Evaluation of formal methods in hip joint center assessment: An in vitro analysis

Nicola Lopomo, Lei Sun, Stefano Zaffagnini, Giovanni Giordano, Marc R. Safran

Research output: Contribution to journalArticlepeer-review


Background: The hip joint center is a fundamental landmark in the identification of lower limb mechanical axis; errors in its location lead to substantial inaccuracies both in joint reconstruction and in gait analysis. Actually in Computer Aided Surgery functional non-invasive procedures have been tested in identifying this landmark, but an anatomical validation is scarcely discussed. Methods: A navigation system was used to acquire data on eight cadaveric hips. Pivoting functional maneuver and hip joint anatomy were analyzed. Two functional methods - both with and without using the pelvic tracker - were evaluated: specifically a sphere fit method and a transformation techniques. The positions of the estimated centers with respect to the anatomical center of the femoral head, the influence of this deviation on the kinematic assessment and on the identification of femoral mechanical axis were analyzed. Findings: We found that the implemented transformation technique was the most reliable estimation of hip joint center, introducing a - Mean (SD) - difference of 1.6 (2.7) mm from the anatomical center with the pelvic tracker, whereas sphere fit method without it demonstrated the lowest accuracy with 25.2 (18.9) mm of deviation. Otherwise both the methods reported similar accuracy (

Original languageEnglish
Pages (from-to)206-212
Number of pages7
JournalClinical Biomechanics
Issue number3
Publication statusPublished - Mar 2010


  • Error propagation
  • Femoral mechanical axis
  • Functional methods
  • Hip joint center
  • Kinematics
  • Navigation system

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Biophysics


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