title: Relative importance of gait vs. joint positioning on hip contact forces after total hip replacement.
abstract: Implant loosening is a common indication for total hip replacement (THR) revision. High contact forces and implant twisting moments are thought to be associated with implant loosening. Relationships between joint positioning and hip forces, or outcomes, have been investigated through in vivo and in vitro modalities. Relationships between hip forces and gait are less understood, despite repeated findings that gait following a THR does not fully return to normal. We tested the hypothesis that gait parameters would be better predictors of implant force (peak contact forces and peak twisting moment during walking) than joint positioning parameters. Subjects underwent gait analysis, hip force modeling, and measurement of clinical radiographs 1 year after successful THR surgery. Gait parameters were consistently more influential in determining hip forces. Alone, gait explained as much as 67% of the variation in force, compared to a maximum of 33% by joint geometry. Combinations of gait and joint positioning parameters together explained up to 86% of the variation in hip force parameters. Results suggest that gait may provide a valuable postoperatively modifiable target to improve hip loads and potentially reduce the risk for implant loosening.
authors.affiliation: Department of Orthopedic Surgery, Rush University Medical Center, 1653 W. Congress Parkway, Chicago, Illinois 60612, USA. kharma_c_foucher@rush.edu
authors.forename: Kharma C
authors.initials: KC
authors.lastname: Foucher
authors.forename: Debra E
authors.initials: DE
authors.lastname: Hurwitz
authors.forename: Markus A
authors.initials: MA
authors.lastname: Wimmer
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation / Q000534:rehabilitation*; D001696:Biomechanical Phenomena / Q000502:physiology; D019544:Equipment Failure Analysis; D005260:Female; D005684:Gait / Q000502:physiology*; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000502:physiology*; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D015207:Osteoarthritis, Hip / Q000150:complications / Q000503:physiopathology / Q000601:surgery*; D010146:Pain / Q000209:etiology / Q000503:physiopathology; D011446:Prospective Studies; D011475:Prosthesis Failure; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology; D013314:Stress, Mechanical; D016474:Weight-Bearing