Contact mechanics of reverse engineered distal humeral hemiarthroplasty implants.
Erosion of articular cartilage is a concern following distal humeral hemiarthroplasty, because native cartilage surfaces are placed in contact with stiff metallic implant components, which causes decreases in contact area and increases in contact stresses. Recently, reverse engineered implants have been proposed which are intended to promote more natural contact mechanics by reproducing the native bone or cartilage shape. In this study, finite element modeling is used in order to calculate changes in cartilage contact areas and stresses following distal humeral hemiarthroplasty with commercially available and reverse engineered implant designs. At the ulna, decreases in contact area were -34±3% (p=0.002), -27±1% (p<0.001) and -14±2% (p=0.008) using commercially available, bone reverse engineered and cartilage reverse engineered designs, respectively. Peak contact stresses increased by 461±57% (p=0.008), 387±127% (p=0.229) and 165±16% (p=0.003). At the radius, decreases in contact area were -21±3% (p=0.013), -13±2% (p<0.006) and -6±1% (p=0.020), and peak contact stresses increased by 75±52% (p>0.999), 241±32% (p=0.010) and 61±10% (p=0.021). Between the three different implant designs, the cartilage reverse engineered design yielded the largest contact areas and lowest contact stresses, but was still unable to reproduce the contact mechanics of the native joint. These findings align with a growing body of evidence indicating that although reverse engineered hemiarthroplasty implants can provide small improvements in contact mechanics when compared with commercially available designs, further optimization of shape and material properties is required in order reproduce native joint contact mechanics.
Department of Mechanical Engineering, Thomas J. Watson School of Engineering and Applied Science, State University of New York at Binghamton, Binghamton, NY, USA; Bioengineering Research Laboratory, The Hand and Upper Limb Centre, St. Joseph Health Care London, London, Ontario, Canada. Electronic address: willing.ryan@gmail.com.
Ryan
R
Willing
Bioengineering Research Laboratory, The Hand and Upper Limb Centre, St. Joseph Health Care London, London, Ontario, Canada.
Graham J W
GJW
King
Bioengineering Research Laboratory, The Hand and Upper Limb Centre, St. Joseph Health Care London, London, Ontario, Canada.
James A
JA
Johnson
D000328:Adult; D000368:Aged; D002102:Cadaver; D002358:Cartilage, Articular / Q000000981:diagnostic imaging / Q000502:physiology*; D004551:Elbow Joint / Q000000981:diagnostic imaging / Q000502:physiology*; D058569:Elbow Prosthesis; D005260:Female; D020342:Finite Element Analysis; D062785:Hemiarthroplasty / Q000379:methods*; D006801:Humans; D006811:Humerus / Q000000981:diagnostic imaging / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D011884:Radius / Q000000981:diagnostic imaging / Q000502:physiology; D014057:Tomography, X-Ray Computed; D014457:Ulna / Q000000981:diagnostic imaging / Q000502:physiology; D055815:Young Adult
Cartilage stress; Contact mechanics; Distal humeral hemiarthroplasty; Elbow; Finite element analysis; Orthopedic surgery; Reverse engineered implants