Skeletal muscles power movement. Deriving the forces produced by individual muscles has applications across various fields including biomechanics, robotics, and rehabilitation. Since direct in vivo measurement of muscle force in humans is invasive and challenging, its estimation through non-invasive methods such as electromyography (EMG) holds considerable appeal. This matrix, developed by the Consensus for Experimental Design in Electromyography (CEDE) project, summarizes recommendations on the use of EMG to estimate muscle force. The matrix encompasses the use of bipolar surface EMG, high density surface EMG, and intra-muscular EMG (1) to identify the onset of muscle force during isometric contractions, (2) to identify the offset of muscle force during isometric contractions, (3) to identify force fluctuations during isometric contractions, (4) to estimate force during dynamic contractions, and (5) in combination with musculoskeletal models to estimate force during dynamic contractions. For each application, recommendations on the appropriateness of using EMG to estimate force and justification for each recommendation are provided. The achieved consensus makes clear that there are limited scenarios in which EMG can be used to accurately estimate muscle forces. In most cases, it remains important to consider the activation as well as the muscle state and other biomechanical and physiological factors— such as in the context of a formal mechanical model. This matrix is intended to encourage interdisciplinary discussions regarding the integration of EMG with other experimental techniques and to promote advances in the application of EMG towards developing muscle models and musculoskeletal simulations that can accurately predict muscle forces in healthy and clinical populations.

BACKGROUND:Bony morphology is central to the pathomechanism of femoroacetabular impingement syndrome (FAIS), however isolated radiographic measures poorly predict symptom onset and severity. More comprehensive morphology measurement considered together with patient factors may better predict symptom presentation. This study aimed to determine the morphological parameter(s) and patient factor(s) associated with symptom age of onset and severity in FAIS.METHODS:99 participants (age 32.9 ± 10.5 years; body mass index (BMI 24.3 ± 3.1 kg/m2; 42% females) diagnosed with FAIS received standardised plain radiographs and magnetic resonance scans. Alpha angle in four radial planes (superior to anterior), acetabular version (AV), femoral torsion, lateral centre-edge, anterior centre-edge (ACEA) and femoral neck-shaft angles were measured. Age of symptom onset (age at presentation minus duration of symptoms), international Hip Outcome Tool-33 (iHOT-33) and modified UCLA activity scores were recorded. Backward stepwise regression assessed morphological parameters and patient factors (age, sex, BMI, symptom duration, annual income, private/public healthcare system accessed) to determine variables independently associated with onset age and iHOT-33 score.RESULTS:Earlier symptom onset was associated with larger superoanterior alpha angle (p = 0.007), smaller AV (p = 0.023), lower BMI (p = 0.010) and public healthcare system access (p = 0.041) (r2 = 0.320). Worse iHOT-33 score was associated with smaller ACEA (p = 0.034), female sex (p = 0.040), worse modified UCLA activity score (p = 0.010) and public healthcare system access (p < 0.001) (r2 = 0.340).CONCLUSIONS:Age of symptom onset was chiefly predicted by femoral and acetabular bony morphology measures, whereas symptom severity predominantly by patient factors. Factors measured explained a small amount of variance in the data; additional unmeasured factors may be more influential.

ABSTRACT Purpose The magnitude and location of hip contact force influence the local mechanical environment of the articular tissue, driving remodeling. We used a neuromusculoskeletal model to investigate hip contact force magnitudes and their regional loading patterns on the articular surfaces in those with femoroacetabular impingement (FAI) syndrome and controls during walking. Methods An EMG-assisted neuromusculoskeletal model was used to estimate hip contact forces in eligible participants with FAI syndrome (n = 41) and controls (n = 24), walking at self-selected speed. Hip contact forces were used to determine the average and spread of regional loading for femoral and acetabular articular surfaces. Hip contact force magnitude and region of loading were compared between groups using statistical parametric mapping and independent t-tests, respectively (P < 0.05). Results All of the following findings are reported compared with controls. Those with FAI syndrome walked with lower-magnitude hip contact forces (mean difference, −0.7 N·BW−1; P < 0.001) during first and second halves of stance, and with lower anteroposterior, vertical, and mediolateral contact force vector components. Participants with FAI syndrome also had less between-participant variation in average regional loading, which was located more anteriorly (3.8°, P = 0.035) and laterally (2.2°, P = 0.01) on the acetabulum but more posteriorly (−4.8°, P = 0.01) on the femoral head. Participants with FAI syndrome had a smaller spread of regional loading across both the acetabulum (−1.9 mm, P = 0.049) and femoral head (1 mm, P < 0.001) during stance. Conclusions Compared with controls, participants with FAI syndrome walked with lower-magnitude hip contact forces that were constrained to smaller regions on the acetabulum and femoral head. Differences in regional loading patterns might contribute to the mechanobiological processes driving cartilage maladaptation in those with FAI syndrome.

