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  • The Measurement of Joint Mechanics and Their Role in Osteoarthritis Genesis and Progression RHEUMATIC DISEASE CLINICS OF NORTH AMERICA Wilson, D. R., McWalter, E. J., Johnston, J. D. 2013; 39 (1): 21-?

    Abstract

    Mechanics play a role in the initiation and progression of osteoarthritis. However, our understanding of which mechanical parameters are most important, and what their impact is on the disease, is limited by the challenge of measuring the most important mechanical quantities in living subjects. Consequently, comprehensive statements cannot be made about how mechanics should be modified to prevent, slow or arrest osteoarthritis. Our current understanding is based largely on studies of deviations from normal mechanics caused by malalignment, injury, and deformity. Some treatments for osteoarthritis focus on correcting mechanics, but there appears to be scope for more mechanically based interventions.

    View details for DOI 10.1016/j.rdc.2012.11.002

    View details for Web of Science ID 000315170300004

    View details for PubMedID 23312409

  • UTE T2* mapping detects sub-clinical meniscus degeneration OSTEOARTHRITIS AND CARTILAGE McWalter, E. J., Gold, G. E. 2012; 20 (6): 471-472

    View details for DOI 10.1016/j.joca.2012.02.640

    View details for Web of Science ID 000304733900002

    View details for PubMedID 22406647

  • The effect of a patellar brace on three-dimensional patellar kinematics in patients with lateral patellofemoral osteoarthritis OSTEOARTHRITIS AND CARTILAGE McWalter, E. J., Hunter, D. J., Harvey, W. F., McCree, P., Hirko, K. A., Felson, D. T., Wilson, D. R. 2011; 19 (7): 801-808

    Abstract

    Patellar bracing is a mechanical treatment strategy for patellofemoral osteoarthritis (OA) that aims to unload the lateral compartment of the joint by translating the patella medially. Our objective was to determine whether a patellar brace can correct patellar kinematics in patients with patellofemoral OA.We assessed the effect of a patellar brace on three-dimensional patellar kinematics (flexion, spin and tilt; proximal, lateral and anterior translation) at sequential, static knee postures, using a validated magnetic resonance imaging (MRI)-based method, in 19 patients with radiographic lateral patellofemoral OA. Differences in kinematics between unbraced and braced conditions were assessed in the unloaded and loaded knee (15% bodyweight load) using hierarchical linear random-effects models. Random slope and quadratic terms were included in the model when significant (P<0.05).Bracing with load caused the patellae to translate 0.46 mm medially (P<0.001), tilt 1.17° medially (P<0.001), spin 0.62° externally (P=0.012) and translate 1.09 mm distally (P<0.001) and 0.47 mm anteriorly (P<0.001) over the range of knee flexion angles studied. Bracing also caused the patellae to extend in early angles of knee flexion (P<0.001). The brace caused similar trends for the unloaded condition, though magnitudes of the changes varied.Bracing changed patellar kinematics, but these changes did not appear large enough to be clinically meaningful because no reduction in pain was observed in the parent study.

    View details for DOI 10.1016/j.joca.2011.03.003

    View details for Web of Science ID 000293323000005

    View details for PubMedID 21397707

  • The effect of load magnitude on three-dimensional patellar kinematics in vivo JOURNAL OF BIOMECHANICS McWalter, E. J., Hunter, D. J., Wilson, D. R. 2010; 43 (10): 1890-1897

