Kelly-Ann Bowles

Higher dynamic medial knee load predicts greater cartilage loss over 12 months in medial knee osteoarthritis

Objective Mechanical factors, in particular increased medial knee joint load, are believed to be important in the structural progression of knee osteoarthritis. This study evaluated the relationship of medial knee load during walking to indices of structural disease progression, measured on MRI, in people with medial knee osteoarthritis. Methods A longitudinal cohort design utilising a subset of participants (n=144, 72%) enrolled in a randomised controlled trial of lateral wedge insoles was employed. Medial knee load parameters including the peak knee adduction moment (KAM) and the KAM impulse were measured at baseline using three-dimensional gait analysis during walking. MRI at baseline and at 12 months was used to assess structural indices. Multiple regression with adjustment for covariates assessed the relationship between medial knee load parameters and the annual change in medial tibial cartilage volume. Binary logistic regression was used for the dichotomous variables of progression of medial tibiofemoral cartilage defects and bone marrow lesions (BML). Results A higher KAM impulse, but not peak KAM, at baseline was independently associated with greater loss of medial tibial cartilage volume over 12 months (β=29.9, 95% CI 6.3 to 53.5, p=0.01). No significant relationships were seen between medial knee load parameters and the progression of medial tibiofemoral cartilage defects or BML. Conclusion This study suggests knee loading, in particular the KAM impulse, may be a risk factor for loss of medial tibial cartilage volume. As knee load is modifiable, load-modifying treatments may potentially slow disease progression.

Lateral wedge insoles for medial knee osteoarthritis: 12 month randomised controlled trial

Objective To assess the effect of lateral wedge insoles compared with flat control insoles on improving symptoms and slowing structural disease progression in medial knee osteoarthritis. Design Randomised controlled trial. Setting Community in Melbourne, Australia. Participants 200 people aged 50 or more with clinical and radiographic diagnosis of mild to moderately severe medial knee osteoarthritis. Interventions Full length 5 degree lateral wedged insoles or flat control insoles worn inside the shoes daily for 12 months. Main outcome measures Primary symptomatic outcome was change in overall knee pain (past week) measured on an 11 point numerical rating scale. Primary structural outcome was change in volume of medial tibial cartilage from magnetic resonance imaging scans. Secondary clinical outcomes included changes in measures of pain, function, stiffness, and health related quality of life. Secondary structural outcomes included progression of medial cartilage defects and bone marrow lesions. Results Between group differences did not differ significantly for the primary outcomes of change in overall pain (−0.3 points, 95% confidence intervals −1.0 to 0.3) and change in medial tibial cartilage volume (−0.4 mm3, 95% confidence interval −15.4 to 14.6), and confidence intervals did not include minimal clinically important differences. None of the changes in secondary outcomes showed differences between groups. Conclusion Lateral wedge insoles worn for 12 months provided no symptomatic or structural benefits compared with flat control insoles. Trial registration Australian New Zealand Clinical Trials Registry ACTR12605000503628 and ClinicalTrials.gov NCT00415259.

Lateral wedge insoles for medial knee osteoarthritis: Effects on lower limb frontal plane biomechanics

BACKGROUND Lateral wedges reduce the peak knee adduction moment and are advocated for knee osteoarthritis. However some patients demonstrate adverse biomechanical effects with treatment. Clinical management is hampered by lack of knowledge about their mechanism of effect. We evaluated effects of lateral wedges on frontal plane biomechanics, in order to elucidate mechanisms of effect. METHODS Seventy three participants with knee osteoarthritis underwent gait analysis with and without 5° lateral wedges. Frontal plane parameters at the foot, knee and hip were evaluated, including peak knee adduction moment, knee adduction angular impulse, center of pressure displacement, ground reaction force, and knee-ground reaction force lever arm. FINDINGS Lateral wedges reduced peak knee adduction moment and knee adduction angular impulse (-5.8% and -6.3% respectively, both P<0.001). Although reductions in peak moment were correlated with more lateral center of pressure (r=0.25, P<0.05), less varus malalignment (r values 0.25-0.38, P<0.05), reduced knee-ground reaction force lever arm (r=0.69, P<0.01), less hip adduction (r=0.24, P<0.05) and a more vertical frontal plane ground reaction force vector (r=0.67, P<0.001), only reduction in knee-ground reaction force lever arm was significantly predictive in regression analyses (B=0.056, adjusted R(2)=0.461, P<0.001). INTERPRETATION Lateral wedges significantly reduce peak knee adduction moment and knee adduction angular impulse. It seems a reduced knee-ground reaction force lever arm with lateral wedges is the central mechanism explaining their load-reducing effects. In order to understand why some patients do not respond to treatment, future evaluation of patient characteristics that mediate wedge effects on this lever arm is required.

