Analysis of Stress and load Distribution on Hip and Knee Joint after Unilateral Total Hip Arthroplasty

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1 Analysis of Stress and load Distribution on Hip and Knee Joint after Unilateral Total Hip Arthroplasty Yuan-Zhu Xin 1,Ki-Jung Kim 1, Seok-Jo Yang 1,1, 1 Chungnam National University, Daejeon, Korea, sjyang@cnu.ac.kr Abstract. Total hip arthroplasty (THA) is a highly successful operation for treatment of osteoarthritis (OA) that can improve mechanical function and condition in the hip joint. Clinical studies have reported that hip and knee OA often occurs on contralateral (non-implanted) side after unilateral THA. Purpose of this study was to analyze and verify the clinical test data result by utilizing 3-demensional (3D) static finite element method (FEM). Various material properties of THR implants were used to perform the analysis to show difference in force reaction and stress distribution in lower extremities. Results from this study suggest that both local and systemic stress-shielding occur on lower extremities. It demonstrates that the force reaction with unilateral THA surgery is carried more in ipsilateral side (implanted side) than contralateral side, while the maximum stress value was higher on contralateral side of femoral condyles than ipsilateral side. Keywords: Total Hip Arthroplasty(THA), Finite Element Method(FEM), Osteaarthritis(OA) 1 Introduction Total hip arthroplasty is a common surgical procedure for the treatment of hip osteoarthritis[1]. THA is highly successful operation performed hundreds of thousands of times worldwide each year and it provides patients with complete pain relief and improved hip functions[2]. However, recent studies have reported progression of hip OA might be related to the progression of knee OA[3]. Study done by Shakoor et al. reported that among patients whose initial THA was followed by total knee arthroplasty (TKA), 71% underwent TKA on the contralateral side[4]. Study also demonstrated that using gait analysis, medial compartment load of the knee was significantly higher in the contralateral knee compared to the treated side at 1-2 years after successful unilateral THA[5]. Another study done by Umeda et al. performed radiographic evaluation of the knee OA after THA. They reported that 33% of test subject showed progression of medial tibiofemoral OA on the contralateral side, while only 10% showed progression on the THA side[3]. The resistance to OA progression on the ipsilateral side may be caused by the lower offset and resultant lateral shift in mechanical axes[3]. Purpose of this study is to analyze and verify the clinical test result by utilizing 3- dimensional (3D) static finite element method. 3D model of lower extremity IST 2013, ASTL Vol. 23, pp , 2013 SERSC

Proceedings, The 2nd International Conference on Information Science and Technology including iliac crest, sacrum, femur, and tibia is created.

lower extremities of a man 47 years old and 176 cm tall was generated from computed tomography (CT) scans provided by Korea Institute of Science and Technology Information (KISTI).

2 Proceedings, The 2nd International Conference on Information Science and Technology including iliac crest, sacrum, femur, and tibia is created. Static loading is placed on the top of sacrum to determine the resultant stress and load distribution at the knee joint 2 Material and Methods Subject specific 3-dimensional finite element model of lower extremities of a man 47 years old and 176 cm tall was generated from computed tomography (CT) scans provided by Korea Institute of Science and Technology Information (KISTI). Left femur was chosen to be implanted with cobalt chrome alloy (Co-Cr) stem and head, UHMWPE acetabular cup as shown in Figure 1. The stem and acetabular cup models were created with commercial software Pro Engineer using the specifications form previous studies [6,7]. Final model consisting bone, implant and acetabular cup consisted of 79,965 nodes and 42,575elements. ANSYS 13.0 was used for this study. Boundary conditions were set to assume the static and stand still position. Proximal part of tibia was set as the fixed support and some surfaces where are anatomically attached by muscles such as adductor brevis, adductor longus, and cracilis were set to have zero rotation in all axes, permitting translation to all 3 axes. Nachemson performed in-vivo measurement on lumbar 3 of 70kg male and reported that the approximate axial load on the L3 is 500N in standing at ease case[8]. Therefore, the loading force of 500 N is applied on sacrum as shown in Fig 1. Two material constants (elastic modulus and poisson s ratio) for typical implant materials were obtained from other literatures and some material properties (as denoted by N###) are arbitrarily created to see the effect of modulus on stress distribution as shown in Fig. 1[9-11]. Fig 1. 3D Finite Element Model and Material Property Used 3 Results Simulation result showed that when Co-Cr implant was used, force reaction in ipsilateral(implanted) side was 269N and contrateral(nonimplanted) side was 233N as 236

3 Analysis of Stress and load Distribution on Hip and Knee Joint after Unilateral Total Hip Arthroplasty shown in Fig. 2. Total force reaction was 15% higher in ipsilateral side compared to the contrateral side. As elastic modulus increased, force reaction increased on the ipsilateral side and decreased on the contralateral side. Interestingly, the result showed that higher stress concentration occurred on the contralateral femoral head and condyles. Maximum equivalent stress value (von Mises) was higher for the model with Co-Cr implant when compared to the intact model (w/o implant). As elastic modulus increased, maximum stress on the contralateral head also increased whereas stress on contralateral femoral condyles decreased as shown in Fig. 3. Fig 2. Force Reaction of knee joint and Max Stress of Femoral Head Increased %(Compared to Intact Model) A B Fig 3. A: Max Stress of Femoral Condyles B: Max Stress Occuring on Medical Position 237

