Increased Q-factor increases medial compartment knee joint contact force during cycling

Area of Science:

• Biomechanics
• Sports Science
• Orthopedics

Background:

• Knee abduction moment (KAbM) increases with wider Q-factor (inter-pedal distance) during cycling.
• The relationship between increased KAbM and medial compartment knee joint contact force (MCF) in cycling is not well understood.
• Musculoskeletal modeling offers a non-invasive method to estimate knee joint contact forces.

Purpose of the Study:

• To determine the effect of increasing Q-factor on total knee contact force (TCF) and MCF during cycling.
• To assess if KAbM and knee extension moments can predict MCF during cycling.

Main Methods:

• Musculoskeletal simulations were employed to estimate TCF and MCF.
• Sixteen participants cycled at two QF conditions (150 mm and 276 mm) at 80 W and 80 rpm.
• Paired samples t-tests and regression analyses were used for statistical evaluation.

Main Results:

• Medial compartment knee contact force (MCF) significantly increased with a wider Q-factor (276 mm).
• Total knee contact force (TCF) and peak knee extensor muscle force did not change significantly.
• Peak knee flexor muscle force was significantly reduced with the wider Q-factor.
• KAbM and knee extension moments, along with QF, explained 87.4% of the variance in MCF.

Conclusions:

• Increasing Q-factor in cycling leads to higher medial compartment knee joint loading.
• This increase in MCF may result from a greater frontal-plane pedal reaction force moment arm.
• Q-factor modulation could be beneficial in cycling-based rehabilitation or training for managing medial knee joint load.