Dynamic knee loading is related to cartilage defects and tibial plateau bone area in medial knee osteoarthritis

OBJECTIVE To evaluate the relationship between dynamic mechanical loading, as indicated by external knee adduction moment (KAM) measures during walking, and measures of articular cartilage morphology and subchondral bone size in people with medial knee osteoarthritis (OA). DESIGN 180 individuals with radiographic medial tibiofemoral OA participated. Peak KAM and KAM angular impulse were measured by walking gait analysis. Tibial cartilage volume and plateau bone area, and tibiofemoral cartilage defects were determined from magnetic resonance imaging using validated methods. RESULTS Both peak KAM (coefficient=0.42, 95% confidence interval (CI) 0.04-0.79, P=0.03) and KAM impulse (coefficient=1.79, 95% CI 0.80-2.78, P<0.001) were positively associated with the severity of medial tibiofemoral cartilage defects. KAM impulse was also associated with the prevalence of medial tibiofemoral cartilage defects (odds ratio 4.78, 95% CI 1.10-20.76, P=0.04). Peak KAM (B=0.05, 95% CI 0.01-0.09, P=0.02) and KAM impulse (B=0.16, 95% CI 0.06-0.25, P=0.002) were positively associated with medial:lateral tibial plateau bone area, and KAM impulse was also associated with medial tibial plateau bone area (B=133.7, 95% CI 4.0-263.3, P=0.04). There was no significant association between KAM measures and tibial cartilage volume. CONCLUSION Peak KAM and KAM impulse are associated with cartilage defects and subchondral bone area in patients with medial knee OA, suggesting that increased mechanical loading may play a role in the pathological changes in articular cartilage and subchondral bone that occur with medial knee OA.

Bone marrow lesions are related to dynamic knee loading in medial knee osteoarthritis

Objectives To evaluate the relationship between mechanical loading, as indicated by the external knee adduction moment (KAM) during walking, and BML on MRI in people with medial knee osteoarthritis. Methods Measures were taken in 91 individuals with medial knee osteoarthritis. Logistic regression analyses were performed with the presence/absence of medial tibial or medial femoral BML as the outcome and either peak KAM or KAM impulse as the independent variable. Analyses were also adjusted for age, gender, body mass index, alignment and walking speed. Results In adjusted analyses, peak KAM was significantly related to medial tibial (OR 2.3; 95%CI 1.07 to 4.7), but not medial femoral (OR 1.85; 95%CI 0.93 to 3.7) BML. KAM impulse was significantly related to both medial tibial (OR 9.4; 95%CI 1.53 to 57.2) and medial femoral (OR 14.4; 95%CI 2.3 to 89.8) BML. Conclusions The findings support the hypothesis that greater mechanical loading of the medial compartment plays a role in the pathogenesis of BML in medial tibiofemoral osteoarthritis.

Effect of length on laterally-wedged insoles in knee osteoarthritis

Introduction Knee osteoarthritis (OA) is a prevalent musculoskeletal condition (1). It imposes a significant economic burden and is associated with considerable pain, disability, and loss of quality of life. Although the causative mechanisms of knee OA are not entirely clear, increased joint loads during walking have been associated with the initiation and progression of the disease and its symptoms (2). The external knee adduction moment, which reflects the dynamic load borne on the medial tibiofemoral joint compartment, has become a biomechanical marker for the risk of progression for medial compartment OA (2). Accordingly, much research is focused on devising and evaluating interventions that may reduce the peak adduction moment with a view to alleviating symptoms and reducing the risk of disease progression in knee OA. Laterally-wedged insoles are an in-shoe orthotic recommended to manage medial knee OA (3). Lateral wedges are hypothesized to reduce the moment arm of the ground reaction force vector relative to the knee center during walking (4), leading to reduced knee pain. Biomechanical studies have demonstrated that lateral wedges can reduce the peak adduction moment in patients with OA and healthy subjects (4–7). However, this finding is not consistent across all studies, with some showing no effect of the wedge on the adduction moment (8,9). Although differences in study samples and measurement methodologies may account for the conflicting findings, it is possible that the varying results may be attributable to differences in the designs of the lateral wedges tested. The most apparent difference in wedge design that is evident across studies relates to the length of the lateral wedge. Most studies that have demonstrated a beneficial effect of the wedge on the adduction moment have tested a full-length insole that wedged the foot from the heel to the forefoot (4–7). In contrast, the studies that demonstrated no effect on knee loading tested insoles that wedged only the rearfoot (8,9). The only clinical trial to evaluate the efficacy of lateral wedges for knee OA used rearfoot wedges and found no significant effect on symptoms or disease progression over time (10,11). Excluding the degree of wedging (which can mediate the effect of a wedge on the adduction moment) (5,7), the design features of laterally-wedged insoles are not considered to influence their efficacy. Evidence suggests that wedging of the entire foot is necessary for a beneficial effect, yet no study has evaluated the influence of wedge length on the adduction moment. The aim of this laboratory study was to compare the effect of a full-length, laterally-wedged insole on the adduction moment with that of a rearfoot wedge in patients with medial knee OA.

Laterally wedged insoles in knee osteoarthritis: do biomechanical effects decline after one month of wear?

