Effect of Knee Bracing on Knee Joint Contact Mechanics During Stair Descend

Transcription

1 Effect of Knee Bracing on Knee Joint Contact Mechanics During Stair Descend Lilly Tran, B.S. 1, Jim Tse 1, Kevin Chao 1, Rafael Minacori, M.S. 2, Yatin Kirane, MBBS, D.Orth, MS, PhD 3, Nikolai Steklov, M.S. 4, Shantanu Patil, MD 5, Benjamin J. Fregly, PhD 6, Darryl D. D'Lima, MD, PhD 5, Mark Lenhoff, B.S. 1, Sherry Backus, PT,DPT,MA 1, Andrew Kraszewski, M.S. 1, Andreas Kontaxis, PhD 1, Howard Hillstrom, PhD 1. 1 Hospital For Special Surgery, New York, NY, USA, 2 Institut Universitaire de Technologie, Besancon, France, 3 Hospital for Special Surgery, New York, NY, USA, 4 Scripps Clinic, La Jolla, CA, USA, 5 Scripps Heatlh, La Jolla, CA, USA, 6 University of Florida, Gainesville, FL, USA. Disclosures: L. Tran: None. J. Tse: None. K. Chao: None. R. Minacori: None. Y. Kirane: None. N. Steklov: None. S. Patil: None. B.J. Fregly: None. D.D. D'Lima: None. M. Lenhoff: None. S. Backus: None. A. Kraszewski: None. A. Kontaxis: None. H. Hillstrom: None. Introduction: Knee osteoarthritis (OA) occurs predominately at the medial compartment. Conservative therapies, such as valgus knee bracing, seek to reduce medial loading, however the direct effect of knee compartment loading has not been verified experimentally. In previous work, a decrease in medial compartment and compressive loading was measured by a total knee arthroplasty prosthesis (e-tibia) under 4º and 8 º valgus adjustments of two braces (MOS Genu and Genu Arthro) during walking, stair ascending and descending 3. There are no known studies that have collected simultaneous collection of knee compartment forces and 3D kinematic and kinetics with and without knee bracing. In our study we estimate and compare the changes in compressive medial and lateral compartment loading on the knee joint measured in vivo from the e-tibia and those calculated from 3D gait inverse dynamics for level walking, stair ascent, stair descent, and sit-to-stand. This abstract focuses on data from stair descent because knee OA patients deem this the most painful activity of daily living. We hypothesized that valgus bracing will be associated with significant reductions in joint reaction forces and adduction moments from the e-tibia and inverse dynamics calculations. Furthermore, we predict that the medial compartment forces (e-tibia) will decrease significantly in valgus braced conditions compared to the unbraced. Methods: Four different valgus braced conditions were chosen for this study: B1 (Ossur Unloader One: off-the-shelf), B2 (Bledsoe B12 OA: custom), B3 (Ossur Unloader One: off-the-shelf adjusted by an orthotist), and B4 (Ossur Unloader Select: custom brace with 4º valgus correction). Unbraced stair descent was used as the baseline condition. One sixty-nine year old female with an implanted e-tibia performed repeated stair descent trials on instrumented steps in a 3D motion capture volume. A standard lower extremity markerset was implemented. 12 e-tibia force transducers embedded in the tibial tray telemetered 6DOF load (three forces and three torques) data acting on the tibial tray surface to an external data acquisition unit. Synced with this unit was the 3D marker motion acquired with a 12-camera system (Motion Analysis Corp, Santa Rosa, CA) and two forces plates (AMTI, Watertown, MA) to which the stairs were attached. Knee kinetics were calculated using an inverse dynamics formulation available in Visual3D software (C-Motion Inc, Germantown, MD). A previously derived subject-specific regression to predict medial-lateral compartment loading from e-tibia data was used to estimate the medial and lateral knee compartment forces 1. Results: Generally, over the step cycle loading from the e-tibia was different in magnitude and pattern compared to inverse dynamics. E-tibia data gave a clearer stratification of the peak compressive forces, F z, and peak adduction moments, M y, compared to that calculated from inverse dynamics, (see Figure 2). For all braced and unbraced conditions, F z calculated from inverse dynamics was, on average, half of that of the forces measured by the e-tibia. There was a decrease in F z for all of the braced conditions when measured directly from the e-tibia. The greatest reductions in F z and M y occurred under brace condition B4, according to e-tibia results. All brace conditions, compared to unbraced, showed a reduction of medial and lateral knee compartment forces during stair descent, (see Table 1). Brace condition B4 showed the greatest reduction in medial and lateral compartment forces compared to unbraced, with a 13.3%, 9.4%, 8.7%, and 18.9% reduction for the first medial peak force, second medial peak force, first lateral peak force, and second lateral peak force, respectively, (see Table 1). Discussion: The results agreed with our hypothesis that valgus knee braces reduced the medial compartment forces in the knee. These results are in agreement with Kutzner, I. et al. The results also showed that compressive knee forces, medial compartment knee forces, and lateral compartment knee forces all decreased under valgus braced conditions compared to theunbraced condition. Significance: The fact that valgus knee braces reduce the load distribution on the medial knee compartment may be used by clinicians for lower extremity rehabilitation. The differences between e-tibia and inverse dynamic results may provide insight into the substantial amount of muscle forces that contribute to contact mechanics during gait and other activities of daily living. Acknowledgments: The authors thank the subject for her contribution to this study. References: 1. D Lima, D.D., et al Knee joint forces: prediction, measurement, and significance. Proc Inst Mech Eng H. 226(2):

2 2. D'Lima DD, Steklov N, Patil S, Colwell CW,Jr. The mark coventry award: In vivo knee forces during recreation and exercise after knee arthroplasty. Clin Orthop Relat Res. 2008;466(11): Kutzner, I., et al The effect of valgus braces on medial compartment load of the knee joint - in vivo load measurements in three subjects. J. Biomech. 44: Mundermann A, Dyrby CO, D'Lima DD, Colwell CW,Jr, Andriacchi TP. In vivo knee loading characteristics during activities of daily living as measured by an instrumented total knee replacement. J Orthop Res. 2008;26(9): Varadarajan KM, Moynihan AL, D'Lima D, Colwell CW, Li G. In vivo contact kinematics and contact forces of the knee after total kneearthroplasty during dynamic weight-bearing activities. J Biomech. 2008;41(10):

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4 ORS 2014 Annual Meeting Poster No: 1669

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