Body mass indices in patients with disabling hip osteoarthritis

Hip osteoarthritis (OA) is a degenerative joint disease that results in substantial morbidity. The disease may be preventable in some instances by reducing risk factors associated with the disease. We undertook a study to determine whether being overweight or obese, a health risk that applies to younger and older age groups, is commonly associated with hip joint OA. The body mass indices (BMIs) of 1021 males and females ranging in age from 23 to 94 years and requiring surgery for end-stage hip joint OA were analyzed to find the prevalence of high body weights at the time of surgery. Being overweight was defined as having a BMI of 25–29.9 kg/m² and being obese as having a BMI >30 kg/m². BMIs indicative of overweight were recorded for 68% of the patients surveyed. Of 35 patients aged 30–39 years, 53.3% had BMIs >25, with a mean of 28.8, which nearly reaches the lower limit defined for obesity. On average, patients who had had previous surgery and complications warranting reimplantation of new surgical devices had BMIs in the obese range. Our findings suggest that a high percentage of patients with end-stage hip OA are overweight, including younger adults and those with symptoms of 3–6 months' duration. Moreover, patients whose BMIs are in the obese range may be at increased risk for removal and reimplantation of their prosthesis.     

Body mass indices in patients with disabling hip osteoarthritis

Hip osteoarthritis (OA) is a degenerative joint disease that results in substantial morbidity. The disease may be preventable in some instances by reducing risk factors associated with the disease. We undertook a study to determine whether being overweight or obese, a health risk that applies to younger and older age groups, is commonly associated with hip joint OA. The body mass indices (BMIs) of 1021 males and females ranging in age from 23 to 94 years and requiring surgery for end-stage hip joint OA were analyzed to find the prevalence of high body weights at the time of surgery. Being overweight was defined as having a BMI of 25-29.9 kg/m2 and being obese as having a BMI >30 kg/m2. BMIs indicative of overweight were recorded for 68% of the patients surveyed. Of 35 patients aged 30-39 years, 53.3% had BMIs >25, with a mean of 28.8, which nearly reaches the lower limit defined for obesity. On average, patients who had had previous surgery and complications warranting reimplantation of new surgical devices had BMIs in the obese range. Our findings suggest that a high percentage of patients with end-stage hip OA are overweight, including younger adults and those with symptoms of 3-6 months' duration. Moreover, patients whose BMIs are in the obese range may be at increased risk for removal and reimplantation of their prosthesis.     

Effects of bilateral medial knee osteoarthritis on intra- and inter-limb contributions to body support during gait

Patients with knee OA show altered gait patterns, affecting their quality of living. The current study aimed to quantify the effects of bilateral knee OA on the intra-limb and inter-limb sharing of the support of the body during gait. Fifteen patients with mild, 15 with severe bilateral knee OA, and 15 healthy controls walked along a walkway while the kinematic and kinetic data were measured. Compared with the controls, the patients significantly reduced their knee extensor moments and the corresponding contributions to the total support moment in the sagittal plane (p<0.05). For compensation, the mild OA group significantly increased the hip extensor moments (p<0.05) to maintain close-to-normal support and a more symmetrical inter-limb load-sharing during double-limb support. The severe OA group involved compensatory actions of both the ankle and hip, but did not succeed in maintaining a normal sagittal total support moment during late stance, nor a symmetrical inter-limb load-sharing during double-limb support. In the frontal plane, the knee abductor moments and the corresponding contributions to the total support moment were not affected by the changes in the other joints, regardless of the severity of the disease. The observed compensatory changes suggest that strengthening of weak hip muscles is essential for body support during gait in patients with knee OA, but that training of weak ankle muscles may also be needed for patients with severe knee OA.     

