The impact of hip implant alignment on muscle and joint loading during dynamic activities

Casey A. Myers, Peter J. Laz, Kevin B. Shelburne, Dana L. Judd, Daniel N. Huff, Joshua D. Winters, Jennifer E. Stevens-Lapsley, Paul J. Rullkoetter

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


Background: Component alignment is an important consideration in total hip arthroplasty. The impact of changes in alignment on muscle forces and joint contact forces during dynamic tasks are not well understood, and have the potential to influence surgical decision making. The objectives of this study were to assess the impact of femoral head/stem and cup component placement on hip muscle and joint contact forces during tasks of daily living and to identify which alignment parameters have the greatest impact on joint loading. Methods: Using a series of strength-calibrated, subject-specific musculoskeletal models of patients performing gait, sit-to-stand and step down tasks, component alignments were perturbed and joint contact and muscle forces evaluated. Findings: Based on the range of alignments reported clinically, variation in head/stem anteversion-retroversion had the largest impact of any degree of freedom throughout all three tasks; average contact forces 413.5 (319.1) N during gait, 262.7 (256.4) N during sit to stand, and 572.7 (228.1) N during the step down task. The sensitivity of contact force to anteversion-retroversion of the head/stem was 31.5 N/° for gait, which was similar in magnitude to anterior-posterior position of the cup (34.6 N/m for gait). Additionally, superior-inferior cup alignment resulted in 16.4 (4.9)° of variation in the direction of the hip joint contact force across the three tasks, with the most inferior cup placements moving the force vector towards the cup equator at the point of peak joint contact force. Interpretation: A quantitative understanding of the impact and potential tradeoffs when altering component alignment is valuable in supporting surgical decision making.

Original languageEnglish
Pages (from-to)93-100
Number of pages8
JournalClinical Biomechanics
StatePublished - Mar 2018

Bibliographical note

Funding Information:
This study was supported in part by DePuy Synthes Products, Inc. , the National Institute on Aging of the National Institutes of Health under Award Number T32AG000279 , and by NIH/NCATS Colorado CTSA Grant Number UL1 TR001082 . One or more of the authors (P.R., P.L.) has received funding from DePuy Synthes. One author (P.R.) is a consultant to DePuy Synthes.

Publisher Copyright:
© 2018 Elsevier Ltd


  • Hip arthroplasty
  • Implant alignment
  • Joint mechanics
  • Muscle force
  • Musculoskeletal modeling

ASJC Scopus subject areas

  • Biophysics
  • Orthopedics and Sports Medicine


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