to 0.19, P < 0.001 to P = 0.767). People with painful KOA hold heightened implicit threat-activity associations, capturing information unique to that from self-report questionnaires. Evaluating links between implicit threat-activity associations and real-world behaviour, including physical activity levels, is warranted.

Painful distortions: people with painful knee osteoarthritis have biased visuospatial perception of the environment.

Visuospatial perception is thought to be adaptive-ie, hills are perceived as steeper when capacity is low, or threat is high-guiding appropriate interaction with the environment. Pain (bodily threat) may similarly modulate visuospatial perception, with the extent of modulation influenced by threat magnitude (pain intensity, fear) and associated with behaviour (physical activity). We compared visuospatial perception of the environment between 50 people with painful knee osteoarthritis and 50 age-/sex-matched pain-free control participants using 3 virtual reality tasks (uphill steepness estimation, downhill steepness estimation, and a distance-on-hill measure), exploring associations between visuospatial perception, clinical characteristics (pain intensity, state and trait fear), and behaviour (wrist-worn accelerometry) within a larger knee osteoarthritis group (n = 85). People with knee osteoarthritis overestimated uphill (F 1,485 = 19.4, P < 0.001) and downhill (F 1,480 = 32.3, P < 0.001) steepness more so than pain-free controls, but the groups did not differ for distance-on-hill measures (U = 1273, P = 0.61). There was also a significant group x steepness interaction for the downhill steepness task (F 4,480 = 3.11, P = 0.02). Heightened overestimation in people with knee osteoarthritis relative to pain-free controls increased as downhill slopes became steeper. Results were unchanged in a replication analysis using all knee osteoarthritis participants (n = 85), except the downhill steepness interaction was no longer significant. In people with knee osteoarthritis, higher state fear was associated with greater over-estimation of downhill slope steepness (rho = 0.69, P < 0.001), and greater visuospatial overestimation (distance-on-hill) was associated with lower physical activity levels (rho = -0.22, P = 0.045). These findings suggest that chronic pain may shift perception of the environment in line with protection, with overestimation heightened when threat is greater (steeper hills, more fearful), although impact on real-world behaviour is uncertain.

Examination of knee extensor and valgus moment arms of the patellar tendon in older individuals with and without knee osteoarthritis

BackgroundJoint moment arm is a major element that determines joint torque. This study aimed to investigate factors associated with knee extensor and valgus moment arms of the patellar tendon in older individuals with and without knee osteoarthritis. MethodsThirty-six participants with knee osteoarthritis (mean age, 78.1 ± 6.0 years) and 43 healthy controls (mean age, 73.0 ± 6.3 years) were analyzed. Magnetic resonance images (MRI) from the knee joint and thigh were acquired using a 3.0 T MRI scanner. The three-dimensional moment arm was defined as the distance between the contact point of the tibiofemoral joint and the patellar tendon line. The three-dimensional moment arm was decomposed into sagittal and coronal components, which were calculated as knee extensor and valgus moment arms, respectively. Quadriceps muscle volume, epicondylar width, bisect offset, Insall–Salvati ratio, and Kellgren–Lawrence grade were assessed. Multiple regression analyses were performed in the healthy control and knee osteoarthritis groups, with knee extensor and valgus moment arms as dependent variables. FindingsKnee extensor moment arm was significantly associated with epicondylar width and the Insall–Salvati ratio in the healthy control group and with Kellgren–Lawrence grade, epicondylar width, and quadriceps muscle volume in the knee osteoarthritis group. Valgus knee moment arm was significantly associated with bisect offset in both the groups. InterpretationKnee size, osteoarthritis severity, and quadriceps muscle volume affect the knee extensor moment arm in knee osteoarthritis, whereas lateral patellar displacement affects the valgus knee moment arms in older individuals with and without knee osteoarthritis.

Characteristics of Acute Cartilage Response After Mechanical Loading in Patients with Early-Mild Knee Osteoarthritis.