Comparative diagnostic accuracy of knee adduction moments in knee osteoarthritis: a case for not normalizing to body size

Previous authors have questioned the practice of normalizing the external knee adduction moment during gait to body size when investigating dynamic joint loading in knee osteoarthritis (OA). The purpose of this study was to compare the abilities of non-normalized and normalized external knee adduction moments during gait in discriminating between patients with least and greatest severity of radiographic medial compartment knee OA. Subjects with mild (n=118) and severe (n=115) medial compartment knee OA underwent three-dimensional gait analysis. The peak external knee adduction moment was calculated and kept in its original units (Nm), normalized to body mass (Nm/kg) and normalized to body weight and height (%BW × Ht). Receiver Operating Characteristic (ROC) curve analysis indicated that non-normalized values better discriminated between patients with mild and severe knee OA. The area under the ROC curve for non-normalized peak knee adduction moments (0.63) was significantly (p<0.05) greater than when normalized to body mass (0.58), or to body weight times height (0.57). Post-hoc analysis of covariance indicated the mean difference in peak knee adduction moment between OA severity groups (7.23 Nm, p=0.003) was reduced by approximately 50% (3.60 Nm, p=0.09) when adjusted for mass. These findings are consistent with the suggestion that non-normalized values are more sensitive to radiographic disease progression. We suggest including knee adduction moment values that are not normalized to body size when investigating knee OA.     

Neuromuscular alterations during walking in persons with moderate knee osteoarthritis.

This paper compared the neuromuscular responses during walking between those with early-stage knee osteoarthritis (OA) to asymptomatic controls. The rationale for studying those with mild to moderate knee OA was to determine the alterations in response to dynamic loading that might be expected before severe pain, joint space narrowing and joint surface changes occur. We used pattern recognition techniques to explore both amplitude and shape changes of the surface electromyograms recorded from seven muscles crossing the knee joint of 40 subjects with knee OA and 38 asymptomatic controls during a walking task. The principal patterns for each muscle grouping explained over 83% of the variance in the waveforms. This result supported the notion that the main neuromuscular patterns were similar between asymptomatic controls and those with OA, reflecting the specific roles of the major muscles during walking. ANOVA revealed significant (p<0.05) differences in the principal pattern scores reflecting both amplitude and shape alterations in the OA group and among muscles. These differences captured subtle changes in the neuromuscular responses of the subjects with OA throughout different phases of the gait cycle and most likely reflected changes in the mechanical environment (joint loading, instability) and pain. The subjects with OA attempted to increase activity of the lateral sites and reduce activity in the medial sites, having minimal but prolonged activity during late stance. Therefore, alterations in neuromuscular responses were found even in this high functioning group with moderate knee OA.     

Gait and neuromuscular pattern changes are associated with differences in knee osteoarthritis severity levels

Knee osteoarthritis (OA) is a multifactoral, progressive disease process of the musculoskeletal system. Mechanical factors have been implicated in the progression of knee OA, but the role of altered joint mechanics and neuromuscular control strategies in progressive mechanisms of the disease have not been fully explored. Previous biomechanical studies of knee OA have characterized changes in joint kinematics and kinetics with the disease, but it has been difficult to determine if these biomechanical changes are involved in the development of disease, are in response to degenerative changes in the joint, or are compensatory mechanisms in response to these degenerative changes or other related factors as joint pain. The goal of this study was to explore the association between biomechanical changes and knee OA severity in an effort to understand the changing role of biomechanical factors in the progression of knee OA. A three-group cross-sectional model was used that included asymptomatic subjects, subjects clinically diagnosed with moderate knee OA and severe knee OA subjects just prior to total joint replacement surgery. Principal component analysis and discriminant analysis were used to determine the combinations of electromyography, kinematic and kinetic waveform pattern changes at the knee, hip and ankle joints during gait that optimally separated the three levels of severity. Different biomechanical mechanisms were important in discriminating between severity levels. Changes in knee and hip kinetic patterns and rectus femoris activation were important in separating the asymptomatic and moderate OA gait patterns. In contrast, changes in knee kinematics, hip and ankle kinetics and medial gastrocnemius activity were important in discriminating between the moderate and severe OA gait patterns.     

Gait characteristics of patients with knee osteoarthritis.

