Evaluating the coupling between foot pronation and tibial internal rotation continuously using vector coding.
Level 4 - case-series / case-control
Case-control observational biomechanics study comparing runners with and without anterior knee pain.
PubMed 25386828 · doi:10.1123/jab.2014-0067
What was done
Researchers evaluated the coupling between foot eversion and tibial internal rotation (TIR) during stance phase in 36 runners: 19 with anterior knee pain (AKP) and 17 pain-free controls, also examining differences by sex. Kinematic coupling was evaluated using both a traditional discrete stance-phase range-of-motion ratio (Ev/TIR) and continuous vector coding.
What was found
Vector coding detected significant coupling differences between groups: runners with AKP demonstrated relatively greater TIR than eversion between 34% and 38% of the stance phase. Vector coding also identified sex differences between 14%-25% and 36%-47% of stance, where male runners transitioned coordination strategies proximal-to-distal while female runners transitioned distal-to-proximal. The traditional Ev/TIR ratio did not detect these coupling differences. Specific numerical kinematic values, effect sizes, and p-values were not reported in the abstract.
Why it matters
Continuous time-series analysis like vector coding can detect transient kinematic coordination abnormalities during stance that standard discrete summary ratios fail to capture, providing finer mechanistic insight into running-related injuries.
Limits
The sample size was modest (n = 36 total: 19 AKP, 17 controls). Because of the cross-sectional case-control design, it cannot establish whether altered coupling causes anterior knee pain or is a compensatory response to pain. Specific kinematic values, dispersion metrics, and running conditions were not detailed in the abstract.
Cited by
- supports When the foot arch collapses, the tibia undergoes torque in its relationship to the foot, transmitting ground reaction forces up through the ankle into the knee, hip, and back.