This study determined whether the acute cartilage response, assessed by cartilage thickness and echo intensity, differs between patients with early-mild knee osteoarthritis (OA) and healthy controls. We recruited 56 women aged ≥ 50years with Kellgren-Lawrence (KL) grade ≤ 2 (age, 70.6 ± 7.4years; height, 153.7 ± 5.2cm; weight, 51.9 ± 8.2kg). Based on KL grades and knee symptoms, the participants were classified into control (KL ≤ 1, asymptomatic, n = 27) and early-mild knee OA groups (KL 1 and symptomatic, KL 2, n = 29). Medial femoral cartilage thickness and echo intensity were assessed using ultrasonographic B-mode images before and after treadmill walking (15min, 3.3km/h). To investigate the acute cartilage response, repeated-measures analysis of covariance (groups × time) with adjusted age, external knee moment impulse, steps during treadmill walking, and cartilage thickness at pre-walking was performed. A significant interaction was found at the tibiofemoral joint; after walking, the cartilage thickness was significantly decreased in the early-mild knee OA group compared to the control group (p = 0.002). At the patellofemoral joint, a significant main effect of time was observed, but no interaction was detected (p = 0.802). No changes in cartilage echo intensity at either the tibiofemoral or patellofemoral joints, and no interactions were noted (p = 0.295 and p = 0.063). As acute cartilage response after walking, the thickness of the medial tibiofemoral joint in the early-mild knee OA was significantly reduced than that in the control group. Thus, greater acute deformation after walking might be a feature found in patients with early-mild knee OA.

The Differences in Parameters in Ultrasound Imaging and Biomechanical Properties of the Quadriceps Femoris with Unilateral Knee Osteoarthritis in the Elderly: A Preliminary Observational Study.

Our study aims to evaluate differences in muscle parameters of the quadriceps muscles in patients with knee osteoarthritis (KOA) in older adults. The study included 40 patients diagnosed with unilateral knee osteoarthritis in the KOA group (KG) and 40 asymptomatic elderly individuals in the control group (CG). Muscle ultrasonic mean echo intensity and shear modulus, as well as tone and stiffness of the rectus femoris (RF), vastus medialis (VM), and vastus lateralis (VL) were analyzed. Additionally, clinical correlations were performed. In the KG group, there were significant differences in echo intensity, shear modulus, and tone between the affected and unaffected sides for RF (p=0.003, 0.019, 0.014), while VM showed significant differences in shear modulus and tone (p=0.006, 0.002). Additionally, VL exhibited significant differences in echo intensity, shear modulus, and stiffness (p=0.007, 0.006, 0.010). Compared to the CG group, the KG group showed significant differences in echo intensity of the affected side RF (p=0.001). VM exhibited statistically significant differences in echo intensity and shear modulus (p < 0.001, p=0.008), while VL showed statistically significant differences in echo intensity, tone, and stiffness (p < 0.001, p=0.028, p < 0.001). The correlation results showed that patients with unilateral KOA, VM, and VL echo intensity were correlated with K-L grade (r = 0.443, p=0.004; r = 0.469, p=0.002). The tone of VL was correlated with VAS and WOMAC (r = 0.327, p=0.039; r = 0.344, p=0.030). The parameters of the quadriceps femoris muscle exhibit asymmetry between the affected and unaffected sides in patients with unilateral KOA, as well as a difference between the dominant side of healthy older individuals and the affected side of KOA.

Association between quadriceps tendon elasticity and neuromuscular control in individuals with knee osteoarthritis

BackgroundKnee osteoarthritis is a complex condition with established risk factors such as female sex, increasing age and body mass index, reduced quadriceps muscle strength and knee injury. Despite known associated risks, the role and behaviour of knee tendons in knee osteoarthritis remains unclear. This study explores the association between quadriceps tendon elasticity, muscle strength, neuromuscular control, proprioception and patient reported outcome measures in individuals with knee osteoarthritis. MethodsAdults with doctor-diagnosed knee osteoarthritis were recruited from rheumatology clinics and general practitioner practices. Quadriceps tendon elasticity was estimated using sonoelastography. Neuromuscular control data including electromyography, electromechanical delay and proprioception measures were included. Participants completed the Knee Injury and Osteoarthritis Outcome Score. Associations between elasticity values, physical and neuromuscular data and patient reported outcomes scores were evaluated using Spearman's correlations. FindingsThirty-nine adults with knee osteoarthritis were eligible for inclusion. Increased tendon stiffness was negatively associated with rate of force development, time to half peak force and passive positioning sense in individuals with knee osteoarthritis. Similarly, patient reported symptoms were found to be associated with sonoelastography findings with moderate-strong associations observed between activities of daily living sport and recreation, pain and symptoms and between neuromuscular control measures and muscle strength. InterpretationStiffer tendon identified within the knee osteoarthritis group was associated with reduced neuromuscular control and knee joint proprioception. Stiffer quadriceps tendon may contribute to the poorer reported symptoms by knee osteoarthritis individuals. These findings may impact disease symptoms and progression which could lead to further joint impairment.