A Biomechanical Assessment of Young, Asymptomatic Individuals With Varus Knee Alignment: Can Gait Retraining be Beneficial?

Links

Abstract

It has previously been reported that individuals with varus knee alignment are at an increased risk for the development of medial knee osteoarthritis. In individuals with established medial knee osteoarthritis, varus knee alignment has been shown to be related to the knee external adduction moment (KEAM) during gait. This moment has been associated with medial compartment loading and disease progression. Preliminary data suggests that the knee external adduction moment is also increased in asymptomatic, varus knees. Therefore, reducing the knee external adduction moment in these individuals may reduce their risk for the development of knee OA later in life.

Three studies were undertaken studying young individuals with asymptomatic, varus knees. The purpose of the first study was to compare the gait mechanics of seventeen asymptomatic, varus-aligned individuals to those of asymptomatic, normally-aligned individuals. We hypothesized there would be group differences in frontal plane mechanics, but no differences in the sagittal plane data. The results largely supported our hypotheses, demonstrating group differences in the frontal plane of the knee and rearfoot. Notably, the knee external adduction moment was significantly higher in the varus-aligned individuals, and was similar in magnitude to that of symptomatic medial knee osteoarthritis. This finding suggests that high medial knee joint loads contribute to the increased risk of developing medial compartment disease in this population. The second study assessed static and dynamic measures of the lower extremity as predictors of the knee external adduction moment using correlation and hierarchical regression techniques. Tibial mechanical axis as measured by an inclinometer, and kinematic knee adduction angle during gait, were the strongest predictors. Rearfoot eversion was also a significant dynamic predictor. In the third study, the effectiveness of a gait retraining program aimed at reducing the knee external adduction moment was examined. In this study, varus-aligned individuals underwent a retraining program utilizing real-time visual feedback to improve dynamic knee alignment during gait. The knee adduction moment was reduced after systematic training, and also at a one month follow-up. The kinematics responsible for the reductions in the knee adduction moment were increased hip adduction and internal rotation, as well as decreased knee adduction.

These studies are the first investigation into the gait mechanics of individuals with asymptomatic, varus knees. The results suggest that varus knee structure is associated with altered movement patterns and increased dynamic knee joint loads. Also, we found that static and dynamic variables associated with frontal plane alignment relate well to the KEAM. Finally, we introduced a novel gait modification aimed at reducing the KEAM. If utilized, medial knee joint loading may be reduced, potentially lowering the risk for incident medial knee OA.

Cited Works (16)

Year	Entry
2000	Stagni R, Leardini A, Cappozzo A, Grazia Benedetti M, Cappello A. Effects of hip joint centre mislocation on gait analysis results. J Biomech. November 2000;33(11):1479-1487.
2000	DeVita P, Hortobagyi T. Age causes a redistribution of joint torques and powers during gait. J Appl Physiol. May 2000;88(5):1804-1811.
2008	Astephen JL, Deluzio KJ, Caldwell GE, Dunbar MJ. Biomechanical changes at the hip, knee, and ankle joints during gait are associated with knee osteoarthritis severity. J Orthop Res. March 2008;26(3):332-341.
2001	Sharma L, Song J, Felson DT, Cahue S, Shamiyeh E, Dunlop DD. The role of knee alignment in disease progression and functional decline in knee osteoarthritis. JAMA. July 11, 2001;286(2):188-195.
2000	Gelber AC, Hochberg MC, Mead LA, Wang N-Y, Wigley FM, Klag MJ. Joint injury in young adults and risk for subsequent knee and hip osteoarthritis. Ann Intern Med. September 5, 2000;133(5):321-328.
1998	Hurwitz DE, Sumner DR, Andriacchi TP, Sugar DA. Dynamic knee loads during gait predict proximal tibial bone distribution. J Biomech. May 1998;31(5):423-430.
2002	Baliunas AJ, Hurwitz DE, Ryals AB, Karrar A, Case JP, Block JA, Andriacchi TP. Increased knee joint loads during walking are present in subjects with knee osteoarthritis. Osteoarthritis Cartilage. July 2002;10(7):573-579.
2002	Miyazaki T, Wada M, Kawahara H, Sato M, Baba H, Shimada S. Dynamic load at baseline can predict radiographic disease progression in medial compartment knee osteoarthritis. Ann Rheum Dis. July 2002;61(6):617-622.
1983	Grood ES, Suntay WJ. A joint coordinate system for the clinical description of three-dimensional motions: application to the knee. J Biomech Eng. May 1983;105(2):136-144.
1999	Setton LA, Elliott D., Mow VC. Altered mechanics of cartilage with osteoarthritis: human osteoarthritis and an experimental model of joint degeneration. Osteoarthritis Cartilage. January 1999;7(1):2-14.
2007	Fregly BJ, Reinbolt JA, Rooney KL, Mitchell KH, Chmielewski TL. Design of patient-specific gait modifications for knee osteoarthritis rehabilitation. IEEE Trans Biomed Eng. September 2007;54(9):1687-1695.
1998	Sharma L, Hurwitz DE, Thonar EJ-MA, Sum JA, Lenz ME, Dunlop DD, Schnitzer TJ, Kirwan-Mellis G, Andriacchi TP. Knee adduction moment, serum hyaluronan level, and disease severity in medial tibiofemoral osteoarthritis. Arthritis Rheum. July 1998;41(7):1233-1240.
2001	Kaufman KR, Hughes C, Morrey BF, Morrey M, An K-N. Gait characteristics of patients with knee osteoarthritis. J Biomech. July 2001;34(7):907-915.
2002	Hurwitz DE, Ryals AB, Case JP, Block JA, Andriacchi TP. The knee adduction moment during gait in subjects with knee osteoarthritis is more closely correlated with static alignment than radiographic disease severity, toe out angle and pain. J Orthop Res. January 2002;20(1):101-107.
2007	Zhao D, Banks SA, Mitchell KH, D'Lima DD, Colwell CW Jr, Fregly BJ. Correlation between the knee adduction torque and medial contact force for a variety of gait patterns. J Orthop Res. June 2007;25(6):789-797.
2008	Zeni JA Jr, Richards JG, Higginson JS. Two simple methods for determining gait events during treadmill and overground walking using kinematic data. Gait Post. May 2008;27(4):710-714.