4 Proceedings, The 2nd International Conference on Information Science and Technology 4 Discussions Shakoor et al. demonstrated that the OA evolves nonrandomly; after the joint is unilaterally replaced, the contralateral limb was significantly more likely to show progression of OA than is the ipsilateral limb[4]. Natural load distribution on the femur is altered after the THA and the implant will carry a higher portion of the load, which is termed as stress shielding[12]. Finite element analysis result showed that load distribution on the ipsilateral side of Co-Cr hip implant was higher than contrateral side by 15%. Also, the contralateral side of Co-Cr hip implant had 8% lower force reaction compared to intact model. However, maximum stress of contralateral femoral head showed increase of 9% and contralateral femoral condyles showed increase of 20% with Co-Cr. This is due to the fact that flexibility tends to be higher on the contralateral side since the elastic modulus of cortical bone is much lower than that of cobalt chrome alloy. This stress distribution rather than load shielding may be related to OA on hip and knee joint. Yoshida et al. reported that anomalous mechanical stress was main cause of progressing OA[13]. Max stress also occurred on the medial part of contralateral side (Fig 4), which showed a strong tendency to clinical OA occurrence[4]. Simulation result showed that as elastic modulus increased, maximum stress on contralateral femoral condyles decreased. Force reaction on knee joint showed similar pattern by decreasing as the elastic modulus decreased on contralateral side. This is caused by the rigidity material and difference in force flow. Since the femoral condyle is further away from the implant position, force reaction seems to be the main cause of this phenomenon. Acknowledgments. This work was supported by research fund of Chungnam National University References 1. Bell CG. A finite element and experimental investigation of the femoral component mechanics in a total hip arthroplasty, Queensland University of Technology; Dopico-González C, New AM, Browne M. Probabilistic analysis of an uncemented total hip replacement. Medical Engineering & Physics. 2009;31(4): Umeda N, Miki H, Nishii T, Yoshikawa H, Sugano N. Progression of osteoarthritis of the knee after unilateral total hip arthroplasty: minimum 10-year follow-up study. Arch Orthop Trauma Surg. Feb 2009;129(2):

5 Analysis of Stress and load Distribution on Hip and Knee Joint after Unilateral Total Hip Arthroplasty 4. Shakoor N, Block JA, Shott S, Case JP. Nonrandom evolution of end-stage osteoarthritis of the lower limbs. Arthritis Rheum. Dec 2002;46(12): Shakoor N, Hurwitz DE, Block JA, Shott S, Case JP. Asymmetric knee loading in advanced unilateral hip osteoarthritis. Arthritis Rheum. Jun 2003;48(6): Griza S, Zanon G, Silva EP, Bertoni F, Reguly A, Strohaecker TR. Design aspects involved in a cemented THA stem failure case. Engineering Failure Analysis. 2009;16(1): Korhonen RK, Koistinen A, Konttinen YT, Santavirta SS, Lappalainen R. The effect of geometry and abduction angle on the stresses in cemented UHMWPE acetabular cups--finite element simulations and experimental tests. Biomed Eng Online. 2005;4(1): Nachemson AL. Disc pressure measurements. Spine (Phila Pa 1976). Jan-Feb 1981;6(1): Watanabe Y, Shiba N, Matsuo S, Higuchi F, Tagawa Y, Inoue A. Biomechanical study of the resurfacing hip arthroplasty: Finite element analysis of the femoral component. The Journal of Arthroplasty. 2000;15(4): Yao J, Salo AD, Lee J, Lerner AL. Sensitivity of tibio-menisco-femoral joint contact behavior to variations in knee kinematics. Journal of Biomechanics. 2008;41(2): Bevill SL, Bevill GR, Penmetsa JR, Petrella AJ, Rullkoetter PJ. Finite element simulation of early creep and wear in total hip arthroplasty. Journal of Biomechanics. 2005;38(12): Hnat WP, Conway JS, Malkani AL, Yakkanti MR, Voor MJ. The Effect of Modular Tapered Fluted Stems on Proximal Stress Shielding in The Human Femur. The Journal of Arthroplasty. 2009;24(6): Yoshida H, Faust A, Wilckens J, Kitagawa M, Fetto J, Chao EY. Threedimensional dynamic hip contact area and pressure distribution during activities of daily living. J Biomech. 2006;39(11):

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[ICESTM-2018] ISSN Impact Factor GLOBAL JOURNAL OF ENGINEERING SCIENCE AND RESEARCHES MODELING AND FINITE ELEMENT ANALYSIS OF KNEE JOINT PROSTHESIS U.D.S.Prathap varma *1,S.Rajesh 2, B.Suresh Kumar 3 & P.Rama Murthy Raju 4 *1 M.TechScholar,