The knee kinematics and kinetics of 139 patients (47 males and 92 females) with Grade II knee osteoarthritis (OA) were measured during level walking, stair ascent and stair descent. There was no significant difference in knee motion between the patients and normal subjects. The patients with knee OA had a significantly reduced internal knee extensor moment compared to normal subjects. This difference reflects the patient's compensation to reduce the knee joint loading. Further, subjects with OA and a higher body mass index have a lower knee extensor moment. The female subjects had significantly greater knee flexion and a greater knee extensor moment. This gender difference may partially explain the increased prevalence of OA in females. Most tests of OA treatments are assessed by criteria that do not reflect functional activities. This study demonstrates that objective gait analysis can be used to document gait adaptations used by patients with knee OA.     

Knee contact force in subjects with symmetrical OA grades: Differences between OA severities

In using musculoskeletal models, researchers can calculate muscle forces, and subsequently joint contact forces, providing insight into joint loading and the progression of such diseases as osteoarthritis (OA). The purpose of this study was to estimate the knee contact force (KCF) in patients with varying degrees of OA severity using muscle forces and joint reaction forces derived from OpenSim. Walking data was obtained from healthy individuals (n=14) and those with moderate (n=10) and severe knee OA (n=2). For each subject, we generated 3D, muscle-actuated, forward dynamic simulations of the walking trials. Muscle forces that reproduced each subject’s gait were calculated. KCFs were then calculated using the vector sum of the muscle forces and joint reaction forces along the longitudinal axis of the femur. Moderate OA subjects exhibited a similar KCF pattern to healthy subjects, with lower second peaks (p=0.021). Although subjects with severe OA had similar initial peak KCF to healthy and moderate OA subjects (more than 4 times BW), the pattern of the KCF was very different between groups. After an initial peak, subjects with severe OA continually unloaded the joint, whereas healthy and moderate OA subjects reloaded the knee during late stance. In subjects with symmetric OA grades, there appears to be differences in loading between OA severities. Similar initial peaks of KCF imply that reduction of peak KCF may not be a compensatory strategy for OA patients; however, reducing duration of high magnitude loads may be employed.     

Do early life factors affect the development of knee osteoarthritis in later life: a narrative review

Osteoarthritis (OA) mainly affects older populations; however, it is possible that early life factors contribute to the development of OA in later life. The aim of this review is to describe the association between childhood or early adulthood risk factors and knee pain, structural imaging markers and development of knee OA in later life. A narrative overview of the literature synthesising the findings of literature retrieved from searches of computerised databases and manual searches was conducted. We found that only a few studies have explored the long-term effect of childhood or early adulthood risk factors on the markers of joint health that predispose people to OA or joint symptoms. High body mass index (BMI) and/or overweight status from childhood to adulthood were independently related to knee pain and OA in later life. The findings regarding the association between strenuous physical activity and knee structures in young adults are still conflicting. However, a favourable effect of moderate physical activity and fitness on knee structures is reported. Childhood physical activity and performance measures had independent beneficial effects on knee structures including knee cartilage in children and young adults. Anterior knee pain syndrome in adolescence could lead to the development of patellofemoral knee OA in the late 40s. Furthermore, weak evidence suggests that childhood malalignment, socioeconomic status and physical abuse are associated with OA in later life. The available evidence suggests that early life intervention may prevent OA in later life.     

Fat mass limits lower-extremity relative strength and maximal walking performance in older women

The purpose of this study was to determine if excess fat negatively affects relative strength and walking gait performance in overweight, older women. Twenty-five older women (65–80 yr) were separated into normal weight (BMI < 25 kg m⁻², n = 11) and overweight groups (BMI ? 25 kg m⁻², n = 14). Strength and rate of torque development (RTD) of the knee extensors and flexors, ankle plantarflexors and dorsiflexors were measured. Participants walked at standard and maximal speeds during which muscle activation, spatiotemporal and kinetic gait variables were measured. Relative to mass, overweight older women had 24% lower maximal torque and 38% lower RTD than normal weight women. Maximal walking speed was slower in overweight (1.25 ± 0.22 vs. 1.54 ± 0.25 m s⁻¹, P = 0.004) and was correlated to strength (r = 0.53, P < 0.01) and fat mass (r = −0.65, P = 0.001). At maximal speed, overweight had 11% lower vertical ground reaction force relative to mass, 8% slower stride rate, 12% shorter strides, 13% longer foot–ground contact times, 21% longer double-limb support times, 65% greater knee extensor and 78% greater plantarflexor activation (P < 0.05). Overweight, older women demonstrated altered gait and reduced walking performance related to poor relative strength and rate of torque development of lower-extremity muscles.     