Background: Anterior cruciate ligament reconstruction (ACLR) together with concomitant meniscal injury are risk factors for the development of tibiofemoral (TF) osteoarthritis (OA), but the potential effect on the patellofemoral (PF) joint is unclear. The aim of this study was to: (i) investigate change in patellar cartilage morphology in individuals 2.5 to 4.5 years after ACLR with or without concomitant meniscal pathology and in healthy controls, and (ii) examine the association between baseline patellar cartilage defects and patellar cartilage volume change.Methods: 32 isolated ACLR participants, 25 ACLR participants with combined meniscal pathology and nine healthy controls underwent knee magnetic resonance imaging (MRI) with 2-year intervals (baseline = 2.5 years post-ACLR). Patellar cartilage volume and cartilage defects were assessed from MRI using validated methods. Results: Both ACLR groups showed patellar cartilage volume increased over 2 years ( p < 0.05), and isolated ACLR group had greater annual percentage cartilage volume increase compared with controls (mean difference 3.6%, 95% confidence interval (CI) 1.0%, 6.3%, p = 0.008) and combined ACLR group (mean difference 2.2%, 95% CI 0.2%, 4.2%, p = 0.028). Patellar cartilage defects regressed in the isolated ACLR group over 2 years ( p = 0.02). Baseline patellar cartilage defect score was positively associated with annual percentage cartilage volume increase (B = 0.02; 95% CI 0.003, 0.03; p = 0.02) in the pooled ACLR participants. Conclusions: Hypertrophic response was evident in the patellar cartilage of ACLR participants with and without meniscal pathology. Surprisingly, the increase in patellar cartilage volume was more pronounced in those with isolated ACLR. Although cartilage defects stabilise in the majority of ACLR participants, the severity of patellar cartilage defects at baseline influenced the magnitude of the cartilage hypertrophic response over the subsequent ~2 years.

Background Anterior cruciate ligament reconstruction (ACLR) together with concomitant meniscal injury are risk factors for the development of tibiofemoral (TF) osteoarthritis (OA), but the potential effect on the patellofemoral (PF) joint is unclear. The aim of this study was to: (i) investigate change in patellar cartilage morphology in individuals 2.5 to 4.5 years after ACLR with or without concomitant meniscal pathology and in healthy controls, and (ii) examine the association between baseline patellar cartilage defects and patellar cartilage volume change. Methods Thirty two isolated ACLR participants, 25 ACLR participants with combined meniscal pathology and nine healthy controls underwent knee magnetic resonance imaging (MRI) with 2-year intervals (baseline = 2.5 years post-ACLR). Patellar cartilage volume and cartilage defects were assessed from MRI using validated methods. Results Both ACLR groups showed patellar cartilage volume increased over 2 years ( p < 0.05), and isolated ACLR group had greater annual percentage cartilage volume increase compared with controls (mean difference 3.6, 95% confidence interval (CI) 1.0, 6.3%, p = 0.008) and combined ACLR group (mean difference 2.2, 95% CI 0.2, 4.2%, p = 0.028). Patellar cartilage defects regressed in the isolated ACLR group over 2 years ( p = 0.02; Z = − 2.33; r = 0.3). Baseline patellar cartilage defect score was positively associated with annual percentage cartilage volume increase (Regression coefficient B = 0.014; 95% CI 0.001, 0.027; p = 0.03) in the pooled ACLR participants. Conclusions Hypertrophic response was evident in the patellar cartilage of ACLR participants with and without meniscal pathology. Surprisingly, the increase in patellar cartilage volume was more pronounced in those with isolated ACLR. Although cartilage defects stabilised in the majority of ACLR participants, the severity of patellar cartilage defects at baseline influenced the magnitude of the cartilage hypertrophic response over the subsequent ~ 2 years.

Background: Studies of walking in those with femoroacetabular impingement syndrome have found altered pelvis and hip biomechanics. But a whole body, time-contiuous, assessment of biomechanical parameters has not been reported. Additionally, larger cam morphology has been associated with more pain, faster progression to end-stage osteoarthritis and increased cartilage damage but differences in walking biomechanics between large compared to small cam morphologies have not been assessed. Research question: Are trunk, pelvis and lower limb biomechanics different between healthy pain-free controls and individuals with FAI syndrome and are those biomechanics different between those with larger, compared to smaller, cam morphologies? Methods: Twenty four pain-free controls were compared against 41 participants with FAI syndrome who were stratified into two groups according to their maximum alpha angle. Participants underwent three-dimensional motion capture during walking. Trunk, pelvis, and lower limb biomechanics were compared between groups using statistical parametric mapping corrected for walking speed and pain. Results: Compared to pain-free controls, participants with FAI syndrome walked with more trunk anterior tilt (mean difference 7.6 degrees, p < 0.001) as well as less pelvic rise (3 degrees, p < 0.001), hip abduction (-4.6 degrees, p < 0.05) and external rotation (-6.5 degrees, p < 0.05). They also had lower hip flexion (-0.06Nm.kg(-1), p < 0.05), abduction (-0.07Nm.kg(-1), p < 0.05) and ankle plantarflexion moments (-0.19Nm.kg(-1), p < 0.001). These biomechanical differences occurred throughout the gait cycle. There were no differences in walking biomechanics according to cam morphology size. Significance: Results do not support the hypothesis that larger cam morphology is associated with larger differences in walking biomechanics but did demonstrate general differences in trunk, pelvis and lower limb biomechanics between those with FAI sydrome and pain-free controls. Altered external biomechanics are likely the result of complex sensory-motor strategy resulting from pain inhibition or impingement avoidance. Future studies should examine internal loading in those with FAI sydnrome.

•No effect of exercise on medial knee loading following meniscal surgery.•At the individual level, high variability was observed for change in knee joint loads.•Individual-specific muscle activation patterns during walking may be present.•Electromyogram-driven modelling is a novel means to analyse knee loads following exercise.