    Abstract

    Studies of three-dimensional patellar kinematics done with little or no applied load may not accurately reflect kinematics at physiological load levels, and may provide different results to those acquired with greater applied loads or in physiologic weightbearing. We report the effect of load magnitude on three-dimensional patellar kinematics (flexion, spin and tilt; proximal, lateral and anterior translation) using a validated, sequential static, MRI-based method. Ten healthy subjects loaded their study knee to 0% (no load), 15% and 30% bodyweight (BW) using a custom designed loading rig. Differences between loading levels were determined as a function of knee flexion for each kinematic parameter using linear hierarchical random-effects models. Quadratic and random slope terms were included in the models when significant. We found that the patellae flexed less with knee flexion at 30% BW load compared to 0% BW load (p<0.001) and 15% BW (p=0.004) load. The patellae showed a slight medial tilt with knee flexion at 30% BW load which was significantly less than the medial tilt seen at 0% BW load (p=0.017) and 15% BW load (p=0.043) with knee flexion. Small but statistically significant differences were also observed for proximal and anterior translation; the patellae were in a more proximal and posterior position at 30% BW load than at 0% BW load (p=0.010 and p=0.005, respectively) and 15% BW load (p<0.001 and p=0.029, respectively). Since differences in three-dimensional patellar kinematics were observed between loading levels, magnitudes of prescribed loads must be considered when designing studies and comparing results between studies.

    View details for DOI 10.1016/j.jbiomech.2010.03.027

    View details for Web of Science ID 000280313300007

    View details for PubMedID 20413124

  • A single measure of patellar kinematics is an inadequate surrogate marker for patterns of three-dimensional kinematics in healthy knees KNEE McWalter, E. J., MacIntyre, N. J., Cibere, J., Wilson, D. R. 2010; 17 (2): 135-140

    Abstract

    Patellofemoral disorders, such as osteoarthritis and patellofemoral pain, are thought to be associated with abnormal patellar kinematics. However, assessments of three-dimensional patellar kinematics are time consuming and expensive. The aim of this study was to determine whether a single static measure of three-dimensional patellar kinematics provides a surrogate marker for three-dimensional patellar kinematics over a range of flexion angles. We assessed three-dimensional patellar kinematics (flexion, tilt and spin; lateral, anterior and proximal translation) at sequential static angles through approximately 45 degrees of loaded knee flexion in 40 normal subjects using a validated, MRI-based method. The surrogate marker was defined as the static measure at 30 degrees of knee flexion and the pattern of kinematics was defined as the slope of the linear best fit line of each subject's kinematic data. A regression model was used to examine the relationship between the surrogate marker and pattern of kinematics. The surrogate marker predicted 26% of the variance in pattern of patellar flexion (p<0.001), 27% of the variance in pattern of patellar spin (p=0.003), 11% of the variance in pattern of proximal translation (p=0.037) and 39% of the variance in pattern of anterior translation (p<0.001). No relationships were seen between the surrogate marker and tilt or lateral translation. The results suggest that a single measure of patellar parameters at 30 degrees knee flexion is an inadequate surrogate marker of three-dimensional patellar kinematics; therefore, a complete assessment of patellar kinematics, over a range of knee flexion angles, is preferable to adequately assess patterns of patellar kinematics.

    View details for DOI 10.1016/j.knee.2009.08.001

    View details for Web of Science ID 000275263000008

    View details for PubMedID 19720534

  • The Measurement of Joint Mechanics and Their Role in Osteoarthritis Genesis and Progression MEDICAL CLINICS OF NORTH AMERICA Wilson, D. R., McWalter, E. J., Johnston, J. D. 2009; 93 (1): 67-?

    Abstract

    Mechanics play a role in the initiation, progression, and successful treatment of osteoarthritis. However, we don't yet know enough about which specific mechanical parameters are most important and what their impact is on the disease process to make comprehensive statements about how mechanics should be modified to prevent, slow, or arrest the disease process. The objectives of this review are (1) to summarize methods for assessing joint mechanics and their relative merits and limitations, (2) to describe current evidence for the role of mechanics in osteoarthritis initiation and progression, and (3) to describe some current treatment approaches that focus on modifying joint mechanics.

    View details for DOI 10.1016/j.mcna.2008.08.004

    View details for Web of Science ID 000262339100006

    View details for PubMedID 19059022

  • The measurement of joint mechanics and their role in osteoarthritis genesis and progression RHEUMATIC DISEASE CLINICS OF NORTH AMERICA Wilson, D. R., McWalter, E. J., Johnston, J. D. 2008; 34 (3): 605-?