Influence of knee osteoarthritis on exercise capacity and quality of life in obese adults

Objective: The objective was to determine whether knee osteoarthritis (OA) reduces exercise ambulatory capacity and impairs quality of life (QOL) in obese individuals. Research Methods and Procedures: There were 56 subjects, with and without knee OA, who were obese. The subjects were evaluated with anthropometric measurements, a body composition assessment, maximal cardiopulmonary exercise test, 6‐minute walk test (6‐MWT), perceived exertion (RPE), self‐reported disability [Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)], and the Medical Outcomes Study Short Form 36 (SF‐36). Results: VO_2peak was significantly higher in the controls when compared with the patients (mean ± standard deviation, 1.584 ± 0.23 L/kg per min vs. 0.986 ± 0.20 L/kg per min; p < 0.001). Obese subjects without knee OA walked a significantly longer distance in the 6‐MWT than obese patients with knee OA (p < 0.001). We also observed significant negative correlation between Vo ₂max and RPE, WOMAC pain and physical limitation, and bodily pain and general health domains of short‐form 36. Discussion: Knee OA reduces exercise and ambulatory capacity and impairs QOL in obese individuals. RPE, WOMAC pain, and SF‐36 items might provide information about exercise capacity in the obese subjects with knee OA. Our study confirms that exercise capacity and QOL might be improved by energetic and intensive treatment of pain resulting from knee OA.     

Application of principal component analysis in clinical gait research: Identification of systematic differences between healthy and medial knee-osteoarthritic gait

For a successful completion of a movement task the motor control system has to observe a multitude of internal constraints that govern the coordination of its segments. The purpose of this study was to apply principal component (PC) analysis to detect differences in the segmental coordination between healthy subjects and patients with medial knee osteoarthritis (OA). It was hypothesized that (1) systematic differences in patterns of whole body movement would be identifiable with this method even in small sample sized groups and that (2) these differences will include compensatory movements in the OA patients in both the lower and upper body segments. Marker positions and ground reaction forces of three gait trials of 5 healthy and 5 OA participants with full body marker sets were analyzed using a principal component analysis. Group differences in the PC-scores were determined for the first 10 PC-vectors and a linear combination of those PC-vectors where differences were found defined a discriminant vector. Projecting the original trials onto this discriminant vector yielded significant group differences (t(d=8)=3.011; p=0.017) with greater upper body movement in patients with knee OA that was correlated with the medial–lateral ground reaction force. These results help to characterize the adaptation of whole-body gait patterns to knee OA in a relatively small population and may provide an improved basis for the development of interventions to modify knee load. The PC-based motion analysis offered a highly sensitive approach to identify characteristic whole body patterns of movement associated with pathological gait.     

Simple Scoring System and Artificial Neural Network for Knee Osteoarthritis Risk Prediction: A Cross-Sectional Study

Background

Knee osteoarthritis (OA) is the most common joint disease of adults worldwide. Since the treatments for advanced radiographic knee OA are limited, clinicians face a significant challenge of identifying patients who are at high risk of OA in a timely and appropriate way. Therefore, we developed a simple self-assessment scoring system and an improved artificial neural network (ANN) model for knee OA.

Methods

The Fifth Korea National Health and Nutrition Examination Surveys (KNHANES V-1) data were used to develop a scoring system and ANN for radiographic knee OA. A logistic regression analysis was used to determine the predictors of the scoring system. The ANN was constructed using 1777 participants and validated internally on 888 participants in the KNHANES V-1. The predictors of the scoring system were selected as the inputs of the ANN. External validation was performed using 4731 participants in the Osteoarthritis Initiative (OAI). Area under the curve (AUC) of the receiver operating characteristic was calculated to compare the prediction models.