Objective: Different exercise types may yield different outcomes in osteoarthritis (OA) subgroups. The objective was to directly compare effectiveness of two exercise programs for people with medial knee OA and co-morbid obesity. Design: We performed a participant- and assessor-blinded randomized controlled trial. 128 people >= 50 years with medial knee OA and body mass index >30 kg/m(2) were recruited from the community. Interventions were home-based non-weight bearing (NWB) quadriceps strengthening or weight bearing (WB) functional exercise for 12 weeks. Primary outcomes were change in overall knee pain (numeric rating scale, range 010) and difficulty with physical function (Western Ontario and McMaster Universities Osteoarthritis Index, 0-68) over 12 weeks. Secondary outcomes included other pain measures, physical function, quality-of-life, global changes, physical performance, and lower-limb muscle strength. Results: 123 (96%) participants were retained. There was no evidence of a between-group difference in change in pain (mean difference 0.73 units (95% confidence intervals (0.05,1.50)) or function (2.80 units (-1.17,6.76)), with both groups reporting improvements. For secondary outcomes, the WB group had greater improvement in quality-of-life (-0.043 units (-0.085,-0.001)) and more participants reporting global improvement (overall: relative risk 1.40 (0.98,2.01); pain 1.47 (0.97,2.24); function 1.43 (1.04,1.98). Although adverse events were minor, more NWB group participants reported >= 1 adverse event (26/66 (39%) vs 14/62 (23%), p = 0.04). Conclusions: Both exercise types similarly improved primary outcomes of pain and function and can be recommended for people with knee OA and obesity. WB exercise may be preferred given fewer adverse events and potential additional benefits on some secondary outcomes. (C) 2020 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

We thank Dr Kardes for their comment on our randomized controlled trial comparing efficacy of non-weight bearing quadriceps exercise and weight bearing functional exercise in people with medial knee osteoarthritis and co-morbid obesity1Bennell K. Nelligan R. Kimp A. Schwartz S. Kasza J. Wrigley T. et al.What type of exercise is most effective for people with knee osteoarthritis and co-morbid obesity?: The TARGET randomized controlled trial.Osteoarthritis Cartilage. 2020; 28: 755-765Abstract Full Text Full Text PDF PubMed Scopus (5) Google Scholar. Dr Kardes highlights that we performed a superiority trial and not an equivalence trial. They correctly point out that the language we used in the conclusion of ‘similar improvement between groups’ is not aligned with our superiority trial design. Instead more appropriate wording would have been ‘although improvements were observed with both exercise programs, there was no evidence that one was superior to the other’ - a subtle but important point. KLB, RKN, AJK, SS, JK, TVW, BM, PWH and RSH authored the TARGET trial. KLB drafted this letter and revised it critically for important intellectual content. KLB, RKN, AJK, SS, JK, TVW, BM, PWH and RSH had final approval of the letter. All authors take responsibility for the integrity and accuracy of the content. The authors declare that they have no conflicting interests. The funders played no role in drafting this letter. The TARGET trial was funded by the National Health and Medical Research Council Program Grant # 1091302 . KLB is supported by a NHMRC Principal Research Fellowship ( 1058440 ). PWH is supported by a NHMRC Senior Principal Research Fellowship ( 1102905 ). RSH is supported by a National Health and Medical Research Council Fellowship (# 1154217 ).

Background Structural features of lateral tibiofemoral (TF) joint osteoarthritis (OA) occur in up to half of all people with knee OA, and co-existing lateral TF OA is associated with worse knee pain in people with mixed compartmental knee OA. Clinical guidelines for management of knee OA advocate advice about appropriate footwear, yet there is no research evaluating which types of footwear are best for managing pain associated with lateral TF OA. Biomechanical evidence suggests that “motion-control” footwear, which possess midsoles that are stiffer medially compared to laterally, may shift load away from the lateral compartment of the knee and thus may reduce knee pain associated with lateral TF OA. The primary aim of this study is to compare the effects of motion-control shoes to neutral shoes on knee pain in people with predominantly lateral TF OA. Methods This will be an assessor- and participant-blinded, two-arm, comparative effectiveness randomized controlled trial (RCT) conducted in Melbourne, Australia. We will recruit a minimum of 92 people with painful lateral TF OA from the community. Participants will be randomly allocated to receive either motion-control shoes or neutral shoes and will be instructed to wear their allocated shoes for a minimum of 6 h per day for 6 months. The primary outcome is change in self-reported knee pain on walking, measured using a numerical rating scale, assessed at baseline and 6 months. Secondary outcomes include other measures of knee pain, physical function, quality of life, participant-perceived change in pain and function, and physical activity levels. Discussion This study will compare the efficacy of motion-control shoes to neutral shoes for people with painful lateral TF OA. Findings will be the first to provide evidence of the effects of footwear on knee pain in this important subgroup of people with knee OA and allow clinicians to provide accurate advice about the most appropriate footwear for managing pain associated with lateral TF OA. Trial registration This trial has been prospectively registered by the Australian New Zealand Clinical Trials Registry on 15/11/2018 (reference: ACTRN12618001864213 ).

This study aimed to evaluate hip joint kinematic variability and segment coordination variability during walking according to pain and radiographic disease severity in people with hip osteoarthritis. Fifty-five participants with hip osteoarthritis had pain severity assessed during walking using an item on the Western Ontario and McMasters Universities Osteoarthritis Index (no pain = 10; mild pain = 28; moderate pain = 17). Radiographic disease severity was graded by Kellgren and Lawrence scale (KL2 = 29; KL3 = 21; KL4 = 5). Hip kinematics variability was estimated as the curve coefficient of variation. Vector coding was used to calculate coordination variability for select joint couplings. One-way analysis of variances with planned adjusted post hoc comparisons were used to compare hip kinematics variability and coordination variability of select segment couplings (pelvis sagittal vs thigh sagittal; pelvis frontal vs thigh frontal; pelvis transverse vs thigh transverse; thigh sagittal vs shank sagittal; thigh frontal vs shank sagittal; thigh transverse vs shank sagittal) according to pain and radiographic disease severity. No main effect of pain severity was observed for sagittal or transverse plane hip kinematic variability (P >= .266), and although there was a main effect for frontal plane hip kinematic variability (P = .035), there were no significant differences when comparing between levels of pain severity (P > .006). There was no main effect of radiographic disease severity on hip kinematic variability in the sagittal (P = .539) or frontal (P = .307) plane. No significant differences in coordination of variability of segment couplings were observed (all P >= .229). Movement variability as assessed in this study did not differ according to pain severity during walking or radiographic disease severity.

