Non-invasive, non-radiological quantification of anteroposterior knee joint ligamentous laxity

D. F. Russell, A. H. Deakin, Q. A. Fogg, F. Picard

Research output: Contribution to journalArticleResearchpeer-review


Objectives: We performed in vitro validation of a non-invasive skin-mounted system that could allow quantification of anteroposterior (AP) laxity in the outpatient setting. Methods: A total of 12 cadaveric lower limbs were tested with a commercial image-free navigation system using trackers secured by bone screws. We then tested a non-invasive fabric-strap system. The lower limb was secured at 10° intervals from 0° to 60° of knee flexion and 100 N of force was applied perpendicular to the tibia. Acceptable coefficient of repeatability (CR) and limits of agreement (LOA) of 3 mm were set based on diagnostic criteria for anterior cruciate ligament (ACL) insufficiency. Results: Reliability and precision within the individual invasive and non-invasive systems was acceptable throughout the range of flexion tested (intra-class correlation coefficient 0.88, CR 1.6 mm). Agreement between the two systems was acceptable measuring AP laxity between full extension and 40° knee flexion (LOA 2.9 mm). Beyond 40° of flexion, agreement between the systems was unacceptable (LOA > 3 mm). Conclusions: These results indicate that from full knee extension to 40° flexion, non-invasive navigation-based quantification of AP tibial translation is as accurate as the standard validated commercial system, particularly in the clinically and functionally important range of 20° to 30° knee flexion. This could be useful in diagnosis and post-operative evaluation of ACL pathology.
Original languageEnglish
Pages (from-to)233-237
Number of pages5
JournalBone & Joint Research
Issue number11
Publication statusPublished - Nov 2013
Externally publishedYes


  • non-invasive
  • anterior cruciate ligament
  • cadaveric
  • precision
  • accuracy
  • in vitro
  • ACL
  • laxity

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