Results

The scoring system and ANN were built using the independent predictors including sex, age, body mass index, educational status, hypertension, moderate physical activity, and knee pain. In the internal validation, both scoring system and ANN predicted radiographic knee OA (AUC 0.73 versus 0.81, p<0.001) and symptomatic knee OA (AUC 0.88 versus 0.94, p<0.001) with good discriminative ability. In the external validation, both scoring system and ANN showed lower discriminative ability in predicting radiographic knee OA (AUC 0.62 versus 0.67, p<0.001) and symptomatic knee OA (AUC 0.70 versus 0.76, p<0.001).

Conclusions

The self-assessment scoring system may be useful for identifying the adults at high risk for knee OA. The performance of the scoring system is improved significantly by the ANN. We provided an ANN calculator to simply predict the knee OA risk.     

Changes in knee joint muscle activation patterns during walking associated with increased structural severity in knee osteoarthritis

PurposeTo determine whether alterations in knee joint muscle activation patterns during gait were related to structural severity determined by Kellgren–Lawrence (KL) radiographic grades, for those with a moderate knee OA classification.ScopeEighty-two individuals with knee OA, classified as moderate using a functional and clinical criterion were stratified on KL-grade (KL II, KL III and KL IV). Thirty-five asymptomatic individuals were matched for age and walking velocity. Lower limb motion and surface electromyograms from rectus femoris plus lateral and medial sites for the gastrocnemii, vastii and hamstring muscles were recorded during self-selected walking. Gait velocity and characteristics from sagittal plane knee angular displacement waveforms were calculated. Principal component analysis extracted amplitude and temporal features from electromyographic waveform. Analysis of variance models tested for main effects (group, muscle) and interactions (α = 0.05) for these features. No differences in anthropometrics, velocity, knee muscle strength and symptoms were found among the three OA groups (p > 0.05). Specific features from medial gastrocnemius, lateral hamstring and quadriceps amplitude and temporal patterns were significantly different among OA groups (p < 0.05).ConclusionsSystematic alterations in specific knee joint muscle activation patterns were associated with increasing structural severity based on KL-grades whereas other alterations were associated with the presence of OA.     

Obesity and Quality of Life: Mediating Effects of Pain and Comorbidities

Objective: To estimate the association between body mass index (BMI) and health‐related quality of life (HRQL) and examine whether joint pain and obesity‐related comorbidities mediate the BMI‐HRQL association. Research Methods and Procedures: Population‐based survey data from the 1999 Behavioral Risk Factor Surveillance Survey. Adults (N = 155, 989) were classified according to BMI as underweight (<18.5 kg/m²), desirable weight (18.5 to 24.9 kg/m²), overweight (25 to 29.9 kg/m²), obese class I (30 to 34.9 kg/m²), obese class II (35 to 39.9 kg/m²), and obese class III (≥40 kg/m²). Data including general health status, unhealthy days in the past 30 caused by physical problems and mental problems, and total unhealthy days in the past 30 were collected. Results: After adjusting for age, sex, race, smoking, education, and income, we observed J‐shaped associations between BMI and HRQL. Compared with desirable weight adults, underweight, overweight, and obesity classes I, II, and III adults [odds ratio (OR) = 1.57, 1.19, 1.95, 2.72, and 4.36, respectively] were significantly (p < 0.001) more likely to report fair/poor general health status. For unhealthy days caused by physical problems, the corresponding ORs were 1.51, 1.15, 1.66, 2.27, and 3.61 (p < 0.001). For unhealthy days caused by mental problems, the ORs were 1.35, 1.14 1.43, 1.57, and 2.25 (p < 0.001). For total unhealthy days, the corresponding ORs were 1.27, 1.09, 1.37, 1.73, and 2.46 (p < 0.01). Adding joint pain and obesity‐related comorbidities into models attenuated BMI‐HRQL associations. Discussion: Associations between BMI and HRQL indices were J‐shaped. Joint pain and comorbidities may mediate BMI‐HRQL associations.     