People who have had anterior cruciate ligament reconstruction (ACLR) are at a high risk of developing tibiofemoral joint (TFJ) osteoarthritis (OA), with concomitant meniscal injury elevating this risk. This study aimed to investigate OA-related morphological change over 2 years in the TFJ among individuals who have undergone ACLR with or without concomitant meniscal pathology and in healthy controls. A secondary aim was to examine associations of baseline TFJ cartilage defects and bone marrow lesions (BML) scores with tibial cartilage volume change in ACLR groups. Fifty seven ACLR participants aged 18–40 years (32 isolated ACLR, 25 combined meniscal pathology) underwent knee magnetic resonance imaging (MRI) 2.5 and 4.5 years post-surgery. Nine healthy controls underwent knee MRI at the ~ 2-year intervals. Tibial cartilage volume, TFJ cartilage defects and BMLs were assessed from MRI. For both ACLR groups, medial and lateral tibial cartilage volume increased over 2 years (P <  0.05). Isolated ACLR group had greater annual percentage increase in lateral tibial cartilage volume compared with controls and with the combined group (P = 0.03). Cartilage defects remained unchanged across groups. Both ACLR groups showed more lateral tibia BML regression compared with controls (P = 0.04). Baseline cartilage defects score was positively associated with cartilage volume increase at lateral tibia (P = 0.002) while baseline BMLs score was inversely related to medial tibia cartilage volume increase (P = 0.001) in the pooled ACLR group. Tibial cartilage hypertrophy was apparent in ACLR knees from 2.5 to 4.5 years post-surgery and was partly dependent upon meniscal status together with the nature and location of the underlying pathology at baseline. Magnitude and direction of change in joint pathologies (i.e., cartilage defects, BMLs) were less predictable and either remained stable or improved over follow-up.

