The Effect of Body Mass Index on the Biomechanics Before and After Total Knee Arthroplasty

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Abstract

Osteoarthritis (OA) is prevalent, commonly affecting weight-bearing joints, such as the knee. In Canada, approximately 40% of Canadians aged 50 to 64 are diagnosed with OA, of which 38% experience knee pain. When conservative treatments do not help those with endstage knee OA, total knee arthroplasty (TKA) is an elective surgical option that can provide pain relief and improve knee function. Individuals living with obesity (Body Mass Index [BMI] > 30.0 kilogram/meter squared [kg/m²]) are at increased risk for developing knee OA compared to normal weight people, partly due to altered knee kinematics and kinetics. Approximately 7 million Canadians were living with obesity in the year 2013.

Quantitative gait analyses via three-dimensional (3D) motion capture have shown that individuals living with obesity or OA have altered knee kinematics and kinetics compared to those of normal weight or those without OA. However, there is a paucity of research on the effect of obesity and OA on knee biomechanics after TKA, particularly in individuals living with Class II obesity (BMI 35.0-39.99 kg/m²). Understanding the impact of BMI on knee kinematics and kinetics after TKA may inform surgical and rehabilitation protocols to improve individual outcomes.

The purpose of this prospective matched series was to evaluate the impact of obesity on time series and parameters of kinematics (angles of flexion-extension, abduction-adduction, internal-external rotation) and external kinetics (non-normalized and normalized moments to body weight of flexion-extension, abduction-adduction), and spatio-temporal parameters (velocity, cadence, stride length) at pre-TKA, post-TKA, and change from pre-to-post TKA, in 20 adults aged 50 to 70 years. Comparisons were made between 5 females/5 males with class II obesity (OB group) and 10 age- and sex-matched normal/overweight adults (BMI 18.5-29.9 kg/m² [N/OW group]) using 3D motion capture on level ground.

Participants received a 3D gait assessment within one-month before and 12-weeks after TKA. Optoelectronic motion capture and synchronized floor-embedded force platforms collected motion and forces during 10-meter walking at a self-selected speed. A hybrid biomechanical model was created, with inertial properties of body segments estimated via the participant’s body height and weight. The data were first screened and interpolated using Eva Real-Time Software and then processed using Visual3D.

To evaluate group differences in kinematic, kinetic and spatio-temporal parameters at pre- and post-TKA, a Wilcoxon rank-sum test was used to compare group medians and interquartile ranges. To evaluate changes over time from pre- to post-TKA between groups in kinematic, kinetic and spatio-temporal parameters, a two-way repeated measures analysis of variance was performed.

The mean BMI for the OB group was 37.1 kg/m² (standard deviation [SD] 1.79), and 27.0 kg/m² (SD 2.15) for the N/OW group (p=0.0005, 95%CI [29.4, 34.8]). Both groups were age and sex matched, with the OB group having mean age of 64.2 years (SD 6.04) with 5 females and 5 males, and the N/OW group having a mean age of 66.8 years (SD 2.86) with 5 females and 5 males. Twenty participants completed the preoperative gait assessment, with 17 (85%) participants (8OB, 9N/OW) completing post-TKA assessment.

At pre-TKA, the OB group had greater maximum flexion angle during swing phase (p=0.05) and greater non-normalized extension moment during swing phase (p=0.03) compared to the N/OW group. At post-TKA, the OB group had greater maximum adduction angle during stance (p<0.001), greater maximum non-normalized moment in adduction (p<0.001), greater minimum flexion non-normalized moment during stance phase (p=0.01), and greater maximum extension non-normalized moment during swing phase (p<0.001), compared to the N/OW group. From pre- to post-TKA, the OB group increased in adduction angle whereas the N/OW group decreased in adduction angle (p=0.02) and the OB group decreased in extension non-normalized moment whereas the N/OW group increased in extension non-normalized moment (p=0.02) during swing. The groups did not differ in any spatio-temporal parameters either pre- or postTKA.

While future work is warranted, this thesis contributes to the knowledge of the impact of obesity on the knee time series and parameters of kinematics and kinetics, and spatio-temporal parameters of level walking in adults undergoing TKA. Exploring this relationship can further our understanding of how these factors interact and may allow us to individualize rehabilitation approaches to address modifiable gait differences or to accommodate differing recovery trajectories to improve patient outcomes.

Cited Works (17)

Year	Entry
2006	Andriacchi TP, Mündermann A. The role of ambulatory mechanics in the initiation and progression of knee osteoarthritis. Curr Opin Rhuematol. September 2006;18(5):514-518.
1969	Clauser CE, McConville JT, Young JW. Weight, Volume, and Center of Mass of Segments of the Human Body. Wright-Patterson AFB, Ohio: Aerospace Medical Research Laboratory; August 1969. Report No. AFRL-TR-69-70.
1996	Piazza SJ, Delp SL. The influence of muscles on knee flexion during the swing phase of gait. J Biomech. June 1996;29(6):723-733.
2009	Andriacchi TP, Koo S, Scanlan SF. Gait mechanics influence healthy cartilage morphology and osteoarthritis of the knee. J Bone Joint Surg. February 2009;91A(suppl 1):95-101.
1995	Cappozzo A, Catani F, Della Croce U, Leardini A. Position and orientation in space of bones during movement: anatomical frame definition and determination. Clin Biomech (Bristol, Avon). June 1995;10(4):171-178.
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.
1990	Kadaba MP, Ramakrishnan HK, Wootten ME. Measurement of lower extremity kinematics during level walking. J Orthop Res. May 1990;8(3):383-392.
2006	Hootman JM, Helmick CG. Projections of US prevalence of arthritis and associated activity limitations. Arthritis Rheum. January 2006;54(1):226-229.
2007	Kurtz S, Ong K, Lau E, Mowat F, Halpern M. Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. J Bone Joint Surg. April 2007;89A(4):780-785.
1991	Davis RB III, Õunpuu S, Tyburski D, Gage JR. A gait analysis data collection and reduction technique. Hum Mov Sci. October 1991;10(5):575-587.
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.
2004	Andriacchi TP, Mündermann A, Smith RL, Alexander EJ, Dyrby CO, Koo S. A framework for the in vivo pathomechanics of osteoarthritis at the knee. Ann Biomed Eng. March 2004;32(3):447-457.
2006	Benoit DL, Ramsey DK, Lamontagne M, Xu L, Wretenberg P, Renström P. Effect of skin movement artifact on knee kinematics during gait and cutting motions measured in vivo. Gait Post. October 2006;24(2):152-164.
2007	Deluzio KJ, Astephen JL. Biomechanical features of gait waveform data associated with knee osteoarthritis: an application of principal component analysis. Gait Post. January 2007;25(1):86-93.
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.
2000	Felson DT, Lawrence RC, Dieppe PA, Hirsch R, Helmick CG, Jordan JM, Kington RS, Lane NE, Nevitt MC, Zhang Y, Sowers M, McAlindon T, Spector TD, Poole AR, Yanovski SZ, Ateshian G, Sharma L, Buckwalter JA, Brandt KD, Fries JF. Osteoarthritis: new insights, I: the disease and its risk factors. Ann Intern Med. October 17, 2000;133(8):635-646.
1997	Reinschmidt C, van den Bogert A, Nigg B, Lundberg A, Murphy N. Effect of skin movement on the analysis of skeletal knee joint motion during running. J Biomech. July 1997;30(7):729-732.