Neuromuscular efficiency during sit to stand movement in women with knee osteoarthritis

The purpose of this study was to investigate the neuromuscular efficiency of women with knee osteoarthritis (OA) when performing a sit-to-stand movement and during maximum strength efforts. Twelve women with unilateral knee OA (age 60.33 ± 6.66 years, height 1.61 ± 0.05 m, mass 77.08 ± 9.2 kg) and 11 controls (age 56.54 ± 5.46 years, height 1.64 ± 0.05 m, mass 77.36 ± 13.34 kg) participated in this study. Subjects performed a sit-to-stand movement from a chair while position of center of pressure and knee angular speed were recorded. Furthermore, maximal isokinetic knee extension and flexion strength at 60°/s, 120°/s and 150°/s was measured. Surface, electromyography (EMG) from the biceps femoris (BF), vastus lateralis (VL) and vastus medialis (VM) was recorded during all tests. Analysis of variance (ANOVA) showed that during the sit-to-stand OA group demonstrated significantly lower knee angular speed (44.49 ± 9.61°/s vs. 71.68 ± 19.86°/s), a more posterior position of the center of pressure (39.20 ± 7.02% vs. 41.95 ± 2.49%) and a higher antagonist BF activation (57.13 ± 20.55% vs. 32.01 ± 19.5%) compared with controls (p < 0.05). Further, women with knee OA demonstrated a lower Moment-to-EMG ratio than controls in extension and eccentric flexion at 60°/s and 150°/s, while the opposite was found for concentric flexion at 60°/s (p < 0.05). Among other factors, the slower performance of the sit-to-stand movement in women with OA is due to a less efficient use of the knee extensor muscles (less force per unit of EMG) and, perhaps, a higher BF antagonist co-activation. This may lead subjects with OA to adopt a different movement strategy compared with controls.     

Proximal gait adaptations in individuals with knee osteoarthritis: A systematic review and meta-analysis

Clarifying proximal gait adaptations as a strategy to reduce knee joint loading and pain for individuals with knee osteoarthritis (OA) contributes to understanding the pathogenesis of multi-articular OA changes and musculoskeletal pain in other joints. We aimed to determine whether biomechanical alterations in knee OA patients during level walking is increased upper trunk lean in the frontal and sagittal planes, and subsequent alteration in external hip adduction moment (EHAM) and external hip flexion moment (EHFM). A literature search was conducted in PubMed, PEDro, CINAHL, and Cochrane CENTRAL through May 2018. Where possible, data were combined into a meta-analysis; pooled standardized mean differences (SMD) of between knee OA patients and healthy adults were calculated using a random-effect model. In total, 32 articles (2037 participants, mean age, 63.0 years) met inclusion criteria. Individuals with knee OA had significantly increased lateral trunk lean toward the ipsilateral limb (pooled SMD: 1.18; 95% CI: 0.59, 1.77) along with significantly decreased EHAM. These subjects also displayed a non-significantly increased trunk/pelvic flexion angle and EHFM. The GRADE approach judged all measures as “very low.” These results may indicate that biomechanical alterations accompanying knee OA are associated with increased lateral trunk lean and ensuing alterations in EHAM. Biomechanical alterations in the sagittal plane were not evident. Biomechanical adaptations might have negative sequelae, such as secondary hip abductor muscle weakness and low back pain. Thus, investigations of negative sequelae due to proximal gait adaptations are warranted.     

Local ASIC3 modulates pain and disease progression in a rat model of osteoarthritis

Background

Recent data have suggested a relationship between acute arthritic pain and acid sensing ion channel 3 (ASIC3) on primary afferent fibers innervating joints. The purpose of this study was to clarify the role of ASIC3 in a rat model of osteoarthritis (OA) which is considered a degenerative rather than an inflammatory disease.

Methods

We induced OA via intra-articular mono-iodoacetate (MIA) injection, and evaluated pain-related behaviors including weight bearing measured with an incapacitance tester and paw withdrawal threshold in a von Frey hair test, histology of affected knee joint, and immunohistochemistry of knee joint afferents. We also assessed the effect of ASIC3 selective peptide blocker (APETx2) on pain behavior, disease progression, and ASIC3 expression in knee joint afferents.