Purpose: Knee osteoarthritis (OA) is a painful and debilitating condition that is highly prevalent in older adults. The type of footwear a person wears can influence the force passing through the lower leg and up to the knee, and certain shoe design features can increase load more than others. In the absence of clinical trial evidence, clinical guidelines recommend that clinicians advise people with OA to wear “appropriate footwear (including shock-absorbing properties)” (NICE clinical guidelines), or use “appropriate and comfortable shoes” (EULAR recommendations), without defining “appropriate” footwear. The aim of this study was to determine the footwear styles, and characteristics, most commonly worn by individuals with knee OA. Methods: This study used baseline data from 91 participants taking part in an ongoing randomised controlled trial investigating footwear. Participants were included in the clinical trial if they: i) were aged ≥50 years; ii) reported knee pain on most days of the past month; iii) reported a minimum pain score of 4 on an 11-point numeric rating scale (NRS) during walking over the previous week; iv) demonstrated tibiofemoral osteophytes on x-ray and; v) demonstrated moderate-severe (Kellgren & Lawrence Grade 3-4) tibiofemoral OA on x-ray. Participants were asked to bring into the laboratory the pair of shoes worn most often in the past month for assessment. Shoes were assessed for a range of features, based on the Footwear Assessment Tool parameters, including: i) Footwear type ii) General features (approximate age of the shoe (self-reported in years); frequency of shoe wear over the past month (estimated as hours per day); shoe mass (right only, was measured in grams using digital scales); length of the participants’ foot) was measured in millimetres); ratio of shoe mass to foot length determined). iii) General structure (heel height; forefoot height; pitch (difference between heel height and forefoot height); measured using calipers (cm)). iv) Motion control features (i) midsole density, categorized as mono- or multiple-density, ii) fixation, documented as either no fixation, laces, straps/buckles, Velcro or zippers, iii) heel counter stiffness, assessed by applying pressure on the posterior aspect of the heel, iv) frontal plane midfoot rigidity, measured by bending the rearfoot of the shoes toward the forefoot, v) sagittal midsole stability, measured by twisting the rearfoot and forefoot portion of the shoe and, vi) sole hardness, determined by pressing firmly into the middle region of the inside heel of the shoe.) The total motion control property score was calculated, with scores ranging from 0 to 11, with higher scores indicating greater motion control properties. Results: Participant characteristics are shown in Table 1. The most commonly worn footwear styles were casual walking shoes (n=20, 22%), runners/athletic trainers (n=14, 15%) and court shoes with a low heel (n=11, 12%). No participants wore court shoes with a heel, crocs/clogs, light-weight lace up shoes, rocker soled shoes or stilettos as their most commonly worn shoe. Participants’ shoes were approximately two years old (mean 2.3 (SD 3.4)), were worn for five and a half hours per day (5.5 (2.3)) and had a ratio of mass to foot length of 1.1 (0.4). Nearly half (48%) of shoes had medium heel height, and 57% had medium pitch. Almost half the participants’ shoes contained stability features such as multiple density midsoles (n=52, 47%), and most had moderate to rigid midfoot sole frontal stability (n=56, 61%). In contrast, most shoes had no (n=27, 30%) or minimal (n=34, 37%) heel counter stiffness. Most shoes had minimal midfoot sole sagittal stability (n=76, 84%), and on average, the total motion control property score was relatively low (mean (SD) 3.8 (2.7) out of maximum of 11). Conclusions: This study found that people with knee OA typically wear casual walking shoes and athletic runners/trainers. Around half of people wear shoes that incorporate supportive features (such as midsoles with multiple densities and moderate to rigid midfoot sole frontal stability), demonstrating a more “stable” shoe to be the preferred choice of footwear for these people. Approximately half of the most commonly worn shoes had medium heel heights and pitch, features which have previously been linked to increased knee joint loading. Further research is needed to determine which footwear styles and features are optimal for reducing knee joint loading and symptoms in people with knee OA in order to inform clinical practice guidelines.Table 1Characteristics of participants. Values are mean (SD) unless stated otherwiseCharacteristicn = 91Age, y65.8(7.5)Male, n (%)31 (34)Body mass index, kg/m232.4 (5.9)Radiographic disease severity, n (%)Grade 351 (56)Grade 440 (44)Currently employed, n (%)47 (52)Pain with walking in the last week (NRS)∗6.1 (1.3)Physical function (WOMAC) in the last week†29.4 (10.7)∗Ranges from 0 to 10; higher scores indicate worse pain.†Ranges from 0 to 68; higher scores indicate worse function. Open table in a new tab Table 2Footwear type. Values are numbers (percentages)Shoe Typen=91Shoe Typen=91Casual walking shoes20 (22)Loafer/boat shoes2 (2)Runners/Athletic Trainers14 (15)Work boots2 (2)Court shoes with low heel11 (12)Ballet flats1 (1)Above-ankle boots10 (11)Slippers with open heel1 (1)Oxford shoes9 (10)Court shoes with heel0 (0)Sandals with closed heel6 (7)Crocs/Clogs0 (0)Sandals with open heel6 (7)Light-weight lace up shoes0 (0)Thongs/flip-flops5 (5)Rocker soled shoes0 (0)Slippers with closed heel4 (4) Open table in a new tab Table 3Shoe Characteristics. Values are numbers (percentages) unless stated otherwiseGENERAL FEATURESn=91GENERAL STRUCTUREn=91MOTION CONTROLn=91MOTION CONTROLn=91MOTION CONTROLn=91Age of shoe (years), mean (SD)2.3 (3.4)Heel height (cm)Multiple density soleHeel counter stiffnessMidfoot sole frontal stability (torsion)Shoe wear in past month (hours/day), mean (SD)5.5 (2.3)Low (>=2.5cm)47 (52)Single density49 (53)No heel counter27 (30)minimal (>45⁰)35 (38)Shoe mass to foot length ratio (g/mm), mean (SD)1.1 (0.4)Medium (2.5 - 5.0cm)44 (48)Multiple density42 (47)minimal (>45⁰)34 (37)moderate (>10⁰-<45⁰)23 (25)High (>5.0cm)0 (0)Fixationmoderate (>10⁰-<45⁰)11 (12)rigid (<10⁰)33 (36)Forefoot height (cm)No fixation29 (32)rigid (<10⁰)19 (21)Sole hardnessLow (>=1.0cm)32 (35)Laces36 (40)Midfoot sole sagittal stabilitySoft32 (35)Medium (1.0 - 2.0cm)51 (56)Straps/Buckles10 (11)minimal (>45⁰)76 (84)Medium21 (23)High (>2.0cm)8 (9)Velcro10 (11)moderate (>10⁰-<45⁰)4 (4)Hard38 (42)Pitch (cm)Zippers6 (6)rigid (<10⁰)11 (12)Low (>=1.0cm)38 (42)Total motion control properties score, mean (SD)3.8 (2.7)Medium (1.0 - 3.0cm)52 (57)High (>3.0cm)1 (1) Open table in a new tab ∗Ranges from 0 to 10; higher scores indicate worse pain. †Ranges from 0 to 68; higher scores indicate worse function.

BACKGROUND: Assessment of home exercise adherence and the degree to which adherence influences changes in patient outcomes is limited by the use of self-reported measures. OBJECTIVES: To determine the relationship between adherence to a home strengthening program, covertly measured by accelerometers in ankle cuff weights, and changes in self-reported pain, physical function, and knee extensor strength among people with chronic knee pain. METHODS: This is a secondary analysis of data from a clinical measurement study in 54 adults, aged 45 years or older, with chronic knee pain who completed a 12-week, home-based quadriceps-strengthening program. A triaxial accelerometer was concealed in the ankle cuff weight used for exercises to assess exercise adherence. Associations between exercise adherence and changes in pain and function (measured using the Western Ontario and McMaster Universities Osteoarthritis Index) and peak isometric knee extensor strength were examined using mixed-effects and linear regression models and fractional polynomials. RESULTS: Exercise adherence declined from a median of 90% (interquartile range. 70%-100%) in weeks 0 to 2 to 65% (interquartile range, 25%90%) in weeks 10 to 12. Significant improvements were observed in knee pain (mean change, -3.2 units; 95% confidence interval [CI]: -2.4, -3.9 units), function (mean change. -10.1 units; 95% CI: -7.8, -12.4 units), and knee extensor strength (mean change, 0.34 Nm/kg; 95% CI: 026, 0.42 Nm/kg) across the group over the same period. Exercise adherence was not associated with changes in pain. function. and knee extensor strength over 2-week periods or over the entire 12 weeks. CONCLUSION: Covertly measured adherence to a home strengthening program was not associated with changes in patient outcomes. These findings challenge the notion that greater exercise adherence leads to greater improvement in patient outcomes during a short-term intervention.