ObjectiveThis study aimed to determine whether the effect of laterally wedged insoles on the adduction moment in knee osteoarthritis (OA) declined after one month of wear, and whether higher reported use of insoles was associated with a reduced effect on the adduction moment at one month.MethodsTwenty people with medial compartment OA underwent gait analysis in their own shoes wearing i) no insoles and; ii) insoles wedged laterally 5° in random order. Testing occurred at baseline and after one month of use of the insoles. Participants recorded daily use of insoles in a log-book. Outcomes were the first and second peak external knee adduction moment and the adduction angular impulse, compared across conditions and time with repeated measures general linear models. Correlations were obtained between total insole use and change in gait parameters with used insoles at one month, and change scores were compared between high and low users of insoles using general linear models.ResultsThere was a significant main effect for condition, whereby insoles significantly reduced the adduction moment (all p < 0.001). However there was no significant main effect for time, nor was an interaction effect evident. No significant associations were observed between total insole use and change in gait parameters with used insoles at one month, nor was there a difference in effectiveness of insoles between high and low users of the insoles at this time.ConclusionEffects of laterally wedged insoles on the adduction moment do not appear to decline after one month of continuous use, suggesting that significant wedge degradation does not occur over the short-term.

Comparison of peak knee adduction moment and knee adduction moment impulse in distinguishing between severities of knee osteoarthritis

BACKGROUND The peak knee adduction moment is a valid proxy for medial knee joint loading. However as it only measures load at one instance of stance, knee adduction moment impulse, a measure that takes into account both the magnitude and duration of the stance phase, may provide more comprehensive information. This study directly compared the abilities of peak knee adduction moment and knee adduction moment impulse to distinguish between knee osteoarthritis severities. METHODS 169 participants with medial knee osteoarthritis completed radiographic and magnetic resonance imaging, the Western Ontario and McMaster Universities Arthritis Index to assess pain and a three-dimensional gait analysis. Participants were classified using four dichotomous classifications: Kellgren-Lawrence grading, alignment, medial tibiofemoral bone marrow lesions, and pain. FINDINGS When using Kellgren-Lawrence grade and alignment classifications, the area under the receiver operator curves were significantly greater for knee adduction moment impulse than for peak knee adduction moment. Based on analysis of covariance, knee adduction moment impulse was significantly different between Kellgren-Lawrence grade and alignment groups while peak knee adduction moment was not significantly different. Both peak knee adduction moment and knee adduction moment impulse distinguished between bone marrow lesion severities while neither measure was significantly different between pain severity groups. INTERPRETATIONS Findings suggest knee adduction moment impulse is more sensitive at distinguishing between disease severities and may provide more comprehensive information on medial knee joint loading. Future studies investigating biomechanics of knee osteoarthritis should include knee adduction moment impulse in conjunction with peak knee adduction moment.

Quadriceps strength is not related to gait impact loading in knee osteoarthritis

Joint loading has been implicated in the pathogenesis of knee osteoarthritis (OA). While compartment-specific measures such as the knee adduction moment have received much attention in the literature, less is known about other measures of dynamic loading in this patient population. This cross-sectional study assessed strength and walking patterns of 204 individuals with radiographically confirmed medial tibiofemoral OA and varus malalignment. Pearson product moment correlations and regression analyses were used to determine the bivariate and multivariate relationships amongst measures of impact loading (rate of loading and heelstrike transient occurrence) with demographic, clinical (in particular, radiographic disease severity, lower limb alignment, and self-reported pain and function), and biomechanical variables (maximum voluntary isometric quadriceps strength and gait kinematics). While maximum voluntary isometric quadriceps strength was significantly correlated with rate of loading (r>0.27) when walking at a freely chosen speed, multiple regression analyses indicated that rate of loading was primarily dictated by walking speed (p<0.001), and the effect of quadriceps strength was insignificant when accounting for all other included variables. Individuals who exhibited a heelstrike transient in their vertical ground reaction force profile were significantly more varus malaligned and were more likely to demonstrate severe radiographic degeneration than those who did not exhibit heelstrike transients. These results demonstrate higher impact loading during walking in those with knee OA with faster self-selected walking speeds, though the relationship with quadriceps strength is less clear. Importantly a potential association between disease characteristics, such as malalignment and disease severity, and higher impact loading was also observed.

Lateral wedge shoe insoles for medial knee osteoarthritis: a 12-month randomised controlled trial

Methods A randomised participant- and assessor-blinded controlled trial was used. 200 people aged 50 or more with clinical and radiographic diagnosis of mild-to-moderately severe medial knee OA were recruited. The interventions consisted of full-length 5° lateral wedged insoles or flat control insoles worn inside the shoes daily for 12 months. The primary symptomatic outcome was change in overall knee pain (past week) measured on an 11-point numeric rating scale and primary structural outcome was change in medial tibial cartilage volume from magnetic resonance imaging. Secondary clinical outcomes included changes in measures of pain, function, stiffness, and health-related quality of life. Secondary structural outcomes included progression of medial cartilage defects and bone marrow lesions. Results There were no significant between-group differences for the primary outcomes of change in overall pain (-0.3 points 95% CI (-1.0 to 0.3)) and change in medial tibial