Quantitative assessment of pivot-shift using inertial sensors

Nicola Lopomo, Cecilia Signorelli, Tommaso Bonanzinga, Giulio Maria Marcheggiani Muccioli, Andrea Visani, Stefano Zaffagnini

Research output: Contribution to journalArticlepeer-review


Purpose: The pivot-shift phenomenon has been identified to be one of the essential signs of functional anterior cruciate ligament (ACL) insufficiency. However, the pivot-shift test remains a surgeon-subjective examination, lacking a general recognized quantitative measurement. The goal of the present study was to validate the use of an inertial sensor for quantifying the pivot-shift test, using a commercial navigation system. Methods: An expert surgeon intra-operatively performed the pivot-shift test on 15 consecutive patients before ACL reconstruction. A single accelerometer and a commercial navigation system simultaneously acquired limb kinematics. An additional optical tracker mounted on the accelerometer allowed following sensor movements. Anteroposterior (a-p) tibial acceleration obtained with the navigation system was compared with three-dimensional (3D) acceleration acquired by the accelerometer. The effect of skin artifacts and test-retest positioning were estimated. Repeatability of the acceleration parameter and waveform was analyzed. Correlation between the two measurements was also assessed. Results: Average root mean square (RMS) error in test-retest positioning reported a good value of 5.5 ± 2.9 mm. Mean RMS displacement due to soft tissue artifacts was 4.9 ± 2.6 mm. The analysis of acceleration range repetitions reported a good intra-tester repeatability (Cronbach's alpha = 0.86). Inter-patients similarity analysis showed a mean acceleration waveform correlation of 0.88 ± 0.14. The acceleration ranges demonstrated a good positive correlation between the two measurements (rs = 0.72, P <0.05). Conclusion: This study showed good reliability of the new device and good correlation with the navigation system results. Therefore, the accelerometer is a valid method to assess dynamic joint laxity. Level of evidence: II.

Original languageEnglish
Pages (from-to)713-717
Number of pages5
JournalKnee Surgery, Sports Traumatology, Arthroscopy
Issue number4
Publication statusPublished - Apr 2012


  • Acceleration
  • ACL
  • Knee kinematics
  • Navigation system
  • Pivot-shift

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Surgery


Dive into the research topics of 'Quantitative assessment of pivot-shift using inertial sensors'. Together they form a unique fingerprint.

Cite this