Background: Deep hip muscle retraining is a common objective of non-operative management for femoroacetabular impingement (FAI) syndrome. These muscles are considered to have an important role in hip joint stabilization, however, it is unclear whether their function is altered in the presence of hip pathology. This exploratory study aimed to investigate activation patterns of the hip muscles during two squatting tasks in individuals with and without FAI syndrome. Methods; Fifteen individuals with FAI syndrome (symptoms, clinical examination and imaging) and 14 age- and sex-comparable healthy controls underwent testing. Intramuscular fine-wire and surface electrodes recorded electromyographic activity of selected deep and superficial hip muscles during the squatting tasks. Activation patterns from individual muscles were compared between-groups using a wavelet-based linear mixed effects model (P < 0.05). Findings: There were no between-group differences for squat depth or speed during descent or ascent for either task. Participants with FAI syndrome exhibited patterns of activation that differed significantly to controls across all muscles (P < 0.05) when squatting using their preferred strategy. Unlike controls, participants with FAI syndrome exhibited a pattern of activation for obturator internus during descent that was similar in amplitude to ascent, despite the contrasting contraction type (i.e. eccentric vs concentric). Interpretation Individuals with FAI syndrome appear to implement a protective strategy as the hip descends towards the impingement position. Future studies should examine patients prospectively to establish whether these strategies are counterproductive for pathology and warrant rehabilitation.