Results

OA rats showed not only weight-bearing pain but also mechanical hyperalgesia outside the knee joint (secondary hyperalgesia). ASIC3 expression in knee joint afferents was significantly upregulated approximately twofold at Day 14. Continuous intra-articular injections of APETx2 inhibited weight distribution asymmetry and secondary hyperalgesia by attenuating ASIC3 upregulation in knee joint afferents. Histology of ipsilateral knee joint showed APETx2 worked chondroprotectively if administered in the early, but not late phase.

Conclusions

Local ASIC3 immunoreactive nerve is strongly associated with weight-bearing pain and secondary hyperalgesia in MIA-induced OA model. APETx2 inhibited ASIC3 upregulation in knee joint afferents regardless of the time-point of administration. Furthermore, early administration of APETx2 prevented cartilage damage. APETx2 is a novel, promising drug for OA by relieving pain and inhibiting disease progression.     

Long term evaluation of disease progression through the quantitative magnetic resonance imaging of symptomatic knee osteoarthritis patients: correlation with clinical symptoms and radiographic changes

The objective of this study was to further explore the cartilage volume changes in knee osteoarthritis (OA) over time using quantitative magnetic resonance imaging (qMRI). These were correlated with demographic, clinical, and radiological data to better identify the disease risk features. We selected 107 patients from a large trial (n = 1,232) evaluating the effect of a bisphosphonate on OA knees. The MRI acquisitions of the knee were done at baseline, 12, and 24 months. Cartilage volume from the global, medial, and lateral compartments was quantified. The changes were contrasted with clinical data and other MRI anatomical features. Knee OA cartilage volume losses were statistically significant compared to baseline values: -3.7 ± 3.0% for global cartilage and -5.5 ± 4.3% for the medial compartment at 12 months, and -5.7 ± 4.4% and -8.3 ± 6.5%, respectively, at 24 months. Three different populations were identified according to cartilage volume loss: fast (n = 11; -13.2%), intermediate (n = 48; -7.2%), and slow (n = 48; -2.3%) progressors. The predictors of fast progressors were the presence of severe meniscal extrusion (p = 0.001), severe medial tear (p = 0.005), medial and/or lateral bone edema (p = 0.03), high body mass index (p < 0.05, fast versus slow), weight (p < 0.05, fast versus slow) and age (p < 0.05 fast versus slow). The loss of cartilage volume was also slightly associated with less knee pain. No association was found with other Western Ontario McMaster Osteoarthritis Index (WOMAC) scores, joint space width, or urine biomarker levels. Meniscal damage and bone edema are closely associated with more cartilage volume loss. These data confirm the significant advantage of qMRI for reliably measuring knee structural changes at as early as 12 months, and for identifying risk factors associated with OA progression.     

Men and women adopt similar walking mechanics and muscle activation patterns during load carriage

Although numerous studies have investigated the effects of load carriage on gait mechanics, most have been conducted on active military men. It remains unknown whether men and women adapt differently to carrying load. The purpose of this study was to compare the effects of load carriage on gait mechanics, muscle activation patterns, and metabolic cost between men and women walking at their preferred, unloaded walking speed. We measured whole body motion, ground reaction forces, muscle activity, and metabolic cost from 17 men and 12 women. Subjects completed four walking trials on an instrumented treadmill, each five minutes in duration, while carrying no load or an additional 10%, 20%, or 30% of body weight. Women were shorter (p<0.01), had lower body mass (p=0.01), and had lower fat-free mass (p=0.02) compared to men. No significant differences between men and women were observed for any measured gait parameter or muscle activation pattern. As load increased, so did net metabolic cost, the duration of stance phase, peak stance phase hip, knee, and ankle flexion angles, and all peak joint extension moments. The increase in the peak vertical ground reaction force was less than the carried load (e.g. ground force increased approximately 6% with each 10% increase in load). Integrated muscle activity of the soleus, medial gastrocnemius, lateral hamstrings, vastus medialis, vastus lateralis, and rectus femoris increased with load. We conclude that, despite differences in anthropometry, men and women adopt similar gait adaptations when carrying load, adjusted as a percentage of body weight.