Finite Element Modeling of the Proximal Humerus to Compare Stemless, Short and Standard Stem Humeral Components of Varying Material Stiffness for Shoulder Arthroplasty

In patients with debilitating pain due to osteoarthritis, total shoulder arthroplasty can restore function and provide effective pain relief. Newer implant designs vary in length and material stiffness. Unfortunately, literature on these newer implants is limited. This thesis investigates the effect of stem length and implant material stiffness on proximal humeral bone stresses. 3D bone models with implants of various stem lengths (stemless, short, and standard) and different material stiffness’s (CoCr, Ti and PEEK) were generated using MIMICS, Solidworks and ABAQUS for varying abduction angles (15°, 45° and 75°). Cortical and trabecular stresses were contrasted with the intact bone state. As expected, the reduction in stem length and material stiffness yielded humeral stresses that better matched the intact stress distribution in cortical bone, but opposing trends presented in trabecular bone. Future work should continue to build on these models and investigate implant fixation through the analysis of micromotion.

Keywords: Total shoulder arthroplasty; Humerus; Implant; Finite element modeling; Trabecular bone; Cortical bone; Hounsfield Unit; ABAQUS; MIMICS; SolidWorks; Arthritis; Young’s modulus; Identical mesh; Shoulder; Abduction angles

Year	Entry
1976	Cowin SC, Hegedus DH. Bone remodeling, I: theory of adaptive elasticity. J Elast. 1976;6(3):313-326.
2013	Willing RT, Lalone EA, Shannon H, Johnson JA, King GJW. Validation of a finite element model of the human elbow for determining cartilage contact mechanics. J Biomech. June 21, 2013;46(10):1767-1771.
1994	van der Helm FCT. A finite element musculoskeletal model of the shoulder mechanism. J Biomech. May 1994;27(5):551-569.
1994	Les CM, Keyak JH, Stover SM, Taylor KT, Kaneps AJ. Estimation of material properties in the equine metacarpus with use of quantitative computed tomography. J Orthop Res. November 1994;12(6):822-833.
1986	Wolff J. The Law of Bone Remodelling. Maquet P, Furlong R, trans. New York, NY: Springer; 1986.
1992	Huiskes R, Weinans H, Van Rietbergen B. The relationship between stress shielding and bone resorption around total hip stems and the effects of flexible materials. Clin Orthop Relat Res. January 1992;274:124-134.
2006	Taddei F, Cristofolini L, Martelli S, Gill HS, Viceconti M. Subject-specific finite element models of long bones: an in vitro evaluation of the overall accuracy. J Biomech. 2006;39(13):2457-2467.
1992	Cifuentes AO, Kalbag A. A performance study of tetrahedral and hexahedral elements in 3-D finite element structural analysis. Finite Elem Anal Des. 1992;12(3-4):313-318.
1987	Huiskes R, Weinans H, Grootenboer HJ, Dalstra M, Fudala B, Slooff TJ. Adaptive bone-remodeling theory applied to prosthetic-design analysis. J Biomech. 1987;20(11-12):1135-1150.
2006	Hadjidakis DJ, Androulakis II. Bone remodeling. Annals NY Acad Sci. December 2006;1092(1):385-396.
2003	Morgan EF, Bayraktar HH, Keaveny TM. Trabecular bone modulus–density relationships depend on anatomic site. J Biomech. July 2003;36(7):897-904.
1977	Carter DR, Hayes WC. The compressive behavior of bone as a two-phase porous structure. J Bone Joint Surg. 1977;59A(7):954-962.
1989	Carter DR, Orr TE, Fyhrie DP. Relationships between loading history and femoral cancellous bone architecture. J Biomech. 1989;22(3):231-244.
2007	Schileo E, Taddei F, Malandrino A, Cristofolini L, Viceconti M. Subject-specific finite element models can accurately predict strain levels in long bones. J Biomech. 2007;40(13):2982-2989.
1993	Rho JY, Ashman RB, Turner CH. Young's modulus of trabecular and cortical bone material: ultrasonic and microtensile measurements. J Biomech. February 1993;26(2):111-119.
1983	Huiskes R, Chao EYS. A survey of finite element analysis in orthopedic biomechanics: the first decade. J Biomech. 1983;16(6):385-409.
2005	Mow VC, Huiskes R, eds. Basic Orthopaedic Biomechanics & Mechano-Biology. 3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2005.
2006	Ramos A, Simões JA. Tetrahedral versus hexahedral finite elements in numerical modelling of the proximal femur. Med Eng Phys. November 2006;28(9):916.
1997	Prendergast PJ. Finite element models in tissue mechanics and orthopaedic implant design. Clin Biomech (Bristol, Avon). September 1997;12(6):343-366.