Purpose: Knee osteoarthritis (OA) is a major global public health problem that causes significant pain and disability. The condition frequently involves the medial tibiofemoral joint compartment and increased medial knee loading has been implicated in the progression of medial knee OA. Previous research suggests that a pronated static foot posture is common in people with medial knee OA, and that a pronated static foot posture, is associated with knee pain and cartilage damage in the medial tibiofemoral joint compartment. Dynamic measurements of foot plantar pressures, provide a greater understanding of foot posture and loading and may provide further insight into how foot posture and function is related to knee OA symptoms. Aim: To investigate the relationships between static foot posture, in-shoe plantar foot forces and knee pain in people with medial knee OA. Methods: Participants: 97 community volunteers aged over 50 years with symptomatic moderate to severe (Kellgren & Lawrence grades 3 or 4) radiographic medial knee OA who completed a baseline assessment in an ongoing randomised controlled trial investigating footwear. Procedure: Participants completed a self-report questionnaire which included i) a numerical rating scale (NRS, 0=no pain and 10=worst pain possible) for knee pain in the past week while walking, and ii) the Western Ontario and McMaster Universities Arthritis Index (WOMAC) pain subscale (score range 0=no pain to 20=maximum pain). Participants also underwent a static foot posture and mobility assessment. These measures included iii)) the foot posture index (FPI, -12=severely supinated to +12=severely pronated), iv) foot mobility magnitude (FMM, a composite distance measure of vertical and medial-lateral mobility of the midfoot, where higher values indicated greater foot mobility) and the v) navicular drop test (NDT, the vertical displacement of the navicular tuberosity with weightbearing, with higher values indicating greater displacement). Finally, participants underwent in-shoe plantar foot force measurement (Pedar-X insoles; Novel), performed walking at their self-selected normal pace in the their most commonly worn shoes from the last month. Data were averaged over 3 walks of a 10m walkway, with each walk comprising between 2 and 8 complete stance phases. In-shoe plantar force outcomes included vi) lateral, vii) medial and viii) whole foot forces; ix) medial-lateral foot force ratio; x) arch index; xi) stance duration; and xii) walking velocity). Plantar foot forces (Newtons) were exported as peaks throughout the whole stance phase, as well as values at mid stance time, and normalized to participant body weight (N/N). Statistical analyses: Statistical analyses were performed with SPSS, and p values <0.05 were considered significant. Descriptive statistics were calculated as mean (SD) or proportions. Regression co-efficients were used to determine the associations between pain and static posture and plantar forces. Results: Table 1 provides descriptive characteristics of the cohort. Just over half of participants had pronated or severely pronated static foot postures (55%) according to the FPI. Static measures of foot posture were not associated with pain (Table 2). Walking knee pain scores from the previous week were inversely related to peak lateral foot force (B co-efficient=-4.67, 95% confidence interval (CI) -8.15 to -1.19) and peak whole foot force (B=-2.68, CI -4.85 to -0.51), such that increased lateral and peak whole foot forces were associated with less severe knee pain. Similar relationships were also observed with WOMAC pain scores (B=-9.73, CI -16.77 to -2.69 and B=-6.96, CI -11.28 to -2.64 respectively). Positive relationships were observed with medial foot force (B=6.59, CI 1.88 to 11.31) and the medial-lateral foot force ratio at midstance (B=0.93, CI 0.13 to 1.73), such that increased medial forces were associated with increased knee pain. WOMAC pain score was positively associated with the arch index at midstance (B=11.30, CI 0.31 to 22.28) indicating more plantar contact across the mid-foot was associated with increased knee pain. Self-selected walking velocity was inversely associated with both NRS walking pain (B=-1.92, CI -3.32 to -0.52) and the WOMAC pain score (-3.18, CI -6.09 to -0.28), such that walking velocity decreased with more severe knee pain. Conclusions: Static measures of foot posture do not appear to be related to knee pain in people with medial knee OA. However our dynamic data suggest that interventions (eg orthoses, footwear) aimed at re-directing pressures from the medial to the lateral plantar surface may potentially be associated with reduced knee pain and are thus worthy of investigation.Tabled 1Table 1 Descriptive characteristics of the group. Data presented as mean (SD) unless indicated.Characteristicsn=97Characteristicsn=97Female gender, n (%)53 (55)Shoe type, n (%)Age (years)65.5 (7.8)Casual walking shoes30 (31)Duration of OA symptoms (years)8.8 (6.8)Runners/athletic trainers18 (19)Height (m)1.68 (0.09)Court shoes with low heel13 (13)Mass (kg)93.5 (17.8)Oxford shoes12 (12)Body mass index (kg/m2)33.1 (5.9)Above ankle boots7 (7)Unilateral symptoms, n (%)20 (21)Other17 (18)Average walking pain in the last week on an NRSˆRanges from 0 to 10 (higher scores indicate worse pain);6.2 (1.7)Shoe age (years)2.6 (3.8)WOMAC pain∗Ranges from 0 to 20 (higher scores indicate worse pain).8.9 (2.9)Shoe wear in past month (hours/day)5.1 (2.6)Radiographic severity, n (%)†Using the Kellgren-Lawrence grading system; NRS = numerical rating scale; WOMAC = Western Ontario and McMaster Universities Osteoarthritis Index.Foot posture index category, n(%)#Supinated=-1 to -4, Normal=0 to +5, Pronated=+6 to +9, Severely Pronated = 10+Grade 342 (43)Supinated2 (2)Grade 455 (57)Normal42 (43)Pronated40 (41)Severely pronated13 (13)† Using the Kellgren-Lawrence grading system; NRS = numerical rating scale; WOMAC = Western Ontario and McMaster Universities Osteoarthritis Index.ˆ Ranges from 0 to 10 (higher scores indicate worse pain);∗ Ranges from 0 to 20 (higher scores indicate worse pain).# Supinated=-1 to -4, Normal=0 to +5, Pronated=+6 to +9, Severely Pronated = 10+ Open table in a new tab Table 2Descriptive data for static and dynamic foot measurements, and their relationship.Mean (SD)NRS walking knee pain∗higher scores indicate worse painWOMAC knee pain scale∗higher scores indicate worse painMean (SD)NRS walking knee pain∗higher scores indicate worse painWOMAC knee pain scale∗higher scores indicate worse painRegression coefficient (95% CI)PRegression coefficient (95% CI)PRegression coefficient (95% CI)PRegression coefficient (95% CI)PStatic Foot MeasuresWhole foot force#force units are normalised to body weight (N/N), with a score of 1 representing a force equal to the participant's body weight.Foot posture index5.8 (3.1)-0.04 (-0.13 to 0.06)0.442-0.11 (-0.30 to 0.08)0.239-overall peak0.95 (0.13)-2.68 (-4.85 to -0.51)0.016-6.96 (-11.28 to -2.64)0.002Foot mobility magnitude (mm)8.9 (3.2)0.02 (-0.06 to 0.11)0.591-0.06 (-0.24 to 0.12)0.536-at midstance0.72 (0.09)2.23 (-0.79 to 5.24)0.146-2.47 (-8.63 to 3.69)0.428Navicular drop test (mm)6.5 (2.9)-0.04 (-0.14 to 0.07)0.4830.00 (-0.21 to 0.20)0.977Medial-Lateral foot force ratioDynamic Foot Measures-overall peak3.12 (2.27)0.11 (-0.01 to 0.24)0.0820.19 (-0.07 to 0.44)0.143Lateral foot force#force units are normalised to body weight (N/N), with a score of 1 representing a force equal to the participant's body weight.-at midstance0.86 (0.35)0.93 (0.13 to 1.73)0.0230.91 (-0.75 to 2.57)0.279-overall peak0.44 (0.08)-4.67 (-8.15 to -1.19)0.009-9.73 (-16.77 to -2.69)0.007Arch index-at midstance0.32 (0.07)-1.42 (-5.60 to 2.76)0.501-5.49 (-13.91 to 2.94)0.199-overall peak0.28 (0.08)1.12 (-2.27 to 4.51)0.515-3.14 (-10.00 to 3.73)0.366Medial foot force#force units are normalised to body weight (N/N), with a score of 1 representing a force equal to the participant's body weight.-at midstance0.22 (0.05)3.59 (-1.89 to 9.07)0.19611.30 (0.31 to 22.28)0.044-overall peak0.35 (0.07)-1.30 (-5.49 to 2.89)0.540-6.39 (-14.80 to 2.03)0.135Gait parameters-at midstance0.23 (0.06)6.59 (1.88 to 11.31)0.0076.32 (-3.54 to 16.18)0.206Stance duration (secs)0.70 (0.07)3.73 (-0.21 to 7.67)0.0632.89 (-5.23 to 11.01)0.481Walking velocity (m/sec)1.22 (0.20)-1.92 (-3.32 to -0.52)0.008-3.18 (-6.09 to -0.28)0.032# force units are normalised to body weight (N/N), with a score of 1 representing a force equal to the participant's body weight.∗ higher scores indicate worse pain Open table in a new tab

