Device to measure intra-operatively the primary stability of cementless hip stems

L. Cristofolini, E. Varini, I. Pelgreffi, A. Cappello, A. Toni

Research output: Contribution to journalArticlepeer-review


The primary stability of cementless prostheses is critical for the long-term outcome of the operation. Surgeons are currently driven only by their experience in evaluating the extent of stem stability achieved. The aim of the present work was to develop a new device that enables the stability of a cementless stem to be quantitatively assessed intraoperatively. The angle of the stem/femur rotation under torsion and the torque are acquired and compared in real-time to a pre-set threshold inferred from the literature. The device indicates whether the stem is stable or not. It was extensively tested and finally validated in vitro on cadaveric and composite femurs hosting different sizes of the same kind of prostheses, implanted with different levels of press-fitting. The overall accuracy (23%) takes into account not only the overall measurement error but also the variability due to differences in bone quality and stem press-fitting. This error was deemed sufficient to discriminate between stable and unstable implants.

Original languageEnglish
Pages (from-to)475-482
Number of pages8
JournalMedical Engineering and Physics
Issue number5
Publication statusPublished - Jun 2006


  • Cementless prosthesis
  • Hip
  • Intraoperative measurement
  • Micromotion
  • Primary stability

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Psychology(all)


Dive into the research topics of 'Device to measure intra-operatively the primary stability of cementless hip stems'. Together they form a unique fingerprint.

Cite this