Year

Entry

1976

Cowin SC, Hegedus DH. Bone remodeling, I: theory of adaptive elasticity. J Elast. 1976;6(3):313-326.

2013

Willing RT, Lalone EA, Shannon H, Johnson JA, King GJW. Validation of a finite element model of the human elbow for determining cartilage contact mechanics. J Biomech. June 21, 2013;46(10):1767-1771.

1994

van der Helm FCT. A finite element musculoskeletal model of the shoulder mechanism. J Biomech. May 1994;27(5):551-569.

1994

Les CM, Keyak JH, Stover SM, Taylor KT, Kaneps AJ. Estimation of material properties in the equine metacarpus with use of quantitative computed tomography. J Orthop Res. November 1994;12(6):822-833.

1986

Wolff J. The Law of Bone Remodelling. Maquet P, Furlong R, trans. New York, NY: Springer; 1986.

1992

Huiskes R, Weinans H, Van Rietbergen B. The relationship between stress shielding and bone resorption around total hip stems and the effects of flexible materials. Clin Orthop Relat Res. January 1992;274:124-134.

2006

Taddei F, Cristofolini L, Martelli S, Gill HS, Viceconti M. Subject-specific finite element models of long bones: an in vitro evaluation of the overall accuracy. J Biomech. 2006;39(13):2457-2467.

1992

Cifuentes AO, Kalbag A. A performance study of tetrahedral and hexahedral elements in 3-D finite element structural analysis. Finite Elem Anal Des. 1992;12(3-4):313-318.

1987

Huiskes R, Weinans H, Grootenboer HJ, Dalstra M, Fudala B, Slooff TJ. Adaptive bone-remodeling theory applied to prosthetic-design analysis. J Biomech. 1987;20(11-12):1135-1150.

2006

Hadjidakis DJ, Androulakis II. Bone remodeling. Annals NY Acad Sci. December 2006;1092(1):385-396.

2003

Morgan EF, Bayraktar HH, Keaveny TM. Trabecular bone modulus–density relationships depend on anatomic site. J Biomech. July 2003;36(7):897-904.

1977

Carter DR, Hayes WC. The compressive behavior of bone as a two-phase porous structure. J Bone Joint Surg. 1977;59A(7):954-962.

1989

Carter DR, Orr TE, Fyhrie DP. Relationships between loading history and femoral cancellous bone architecture. J Biomech. 1989;22(3):231-244.

2007

Schileo E, Taddei F, Malandrino A, Cristofolini L, Viceconti M. Subject-specific finite element models can accurately predict strain levels in long bones. J Biomech. 2007;40(13):2982-2989.

1993

Rho JY, Ashman RB, Turner CH. Young's modulus of trabecular and cortical bone material: ultrasonic and microtensile measurements. J Biomech. February 1993;26(2):111-119.

1983

Huiskes R, Chao EYS. A survey of finite element analysis in orthopedic biomechanics: the first decade. J Biomech. 1983;16(6):385-409.

2005

Mow VC, Huiskes R, eds. Basic Orthopaedic Biomechanics & Mechano-Biology. 3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2005.

2006

Ramos A, Simões JA. Tetrahedral versus hexahedral finite elements in numerical modelling of the proximal femur. Med Eng Phys. November 2006;28(9):916.

1997

Prendergast PJ. Finite element models in tissue mechanics and orthopaedic implant design. Clin Biomech (Bristol, Avon). September 1997;12(6):343-366.

Year	Entry
2022	Soltanmohammadi P, Tavakoli A, Langohr GDG, Athwal GS, Willing R. Structural analysis of hollow versus solid-stemmed shoulder implants of proximal humeri with different bone qualities. J Orthop Res. March 2022;40(3):674-684.
2018	Synnott S. The Effect of Implant Girth and Implant Collar on the Degree of Bone to Implant Contact and Bone Stresses in the Proximal Humerus [Master's thesis]. University of Western Ontario; 2018.
2024	Cunningham D. An Analysis of Primary Stability of Stemless Humeral Implants in Shoulder Arthroplasty [PhD thesis]. University of Western Ontario; 2024.

Year

Entry

2022

Soltanmohammadi P, Tavakoli A, Langohr GDG, Athwal GS, Willing R. Structural analysis of hollow versus solid-stemmed shoulder implants of proximal humeri with different bone qualities. J Orthop Res. March 2022;40(3):674-684.

2018

Synnott S. The Effect of Implant Girth and Implant Collar on the Degree of Bone to Implant Contact and Bone Stresses in the Proximal Humerus [Master's thesis]. University of Western Ontario; 2018.

2024

Cunningham D. An Analysis of Primary Stability of Stemless Humeral Implants in Shoulder Arthroplasty [PhD thesis]. University of Western Ontario; 2024.