Clinical guidelines recommend exercise as a core treatment for individuals with knee osteoarthritis (OA). However, the best type of exercise for clinical benefits is not clear, particularly in different OA subgroups. Obesity is a common co-morbidity in people with knee OA. There is some evidence suggesting that non-weight bearing exercise may be more effective than weight bearing exercise in patients with medial knee OA and obesity. To compare the efficacy of two different exercise programs (weight bearing functional exercise and non-weight bearing quadriceps strengthening) on pain and physical function for people ≥50 years with painful medial knee OA and obesity (body mass index ≥30 kg/m2) 128 people in Melbourne, Australia will be recruited for a two group parallel-design, assessor- and participant-blinded randomised controlled trial. Participants will be randomly allocated to undertake a program of either weight bearing functional exercise or non-weight bearing quadriceps strengthening exercise. Both groups will attend five individual sessions with a physiotherapist who will teach, monitor and progress the exercise program. Participants will be asked to perform the exercises at home four times per week for 12 weeks. Outcomes will be measured at baseline and 12 weeks. Primary outcomes are self-reported knee pain and physical function. Secondary outcomes include other measures of knee pain, physical function, quality-of-life, participant-perceived global change, physical performance, and lower limb muscle strength. This study will compare the efficacy of two different 12-week physiotherapist-prescribed, home-based exercise programs for people with medial knee OA and obesity. Findings will provide valuable information to help inform exercise prescription in this common OA patient subgroup. Australian New Zealand Clinical Trials Registry reference: ACTRN12617001013358 , 14/7/2017

Background: Pain is a cardinal symptom of knee osteoarthritis (OA) and although conservative treatments such as exercise and diet related interventions can reduce pain, effects are modest and can be improved. Frontal plane knee joint motion has been associated with knee pain, and is suggested as a patient-specific characteristic on which to tailor interventions. Research question: Does the association between baseline frontal plane knee joint kinematics and pain-relief differ among overweight and obese people with knee OA who underwent an intervention from the Intensive Diet and Exercise for Arthritis (IDEA) clinical trial: diet-only, exercise-only, and combined diet and exercise intervention? Methods: 323 participants with knee OA were included in the analysis (77% females; 66 +/- 6 years; 33.5 +/- 3.7 kg/m(2)). At baseline, frontal plane knee joint kinematics during walking were measured using 3-dimensional gait analysis and characterised as peak varus-valgus knee angle, peak varus-valgus excursion, and peak varus angular velocity. Pain was assessed at baseline and 18-month follow-up using the Western Ontario and McMaster Universities Osteoarthritis Index pain subscale. Linear regressions were performed unadjusted and adjusted for covariates to determine if the associations between baseline frontal plane knee joint kinematics and 18-month change in pain differed according to intervention. Results: The interaction terms between the intervention and measures of frontal plane knee joint kinematics were not statistically significant (all P >= 0.05). Significance: We found no evidence to suggest that 18-months of either exercise, diet, or a combination of diet and exercise could be more effective than the other to improve pain based on frontal plane measures of knee kinematics.

Objectives:Wearing a soft knee brace has been shown to reduce self-reported knee instability in persons with knee OA. There is a need to assess whether a soft knee brace has a beneficial effect on objectively assessed dynamic knee instability as well. The aims of the study were to evaluate the effect of a soft knee brace on objectively assessed dynamic knee instability and to assess the difference in effect between a non-tight and a tight soft knee brace in persons with knee OA.Methods:Thirty-eight persons with knee OA and self-reported knee instability participated in a laboratory study. A within-subject design was used comparing no brace vs brace and comparing a non-tight vs a tight brace. The primary outcome measure was dynamic knee instability, expressed by the perturbation response (PR). The PR reflects deviation in the mean knee varus-valgus angle during level walking after a controlled mechanical perturbation. Linear mixed-effect model analysis was used to evaluate the effect of a brace on dynamic knee instability.Results:Wearing a brace significantly reduced the PR compared with not wearing a brace (B = -0.16, P = 0.01). There was no difference between a non-tight and a tight brace (B = -0.03, P = 0.60).Conclusion:This study is the first to report that wearing a soft knee brace reduces objectively assessed dynamic knee instability in persons with knee OA. Wearing a soft brace results in an objective improvement of knee instability beyond subjectively reported improvement.Trial registration:Nederlands Trial register (trialregister.nl) NTR6363.

ABSTRACTCartilage T2 relaxation time in isolated anterior cruciate ligament reconstruction (ACLR) without concomitant meniscal pathology and their changes over time remain unclear. The purpose of this exploratory study was to: (i) compare cartilage T2 relaxation time (T2 values) in people with isolated ACLR at 2–3 years post‐surgery (baseline) and matched healthy controls and; (ii) evaluate the subsequent 2‐year change in T2 values in people with ACLR. Twenty‐eight participants with isolated ACLR and nine healthy volunteers underwent knee magnetic resonance imaging (MRI) at baseline; 16 ACLR participants were re‐imaged 2 years later. Cartilage T2 values in full thickness, superficial layers, and deep layers were quantified in the tibia, femur, trochlear, and patella. Between‐group comparisons at baseline were performed using analysis of covariance adjusting for age, sex, and body mass index. Changes over time in the ACLR group were evaluated using paired sample t‐tests. ACLR participants showed significantly higher (p = 0.03) T2 values in the deep layer of medial femoral condyle at baseline compared to controls (mean difference 4.4 ms [13%], 95%CI 0.4, 8.3 ms). Over 2 years, ACLR participants showed a significant reduction (p = 0.04) in T2 value in the deep layer of lateral tibia (mean change 1.4 ms [−7%], 95%CI 0.04, 2.8 ms). The decrease in T2 values suggests improvement in cartilage composition in the lateral tibia (deep layer) of ACLR participants. Further research with larger ACLR cohorts divided according to meniscal status and matched healthy cohorts are needed to further understand cartilage changes post‐ACLR. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2022–2029, 2018.