Effect of random variation of input and various daily activities on wear in a hip joint simulator

Raine Viitala, Vesa Saikko*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

6 Citations (Scopus)
75 Downloads (Pure)


The ISO 14242-1 standard specifies fixed, simplified, sinusoidal motion and double-peak load cycles for wear testing of total hip prostheses. In order to make the wear simulation more realistic, random variation was added for the first time to the motion and load control signals of a hip joint simulator. For this purpose and for the simulation of various daily activities, computer-controlled, servo-electric drives were mounted on a biaxial hip simulator frame and successfully introduced. Random variation did not result in a statistically significant difference in the wear factor of large diameter VEXLPE liners compared with fixed sinusoidal waveforms. However, level walking according to biomechanical literature surprisingly resulted in a 134 per cent higher, and jogging in a 57 per cent lower wear factor compared with the fixed sinusoidal waveforms. These wear phenomena were likely to be caused by a variation in the lubrication conditions and frictional heating. Simplified motion waveforms may result in an underestimation of wear in walking.

Original languageEnglish
Article number109831
Number of pages7
JournalJournal of Biomechanics
Publication statusPublished - 9 Jun 2020
MoE publication typeA1 Journal article-refereed


  • Computer-controlled hip simulator
  • Extensively cross-linked UHMWPE
  • Orthopedic biomechanics
  • Servo-drive
  • Wear of artificial joints


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