Comparison of 2-dimensional measurement techniques for predicting knee angle and moment during a drop vertical jump

Ryan L. Mizner, Terese L. Chmielewski, John J. Toepke, Kari B. Tofte

Research output: Contribution to journalArticlepeer-review

74 Scopus citations


Objective: To determine the association of 2-dimensional (2D) video-based techniques and 3-dimensional (3D) motion analysis to assess potential knee injury risk factors during jump landing. Design: Observational study. Setting: Research laboratory. Participants: Thirty-six female athletes in cutting and pivoting sports. Assessment of Risk Factors: Athletes performed a drop vertical jump during which movement was recorded with a motion analysis system and a digital video camera positioned in the frontal plane. Main Outcome Measures: The 2D variables were the frontal plane projection angle (FPPA), the angle formed between thigh and leg, and the knee-to-ankle separation ratio, the distance between knee joints divided by the distance between ankles. The 3D variables were knee abduction angle and external abduction moment. All variables were assessed at peak knee flexion. Linear regression assessed the relationship between the 2D and 3D variables. In addition, intraclass correlation coefficients (ICC) determined rater reliability for the 2D variables and compared the 2D measurements made from digital video with the same measurements from the motion analysis. Results: The knee-to-ankle separation ratio accounted for a higher variance of 3D knee abduction angle (r2 = 0.350) and knee abduction moment (r2 = 0.394) when compared with the FPPA (r2 = 0.145, 0.254). The digital video measures had favorable rater reliability (ICC, 0.89-0.94) and were comparable with the motion analysis system (ICC, ≥0.92). Conclusions: When compared with the FPPA, the knee-to-ankle separation ratio had better association with previously cited knee injury risk factors in female athletes. The 2D measures have adequate consistency and validity to merit further clinical consideration in jump landing assessments.

Original languageEnglish
Pages (from-to)221-227
Number of pages7
JournalClinical Journal of Sport Medicine
Issue number3
StatePublished - May 2012


  • ACL injury prevention
  • Female athlete
  • Screening


Dive into the research topics of 'Comparison of 2-dimensional measurement techniques for predicting knee angle and moment during a drop vertical jump'. Together they form a unique fingerprint.

Cite this