    Abstract

    Justifying and improving mechanically based approaches to the treatment and prevention of osteoarthritis (OA) requires a critical understanding of the methods used to study joint mechanics and the current evidence for the role of mechanics in OA. The objectives of this article are (1) to summarize methods for assessing joint mechanics and their relative merits and limitations, (2) to describe the current evidence for the role of mechanics in OA initiation and progression, and (3) to describe some current treatment approaches that focus on modifying joint mechanics.

    View details for DOI 10.1016/j.rdc.2008.05.002

    View details for Web of Science ID 000258964700007

    View details for PubMedID 18687275

  • Relationship between varus-valgus alignment and patellar kinematics in individuals with knee osteoarthritis. journal of bone and joint surgery. American volume McWalter, E. J., Cibere, J., MacIntyre, N. J., Nicolaou, S., Schulzer, M., Wilson, D. R. 2007; 89 (12): 2723-2731

    Abstract

    Abnormal varus-valgus alignment is a risk factor for patellofemoral osteoarthritis, but tibiofemoral alignment alone does not explain compartmental patellofemoral osteoarthritis progression. Other mechanical factors, such as patellar kinematics, probably play a role in the initiation and progression of the disease. The objective of this study was to determine which three-dimensional patellar kinematic parameters (patellar flexion, spin, and tilt and patellar proximal, lateral, and anterior translation) are associated with varus and valgus alignment in subjects with osteoarthritis.Ten individuals with knee osteoarthritis and varus (five subjects) or valgus (five subjects) knee alignment underwent assessment of three-dimensional patellar kinematics. We used a validated magnetic resonance imaging-based method to measure three-dimensional patellar kinematics in knee flexion while the subjects pushed against a pedal with constant load (80 N). A linear random-effects model was used to test the null hypothesis that there was no difference in the relationship between tibiofemoral flexion and patellar kinematics between the varus and valgus groups.Patellar spin was significantly different between groups (p = 0.0096), with the varus group having 2 degrees of constant internal spin and the valgus group having 4.5 degrees of constant external spin. In the varus group, the patellae tracked with a constant medial tilt of 9.6 degrees with flexion, which was significantly different (p = 0.0056) from the increasing medial tilt (at a rate of 1.8 degrees per 10 degrees of increasing knee flexion) in the valgus group. The patellae of the valgus group were 7.5 degrees more extended (p = 0.0093) and positioned 8.8 mm more proximally (p = 0.0155) than the varus group through the range of flexion that was studied. The pattern of anterior translation differed between the groups (p = 0.0011).Our results suggest that authors of future large-scale studies of the relationships between knee mechanics and patellofemoral osteoarthritis should not rely solely on measurements of tibiofemoral alignment and should assess three-dimensional patellar kinematics directly.

    View details for PubMedID 18056505

  • Use of novel interactive input devices for segmentation of articular cartilage from magnetic resonance images OSTEOARTHRITIS AND CARTILAGE McWalter, E. J., Wirth, W., Siebert, M., von Eisenhart-Rothe, R. M., Hudelmaier, M., Wilson, D. R., Eckstein, F. 2005; 13 (1): 48-53

    Abstract

    To study the effect of new interactive computer input devices on cartilage segmentation in terms of time, consistency between input devices, and precision in quantitative magnetic resonance imaging (qMRI).We compared two new input devices, an interactive digitizing tablet and an interactive touch-sensitive screen, to a traditional mouse. Medial tibial and patellar cartilage of six healthy and six osteoarthritic knees were segmented using each input device. Cartilage volume, surface area and mean thickness were assessed using a validated algorithm and used to determine consistency and precision. Segmentation time was also measured.Segmenting with an interactive touch-sensitive screen reduced segmentation time by 15% when compared to the traditional mouse but we found no significant difference in segmentation time between the interactive digitizing tablet and the traditional mouse. We found no difference in consistency or precision of cartilage volume, mean thickness or surface area between the three input devices tested.We conclude that measurements of cartilage made using articular cartilage segmentation from MR images are independent of the input device chosen for user interaction.

    View details for DOI 10.1016/j.joca.2004.09.008

    View details for Web of Science ID 000226546700007

    View details for PubMedID 15639637

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